781 vs 990 heads. Aug 13, 2020 · Hello all.

781 vs 990 heads 5 to 1 cr and thats going to kill me, would i not be better off to have the extra compression since the flow at lower rpm is basically the same? Thanks for any help guys. Heck, GM put similar square ports on 396's so they should work fine on a well prepped 496. With the 882 heads it got 16 and ran 85 in the quarter, both before and after replacement. I'd use whichever ones that fell to hand, or if you're going to have them completely done over, do the worst set and keep the better set for another project that might not need "the works" unless one set has much worse valve seat recession than the other set. The date code is irrelevant unless you’re really trying to re-create a piece that matches some original documents and sales dates. Heads and cam are where you want Torque monster on the 049 or 781 heads will require some work. But if you plan on shifting it at 7000 plus than the 990 head is pretty good. They did a test on a 600 hp bbc 454 and the Summit head made like 50 hp and 30 tq out of the box over a big port (power everywhere not just peak), open chamber head the best gm had to offer back in 1971. But as other's have stated already, the heads that I have will suit my needs. 5:1 compression. Right now with flat top pistons you are you are close with that 9 to 1. car in the 11's or low 12's without porting. Port shape, chamber design, and valve size […] Nov 22, 2007 · 990 heads are too large in port volume for a 468ci motor. May 30, 2006 · Keep the heads, swap the pistons for ones with a small dome. They will be the best alternative IMO for a heavy street car. Oct 2, 2008 · Dart Machinery 353 Oliver Street Troy MI 48084 248-362-1188 www. Jan 18, 2007 · but i never got tired of the compression ratio, and i spun those closed chambered heads past 7000 rpms with 2. Don't forget about a little squirt squirt with a 100 hp NOS shot. 73gears. Cast-iron high-performance rectangular port “990” head with open 118-cc combustion chambers. Nov 27, 2006 · what is the biggest lift on large port oval 781 heads. 825 on intake valves. He also had a classic SY1 (smokey yunick cross-ram) intake. Heads had 2. Install larger vlaves (2. 06 intake and 1. Both heads can feed a 600 + hp bbc 55 Chevy Field car Jan 23, 2011 · One of my 990 rectangle ports cracked. Jan 29, 2016 · The use of . Carefully trim a piece to EXACTLY fit one head; insert it into the same port in the other. torque. 748 roller and made 740 some horsepower at 7500 and on spray made 1000. That leads to fuel dropping out and other issues. 88 will work fine. 045" and then order a set of forged pistons to get the CR up to at least 9. Jan 15, 2008 · supposedly the #781's cured or fixed exhaust seat cracking problems across the valve seat and short turn curve on the #049's what i heard seems to bear out because i've see a bunch more #049's cracked in that area -than- the #781's. #1 Brodix Race Rite -2plus(312cc) heads bare and use all the parts from the 990 heads. Weiand lists the Action + as being for peanut port heads with a max RPM of 5000. 060 over 10. GM Cast Iron 188 Heads, which are the same as 990's. Yes these were fairly rare from the factory. I can pick the heads up for a pretty good deal if you think it would be worth the swap. ; 750 Holley vacuum carb. If it was my money I would run the 781's. Just run it like it is until the 454 is ready. Aug 17, 2005 · i have a chance to buy a set of these cast iron heads. 990s bad heads for a 427. The oval ports would be with the larger 2. 19 / 1. Jan 21, 2016 · The 781 heads are the best cast iron large oval port heads GM ever produced for the big block Chevy engine. On your motor those heads will support up to 7000 rpm. They are worth rebuilding and respond well to pocket porting, bowl blending and larger valves. 40s all day Dec 11, 2011 · My wifes 77 L-82 vette had them. 880 combos and make 700+ HP on 468's CID and upwards i've Ported a few pairs of #781's all-out, its a lot of work, but you can get into the 800+ HP range on 496cid upwards and with 2. I just did a swap on a 427 and went from a weiand dule plane intake and a set of 781's to a set of 308 iron eagles and a dart single plane intake. 3300 pounds weekend street strip toy. Box 1347 Mena AR 71953 479-394-1075 www. 5/1 pistons. 1 454 O intake 644/644 reed cam, glide steel O port 990 heads off my Dulley no major work in heads just big valves car runs 5. Jul 27, 2022 · The GMPP head (PN 12363400) with 300-cc rectangular intake ports (left) performs very similarly to the oval port head (PN 12363392) with 290-cc intake ports (right), if both have the same compression ratios. _____ Mar 10, 2021 · As I was told the 188 is a replacement for a 990 head that was the head on a lot of over the counter LS7's. 19 and 1. It had a 253/261@. Nov 1, 2013 · Ive been pushing this Comp Nostalgia LS6 hyd. 040" head gasket and a 0. 5 to 1 for low octane fuel and 10. A interference fit of . Make it a condition of the sale that it pass magnafluxing. 00 to open up the spring pockets for the new valve springs. 42s Mar 21, 2007 · I have a couple sets of 781's and 1 set of 049's. Simple port templates made from . "Which head flows better" is academia, not pertainent to the street/low budget arena and mild camsall we're talking here is brute force and ignorance. cam and stock rocker arms May 25, 2010 · Well my issue is this, I've got a pair of 049 heads but one is cracked in two places. Bad. I really don't know if the ports are that much different. The port size on these is perfect for a NA 468. Put some more duration in that 496 and those heads will pull a lot harder. 050 to 9500 rpms. Nov 22, 2010 · while its true that the low rpm torque does tend to be reduced with stock oval port heads vs stock rectangular port heads ,its also true that the compression, intake manifold, cam timing,rear gearing and header designs all change the results and its very easy to build a rectangular port engine that destroys tires, and theres a huge range in The factory heads had worn guides and seats, so valves with an oversize stem and 0. I am using a set of factory 781 oval port heads. flat tappet cam 240/246 @ . Jun 17, 2009 · Friends pump gas 502 camaro(3250lbs) went 10. 300 intakes will shroud the valves considerably. 06's and 1. It's about cross section,velocity profiles and a bunch more that the big head guys can explain that makes the heads perform way better. we put together a 454 years ago. I dont think a roller is going to make that much differance in the ramp rates that it will cure this problem,I think Apr 6, 2012 · I'm putting together a 496 for my brother with some 990's-2. Oct 11, 2007 · On a other note,there were the big 990 rectangular port heads too! I have never seen a 990 casting before and was very suprised. Open or closed chambers were available with soft or hard valve seats. 005" is all that is needed . This Cylinder Head has a core charge of $50. the 990 heads are the best flowing heads for the big block chevy. If you are around town driving and staying below 6500 rpm max, I think a good 781 casting head would do great. Jun 11, 2014 · On the plus side, for the budget conscious, there are still great iron cylinder head castings available from the aftermarket—all the latest technology in port design applied to fancy aftermarket Apr 18, 2009 · The car should run pretty good. Apr 11, 2022 · i'll Post 2 more BBC #781 Head Engines that were Dyno tested on Pump Gas with Low Compression Ratios 1]= on 9. GOOD! ( liked my 049s better as cores, but their former marine use FUBARd up the passages too much) Feb 23, 2008 · 454 + . 89@102mph 1/8 mile 6-24 L-29 461 BBC 11. 00 in the engine. but not many dyno results or cars that have 1/4 mile times. 868 Exh=3. The 781's I have been quoted 250. Looks like they have been machined for larger valves possibly, but am not certain. 5 to 1 home ported 781 heads 2. I`ve actually experienced a 454 with these 990 heads and the car was yanking the front tires on a G60 McCreary dirt tire so I`d say there is plenty of power to Jan 1, 2021 · Get the die grinder out and let's go ape shit. 250" to . I've never seen one either and it was in good shape and unmolested also. 880 or 2. I think that would be limiting your engine and not making the best use of the heads and cam you do have. 90 to 10. Dec 23, 2007 · Just a little different comb. Sometimes it helps to check TWICE, clay is CHEAP Feb 27, 2017 · 4. The oval port head has 110-cc chambers, and the rectangular port head comes with 118-cc chambers. I was thinking of trying a set of 781 or 049 oval ports. I have ordered a set of Comp 930 springs. Vortec 062's 406 w/hyd. With a set of 2. The only down side to the 781's is of course the weight of the cast iron compared to the aluminum. Jan 4, 2011 · That dome will work with those 990's FWIW,Car Craft recently tested a 454 with a mild Comp XE268 w/ stock peanut port heads and it made 450+ HP and 542 ft/lbs. Most people seemed to think they would be a major restriction without alot of porting($$$). Couldn't really find much on stan weiss's site and mortec just listed the 781's with 118cc chamber, 256/114cc ports and the 049's with 122cc chamber, 255/119cc ports. 575 Jan 15, 2008 · supposedly the #781's cured or fixed exhaust seat cracking problems across the valve seat and short turn curve on the #049's what i heard seems to bear out because i've see a bunch more #049's cracked in that area -than- the #781's. 88) with some bowl work. Learn more about Chevrolet Cylinder Heads. Both combos had identical 1. 50 639/646 lift solid roller cam Oct 21, 2010 · Much of what makes one head better than another is not readily visible to the naked eye. 30" intake valve with 337cc port? Sounds excessively hogged out. It replaced the earlier '820 PASS head in 1974 and went out of production in early 1975. Maybe go with the 2. Note that they are not normally supplied with the bowl blend. Sep 16, 2017 · These heads are real large ovals and they have anywhere from 96. The 049s are from a 73 454. you don't have to do much unshrouding . I have a set of 781 oval ports or maybe buy some new patriot 320cc heads. I'm not saying one head is better than the other, just that sometimes the mix of parts prefers a rectangle head. 84" or 1. Jan 11, 2013 · The 990 head is a 118cc open chamber rectangle head. BTW, they BLEW the "HI PERF" 990s away all over the place. Get your 781 heads today and experience the difference. The seats were cut to a three-angle performance spec with a fourth-angle bottom cut at 75 degrees. 781's are very good heads and they flow very well and will make a 454 scream with the right parts! Feb 27, 2008 · The 781 heads are a much better head for a truck application. flat tappet part no. Thanks for the info guys, now I just need to get those heads tomorrow. These heads have 123cc chambers and have had some mild professional port work, I do Square port heads came with larger 2. In an effort to get more power which we always want, I came across a set of 781 big oval port heads. 5 or 10. Im hoping these heads can squeeze a 3500 lb. 88 valves and i did as much work as possible to unshroud the valves. 57 gears. 990 Heads with a 600 + liftcam will give you some nice torque and power. For your boat application, it all depends how much power you would like to make. 050, 314/324 advertised) 2 1/8 headers static CR ~ 11:1, dynamic CR ~ 6. 038" Composite gasket in order to keep the QUENCH a in a respectable . Oct 2, 2008 · Cylinder Pressure Note: youll generally want to try hard to maximize the useable compression as the higher the compression before you get into detonation the more efficiently the fuel can be burnt and the more torque the engine can produce, if limited to pump high test 92-93 octane fuel,165 psi # of cylinder pressure is about the best cylinder Oct 12, 2014 · This is a pristine pair of Big Block Chevy 188 square port cylinder heads, the 188's are identical to the 990's just a later casting. 73 rear, and a b&m 10" converter. I fear that any increase in flow will be accompanied with a decrease in velocity. Nov 3, 2018 · Mr 4Speed hit the nail on the head. Much less work to make 700HP than with 781/049 heads and they won't lack any torque compared to the ovals. 40 in any door car and 8. Sep 29, 2010 · It's a 540 instead of a 496but they started with a Voodoo hyd roller and 049 unported heads with 2. port heads. O. 88 valves and dual rate comp springs for $300 but they are going to charge me another $100 to mag flux them and adjust the springs to my cam spec. Ports on the late models are too small. Sep 25, 2020 · Any piston considerations with these heads vs the other heads? So long as I could upgrade later to different heads I’d probably be alright for now. ” Finally, if you are looking for a closed-chamber head, you will need to use an OE cast-iron unit. com Brodix 301 Maple P. What can I expect in the way of performance change if I make this Feb 18, 2012 · The 336781 heads I've used , have 2. 70 to 9. Good luck and keep us posted. Jul 23, 2012 · 241 heads were just at the very beginning of the "smog motor" era, the 781's into it full fledge. I come up with 9. Feb 19, 2004 · I think either the 990 rectangle ports or 781 ovals would work but each have their own trade offs. 06" intake valves and 1. 020" thick steel shims to set the quench at . 040, 781 heads with large valves, 10-1 CR, 60204 Voodoo cam, Performer RPM intake, 770 SA Holley carb, 3000 stall, 4. in fact, i think i've only seen 1 pair of #781's crack there likewiseits the same reasons for the #026 -vs Nov 22, 2023 · If you want a budget iron head even the Summit iron head are light years ahead of the oem non-ported head. Save the 781 for the total rebuild when you go to domed pistons. 119cc open chamber Rectangular Port. 5:1 compression, solid roller cam, then comes what type of heads, oval vs square port, closed vs open chamber and I'd like to stay with a cast head. Cast-iron late-1960s “206” head with bathtub-shaped 98-cc closed combustion chambers. 5 to 1 for premium fuel. (tho both heads look great to me). Put some mild ported 049 or 781's on that engine and it will come alive. 72" exhaust valves. This head would best work on pump gas 396ci to 502ci motors. The stock valve sizes for these heads are only 2. 112cc semi open chambers with a very good I/E ratio. 337cc seems large for 990s. Mike(wolfplace) and Mark(vortecpro) have given you many answers to your questions that being Choosing big-block cylinder heads depends entirely on the application. Dec 29, 2007 · The 781 are the Largest Oval Port and Ideal for the Street and still excellent for the Strip; however, the Combustion chamber CC's Vary - choosing the Proper Dome Size is critical to get that 9. Mar 26, 2009 · the car is a 1986 cutlass 700r4 trans ,8. 65@125mph 406 with home ported Dart 215 heads. These heads are fresh from the machine shop and need nothing. 00 but they have cheaper port prices,than this all out model. 5 to 1 468 with ported 990 heads, a team g intake with 1050 dominator and a 704 lift solid roller crane cam. 88 valves plus another 70. Oct 7, 2008 · I have had several BBC engines with 049 and 781 heads that ran really nice. The rectangal port 088 and 990 heads are for nothing but top end HP for race cars and i'm surprised you were even happy as low as 2500rpm. iam still running mine with 385 seat and 960 open over the nose spring pressures using a 820 790 302@ . 030 over 454 in it with a ported set of 990 heads and a set of closed chamber LS6 replacement pistons with a Crane CC310 a strip dominator intake and an 850. 88 stainless valves with minor port grinding/deburring. 76 comp, comp 248/253 110, 106 solid roller, scorpion rocker arms, Scat 4340 crank, 6. A set of the Merlin oval ports and . The 026 head is a LS6 rectangle head. Just started taking the springs and stuff of my 990's today, they are a pretty good head out of the box but with a little cleaning up in bowl area and adding a 2. 478:1 CR on Exxon pump gas 707. Oct 3, 2005 · 781 is not hte best flowing heads. Bored 30 over with a 'mild cam'. Jump to Latest Follow Dec 30, 2021 · If your 454 has the dished or the flat top pistons that is going to be the cork in getting to where you want to be at with any of these heads. Aluminum aftermarket cylinder heads offer tremendous airflow potential to maximize power potential. 300/1. 50 around 112-113 mph (this was in a untuned state never dialed in the carbs or timing, just a fun day) that combo 454 . One of the best big blocks I ever had. 72" exhaust valves as standard equipment ; they're oval ported , open chamber heads , and about as good as GM had at the time in iron heads. Mar 14, 2012 · the question is we are looking to get this 69 Impala in the low 10z, and we were looking to do a set of GM 990 heads but I am leaning towards a 781 head build. If restoration is your goal, your choice is limited to locating the correct casting for your original engine. 8:1 compression. 25/1. we dyno it in my shop and it makes 200 wheel horsepower… yikes. 72's with just a good valvejob. Do you think there is power to be made with the 215's vs the 781's without changing any other components out. there suppose to be 113. Currently, with shims & rotators removed, my heights are avg. May 18, 2015 · I am building a . Dropping on a set of Brodix Race Rite ovals got it to 604hp/615 lb ft. Feb 28, 2009 · Back to the magazine buildups which are very hard to believe but they built a 427 about 8-9 years ago that was about 14:1 Manley alum rods, 990 heads with minor work, Lunati . 10-18-10 07:58 PM - Post# 1991558 Never had my heads flown but was curious what a set of 990 heads are capable of on the intake and exh sides during a prostock type porting effort. Whats a good asking price for the 781's? Dec 17, 2007 · Hi Larry, the 781 or the 049 oval port head will go to that rpm on a bracket engine of that size easily. 70 60 foots, but the 990 heads worked better at the same rpms for MY particular combo: 11. The 781s are from a 78 454 with 120k (mostly highway miles) and probably have less miles on them than the 049s that I have. But the two-bolt main would concern me a little there. The Merlin has a raised exhaust port that will help flow substancially. Just an add on Mar 12, 2015 · The 990 heads and similar square port heads are not too big for this set up and wont cause a lack in low end power. Jan 22, 2011 · I'm building a 496 BBC and have 2 sets of heads, 781 ovals and 990 rects. They have never been hurt, no repairs, ever, and are ready to run. Oct 11, 2017 · Tony they are closer to 118cc and the 781 heads should have exhaust valve spring rotators on them vs the 049's do not. I know the exhaust side is weak on the 990s. Mar 20, 2004 · Well for starters,I think the pistons are going to need to be fly cut to clear that cam especially on the exhaust side. The car is a 69 Camaro back halved, weight is around 2800-2900 lbs, P/G w/ 8" converter, ladder bar, coil overs, 32 x 14 slicks, 4. 250" bore, 2. 11 gears, street driven What would be the best choice in plug part numbers? Save Share Feb 5, 2010 · I have both 049 and 781 sets of heads. I am building a motor I hope will make me around 500 hp. 19/1. The 781's are usually closer to 120cc chambers, you have to check them yourself to be sure. That will depend on the compression ratio used and the camshaft used. With the 12. 19/ 1. 015 oversize heads were installed. and the ZL1, L88 and L89 427 in Corvettes. Measure your head chambers, as well as the gasket volume, deck height, and piston dome volume and measure/calculate the exact compression ratio before assembling. Re: bbc 781 heads 01-30-04 10:17 AM - Post# 382381 In response to Doug_F Hi Doug , if you look closely at picture of chamber i posted link to and your heads you'll see compared to heads like #990 rect-port 's chambers, the #781 is GM's MOST cast unshrouded head they ever offered . I am currently working on the heads. Have a new set of valves for either, Ferreas and Manleys 2. 4/124 Tweety TC member FourEightyNine Jul 28, 2005 · heads You are not going to find any better head (including the aftermarket head) for a street/ strip big block then the 781 (and other oval port open chamber) heads. 250/1. 7 to 98 cc chambers. car was running 12. 060 over 289 casting block, 10. What's the better? 1/20/2022 6:10 PM , updated: 9/27/2024 2:58 AM Jul 14, 2021 · Now these are stock untouched GM heads --- because there are a few guys on here who can make the old GM head flow very well - so stock head is what we are talking about. Motec is NOT dead nuts accurate on this info, GM spec for both theese castings is 119cc's. 73 gears. I ran Dart 325cc heads on my 509 and they were a little small on my 540. Specifications: . But make the swap worthwhile. 88 valves. still clearing trw 10. 600' fixture doesn't effect the # much. I am not saying leave the peanut port heads on your motor,but I will say they will work better than you think. I've heard the 781 was basically the same head just different casting numbers, so after looking for afew years for another 049 I've run across a few 781's well the last one just hopped up into my lap! Jan 25, 2023 · I had a 224/230 cam in the truck before with 291 heads and a redone top end. Both are presently stock, no porting but have been cleaned and maged. Apr 17, 2006 · The only problem I see is that the BB Vortec heads only have right at 230 or so cc intake ports even though they claim to be large ovals! Sure, the more eff. Sep 16, 2006 · The AFR heads had about 2 less cc's than the 990's so maybe a little of the et came from a slight increase in compression. a true hotrodder wouldn't be content until he had created a car so violent, so totally sick that the act of dropping the hammer would result in Aug 17, 2017 · Decent damn head for something that says " PASS" and not " HI PERF". Trust in the heritage and excellence of Chevrolet with the 781 Chevy big block heads. It also is 118cc open chamber head. 8:1/T56/3. They have already been fitted with 2. Mar 22, 2019 · These are from Larry Meaux / MaxRaceSoftware Int=5. 016" card stock you can get at the office supply stores, are an EXCELLENT way to compare one to another. I think in most street applications, the 049's are going to stand up to the rectangular heads pretty well. I know that is too much for a pump gas build. 70 gear. off the front of the car. Aug 13, 2020 · Hello all. 0 cc. 030 over 1978 454 for my 72 4sp nova. 19 intake and a 1. Do you have any flow data on the 990 heads? I think on a small 4. 25:1 CR 165 cranking psi 700. 88 valves and a local head porter did the nominal head work. 95 @ 113 with the 990s, and 12. 19 & 1. Low and mid-range power would be superior compared to the large rect. Apr 15, 2013 · GN7 On the Dyno. 88 valves, eddy rpm hyd. Once again, the open chamber designs on production heads will flow more air than the closed chamber production variety. 4-1 static compression. 034 Jan 14, 2009 · The RPM head features a large-volume oval port with a unique rectangular oval-port entry, or "roval" for short. 5. 050 hyd roller cam made 625hp on an engine dyno. anyone know valve sizes, and weather they'ed be good street performance heads when equiped with 2. 820's heads work nicely on a 454. It is a service replacement head, also used on Mark IV crate engines. 88 valve 049's. 060, 60203 voodoo cam). 1 or 10. *69 SS 502 EFI /224-228* HR/9. This charge is FULLY REFUNDED upon return. Feb 18, 2006 · The 781/049 heads have a better port than the 990's, with a better short side (more radius), so IMHO they would be less efective on those heads, maybe Wolfplace (or someone) knows more about them ". 5/124mph -with a "top fuel" timing curve - sold Nov 29, 2006 · 781 vs 049 heads; Welcome to Club Hot Rod! The premier site for everything to do with Hot Rod, Customs, Low Riders, Rat Rods, and more. Also remember we lost about 65 lbs. Note the lazy-D shape of the chambers. 019 Head Gasket or you 0-Deck and run a . You can flow more "out of the box" with any of these castings. with the same cam I picked up 30HP and 40 ft pnds trq. You could find one with smaller than 269cc runner, but casting # was always same. 990's vs 781; Search Turbine aluminum "A" impeller (untouched, out of the box), single plane Merlin intake, single stock 1050, AFR 320 heads, Comp roller cam, 10. My question is will it make a big difference by switching the heads or would it be worth the money to get some aluminum heads? Oh I have a edelbrock rpm performer intake, 800 cfm carb, plan on switching cam with head swap. Jun 5, 2010 · I have a set of 781 laying in my garage now, stock valves comp cam springs Shop is going to charge around $600-700 for a full rebuild with larger valves, or they have a set of 206's with 2. Dec 3, 2010 · well if you are serious about the class and want to make alot of hp HVH heads does amazing things with cast iron 990 heads but be ready they aint cheap for this level of a factory head. Shoot for 9. 72 exhaust. these heads came on early 70's 396 and 402's. This combination ran 9. only very necessary at exh valve/quench pad area corner if you are going Jan 18, 2018 · Other than very high-end race heads, most big-block Chevy heads have chambers around 119 to 120cc, so the choice is more one of piston design for street/strip engines. com Trick Flow Specialties Feb 14, 2017 · 990 heads performer rpm air gap old mechanical cam with lazy lobe profiles (248/258 @ 0. but i think my thinking was a little narrow so the last few head choices i have made have been the open chambered design like the 148 heads and the 049 heads. Consider larger valves and or pocket porting. 19 1. May 21, 2009 · The 781's are some the better heads around from the factory, so I say pick them up for your future 454 build, and leave the 148's on the 396. Except for the chamber cc difference, are these heads basically the same, or is there a chance that the 049's are a better head? Nov 27, 2008 · i only Bowl-Port #781's 2. Jan 15, 2008 · What are the differences in the 049 and 781 heads? Is one better than the other for a pump gas 502 in a 2800 lb drag only Nova? Mar 15, 2013 · Then you would be far better off with 049 or 781 heads if stock type oval ports are required or 088-990 style heads if rectangle port heads can be used. Aug 17, 2012 · well I guess I might be the guy with real world experience to talk to, I took my oval port heads off my 454 . 19 valves and a roller cam since we have all the valve train parts already. Shifted at 6500. than whats on this site but blew a motor in my bracket 27 roadster, car is 2300 w/me in it pulled motor out of street car to stay in points motor is 454+30 (460 cid) 11. The 990's had a basic bowl port ( 88%) of the valve diameter. 030 over, Speed Pro small dome -22cc hyper pistons, thumb rods with ARP bolts, balanced on cast crank. 5-1 the cam Im looking at right now ix the CC xr274r 274/280 seat to seat, 236/242 @. performer rpm intake and stock 800 holley dp. 10 sec. The late L29 heads, 1996 - 2001, have a much smaller heart shaped chamber that will give you a compression ratio in the low 9s, no other changes . cc them to know for sure. Oct 13, 2011 · Those two heads are as close to the same as any two different castings can be from a functional stand point. i think i remember flow up around 440 cfm from a 990 head=8,000. ie 049 or 781 castings with the upgraded valve sizes 2. 303 GM 990 BBC cast-iron Good-Port in ported shape Int=5. We spent about $3500 for that 1/10 of a second. 020" thick steel shim head gaskets. 10@118mph 9-30-22 10. Made great low/midrange torque and peaked at 6200rpm on dyno. 33:1 cr assuming a 0. The Bowtie heads were an over the counter head offered from Chevrolet for racers. stuck it in a 78 ,all steel gbody with a small set of headers, 3. Jul 23, 2009 · I'm thinking more on the line of a 468, maybe 11. Hard to believe but some of the old super stock cars back in the day went 9s with stock head 427s Aug 27, 2011 · The 990 heads have big runners so the mixture velocity is low at idle and around town speeds ( <3,500 say). 1 static compression your after in order to choose a cam and dial in your desired DCR and Quench. 9 HP @ 6800 RPM solid roller 1]= on Chevron Pump gas 10. 3-8. Both of these engines had mildly ported 781's with 2. 25 to 1 CR using the . . 88 valves without any porting if I have them redone. It appears that the cost to rebuild them will be about half the cost of new aluminum heads. 858-16 which are preload adjusted 1/8 turn from zero lash any more will ruin them , which I found out by going a 1/4 turn ,1/8 turn is key no more. A few years back I had a 289 block with 990 heads and a 600 isky cam with an 850 Speed Demon on top. The 781 will work better in the lower rpm range where your motor will be running. in fact, i think i've only seen 1 pair of #781's crack there likewiseits the same reasons for the #026 -vs Dec 9, 2007 · I was wondering what is you guys experience with these heads. 42 the engine will be a 496 BBC wit ha CR around 9. 15 @ 110 with the 049s. Sounds like about the number im looking for, i was wanting between 450 and 500hp. Here are two options I'm looking at. Looks like there is about a 18cc reduction. They are a very desirable street head. Dec 20, 2007 · The deal about the early closed chamber head is that it functions more like a crude fast-burn head b/c the chambers are so compact vs the open chambered head. Nov 10, 2014 · Anne, I have heard nothing but good things about the 781 heads. 050" square port tunnel ram and two Aug 13, 2011 · I can either use 781 or 290 heads, was leaning towards the 290 heads for the compression, i know the 781 heads flow the best but they would put me at 8. Sep 28, 2010 · The new AFR 290 CNC ported head was tested on the 496 today. 0s with 781 heads/10inch converter and 3. I am not familiar with the 820 oval ports. 25" vs 4. This head sacrifices low lift efficiency just a little for its high lift flow numbers up around 0. 80s/9. They allow slightly less timing to be ran, OR you can up the CR a schosh more due to them not detonating as bad as the open chambered heads. Apr 26, 2010 · 2. Ask 10. # 336781 made between 1973 and 85. are these open ports? Sep 2, 2009 · Eric Christie Houston Chevelle Club 1965 El Camino - Undergoing frame off resto, build thread (2011- 1970 SS 496 - Cortez Silver, black stripes, black int, forged bottom end, ported 781s, Eddy Air Gap, ProSystem carb, Lunati cam & rockers, Sanderson headers, Vintage Air Front runner, Century Transmission - 200R4, 12 bolt, 3. There have been a lot of magazine articles where they change the stock head with an aftermarket head and most of the changes result in a 50-70 hp gain whether it be oval or Oct 12, 2011 · Unless you try back to back tests driving with a new design vs the 990s you'll be happy. The car had a TH350 with a 9" converter and a 3. 88 exhuast (if they would fit) valves. They will easily support over 500 horsepower. In the aftermarket, most performance heads are aluminum rectangular port, open-chamber designs reminiscent of t Jul 10, 2002 · You could probably clean up the 990's and they would work ok, but I think you would loose a bit of performance with em. The head faces were also milled to more closely match the chamber volume of the TFS heads (114 cc). Always thought they were basically same head as the #049 which alot of places have listed also at 113cc, but due to a recent post seem to be more like 121cc. 250 long rods used on a 468 with good compression and an open plenum intake manifold makes for a sweet street Jan 3, 2009 · Sure, the closed chamber oval port heads are goodjust the 781 and 049 start out a little better. 7 ratio Crane Gold Rockers Lunati Solid Roller Cam (50204) with Lunati Solid Roller Lifters Edelbrock Torker II Intake TRW . As remember that you can get the results like Ed Bigley's for about $6,500. heart-shaped 100 cc chamber is a winner, but not against a reworked -781 head that should be right at 260 or so cc's IF the engine the -781's are used on has good CR. Big difference. Currently running a TH350 with a 1700 stall and 3. Heads are a very important choice, for something in the range of 450-550hp around 6,000rpm open chamber massaged oval port heads. 060 engine. Apr 5, 2012 · I'm putting together a 496 for my brother with some 990's-2. Feb 20, 2008 · As for the 088 heads compared to a set of 2. Oct 18, 2009 · You will feel the difference by going to an early head. 06:1 L88 pistons you can run about . Feb 5, 2004 · If this is going to be mainly a "street car" you would be much better off selling the 990's and looking for a set of 049 or 781 oval port heads. 050" with a flat tappet. 5 or 11. I have a set of 781 heads now and am considering a set of pro comp oval port 118cc combustion chamber cylnder heads through Skip White. Some early closed chamber heads had 1. 11-670-4 with magnum short stroke or travel flat hyd lifters part no. Picked up a set of 290 heads over the weekend for what I thought was a deal I couldn't pass up. 2. We will include a prepaid label for the return Jan 25, 2006 · I was planning on running closed chamber pistons with my 781's, they seemed to fit fine until I put in 2. 3. 035" to . 2:1 Jul 1, 2013 · C3 Tech/Performance - Will '990' heads wake up my low compression 454? - Ive got a low compression 454 (1972). 19" intake and 1. (dont know specs) and all the other go fast stuff (carb, exhaust, intake, etc) I found a set of 990 heads locally any they seem to be in my budget (guy wants 850 for em) With Oct 4, 2006 · The 990 head is a rectangular port open chamber head. The 990 heads have a bigger intake port which will move the powerband up in the rpm range which is not important in a heavy car like yours. 10:1,hydraulic roller 236/242 590/612 on a 110. 19 or 2. 9 to 1 CR up to about 9. but what could the heads take biggest valve lift? right now is . 030 over L2308A Pistons Now the question, the Heads were resurfaced and with those pistons were supposed to make 11. Not bad considering what the super stockers spend. (Already had the shortblock when I got the heads) Then I had to ditch my shim head gaskets and flycut the pistons for clearance (zero decked, L2349F . 88 valves and just a tick of port work right under the valves they will work perfect. 25 and 1. Overall you would probably save the money for larger valves and possibly milling of the 781's and get decent performance if everything else is chosen well. May 1, 2017 · I'd suggest trading for a set of 990/188 Rectangle port heads in that case. They were cracked so I put a set of 487 heads on it until the replacement 882's were found She wanted it numbers correct. Dec 18, 2011 · Edelbrock RPM (6055) Heads cnc ported 1. These were a revised version of the older factory offerings. GM Cast Iron 781 Heads, Oval Port, open Chamber, fresh valve job, springs, etc with Edelbrock dual springs I believe are . using an Air Gap intake and a 950 Holley. 115 on exhaust & 1. The flow numbers and cross section area are good on theses heads. I think if you wanted to put bigger valves in the 781's and can get the right compression ratio with them go for it. I had the choice of using a set of stock 781's or the 990's and my engine builder leaned towards the 990's. But the 241 head was on the lower HP LS-5 of '72, but that is also the year that GM stared rating HP as net instead of gross. I recommend that you use them. Nov 1, 2006 · quite a bit, depending the size of your cam, you could unleash 30 horsepower, 236 are only good for stump pulling torque and that it. If you are on a budget, and are not changing pistons, you might consider a different set of heads. 049 vs 990. Probably go from something like 7. Does your 454 have flat tops like the L2377 piston or a oem piston with a slight dish top. Jun 13, 2009 · I'd use stock type GM . 90/ 4000lbs RW 11. With the 487 head it got 18 mpg and ran right at 100 in the quarter. Dec 29, 2020 · there are tons of sound clips of these cams online. Their #s were with Manley racemaster valve. Apr 30, 2005 · Otherwise everything was the same. Jun 1, 2003 · Aluminum heads reduce front end weight, allows engine to run cooler with higher compression and less chance of detonation, and will always produce more power at greater velocity. Was just wondering if #781 are also really 121cc chambers. Jan 20, 2022 · Side by side comparison between Samsung Galaxy S20 FE 5G vs Samsung Galaxy S21 FE phones, differences, pros, cons and full specifications. Much better heads for driving around on the street in a heavy car. They are both oval port open chamber heads and easy to find. My last real street car had a . 760 Exh=3. 25 intakes and 1. Sep 15, 2008 · Have a 454 with flat top pistons, 781 heads currently around 8. 88, no porting. Oct 16, 2008 · It was a 13. 015" deck. Feb 25, 2014 · I came across some 215 closed chambered heads. Below is a test of a very mild application with the factory rectangular heads compared to a set of 2. 75 to 1 CR, if not right at 10 to 1 WITH the cc of your -781 heads!! Dec 31, 2009 · put a set of 820 heads on a 427, 11 and ahalf compression, 219, 188 exhaust, actually had to grind down in the middle a little bit, pistons were touching, heads ended up with 132 cc:s, motor ran like a banchee, in a 18 ft rogers bubble hull, turning over 10 grand coming out of the hole, never blew, judson masingale in houston, did the machine work, i did the porting, wish i could find that Nov 30, 2001 · Re: Opinions On Big Block "990" Heads (bence13_33) My 2 cents is the the factory exhaust flow fizzles out at around . some tune-up in the port and under the valve closed chamber ovals run well. Aug 8, 2020 · 781 heads vs 208's Jump to Latest 1. However, 496 is a great option too. 25 intake valve the 990's become a great head. Not the hot ticket like the newer open chambered heads, but as I figure like GOSFAST said, a little hand-work and you should be good to go. If sticking to factory heads, I would run the 781 or 049 large oval port heads. Apr 13, 2004 · What is the actual combustion chamber size on #781 big block cylnder heads???? Most places have them listed at 113cc. 0 in most rails. Oct 31, 2006 · Well, a 454 is still a good sized engine (and was the largest out there when these manifolds were designed). 00 to rebuild and machine for 2. 300 Int Valves usually when a Racer wants more than 750's HP out of #781's i try and steer him towards #990's or #188's The oval port head has 110-cc chambers, and the rectangular port head comes with 118-cc chambers. Jun 25, 2009 · The "781" ovals with work seem to be the good oval/cast head and 990 seem to be the pick of the rec/cast heads. Jul 18, 2012 · Two issues back, we subjected a 468-inch big-block Chevy to a variety of different oval-port cylinder heads, ranging from stock peanut-port-style heads to full CNC-ported versions (see “The Big Aug 25, 2009 · Be careful when using dome pistons (designed for open chamber heads) with close chamber heads. 781 GOOD HEAD. Both in the right hands will make good power. The smaller oval ports should help your throttle response as well. Mar 5, 2008 · Instead, I found '73 049's. Same deal, Weiand intake, 291 heads, Holley sniper, double roller timing, but complete stock bottom end with the dishes pistons from 1986. Have you guys ever driven 454 cars or BBC cars with 781s and 840s to compare Hello Shooter, I had two 454 street engines; 10-1 CR and small hyd flat cams; 224 dur and a 228 dur. 800-inches of lift. 781 heads are stock 120cc, stock valves, have comp chromemoly pushrods, Comp magnum roller tip rockers and Comp 924 springs and 10 deg hardware. 88 valve 049 heads, It depends on the RPM range/cam specs. Nobody makes an aftermarket closed-chamber head. all my heads cc'd at over120cc's, 781's 122, and 124, 049'sat 122. The 990s have a 320 cc volume and the newer heads are way smaller 265,290, 305, 308, 315 etc. 375"thick seats should not be a issue for the depth of the chamber in the iron heads, of course on anything run on the street in terms of rust , but also core shift it may pay to get two chambers in each head sonic tested. Nov 20, 2010 · Like Ray stated aqbove; this was the last PASS (aka Oval Port) head made before the "Peanut Port" heads where introduced in 1975. If they are post 1975 truck heads, then avoid them like the plague. It made 535HP/615lb ft. 00 included in the cost. should make 9. 590 lift. But spinning a big motor at 3,500 rpm plus all the time will drink expensive Euro gas by the bucket - not good. they do these for guys in truck pulls that have to run a factory head. I work for gm in the high performance research and development dept. dartheads. Early closed chamber heads from a 396/427 will give you even more compression. ran Mar 12, 2008 · 781 is not hte best flowing heads. Apr 7, 2008 · I have a stroker 496 bbc in a 70 Nova approx. these are bare heads that were supposedly magnafluxed and found to be in good shape. In a 86 Chevy shortbed. Jul 2, 2020 · Those heads do require some more compression to make good power but down low the 990's are a lazy port. 550 pres. Current heads may have Erson valves, but #s should be very close to the Manley. 303 GM 990 BBC cast-iron Bad-Port in ported shape Jun 14, 2019 · 520 BBC 6. The 049/781 large chamber heads in particular want the small dome 454 pistons to get the cr up in the ball park. Jun 29, 2010 · Those heads were on the L78 396's in Nova's, Camaro's, Chevelles, etc. had bone stock 049 heads with a fresh valve job. 3K views 6 replies 5 participants last post by jeff swisher Aug 10, 2020 Dec 6, 2024 · Have a fresh 454 . it was a stockish type rebuild at 9-1 compression. Or just get the new Patriots? I need a hydraulic roller cam, heads, and intake advice. I need help with valve spring height. Nov 28, 2010 · With a 496 to reach a 10:1 Static Compression with say the 113cc 820 heads you going to need a Piston with a 10cc dome, or approx a 15cc Dome with 781 casting, or choose say a 98cc Closed Chamber with a Flat top piston running a . 5 rear with 3. 88" exhaust valves. 9 HP @ 6700 RPM solid roller Note : none of these Engines had all out max-Ported #781 Heads Sep 22, 2008 · Thats good news. 385 I beam rods, Milodon 66 chevelle oil pan, M77 oil pump blue spring, ported RPM air gap intake, holley HP1000 carb, open 1 inch plastic spacer, 2 inch hooker headers, 3 inch magna flow mufflers Sep 4, 2011 · Those heads are about 320cc intake ports and can handle up to about 725-750 hp. If YOU have a problem with guys that run aluminum heads, don't buy them. brodix. 575" lift with a duration of 260 at . Big-block Chevy factory heads are offered in aluminum and cast iron, with either open or closed combustion chambers, and with oval or rectangular intake ports. mgevzoj xihm wgg ggsnsce rne vecvo duoru yerepf mtzl hrayuvp