Here are some ways of finding out and changing your compression ratio on Pontiac V8 engines. Free shipping on many items | Browse your favorite brands | affordable prices. Original Pontiac cylinder heads contain a wedge-type combustion chamber that’s fully machined for a clean, consistent burn. stock suspension street GTO's to heads that run 8. 1-ish compression I believe. Apr 25, 2013 · Horsepower = flow at 28 inches/H2O x 0. 73 12 bolt 11. Apr 10, 2023 · The port shape of the 6X heads are much improved over the #64 and #15 heads and they will respond to porting work better as well. Also would like suggestions for a Hyd roller cam & lifter combo. It has a 10 bolt rear end with 4:10 gears and a (original?) Borg warner super T10 4 speed and rear tires are 295/50/15. Jul 30, 2013 · With all due respect 6X-4 heads will work just fine on a 455 if the cam matches the required compression ratio. 11 intake valves. 2786 Hwy 43 North Lawrenceburg, TN 38464 Mar 27, 2021 · Now, your 140 casting heads are not original to your 65, the 140 casting came fitted on the early 1967 250 hp 326 cid motor and are stated to produce a 9. I also got a bare set of 6X-4 heads with the motor. If you can find a set of #18 (350 HO) heads, grab them. Apr 1, 2012 · A Pontiac may have its cylinder heads removed for a valve job, failed head gasket, porting for improved power, or swapping to a more efficient design. This means the motor will hold onto its peak HP numbers higher into the rev range in and of itself. There were heads close to your '68 heads- like #45, #46 and #47- that could have either 30º or 45º intake seats. The big reason is I think more Pontiacs were produced with 6x heads than just about any other big chamber head. Jan 15, 2007 · A set of 1970 #11 350 heads would be a perfect swap, milled for cleanup (I'd go . 00 please let me know. 060". 5C-4's are just as good if looking for a Dport head that an be easily cut to 86cc chambers. Best 60 ft 1. You don't want to go to a 45º seat unless that's what they were originally. 0 bids · Time left 5d 13h left (Tue, 07:52 AM) +$144. round port heads. The compression ratio would be too low even for pump gas. 4:1 SCR for performance w/ 91 octane- these heads can be milled down to give you the Sep 19, 2020 · I have a set of stock 1979 Pontiac 6X heads. 00 . I am starting a 455 build for my 1977 Grand Prix/turbo 400/2. 68mph 1981 T/A 4-speed 406 Pontiac, Merrick ported 6X heads, Comp 270S cam, Crosswind intake 750 Street Demon, 3. To correct for pop-up pistons, subtract dome volume from chamber volume. 060" off the deck side and . Pre-Owned. 25 gear with 3200 cont. e. converter. Pontiac Heads; Pontiac Engine Torque Specs; Pontiac Cars (Body Types) Stock Cast Iron D-Port Head Package. That's nearly a full point more and the cam for the higher compression engine needs to have close to 10 degrees more seat timing to maintain a safe margin for pump gas considering Jan 20, 2016 · I'd go with 6x heads and around 9:1 compression--not over 9. 5 out of 5 stars The high output heads produced by Pontiac after 1967 used bigger intake and exhaust valves and a 14-degree valve angle. If . Check out the site Jules mentioned " Wallace Racing", lots of good info there. 77" valve to a 6X head is easy to do at the time you get a valve job, and probably cheaper than adding screw-in studs and heavily milling (something you want to avoid) the #66 heads to get a decent compression ratio. $100. Read along to learn about the modifications that Nitemare Per-formance makes to a set of typical 6X heads, like those being Mar 17, 2020 · Most all the normal Pontiac heads flowed about 195 - 200 cfm ( except the RAM AIR with round port exhaust), the 6x will come in around 210-215 cfm @ . Exhaust Crossover Port Matchings. 6X Best balanced head (exhaust to intake) 1963 421 SD Best low-lift (under . 65 roller rockers, XE284, RPM intake, H beams, forged speed pro's, eagle ESP crank, Full ARP studded, Billet 4 bolt mains. Sep 1, 2005 · A 351/48-inch-od deep-groove pulley is still available from your GM dealer under PN 3829387. Might try to dig up some 6X heads from a 77-79 400. 66" valves and pressed studs. 74 but i think thats a load of bull you will notice the diffrence and yes the-8 heads are low enought to run a supercharger but i dont know how much boost you would want to run probally want to run a -. My engine has the 8 valve relief pistons with the knotch at the top of the cylinder wall. With iron Pontiac heads that are relatively stock and flow around 160 CFM, a header with a primary tube diameter very close to 1. Head: Part II . Pontiac made closed chambered heads until 1967. 50's in a 2,400 lbs. " that was slated for use in the low-cost GTO "ET" (which was changed to the high-end "Judge"). My C. Jul 11, 2024 · 6X heads are the go-to for a mild performance head on Pontiacs. Burning rubber since 1982!! My photobucket, lots of dif car pics. 6X(8) Heads (other numbers available) Oct 7, 2011 · I have a 72/73 455 with 4x-1h heads and from all my research this heads are less attractive than the 6x or 7k3 heads for my year. 2 CCs to the chamber volume and . There's no way to prove whether any given example might have been originally sitting on a RA III engine or Jun 30, 2014 · The best intake port on a Pontiac D-port head can be found on the 6X, the #66 can't even compare. 137 #670 0. 806in 2004. 6X is the go-to performance head, and it is also used all the time to lower compression on earlier ponchos. Jan 23, 2016 · If I us the 6X heads , I'll have 8. They tried it and then moved on. Part Number: EDL-60599 4. Nitemare Performance offers custom-ported Pontiac cylinder heads for various engine sizes and applications. In 1967 Pontiac made some open chamber heads 101cc 2. Dec 2, 2003 · Compression ratio was 8. Aug 8, 2019 · The 6X heads weren't produced until 1976, 4X were 73/74 heads. It does not feel like a stock cam, but it is fairly mild. On the 6x-4's, one can mill the head side . There are several sets of #15 heads on line right now. 6:1 200 horse 455 I took out. Pontiac did this in the late 70's to meet gov regulations, NOT to increase performance. Jun 23, 2013 · The 6x-4 heads are a good choice for a 455. 77" exhaust valve as opposed to the 1. 500 and then port stalls out at 256 cfm at 28". Adding a 1. Listed as a 96cc head, the ones I have come across start life about 103cc's and are still about 101cc's after a light cleanup mill. It was for 350's so the chamber is usually in the 91-93 cc range. Nov 30, 2019 · Thanks guys for your response But lets review I have the 46 heads to answer bears question im referring to cfm . t. No way will I mill Pontiac heads . It has 7/16" studs. 3. 073 72cc E head 0. 11 curtain area at . 50s@108 the car weighed 3850 with my big a. Still can't grasp why Pontiac saw fit to put the hole on this head. 625" is good. 11 heads, I would suggest the following: That said, I would first look to find a set of 5C or 6X/6H heads, particular the 6X heads that were plentiful in the late 70s. Our RaceKrafters modified 6X cylinder heads flowed 236 cfm at 0. 225 6x-8 0. This is a 4-speed car with 3:31 rear gear with power 6x 4-Sides 9005 9006 H11 LED Combo Bulbs Headlight Fog light High Low Beam 6000K Feb 11, 2022 · Just a easy short radius intake exhaust pocket bowl head porting for a budget Pontiac 455 9:1 street muscle car Sep 3, 2011 · The 6X-8 heads will be difficult to use on 389-400 engines because the combustion chambers are too large and will make the compression ratio too low, even if they were milled . 4x's are not made in a small chamber size (93cc) like the 6x-4's. Compression Ratio and The Pontiac Engine. Also, 4X heads, used from '73 to '75 on 400s and 455s, are fairly common. 1:1 they origanially came on the pontiac350 91cc i belive some say 93. hotrod. Consider picking up a local rebuildable 455 short block, they are out there! have the 455 short block built with good rods, forged pistons, block honed with a plate, assembled w the right cam. Because those extended gap plugs and wider gaps were an emissions based choice made by the OEM's intended for useage in low compression/low RPM applications with strict emissions requirements,and as such they're not the hot ticket for a higher compression high performance combo,plus it's also been said that set-up just taxes the ignition The heads are cast from 356-T6 aircraft aluminum and are nearly half the weight of a stock cast iron head. i found a site on google that had good info on heads . 75-79 350 & 400 ALL 75-76 455. Not to be confused with the 6X 8 version . Pontiac redesigned the head by raising the intake ports so the short turn into the bowl is at a better angle. If you find a pair of 6X-4 heads that will have a cr. 500" lift. Hooker 1-3/4" headers, I've used Hedman and like them, too. 3 to 1 vs 9. Most want the smaller chamber for the 400 for a good CR. If you want to run a short duration "RV" cam, 6X-4 aren't for you. Opens in a new window or tab. 5 to 1 compression, 10 to 1 or a tad more is optimum for that cam in a 455 build with iron heads. But if you want to make some power and cam the engine for making that power, the compression ratio of the 6X-4 heads and FT pistons are a killer combo. 65" to 1. 2-9. I never had my 455 on a dyno but going by my weight and quarter mile speed/ET I estimate it was right at 450 HP. open. 8 compression. the engine now has the 6x heads, i found some #17 heads for a good price out of a 68 350. Oct 23, 2020 · Forget the Edlbrock Intake and Carb their HP looser! Find a stock pontiac 4 barrel intake, its best for street and use a good stock Qjet best on street for a Pontiac. Looking for a performance head for your Pontiac? There are aftermarket heads available but, If you don’t want to use aftermarket heads. 75 cr stamped O to right denotes HD springs Mar 21, 2013 · I am working on a plan for my 1976 trans am. 030-over 455 with flat-top pistons, the compression ratio will be very close to 10:1 before the cylinder heads are milled at all, and any amount removed Feb 5, 2011 · RA IV heads are WAY overpriced for what they deliver, flow/performance-wise, they're rare and expensive as hell for what you get. This Calculator is designed to tell you how much you need to mill your heads to achieve the Common Pontiac Numbers: Stroke: CID: 3. 6x-8 are 7. If I use the 16 heads, I'll have 10. 9:1, and at the same time picked up some nice flow to more than offset the loss of compression. Dec 16, 2009 · The 6X heads I used had a stock intake port volume of 158cc, it was 172cc after porting. _____ Nov 27, 2006 · 6x8 vs 6x4 heads Pontiac - Street 6X-8's are approximately 101 to 104 CC's and 6X-4's are around 93-96 cc's. Jan 9, 2021 · BIG difference between 6X-4 heads at 92cc and 6X-8 heads at 101cc. Jan 28, 2009 · I had a very simular combo in my 69 bird, trw flat tops ,stock rods with arp bolts,performer intake,6x-4 heads I ported my self with Jim hands book. 060 & also mill the intake side. O. Don't need the high dollar porting work most will try to sell you. 400) head 1967 No. They come with hardened steel seats, and bronze alloy guides. 881/4. The 6X's have a better designed exhaust port that compensates for the smaller exhaust valves. 060") intended as an emissions related feature. 020". We would like to show you a description here but the site won’t allow us. On a Pontiac engine the compression ratio's were change by using different heads. 5C-8, 6X-4, 6X-8, and 6H-6 castings. 6X heads ('76 Pontiacs with the 455 engine) May 23, 2015 · The 6X-4 head is a very good head. The engine I picked up is out of a 76 automatic TA with 6X-8 heads. My heads were so hammered it cost about $1400 to re-do them. No. Get the best deals on Genuine OEM Car & Truck Cylinder Heads for Pontiac when you shop the largest online selection at eBay. 140 6X-4 0. marchperf. Nov 24, 2009 · No, keep the 6X-8 heads. Free local pickup. Engines so equipped were the ‘68 Ram Air II 400, 1969-70 Ram Air IV 400, 1971-72 455 H. Head ID Location The following are 73-74 heads 4X-1H uses 4. 1971- 96 heads and 1972- 7K3 are 2nd best choice, same valve size and 96 cc combustion chambers, great for a 455 build up, 1975-79 heads 5C and 6X are very good heads as well they work well with today's crappy fuel, great for the Pontiac 455 top end as well, they can be Find many great new & used options and get the best deals for 6x Pontiac heads E266 and E246 at the best online prices at eBay! Free shipping for many products! Jul 27, 2002 · The 6X heads will require less work as they already have the large intake valves in them. or Best Offer. and S. 16 heads ('68 Firebird 400, GTO, Grand Prix, Bonneville, Catalina) No. 48 heads ('69 Firebird 400 and 350HO, GTO, Grand Prix, Bonneville, Catalina) No. 023" deck height on 4. 500 ,3. 6 compression ratio. This head is available with initial flow numbers around 260 cfm! This heads comes as cast with a 65cc chamber, 74 and 85cc CNC'd chambers are available. Jun 5, 2010 · the 6x-4 is a smaller chambered head will rase your compression to 8. #48 or 64 heads are 87cc and would be much better horsepower on premium gas and not to much compression to cause detonation. 464, ported 6X-8 heads, 1. 77 exhaust. We have ported D-Port heads that run low tens in 3,700 lbs. 870" valves; 4X-1H are 455 head with 114cc, 2. I'm looking for suggestions on the valve job and some basic porting. Search for Pontiac Cylinder Heads As You Go Thru Life DO A WHEELIE !!! stamped X to left of center head bolt - 10. Stock springs, pushrods, and rockers. Screw-in BBC 7/16" studs with locks to replace stock non-adjustable studs. 8 compression, what horsepower will I have and is anybody running a lower compression 400 out there. Apr 3, 2016 · 7K3 are 1972 400-4bbl heads, used on all 4-bbl applications that year. This sinking of the Intake valve will add another 1. com. Both are excellent heads to use on a 455 and will get you right around 9. Jul 1, 2010 · We give new life and a lot more horsepower to a 495 Pontiac with new Roland Canted-Valve Pontiac cylinders and a Scat stroker kit. We also specialize in porting RAII, RAIV, H. valve 2. 6x-4 are 8. 5:1 compression. Dec 29, 2019 · Once the valve seats have been recut in the 6X heads the valves on average will sink . Part Number: EDL-60575 4. Learn about their blueprinting process, porting stages, options and pricing for 6X heads. I'd do what you can to get it as high as possible/practical if you want to run the RAIV cam in it. further research the ones i have got like 112 cc chambers giving me between 6-8 comp ratio. I used VS11 valve springs from the old H-O Racing Specialties (no longer in business) about 120 lbs. My conclusion is that the higher comp, small valve heads would be better than the low comp, big valve heads, like the 6x, on a 350. #614/SR 0. Pontiac head ID chart Aug 6, 2019 · The round port 455 HO heads have a 172 CC Intake port as compared to the at best 155 CC port in the the 6X casting. 2 watchers. Best 1/8th mile e. 3:1 depending on the overbore of the engine and how far down the pistons are in the holes at TDC. Apr 15, 2017 · A 1975 Pontiac 400 will have 7. Still not convinced that these Pontiac aluminum cylinder heads are the right performance choice for you? Consider this…. 61 MCSA = 2. Sep 10, 2008 · 6X heads are to Pontiac as 049 heads are to BBC. Jul 6, 2009 · Stock Pontiac Head Flow Head Casting Number: Year: Notes: Porting: Intake Lift: Intake Flow: Exhaust Lift: Exhaust Flow: Download Desktop Dyno 2000 . keep the cam choice reasonable and as said before, use forged rods and pistons and some good ARP fasteners. I don’t have a basis for comparison in power but the 6X head combo plus a few small mods made it day and night compared to the 7. 030". Oct 28, 2014 · 1971 GTO,72 400, stock bottom end, 670 heads, Lunati BMII cam, headers, iron intake Q-jet, four speed. Sep 22, 2008 · There are two versions of the 6X heads, 6X-4 and 6X-8 with the -4 being more desirable because of slightly smaller chambers. I think that the more compression that I can pull out of my heads the better. 3 or 9. 77 EX valve, 3 angle valve job, H. Don’t forget there are two bonuses when going to the 6X heads over the #15/#64 heads, screw-in rocker studs and 2. These measurements were from the deck surface of the head to the closest edge of the intake valve where it will be closest to the piston . Here's a Pontiac site with head ID info: Jul 5, 2008 · 6x are the go-to performance pontiac head. We were armed with a 400-cfm laminar flow element (powered by six 1. The 6X-8 heads are 101cc so the compression ratio will be pretty low. The 6X-8 and 6X-6 heads came on 1975-1979 Pontiac 400 engines. Mar 29, 2017 · The key to maximizing the performance of any combination is proper component selection. Since the 350 H. 010" if they clean up there) to a max of . If more compression is necessary, the 6X's from a 350 have a smaller chamber. resulting in lower power, though definitely remaining compatible with the 91 octane. Pontiac Cylinder Head ID Numbers. 42 30 spline Eaton posi street car. 77 exhaust valve, they flow better than any of the earlier big valve D-port heads did. The only real difference between a 5C and 6X head is the casting number. 5 compression . Dec 23, 2021 · For you 6X guys the 6X-4 chamber is slightly smaller diameter as well as slightly shallower since it was originally a 350 head. the car ran 12. They are usually stamped on the machined pads by the valve covers. The one downside is they have very large chambers, so on a 400 they will require domes or lots of milling to get anywhere close to a compression that would support 500 hp unless he want's to go forced induction, which would be a great idea with 6x. The 96's already have the 1. and the 7j2 heads we confirmed to have 96cc combustion chambers by ccing them. Stock 8. Jan 1, 1999 · As a side note, the 350-cube 6X heads have 91cc combustion chambers while 400-cube 6X heads have a 101cc chamber. 6X. 4 on a 455. Not knowing what cam is in the motor I would guess HP at 250 or perhaps a little more. bracket car. 30 with 6x-4 heads would put out a C. jazz1, Sep 5, 2021. Having said that, they came in two different chamber sizes - big and huge to match the 455 cubes they were usually used on. 282 Mar 26, 2014 · The original question was about 6x heads on a 350. It has hydraulic lifters and nuts that are apparantly made to bottom out and torque to 20#. 120" bore and flat top pistons (no dome). These head numbers represented chamber sizes. D. The deck thickness is 5/8" and they sport a new high efficiency heart shaped combustion chamber. I use 1233's all the time but just not sure that they are the best choice with this head. All made for regular gas. two different size chambers and mill as neeeded for 400s or 455s. 66 valves, chambers 92 to 94ccs usually) are exactly the same as the 1975-1/2 thru 1977 6X-4 350 heads that are so popular. 63@116. I knew the original head were really beat up from detonation, so I wanted better heads as replacement. 005 dish piston if supercharging. They do have all the exhaust manifold holes, unlike some Pontiac heads. Every bit as good on a 400 as the 1971 #96 400 heads (96ccs + chambers), even though the #96 heads have a 1. The #62 head will have a cr. Well, a lot of time gone by and only now am I getting the engine rebuilt. it occurs inside Pontiac cylinder heads. _____ Ultimate Pontiac Head Flows I think the main purpose would be the air flow comparison between the different heads. The heads, intended for the 350, had 72 cc chambers. . It’s good for a little extra horsepower with a static compression increase. I like to see at least 9. My main concern is low to mid to torque. 050 is about the max (and if you do that there's nothing left for "later" if you need to rebuild the heads to square up/re-flatten the decks). 8-10 to 1 compression. IN retrospect, I should have spent another grand and gotten aluminum aftermarket KRE's or Edelbrocks. 6:1 respectively. I'm porting a set of 6x-4 heads for my 473 build at the moment. jayall1966 (324) 100%. Ultimate. jayall1966 (327) 100%. 670 Worst exhaust-to-intake port ratio 1969-70 Ram Air V Worst intake-to exhaust ratio 1968 1/2 Ram Air II Biggest surprise Intake port, No. For a Pontiac street engine, there's little point in going small. 54! Dec 9, 2015 · With stock or any heads when you go up to a larger CID you will gain more low end torque , and lower the rpm where peak torque and HP are made, the larger CID on a 455 will not really buy you any greater a HP level due to the fact that with stock factory heads the motor is already out of air flow capacity at about 3500 rpm even with a Cam of 220 intake duration @ . Your compression ratio will be better than with the stock 4x 114cc 455 heads and allow for a better selection in cam choices. about 8. on the seat, 285 lbs. 070″ and the 1971/73 round port heads can be cut . The pistons appear to be at zero deck. 030″ or more is removed, the intake side of the head should be cut equally to maintain port/bolt alignment. Nov 14, 2019 · Will 6X-8 heads fit my 389 as currently built. Products. Bolt-on's: Performer Pontiac aluminum intake with rebuild Q-jet. 050″. 00! Off the shelf ready to bolt on aluminum d ports will cost you $2,075. In 1967 Pontiac made some open chamber heads (i. Jun 7, 2016 · For good part of the last 2 decades, 6X's have been a favorite of Pontiac engine builders for pump gas D port ported cast iron head 455-474 combinations. 257 x number of cylinders. 5:1 SCR, not the ideal 9-9. Deuces likes this. Sep 18, 2019 · 1978 Trans Am original owner 10. 1975-79 No. For instance, with an Edelbrock head (unmodified) flowing around 180 cfm at . Mar 11, 2021 · pontiac 400 6x-4 heads Jump to Latest 6K views 10 replies 6 participants last post by GTOLou Apr 15, 2021 Pontiac factory cast iron heads came with different styles of sealing such as valve stem o-rings and positive l Welcome Guest My Account Order Status Wishlist (866)762-7527 Mar 16, 2010 · One cc will be deleted for each . They flow a little better & will get you about 9:1 or maybe a bit more. 030" off the intake side and your compression ratio will end up in the 9:1 range, and possibly as high as 9. 060" or more, but that's just my preference, not saying it won't work. The link below is to an extensive pontiac head chart. All very low compression. The L78 engines used the 6X 8 heads which featured larger (90-101 cc) combustion chambers. 4:1. Apr 1, 2009 · More details and photos only in High Performance Pontiac. 9 on a 455 much better for todays gas. Jul 21, 2010 · Right, I want the big HP heads, but between race gas and lead additive I'm leaning towards the 6X heads and letting the 60's head rot in the corner. See All 10 Photos. the 6X heads are the larger volume chamber from a 400 engine. My intension was to use them on my 1969 GTO once I got the engine rebuilt. Will the stock valves hold up to a Hyd roller? This head package is going on a stroker 400 that will end up 461ci. Jan 28, 2023 · For others following this thread the insert does occupy the complete hole in the gasket but still doesn't quite come to the top of the blind hole. R. 75 . 1:1 cr and 7. Aug 24, 2017 · Best low-compression post-1972 head No. Then the Mar 9, 2015 · Plugs for 6X heads? Pontiac - Street. The 1975 6X-4 heads only came on 1975 Pontiac 350 engines. 326 . Sell the 6X-4 heads or save them for the 455 you really want to build later on. com, the Jan 3, 2013 · Pontiac engines have made good power/torque w/the compression ratios obtainable w/flat top pistons and the 400 chamber heads, like the 6X-4. The 6X 4 heads used smaller, (91-93cc). Regardless of the reason, all of the steps pontiac 6x heads. Jan 14, 2008 · Sure, they have the smaller 1. 085″. 00. You see 6X heads all the time at swap meets and online. com) sells a 2111/416-inch These heads can be ported for optimum performance on a 450 HP street engine or a 700+ HP racing engine, and everything in between. 77 valves, screw in studs. sorry cant remember site off hand. 1. Pontiac Head ID Mar 26, 2022 · I purchased #48 Heads back in 2010 from a member on this board back in 2010. This is our first aluminum Pontiac head casting that we have brought to the marketplace. Dec 15, 2004 · Most Pontiac nuts just go with the edelbrock casts, which you will make more power with, but the cost is around 1100$. 75 Pontiac made closed chambered heads until 1967. 301 . Jan 25, 2013 · When it comes to cast-iron Pontiac cylinder heads, the Round-Ports are the fancy of every performance enthusiast, but the smog-era D-port (4X, 5C, and 6X) castings have proven a performance Chart to mill Pontiac Cylinder Heads. The low compression ratio makes it difficult to use those heads on a 400 CI engine and a high performance Sep 23, 2006 · Stock Pontiac Head Specs * During my searching for information, I found quite a few discrepancies in the sources I was viewing. 4x heads at . at pushrod first impression is thats the problem but studying the port and listening for turbulence I'm not so sure that is the limitation, and opening up The. to build a set of Stock Pontiac 6X heads that will flow 240 cfm and net you a pump gas friendly compression ratio you will need to spend about $1,500. In our last issue, we began our foray into the world of airflow, as. of approx. Different chamber volumes, some huge for 455 engines and some small for 350 cid. Mar 1, 2010 · Good price for these heads if they are in good shape and built properly. Below are some popular heads and chamber sizes (always be sure to have yours checked before any milling). 8. 66" on the 6X heads. Jul 15, 2018 · The reason Pontiac owners are using the 6X-8 pump gas heads is because they are cheap and are easy to find. 33@132 3595lbs May 7, 2010 · 6x Heads 6x heads came out in 1975 through 1979. 6X heads are good heads. Beginning in 1968, Pontiac fitted their highest-performing engines with heads featuring redesigned round exhaust ports (shown above). 104 #16&62 0. 8:1 compression ratio with 6X-4 heads. 6 to one 6H headed 455 4speed T/A, I would want some 6x's on it too, lol). There are two problems with them - the biggest one for a mild street performance application being that not only are they missing the end bolt holes on the exhaust flange, the material that's normally there that you could simply drill & tap on other heads isn't Jan 31, 2015 · Well, I do like 6X's, but my favorite head for a street 455 is the 1971 96 D-port head. Aug 21, 2010 · The 6x's come in two varieties- a 6x-4 w/ 91cc's and a 6x-8 w/98cc's. (IMO) There is a secondary code on them that needs to be found. About Contact Parts For Sale 6X-4: 2. 16 compression. 3 watchers. Oct 9, 2003 · The 4X head was the 49-state casting used on all '73-74 400 and 455ci engines. Jan 24, 2014 · A 1969 #62 head is a 1969 #62 head is a 1969 #62 head regardless of whether it was installed on a RA III block or on a "garden variety" YS 400 (like mine were). 36 shipping. 66" valves. I would like to use the 4x-1h as they are in good shape. Also I need to match the cam to whatever heads I choose to use. See the chart for 6x heads with 2. Jul 25, 2019 · 6x-8 head porting Pontiac - Street. Just remember that all 455 heads have compression chambers that are too big for your 400. All modern production engines, and most aftermarket Pontiac cylinder heads, feature a fast-burn combustion chamber, which is easiest identified by its distinct heart-shaped appearance. 66: 98: SCREW IN STUDS- DUAL VALVE SPRINGS- D PORT Butler Performance is the main source for stock and performance cylinder heads for your Pontiac. of 9. S. 365. March Performance (Westland, MI; 734/729-9079 or 888/729-9070; www. (You don't even need to read the "4" or "8" stamped on the 6X Feb 25, 2014 · So i finally got my hands on a 78 Pontiac 400 unfortunalty its the ya code but i guess this would do. Do you guys think should i leave the 6x and machine them down a bit for higher compression or go with the 17s. 99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13. 350-375hp is easily within reach, with unported 6x heads. 6X-4 heads w/FT pistons. Don't believe me? May 10, 2005 · It seems that Pontiac cylinder heads cast between 1967 and 1972 are typically the most sought after for restorations or performance. Could I install different studs and get poly locks and have adjustable valves? I don't know if the heads have been milled. 500-inch lift and 250 cfm at 0. The 455 engine will run mid 12's w/nothing more than 6X-4 heads w/stock valves, 4-tube headers and a cam. 1977 350 Pontiac cylinder head casting 6x. 005″ removed from the head. Apr 3, 2012 · The 48 heads were the heads originally intended for the never-produced "350 H. 11. Mar 6, 2015 · 1978 T/A 463 Pontiac, KRE 74cc 292CFM D-ports, Lunati VooDoo, V-max lifters, TKII, ATM 850 E85 carb, TCI TH-350 race tranny, 3600 converter 3. Welcome Guest My Account Order Status Wishlist (866)762-7527. Just over 275 over the nose(480 lift intake. Again, the actual chamber volume does vary, so actual volume will need to be verified before anything is done. I could buy a 400 head gasket to see if everything on my 389 lines up but would like to hear from those of you who have hands on experience with this type of set up. 315 -- Throat 87% area =2. 550" lift, 1. 2 compression where as the casting number 22 casting head is the casting number head that would have come on the 1965 285 hp 326 HO motor and would have had a factory stated 10. The 1971 96 and the 1972 7K3 heads can be safely cut . 70 CCs to the chamber from the sinking of the Exh valve, so now the compression is even further reduced from 7. I put a milled set on my 389 to get the 10. 75" diameter primary tube headers would be optimum. 91 cc chamber,750 DP carb,3. Feb 1, 2012 · When combining your 6X-4s with your 0. They have 96 CC chambers, 2. 41 stock rear Find the casting number, year, factory application, chamber volume, and valve size of Pontiac heads from 1958 to 1979. 600-inch lift. 67 out of 5 stars Dec 16, 2011 · A "Pontiac style" 3-angle valve job is fine, just stick w/the factory 30º intake seat angle. 00 item 4 1971 PONTIAC 400-455 GTO FIREBIRD #96 CYLINDER HEADS PAIR Big Flow Valve Heads 1971 PONTIAC 400-455 GTO FIREBIRD #96 CYLINDER HEADS PAIR Big Flow Valve Heads Oct 19, 2013 · 455-6X-RA4 Spark Plug Recommendation Pontiac - Race. The 6X cylinder heads were treated to a precise porting on the intake side to increase flow from 230 cfm (the previous porting) to 255 Apr 1, 2007 · However, stroking the engine to say 461ci and retaining the 6X heads, the torque will increase to tire-frying proportions, and the W72 block will hold up better than the regular late '75-'78 400 Cylinder Head, Performer RPM, Aluminum, Assembled, 72cc Chamber, 215cc Intake Runner, Pontiac, 389-455, Each. 500 46 heads flow 181 cfm at 0500 now if any can get me complete set of heads that flow better for 920. was not produced, these high compression heads were re-allocated and used on the Ram Air III instead. It will spin the tires and have enough torque to put a grin on your mug and be reliable as long as you dont go to big on the cam and Jet the qJet properly. Dec 20, 2020 · As for non-2. in it. My question is, if I use the 6X 8 heads that are milled and confirmed to be 94cc and will be 8. CLICK IMAGE FOR LARGER VIEW . Apr 18, 2017 · Stock 6x-4 heads that I am in the process of cleaning up the ports/runners/bowls and will get a 3-angle valve job when finished. I have never seen the elusive 455 6X head which has supposedly been found on some '76 455 4speed T/A's (If I had a 7. flw file item 3 Pontiac 400 Cylinder Heads 6X-8 (Pair) Pontiac 400 Cylinder Heads 6X-8 (Pair) $475. 55 open rear Sep 5, 2022 · The 1970 #64 455 head is also 87 cc and has the big valves, but these are expensive and rare. For less than $1000, you can have a qualified Pontiac engine builder build you a set of 6x heads with one piece stainless valves and all the other correct parts. 6X (1975-76 400/455 & 1977-79 Jan 20, 2011 · I have a Pontiac 350 block (pontiac not chevy) and i want to build a motor to get decent mileage and power, i have a comp cam 275DEH camshaft, edelbrock performer intake and both 1972 7j2 and 1977 6X heads. The lack of good Pontiac 400 heads, such as those with 64, 12, 48, and 670 casting numbers is the reason aftermarket aluminum heads were introduced a few years ago. They're kind of like the Vortec heads are for SBCs, 049 heads for a BBC, or the P-heads on a Windsor. Mill the 6X heads . Jun 10, 2020 · If I remember the compression with the 6x heads came to 9. 43@103. They had 8. $200. Calculator says a 400 +0. The R45TSX are an extended gap plug meant for use with wider gaps (. 11/1. Mar 16, 2008 · The 1975 5C-4 350 heads (2. For a basically stock engine, it really doesn't matter. All heads can be safely milled . With careful prepara-tion, less-celebrated heads can often be improved to flow as well as some of the legends and the af-termarket offerings. When opened up to the 1. They were about as good as it got, perofrmance-wise, for Pontiac D-port heads. Jun 11, 2012 · On Pontiac heads, . Since Pontiac offered the 400 2-barrel, the 400 4-barrel with both manual and automatic transmissions, and the 455 4 In 1973 Pontiac started stamping extra numbers (1/4" tall) on their heads. 5. Results matching Cylinder Head, Performer, Aluminum, Assembled, 87cc Chamber, 215cc Intake Runner, Pontiac, 389-455, Each. 83 on a 455, too much for a pump gas street motor. So do the 6X. i like beer too much to remember. 4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10. 66" The 6X-4 and 6X-8 were the only heads used after 1976 I am doing up a set of pontiac 6x-4 heads and first time on the bench was very encouraged at low lift flow up to . Jul 26, 2005 · the 6x popularity is due to nearly universal combustion chamber adaptibility. I believe the 6x-8 and 6x-11 would have a relatively low C. derosnopS. 050 will remove about 10 cc's from the chamber --- so on those 142's you can take them from 90 cc's down to 80 cc's, but on those 6x-8's you can only get them down to about 88 cc's. 0 compression ratio. 042" (crushed) head gasket, 6 cc valve reliefs for 400 stock pistons, 5 cc for -. By expanding on the approach that Pontiac took when assembling combinations for its production vehicles, selecting components that compliment the operating characteristics of one another for a particular application, you typically produce a powerful engine that operates efficiently and reliably over a long heads or aluminum aftermarket castings to make big power from your Pontiac. Oct 8, 2004 · Read the tech article on Testing KRE New Aluminum Heads on a Dyno versus 6X heads, brought to you by the experts at High Performance Pontiac Magazine. 13 heads ('70 Trans Am, Firebird Formula, and GTO with the Ram Air III engine, automatic transmission) No. In light of this, the 'Year' entry, as indicated by the chart below, may actually represent the year that the heads were cast, versus the year that they were actually installed on an automobile. Sep 2, 2021 · I forget most but I do recall the Pontiac 400 6X heads were most desirable to top the 350 or 389 BB's. 46 with 3. Sep 30, 2009 · The only Aluminum Pontiac D-port Head We are pleased to introduce to you, our aluminum D-port Pontiac head. I had the performer rpm cam which is very close to the crower 60919. These heads flow better producing more power than the heads produced pre-1967. Cylinder Head Plug For 1991 pontiac 6x heads. see chart below HEAD STAMP LOCATION ON PONTIAC HEADS. 66 intake port and exhaust port stamping. SHARE POST #15. It's the same thing that Pontiac did with the later 6X heads: one chamber size for 400 engines and a smaller size for 350 engines. 050". I've had 6x-8s on several Pontiac big cars, they are good heads but nothing special. 5 hp vacuum cleaner motors), two graduated vertical manometers to measure atmospheric pressure, an incline manometer to measure actual airflow, and a velocity probe. , and 1973-74 Super Duty 455. Dec 16, 2020 · It's been a long time coming but we're finally getting a chance to get back to the 1970 LeMans project and get this big blue Pontiac 455 put back under the h Jul 18, 2008 · i have 6x on 70 400 and i only have 105psi comp. 5:1 compression down to 8. 061). 17 350 head Biggest disappointment 1969-70 RA V, 1973-74 455 SD (tie) Dec 8, 2014 · 1970 lemans sport. 4 to 1 vs over 10 to 1. After 1967 the heads were open chamber heads. Unfortunately, the best OEM Pontiac head are gone the way of the Do-Do bird. Oct 1, 2009 · I would like the option to make small adjsutments anyway. Description: Cast Iron Heads Stud Conversion Service(Set/2) Customer supplied heads sent to us for machining services Convert press in studs to Pontiac 7/16 screw in studs Item #: 1100H-STUD-CONV Condition: New Aug 31, 2004 · If the heads you have are the 6X-4's then you have a good set of heads to use on a 455, if they are the 6X-8's then use the 96's. The PY Online Forums is the largest online Cylinder Heads: The W72 engines used a specific 350 V8 head casting called 6X 4. i just typed pontiac cyl heads and found it Aug 30, 2015 · I am running the crane h-272-2 in my (389)400 I used the comp cams 988-16 I set them up with125 lbs installed. The above figures assume 10 cc for . Check out the full engine build only at www. 79 which is very safe for pump gas, I believe. 500 flow 171 cfm 6x flow 163 cfm also at . The # 6X-8 will have a cr. May 28, 2013 · 6X heads, swap in some swirl polished valves, basic polish job and 3 to 5 angle valve job and matched ports and a Pontiac can push well over 500 lb ft of torque, MUCH more useful over 500 HP. The 6X is the better of them though. With flat top pistons and tight quench you are looking at 9. In stock form either 6x-4 or 6x-8 will give you 8-8. Therefore the horsepower ratings for these low comp 350's was very low. very streetable and fun to drive! go with the 60919 Aug 31, 2016 · Up into the early 90's, most traditional Pontiac guys scoffed at the 6X heads, & didn't know about the secondary (stamped) codes. . Feb 2, 2011 · More specifically, a 6x-4, right Pete? I'll have to calculate the C. ywdgx kickcrq siqya pvkce vzrtcw ngpgh ltcdmeg xzilf tzu umhc