Pontiac head tech, chamber sizes , approximate compression ratios ... Bad assembly combos
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- เผยแพร่เมื่อ 19 ม.ค. 2023
- Pontiac like others have differences you don't see in boring common Chevy Ford stuff and ya need to know what ya got or doing stuff especially if your not the one doing the work. Don't let a pro mechanic that's completely ignorant to your brand information and full reign. Know your stuff and be the leader aka manager of your build.. Easy to learn up just try it... Terrible parts combinations that will bolt together explained..
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I just bought a really nice 455 for my T/A. A buddy of mine bought a rotted firebird with this motor for 400 bucks and sold me the motor for 1400 and it was in excellent condition. Took it home and opened it up and turned out it has forged internals and is stroked with ported heads and a dominator intake. Some one must have been going for a real sleeper motor.
When I said 6.25 compression meant 6.75 as far as these heads on a 350
Thank you ! If memory serves, these went in my buddies 455 so about 9.0:1
The 68' 69' Pontiac 350 HO came withe 400 heads and cam from the factory.
The 68 350 HO had the #18 small valves small chamber head specific to only the 350 HO actually and small 66 cc chamber like the 69 #48 RA3 head they used a special small 66 cc version but 68 was not a 400 head actually
@@OneManGarage Ok thank you on the info. I read that years ago article was wrong.
-not true. Only the 350 HO had good (400) heads.
Keep the craft alive
Excellent discussion of valve spring heights, pressures and clearance issues. What is your compression /height tester? Looks like you added a vernier caliper to the side to get your heights, great idea. Great video/good instruction. Thank you.
My 73 year old father has been a Pontiac man his entire life, I was helping him clean out his garage and found 2- 1970 455 with 7F6 heads.
A 69 - 400 & There’s also a 65 421 with a tag riveted on the side of the block by where the oil pan mounts that says is 0.040” and a companies logo but I haven’t been able to figure out what logo it is. I’m trying to figure out what all the heads & other parts are from, thank you for making vids like this
YW and WOW 7F6 round ports x 2 sets ???? !!!!! What's the two letter block codes and 455 casting dates by dizzy ?
@@OneManGarage do you mean the code where the distributor is? H129
@@stephen_crumley yeah that's the date . Just also curious what code application ya had at front below engine sequence stamping
@@OneManGarage another one of the block number is 9778791 and has WG 035559
That’s the one with the tag by the oil pan that says 0.040” 421
@@OneManGarage 0073100 and YA under it
I remember how Good a 400 cid Pontiac .030 over can run back in the 90's w/ the correct high compression heads w/ minor porting & a 3 angle valve job, etc I think the cam was a Comp Cams 292 as I recall; 560 lbs ft at like 54-5600 rpm on the dyno and what shocked me was 461 lbs feet at 2800 rpm! This was when I was machinist at at high performance/ race shop in Detroit. I'm retired & old now but I said then, I'd own & race a Pontiac Any Day! (Coming from a Mopar fan) 😊
Great info!
The chamber size is rarely correct. You gotta measure them. My 1970 #15 heads are supposed to be 87 cc. They are (after milling) between 91 and 92 cc.
Yep. I always initially believed like 6X-4 heads were 89 but they are 93 and like #62 1969 72-75 but really more like 75-78
I would love to see a dyno test on a 462 with 275-280 cfm ported 4x-6x iron heads vs out of the box 87cc Edelbrock heads. They have same airflow, so in theory would produce same hp but with more lower rpm torque and vacuum for the iron head since it has 180cc runners vs 205cc for the Edelbrock.
My buddy has well ported 6x-4 on a flat top decked 469 (060 455) pump gas 93 RPM intake. Flat tappet Hyd with long branch HOs on his heavy 66 Catalina cruiser with 2.93 Safe T Track and hooking on 235 60 15 MT SS DRs it runs high 12s 1/4 and 8.2 in 1/8 !
@@OneManGarage In mid 1980s I saw a 67-68 Firebird with 462 and fully ported 16 d-ports run low 10s. Crazy fast for the era. I talked with owner and he told me that he had trouble getting traction with the 462 and might build a 428/434 and use same heads. He had them ported by H-O racing. Long time ago but I think he said they flowed 285 cfm. I was shocked because my 1968 GTO had same #16 heads.
#16 were closed chamber heads and did not make as much power as a similar open chamber head. A big 455 based motor would love a set of early 70's #96 (not RA2 heads) casting heads. They are very hard to find at this point though. Big Valves- screw in studs- standard port- mid-size chamber- all the exhaust bolts, great head casting. @@tomsettles6873
What would the comp ratio on a 74 400 with 67 670 heads be?
Depends on pistons used and if block and heads were surfaced. If original 74 Flat tops same as 67-74 all 400. Then factory 67 rating would be the same ..they call it 10.5-10.75:1 but reality is closer to 9.8-10.0:1 area if not machined and a modern .041 gasket has it in upper 9.6-9.9 range
Always like the 670 heads…
They are nice and I have usually run 68-69 #16 and #62 and still do sometimes but a street budget 455 needs to be pump gas and also just stock ish W72 87 octane TA 6.6 400 builds
Should I put # 92 on a 1974 350 ci
Are you referring to a 1966 389 #092 head ? If so that would be a nice HP and TQ boost as it will be close to 20 cc smaller than the 1974 350 #46 head getting you up to around 9.5:1 and 93 octane. Don't use a high lift cam though it is a valve angle mismatch but stock 350 piston and a OEM 066 cam would run real good. I would not go over .420" valve lift but it's a cheap hop up for sure
@@OneManGarage good information thank you
I put a set on my 1972 350. Helped a good bit. Had to use different head bolts and push rods from AMES Performance. The 092 head raises the compression by having small combustion chambers. Piston clearance not problem with 067 cam. Small valves compared to later heads, but plenty big enough for a 350.
I'm rebuilding my 1969 lemans with a 350 and i have no clue what I'm doing, between pistons, rods, lifters, heads, cam. How do i know what all can go together?
The original #47 heads and correct stock flat top pistons will make a good strong combo.. consider block surface deck .010 milled off for pistons .005 I the hole and a correct small bore 350 specific head gasket and keep cam not too big. A OEM replacement #066 cam is the minimum choice with a good iron QJet stock 4 barrel intake and dual exhaust it will run good. Good for over 300 HP. One can do bigger valves too rebuilding if ya got #47 common 350 2 barrel 69 heads
@OneManGarage thanks for answering me back, it's greatly appreciated! Another question, could I put a pontiac 400 out of a 1981 trans am into my 69 lemans? Not sure if there's a difference in 12 years
@@Gor3osrs well 78 79 was last year of a 400 trans am. Need year of block a 64-69 389 400 block has holes for 69 LeMans mounts but a also 70-76 block has a dual pattern with patterns that work for 69. If 400 is 77-78 date nope it won't have holes drilled tapped for 69 LeMans mounts .. look at casting # along bell house and date code by distributor hole
@@OneManGarage would the 70-76 blocks have the same motor mount holes as a 69 block? The 400 motor I'm looking at will bolt into my engine bay but now that you said that about the transmission has me a bit worried
@@Gor3osrs transmission starter bolt up is same 64-81 .. The 70-76 Pontiac blocks have 5 threaded mount holes two for 69 mounts and 3 others for 70-81 Firebird style
6x 8. 6x5. L89 vs w72
Great valvetrain and head rebuild information. 🗜📏
I have a 70 GP 400 13 heads
Great engine those 69-72 GPs ! 13s can make some great power
Also cast 62,s that came on my 69 gp
Never use those shit shields! Always remove them immediately or any stomping it can cause them to crack and put metal shrouds in the oil pan then your crank bearings, won't ever happen to me again! I like 4x heads Better but I'll stay with my 13-16 castings. They are several other better casting heads out there with 2.11-1.77 valves ..6x we used to use for trunk weight in winter..
Never had a problem. If you use them on larger than 1.38 OD Springs and stick them on a 1.40 it's on ya. The oil control of a stock valve with only a o ring under lock with oil shield and stock guide boss is superior oil control. This is a low lift application under .500 lift . Umbrellas and or PC seals with no shields is not always best
@@OneManGarage they don't work out 2good on low 13 and faster cars
@@scottnangle246 I know have done faster with it no issues but it's preference either way results vary. If I am doing a .472 or less lift mild budget build it's fine to me.
@@OneManGarage I had a real bad experience and won't risk it,even DCI said get em out,no worries at all then. Personal preference agreed
@@scottnangle246 yeah I mean actual race stuff and over 5500 rpm sure. I don't use either ..
Never cared for 6x heads…
They have there place but younger me ran high compression heads whenever I could. Old me likes pump gas easier cheaper