# Trying to id my heads and engine



## Lithium (Apr 23, 2009)

Im having problems with iding my heads due to the mechanic that did all the work has disappeared and im coming up with conflicting answers on the web if anyone could help would be greatly appreciated.

This pontiac stuff is all new to me so kinda learning as I go with this project and its been about 25 years since my last muscle car which was a cuda.
This is a 1968 GTO with a 400 
What I have found on the heads are 1h--4x--B073--DN--GM8 on passenger side and GM6 on driver side.

I am confused by the 1h

My engine numbers are by the transmission 481988 on the front is c278970 ys and by the distibutor is hard to read it either is 0021 or 1200 and one large number1 and possibly the letter d.

If any of you guys could help me out it would be greatly appreciated thanks.


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## upinsmoke (Aug 24, 2009)

Sorry to not have an answer for you, I am having the same troubles. Just bought a 66 GTO and the engine block has 0C65392 YP. I looked at some of the pontiac sites that have id's but I get nothing... I'll keep trying and if I find something I'll come back n let you know. GL


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## Lithium (Apr 23, 2009)

AHHH yes the joys of crawling all over looking for hidden numbers LOL and then I just love the internet ill tell ya! I did Realize by my distributor the code is c021 took me awhile to force my big head into a cramped hole.


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## Lithium (Apr 23, 2009)

try this site up might help Pontiac Power


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## upinsmoke (Aug 24, 2009)

LMAO!! I am there right now, I was just about to recommend you the same exact site.


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## Lithium (Apr 23, 2009)

HaHa to funny man I been ready to pull my hair out with this engine let alone the heads, The guy that owned the car before me told me it was a 74 the n another guy told me it was a 76 and by what I see its a 71 for the love of god .

And the heads have me baffled due to what i have read says 1h 4x heads are for a 455 so im totally lost on them!


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## upinsmoke (Aug 24, 2009)

I'm still wet behind the ears about all this stuff. I only got my very first muscle car yesterday. Drove forever and back to get it. the heads on mine are the 6x heads and I think thats stock for the 389's but not sure. The guy that I got the 66 from said it was not the original engine and he had no idea what went in there so I have to chase down an elusive code. I cannot get under my car just yet still on the car hauler. Gonna take it to a freinds and start to take it all apart. Maybe I can find some more numbers to search. So far, the Pontiac Power site says a 66 with YP on the block means a 326/285 HP. I was hoping for a bigger number lol.


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## ddearborn (Aug 24, 2009)

*your heads*

the B073 is the date code b=february 07 is the date and 3 is 1973. tells me it is a 1973 head. the 4x is the casting # its gonna be either a 400 or 455 (4x shows two different motors for that year) head from 1973. Regaurdless of this, 73 where low compression heads.


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## 68greengoat (Sep 15, 2005)

I have that same head on my 455. The 114cc head(if your's is a 400 head it's 98cc) is producing a whopping 8:1 compression. When I get so extra money the plan is to go with some 87cc Edelbrocks. If you want to stick with Pontiac heads, I would look for #16, #62 heads or others in the 72cc range for your 400.


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## Lithium (Apr 23, 2009)

Thank you very much for all the responses its had me baffled for awhile.

Now I get to figure out how to explain to my wife them are not gonna work LOL, The edelbrock heads your talking about go for about 2k Im assuming think I seen them on another website? {looks like I'll have to sell some other toys soon}

My next question is on all the different motors they all have different horse power ratings are them ratings what the engine was putting out stock?

And thanks gents I appreciate you guys here I have learned a ton of info here and continue to learn from you guys:cheers


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## 68greengoat (Sep 15, 2005)

Lithium said:


> Thank you very much for all the responses its had me baffled for awhile.
> 
> Now I get to figure out how to explain to my wife them are not gonna work LOL, The edelbrock heads your talking about go for about 2k Im assuming think I seen them on another website? {looks like I'll have to sell some other toys soon}
> 
> ...


If you're talking about the ratings at the Pontiac Power website, yes.... Edelbrock isn't cheap. You could go with other brands that have 72cc heads that would be alot cheaper...


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## 6T5GOAT (Nov 23, 2008)

Try this link, it may help you deternine what you have: Pontiac V8 Cyl Head Info

I can tell you, 6X heads are a later model head and not installed on early GTO's.

Hope this helps.


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## geeteeohguy (Feb 2, 2008)

I would not run 72cc heads on a 400 unless prepared to use racing fuel at all times. 72cc on a 400 is 10.75 compression, higher if the block is bored out. Dished pistons are the answer with the small chamber heads. The optimum chamber size for stock pistons in a 400 incher is around 80-90cc, for about a 9.5--9.0 to 1 compression ratio. You can mill "smog" heads to increase compression. I recommend looking up the head charts on the web and doing the math. You want a 80-90cc head with the big valves. There were lots of big valve, 96-99cc heads in the early '70's....you could get a pair of those and mill them a small amount and have a nice performing head.....BTW, 389's never had a "6X" head. That's a '70's 455. A '66 389 head would be an 092 or an 093.


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## Lithium (Apr 23, 2009)

Thanks gents sure helps me get going in the right direction with this thing and geeto your right about the cc im gonna go with 80-90cc I think due to who can afford high octane at the price of low octane.

Gonna have to do some research thanks again.


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## 68greengoat (Sep 15, 2005)

geeteeohguy said:


> I would not run 72cc heads on a 400 unless prepared to use racing fuel at all times. 72cc on a 400 is 10.75 compression, higher if the block is bored out. Dished pistons are the answer with the small chamber heads. The optimum chamber size for stock pistons in a 400 incher is around 80-90cc, for about a 9.5--9.0 to 1 compression ratio. You can mill "smog" heads to increase compression. I recommend looking up the head charts on the web and doing the math. You want a 80-90cc head with the big valves. There were lots of big valve, 96-99cc heads in the early '70's....you could get a pair of those and mill them a small amount and have a nice performing head.....BTW, 389's never had a "6X" head. That's a '70's 455. A '66 389 head would be an 092 or an 093.


I think this is the first time I may have to disagree with GTOGuy! According to the chart below(using '68 as an example), 90cc will only give you 8.6 compression. 72cc heads on 400's were very common from '68 - '70 and they didn't use racing fuel. Granted, you would want to run premium. But we're all probably running that now anyway. My friend has #16 heads on his '68 400 with no issues. I guess I wouldn't hesitate to run 72cc on a 400. From what I can tell, to get the hp to 330 -360 you'd want to run the 72cc. Please correct me if I'm wrong. I can take it!

1968 400 265HP 14 1.96/1.66 8.6 c.r. 90cc
1968 400 290,340HP Big Car 15,215 1.96/1.66 10.5 c.r.
1968 400 350HP(GP) 16,216,62 2.11/1.77 72-75cc
1968 400 330HP (FB) 16,216,62 2.11/1.77 72-75cc
1968 400 335,350,360HP 16,62 2.11/1.77 72-75cc
1968 400 335,360HP RA I 31,(37) 2.11/1.77 72cc
1968 400 340(FB),366(GTO) R,96,A(RA II) 2.11/1.77 71cc,rd port


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## Lithium (Apr 23, 2009)

I just found a pair of #14 heads from 1968. FRom what I could find they are 72cc heads correct? The guy only lives 2 hours away from me and has them on ebay. Since Im no expert could someone possibly look at the ad and tell me what you think. Im just hoping im in the right place at the right time Ill be going south tomorrow if thats the case. Appreciate any feed back


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## 68greengoat (Sep 15, 2005)

Lithium said:


> I just found a pair of #14 heads from 1968. FRom what I could find they are 72cc heads correct? The guy only lives 2 hours away from me and has them on ebay. Since Im no expert could someone possibly look at the ad and tell me what you think. Im just hoping im in the right place at the right time Ill be going south tomorrow if thats the case. Appreciate any feed back


No. Those are 90cc. 8.6 compression for 265hp. Small valves..... Do you have the link to the auction?

I'm guess they're these?

Pontiac 68 GTO #14 Cyclinder Heads :eBay Motors (item 110427434673 end time Aug-30-09 18:24:28 PDT)


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## Lithium (Apr 23, 2009)

Never mind just realized im looking for #16s lol jesus I been searching the internet to long on top of doing electrical work in the garage time for a break lol. Sorry for the mix up I think its all the 14 guage wire laying around here lol


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## geeteeohguy (Feb 2, 2008)

Lithium: I have a pair of 1970 Ram Air III heads for sale if your interested. 72cc, screw in studs, big valves. Number 12 heads. Have about 30k miles on them but I would recommend a freshen-up. They're 72cc's, and on my '67 GTO 400 bored .030 (406 cubes) they pinged like hell on 92 octane even with the timing retarded and with water injection. PM me if your interested. Green Goat, I've been running these cars in hot and sunny California for over 30 years, and have not been able to run a 72cc head since about 1988, when a local selling 94 octane leaded dried out and went out of business. Some of it's the heat, some the California fuels, but I've tried to run high compression for over 20 years without luck. Broke 4 pistons in my 428 from a ping I never even heard. I run booster in my '65, which is 10.75, but it's a stickshift with a huge cam. My automatic stocker '67 does NOT like 72cc. I ended up running some re-worked 87cc 1970 455 heads. My compression is around 9 to 1...maybe a little more or less. Car runs great on 89 octane. But, I have to tell you, back in 1983, on good leaded gas, with the stock, 72cc 670 heads on it, the car was a LOT quicker. In the humid, cooler Midwest or North, you may be able to pull off running more compression. But in 100 degree heat with less than 10% humidity, you need LOTS of octane!!


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## 68greengoat (Sep 15, 2005)

Huh. I guess I never thought demographics would play that much of a part on how an engine would perform. Altitude yes, but I didn't realize heat would too. Believe me, I don't doubt the issues you had/have for one second. I do know that when I would get caught out in a cool rain it seemed to wake up the motor. It seems to like moist air all right. For the most part we only have access to 91 octane. It seems to work well. Like you said, maybe it has something to do with the area we live in. I see Lithium is in Michigan. Maybe that will help too. Although, if it's lower MI, it can get dang hot down there. But, it's plenty humid at the same time. My inlaws live in lower MI and we visit them once a year usually in July. Most of the time we're sweatin' bullets. At any rate, it's definitely something to consider.......


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## Lithium (Apr 23, 2009)

I think geographics effects alot and Im in northern michigan about 2 hours from the u.p I can count the hot days on two hands this summer LOL. I would be really interested in them heads I will send ya a pm and thank you all for all the help I was driving myself crazy with the heads and engine I have but learned alot over the last 24 hours thanks again.


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## Lithium (Apr 23, 2009)

68Greengoat was reading the posts again my question is my engine block is a 1971 ys block came stock with 300hp do you think that will make any difference as I relooked at your post most the 72cc heads were on 300+ hp engines??


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## 68greengoat (Sep 15, 2005)

Lithium said:


> 68Greengoat was reading the posts again my question is my engine block is a 1971 ys block came stock with 300hp do you think that will make any difference as I relooked at your post most the 72cc heads were on 300+ hp engines??


All 400's , regardless of year, came with the same bore and stroke(I'm quoting '68 - '74). The block is a 4.120 bore x 3.75 stroke.
You would be crankin' alot of hp with the original 96cc 2.11/1.77 heads already at only 8.2 compression. I would think using 72cc heads would put you around 360hp. 

I plugged those numbers(96cc) in this calculator without the gasket thickness and piston cc's and it came up 9.5 compression. Apparently, that info is a must to get an accurate ratio since the original heads should be 8.2. I thought it would automatically put in default values if nothing was entered. It looks like it assumes 0 for piston cc's but nothing for the gasket(like there was no gasket installed). I have no idea on head gasket thicknesses to plug in a number to get an approx. C.R.

Engine Size and Compression Calculator

Your current 4x heads would give you 200hp, 230 if they're screw in studs.

As mentioned before, my buddy has 72cc(#16) heads pushing 360 hp on his 400 with no pinging issues on 91 octane. If he uses a lower octane, then he does have problems. There has to be alot of 400's with 72cc heads out there. I would like to hear if they're having any negative issues... Anyone?


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## Lithium (Apr 23, 2009)

Thanks wanted to make sure :cheers


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## 68greengoat (Sep 15, 2005)

Lithium said:


> Thanks wanted to make sure :cheers


I have a 455 that I plan on using 87cc heads which would bring it around 360hp. You could play it safe if you have any reservations and use 87's too. That should bring you somewhere between 300 and 360hp. I don't know exactly where, GTOguy should be able to give you that info. Not trying to confuse you more, just want you to make the right decision for your needs/expectations.....


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