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Discussion Starter · #1 ·
Hi guys,

I’m restoring in my garage a beat up 1979 firebird off eBay for £5k
I’ve put a 1972 front end on sprayed it black redoing interior and spending a lot of time In garage and yes my wife is starting to hate me!

The Motor I believe is an earlier 400 ci WT 0297501 1971 with 3 speed auto

The heads are the bit I’m not sure on all the external casing codes have rusted off

I can see a number 4 externally

650 cfm carb fitted

i think they are D shaped port

There is a cast number inside the valve cover K24 9780562

My question is are the heads from a 64 ? And what compression would it likely have? / horse power? Is it worth changing the heads? Or skimming them?

cheers
mark
 

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According to this page...

Pontiac V8 Cylinder Heads (wallaceracing.com)

Your head # corresponds to a 1965 set for a 326. The "4" you are seeing may be the casting date that corresponds to 1964, but probably made for 1965.

I'm not familiar with swapping heads from a 326 to a 400, so I can't help with that, but I can say that the '65 heads with that casting number have the smaller valves and could be greatly improved if you're looking to build better power. And, you should check the chamber size by measuring the cc's. This will tell you what kind of compression ratio they will produce along with the rest of the engine specs. Those were a low compression heads on a 326, but could be much higher on a 400...I just don't know, but someone here will.
 

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Head identification seems pretty striaght forward until you start looking at a second chart. For example, the page I posted before connects your 9780562 number to the number "62". This page...


says that a "62' head is...

68 & 69 GTO AUTO TRANS with 75 cc chambers, but does not give the valve sizes.

Bottom line is you have to take everything you know about the heads, check several charts, and boil it down by elimination.

Without more info...my guess is '65, 326 heads with 1.88/1.60 valves. Do your valve sizes correspond to this? If so, that's a good clue...if not, someone may have enlarged them at some point and they still might be the '65 heads.

Does your "4" show up where the date casting is?...

Rectangle Font Parallel Pattern Drawing
 

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Discussion Starter · #4 ·
Thanks for the help

The number 4 is above right exhurst port

With our taking the heads off and measuring cc’s valve sizes I probably won’t be able to find out true specs.?

I may just run her on the road and take to rolling road to get some HP figures and decide then what to do next. If it’s less than 250hp may look a striping down and redoing heads or change them, rings and top end refresh.

I will do compression pressure check first should be blowing 150 psi?

Really appreciate the advice there aren’t too many knowledge people to ask this side of the pond!

Cheers
Mark









 

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...With our taking the heads off and measuring cc’s valve sizes I probably won’t be able to find out true specs.?...
I do not know of any way to determine valve size or chamber size withuot taking the heads off.

...I may just run her on the road and take to rolling road to get some HP figures and decide then what to do next. If it’s less than 250hp may look a striping down and redoing heads or change them, rings and top end refresh...
You should get more than the 250 HP due to the block being a 400. Closer to 300 HP, maybe more. You nee to be concerned with the chamber size, at this point more than anything. If they are considered small chambers, they will require a much higher octane fuel. What little I have found on the cc's of the '65 "62" head are that they are about 70 cc's. That's pretty small to be running today's 91 OR 93 octane fuels that are available in the US. There is a fair amount that goes into determining the compression ratio of your engine, but given that your engine has been put together with mixed parts and none of them have been modified...I'd say your head chambers may be too small to run well on pump gas.

I'm no expert on the mixing of Pontiac heads, but the above thoughts should give you a lead on what to research and I am sure someone here will chime in with more confident head info. Not knowing what you have is the first hurdle, however.

...I will do compression pressure check first should be blowing 150 psi?...
I would consider 150 psi decent for a dry compression test. I'd like a bit more if the test was done wet, maybe 170. Near 150 psi in all cylinders, regardless of wet or dry, would mean a used engine, but not close to a rebuild. The key is that they are all close to the same reading...within 10 psi on either side of the median. Opinions vary on compression results, but the above is what I have found to hold well for the several V8 engines I have been acquainted with.
 

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Discussion Starter · #6 ·
Thanks Noel i just googled UK regular pump gas and its is 95 octane and the premium pump gas is 97

best use the premium 97 stuff and see how she goes?

not sure about burning the valves with unleaded fuel? I‘ll just run without any additives and see how it goes. Rebuild when it blows up!
 

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Discussion Starter · #7 ·
i could be wrong on the fuel I think they are the same octane US and UK

”In Europe, the octane rating on the pump is simply the RON figure. America, by contrast, uses the average of the RON and the MON figures, called the AKI (anti-knock index). Thus, 97 octane “super unleaded” in Britain is roughly equivalent to 91 octane premium in the United States.”
 

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Does the date code adjacent to the distributor on the flat confirm that it is a 1971 block? Pontiac was really fond of the WT code and used it in multiple years.

The heads have a casting date of K24 which would be November 2, 1964 making it a 1965 head, and I agree that the casting number says those heads were originally on a 326 engine. Those heads have very small valves and would be a bottleneck on a larger performance engine. The head would also have the early valve angle which would be at odds for the later 400 piston. Not a problem on mild lift cams but you could have valve/piston contact running higher lifts. The compression of 8.6:1 on a 326 becomes 10.44:1 on a .030" over 400 unless the previous owner went with dished pistons. A chamber size between 83 to 85 cc's with flat top pistons would be perfect for a .030" over 400 with 91 octane gas.

I see that polylocks have been installed so other changes have probably been made also.
 

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Discussion Starter · #9 ·
Does the date code adjacent to the distributor on the flat confirm that it is a 1971 block? Pontiac was really fond of the WT code and used it in multiple years.

The heads have a casting date of K24 which would be November 2, 1964 making it a 1965 head, and I agree that the casting number says those heads were originally on a 326 engine. Those heads have very small valves and would be a bottleneck on a larger performance engine. The head would also have the early valve angle which would be at odds for the later 400 piston. Not a problem on mild lift cams but you could have valve/piston contact running higher lifts. The compression of 8.6:1 on a 326 becomes 10.44:1 on a .030" over 400 unless the previous owner went with dished pistons. A chamber size between 83 to 85 cc's with flat top pistons would be perfect for a .030" over 400 with 91 octane gas.

I see that polylocks have been installed so other changes have probably been made also.
 

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Discussion Starter · #10 ·
So on the flat next to dizzy it has a large 75 stamped on and then smaller numbers 8285 so could be 75 block ? then number 481988 stamp led side ways a bit lower down. I’ve just been cleaning block and painted took off rocker covers to clean then up and noticed some mayonnaise on top of some of the push rods on one side and on valve spring caps ! 😢 Motor could be toast. It ran ok when started few months ago didn’t over heat or smoke bad. The I changed the oil The old oil was like piss not milky just really thin. I didn’t know if it had just been sat for few years and degraded / old owners had never changed it or had too much fuel ending up in the pan?

The new oil hasn’t mixed with water and seems clean and no oil in the water, no lost water. so maybe just some legacy crud? Hopefully it ok going to run it on the road when ready and see what’s what.

So desperate to have a go on the road can’t face any more set backs at this stage!

I really wanted a 350hp motor if it knackered or only good for 200-225hp I will get heads off and get measured properly. Maybe go for some refurbed heads or the aluminium performer ones from summit. Are the aluminium ones any good? Or better just refurbing some Pontiac ones?
I’ve got someone who can help says he should be able to rering hone with block still in car in put new bearings gaskets sort valves head etc
 

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Discussion Starter · #11 ·
So on the flat next to dizzy it has a large 75 stamped on and then smaller numbers 8285 so could be 75 block ? then number 481988 stamp led side ways a bit lower down. I’ve just been cleaning block and painted took off rocker covers to clean then up and noticed some mayonnaise on top of some of the push rods on one side and on valve spring caps ! 😢 Motor could be toast. It ran ok when started few months ago didn’t over heat or smoke bad. The I changed the oil The old oil was like piss not milky just really thin. I didn’t know if it had just been sat for few years and degraded / old owners had never changed it or had too much fuel ending up in the pan?

The new oil hasn’t mixed with water and seems clean and no oil in the water, no lost water. so maybe just some legacy crud? Hopefully it ok going to run it on the road when ready and see what’s what.

So desperate to have a go on the road can’t face any more set backs at this stage!

I really wanted a 350hp motor if it knackered or only good for 200-225hp I will get heads off and get measured properly. Maybe go for some refurbed heads or the aluminium performer ones from summit. Are the aluminium ones any good? Or better just refurbing some Pontiac ones?
I’ve got someone who can help says he should be able to rering hone with block still in car in put new bearings gaskets sort valves head etc
 

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I've seen that, on occasion, when I pulled valve covers off an older engine in the middle of winter. It looks to be condensation and nothing to worry about. Moisture gets in the valve covers, mixes in with the oily crud on the bits and pieces, then forms your mayo. The times I have seen this, driving the car more would make it go away. You know you have a real problem if your oil in the pan gets milky or your coolant gets milky...that's something to get worried about. I'd wipe it off and clean it up some, then run the engine more often...for 30-minute sessions in the driveway once a week or so, if nothing else...then check it again. I'd say you are fine.
 

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Wonder if the 8 in 8285 could be a B? That would make the date February 28, 1975. With the big 75 I guess it really doesn't matter since that identifies it as a 1975 block and the WT locks it in as a 400.

The moisture could be from you washing the engine compartment and the water ending up in the bottom of the pan waiting to be distributed next time you fired up the engine.

Aluminum heads are wonderful but a healthy outlay of funds, and in round numbers about twice that of refurbishing iron heads. The good news is they are new and ready to run and the performance of even "as-cast" aluminum heads start off about where nicely worked iron heads are done. Around my area you would be in for a total bill for iron heads about $1,600 with new valves, springs, and associated machine work, but before additional cost of having them ported for additional flow. You might find the iron heads you purchased don't pass magnafluxing and have cracks and you might be out the first cost, and again looking for suitable heads. Aluminum hits the budget hard at over twice that but pretty much a sure thing for bolting them on and running.
 

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Thanks Noel i just googled UK regular pump gas and its is 95 octane and the premium pump gas is 97

best use the premium 97 stuff and see how she goes?

not sure about burning the valves with unleaded fuel? I‘ll just run without any additives and see how it goes. Rebuild when it blows up!
Lucky dogs on that side of the pond to have 95 and 97 octane ! We have what I call corn water here 😂😂!!!! 😎👍
 

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Discussion Starter · #17 ·
I was in California a few weeks ago think we were paying $3.80 a gallon for regular gas

In UK now its £1.70 per litre so one US gallon = 3.8 liters so £6.50 or $7.82 per US gallon.. omg more than double thats terrible 🤮!

The government here needs all that extra tax tho its part of the UK managed decline agenda!

Can't wait to light up the rears tho when shes back on the road worth every penny when that V8 roars, hopefully its got a lumpy cam in and goes fast !

i'll borescope one of the spark plug holes later and see if it has dished pistons in the could affect the cc volume of heads
 

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Hi guys,

I’m restoring in my garage a beat up 1979 firebird off eBay for £5k
I’ve put a 1972 front end on sprayed it black redoing interior and spending a lot of time In garage and yes my wife is starting to hate me!

The Motor I believe is an earlier 400 ci WT 0297501 1971 with 3 speed auto

The heads are the bit I’m not sure on all the external casing codes have rusted off

I can see a number 4 externally

650 cfm carb fitted

i think they are D shaped port

There is a cast number inside the valve cover K24 9780562

My question is are the heads from a 64 ? And what compression would it likely have? / horse power? Is it worth changing the heads? Or skimming them?

cheers
mark
The engine code appears to be an early 1975 engine as the later 1975 engines had a different block casting number, so you have the better block. \

I would assume the heads are the heads that came with then engine November 1974. I see screw-in rocker arm studs which again indicate correct heads. Screw-in heads are a big plus and they are the large 2.11" intake valves. They should be the "5C" heads which have 99-101 CC chambers making the engine a 7.6 compression 185 HP 400CI. You can pee in the gas and it should run.

Stock specs for the cam show it to be the "067" - not a bad cam for that era/year engine at the time.

Get all the correct info for your engine and what you think you need to do a rebuild, IF you do it, and do not "assume" or listen to others who do not build/work on Pontiac engines regularly. They can very easily steer you wrong basing an engine build on a more common Chevy, AND, building a Pontiac engine is not inexpensive like a Chevy or Ford, so you want to have a build plan that meets your budget if you have a budget.

Educate your self by purchasing a couple books off our reading list of Pontiac books and materials.

(y)
 

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Discussion Starter · #19 ·
The engine code appears to be an early 1975 engine as the later 1975 engines had a different block casting number, so you have the better block. \

I would assume the heads are the heads that came with then engine November 1974. I see screw-in rocker arm studs which again indicate correct heads. Screw-in heads are a big plus and they are the large 2.11" intake valves. They should be the "5C" heads which have 99-101 CC chambers making the engine a 7.6 compression 185 HP 400CI. You can pee in the gas and it should run.

Stock specs for the cam show it to be the "067" - not a bad cam for that era/year engine at the time.

Get all the correct info for your engine and what you think you need to do a rebuild, IF you do it, and do not "assume" or listen to others who do not build/work on Pontiac engines regularly. They can very easily steer you wrong basing an engine build on a more common Chevy, AND, building a Pontiac engine is not inexpensive like a Chevy or Ford, so you want to have a build plan that meets your budget if you have a budget.

Educate your self by purchasing a couple books off our reading list of Pontiac books and materials.

(y)
 

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Discussion Starter · #20 ·
Thanks Jim I’ll try get all the info together
Once running if it feels slow I’ll look at a whole new top end set up
Pls Forward a link for books and I’ll buy a couple to get my head around it
If it’s a 185hp motor that motivates me to do an upgrade as lot of bang for your buck on the upgrade
Is a performance kit like below just bolt on and forget? I may just leave bottom end and put new heads cam headers carb on as a package kit. Less chance of going wrong if it’s as easy as plug and play ?
 
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