 Jim.Biron
"6th Year" Platinum Supporting Member
Posts: 2288
Age: 62
Loc: Saugerties, NY
Reg: 04-10-08
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12-19-08 06:15 PM - Post#1588566
I'm about to pick up a 454 casting # 361959 (4 bolt from 1973-85) I understand this to be a 4 bolt main block but I wondering about the heads that may have come on it. I'm told it was pulled from a 1 ton pickup. Is there any way we can guess at the heads casting, port (peanut, oval) or valve size that would be likely to have come on the block without pulling a valve cover?
Also what would we guess the compression ratio to be? Is there any way we can make a guess about that? I can't remember... Is there an easy way to get a date and back into compression ratio given that?
One more question... since I'm told this has been recently rebuilt/refreshed if I want to keep the internals and just replace the heads how do I know which combustion chamber size I need assuming the internals are stock?
(I realize different sizes mean different compression ratios but what I'm getting at is if this is a truck 73-85 block what would that std piston size make in a 113cc head for example.That would give me an idea as to what to replace the heads with it they are really bad peanut port heads. Which is my assumption.)
Of course as with many of these questions there is not a lot of data to go on right now so I'm just looking for comments and ideas.
Thanks!
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Impala65SS
Valued Contributor
Posts: 3354
Loc: Sweden
Reg: 08-23-07
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12-19-08 09:55 PM - Post#1588652
In response to Jim.Biron
Ask the seller!
Date code on bell flange: 4 signs. Day (digit 1-31), month (A-L), year of the decade (0-9).
VIN-code on block deck pad under alternator - 2 or 3 letters check them here
Ask for casting number and date on the heads too.
My 460 block is a #959, but the 2bolted variant.
It came out of a 1978 suburban with measured combustion chambers 123-126cm³ in the #236 heads and cast symmetrical pistons with slight dome and symmetrical intake valve dish. Somewhere "they" said that engine was 8:1. Could be right. I'd say you need closed chamber heads with hardened exhaust seats. No use building an engine under 9:1 unless it's supercharged I'd say.
I'd save those 236 anyway because you wont get much money, better to use as a back-up or assemble another engine when the opportunities for good cheap parts turn up.
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Jim.Biron
"6th Year" Platinum Supporting Member
Posts: 2288
Age: 62
Loc: Saugerties, NY
Reg: 04-10-08
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12-20-08 07:15 AM - Post#1588765
In response to Impala65SS
Ask the seller!
Date code on bell flange: 4 signs. Day (digit 1-31), month (A-L), year of the decade (0-9).
VIN-code on block deck pad under alternator - 2 or 3 letters check them here
Ask for casting number and date on the heads too.
My 460 block is a #959, but the 2bolted variant.
It came out of a 1978 suburban with measured combustion chambers 123-126cm³ in the #236 heads and cast symmetrical pistons with slight dome and symmetrical intake valve dish. Somewhere "they" said that engine was 8:1. Could be right. I'd say you need closed chamber heads with hardened exhaust seats. No use building an engine under 9:1 unless it's supercharged I'd say.
I'd save those 236 anyway because you wont get much money, better to use as a back-up or assemble another engine when the opportunities for good cheap parts turn up.
At this point I can't get the valve cover off (the motor is buried in a garage not easily reached... long story).
So, here's the next question. If the heads are the peanut port 236 heads and they have a 123-126 cc volume AND I want to go with a 113CC (or some other volume) how can I tell what the difference in compression would be? Is there a calculator for that somewhere?
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fritz1990
Senior Member
Posts: 6068
Age: 51
Loc: Kansas
Reg: 02-16-03
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12-20-08 07:31 AM - Post#1588777
In response to Jim.Biron
Here is a compression calculator to play with. I punched in some numbers and came up with about a .5 compression increse from 122-113 cc heads. This is assuming head gasket thickness and deck height were the same with both head cc volumes. Play with it and you will see, just change one variable and it will show you the difference. Most 454's are gonna be at 7.8-8.0 range tops stock.
If it came out of a 1 ton more than likely it will be the 236 heads. I have a 959 block from a '79 1 ton and it is 2 bolt and had the 236 heads.
Also what color is the engine? That will narrow the year down assuming it hasn't been rebuilt. If it is orange it won't be any newer than '76. I had a '77 C10 with a 454 and it was blue. There may be a few '77 that are orange but this is about when GM changed colors.
http://www.cswnet.com/~carother/compression _ratio....
Regards, Jeff
1998 K1500 6.5 Coal burner
1965 C10 with 498 BBC AFR Heads
1964 C10 Ran 348W for 6 years, now SBC.
Corvettes owned: '74 L48 '77 L82 '78 L82 Silver Anniversary
Don't have a nervous come together!
http://picasaweb.google.com/fritz199090
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Edited by fritz1990 on 12-20-08 07:37 AM. Reason for edit: No reason given.
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