TAC Tech => Number Crunching => Topic started by: 81Resto on April 30, 2024, 04:14:34 PM
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I have been searching out a Pontiac 400 block. I had a couple of near misses, responses saying it was just sold. A new one popped up and talking to the seller, he gave me a casting code of 039962 and y4.
I know y4 is an engine code but can't seem to find out what the other number means. I looked on some websites thinking he sent me a wrong number, it doesn't match what I can find for heads, intake manifold,
exhaust manifolds... For the hell of it I put it in google and the AI part of the search said it is a sbc. So I found some other websites for chevy and cannot find the number there either. At this point
I am just curious. Also looking to avoid the 500557 blocks based on advice from some books I bought about building a Pontiac engine.
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Not sure where they got that casting number from but it is not for a later built pontiac 400.
The 400 block you want is casting number 481988. You can use the 568577 or 500557 block but it's not as strong as the 481988.
The 557 block is good for 450-500 hp.......still usable if it's the only thing available.
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Thanks for the reply. I think I am going to steer clear of this one. I got another picture with 500813 code which is for a 455 with 2 bolt mains, but it is being represented as a 400 with 4 bolt mains.
With all the conflicting info I am getting, I think my best option is passing at this point.
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I have not looked up the block codes, but there were 455 blocks with four bolt main caps that may not have been documented, therefore, few would know about. I bought a thrashed '70 455 auto Bonneville for a 455 to build back in the mid 1980's. Block and engine codes both indicated a standard low performance 4bbl 455. I drove it home and removed the engine and 400 auto trans. Sold the turbo 400, junked the body and frame after removing other usable parts. I started disassembly by removing the entire top end, nothing special there. Rolled it over and pulled the oil pan to find 4 bolt main caps and a nodular iron HO crankshaft! It did not appear that the engine had ever been removed from the car or even opened up for service for that matter. I can only assume that when being built those parts were on the shelf so they used them and assume other anomalies may also exist from that time period. A quick bore size measurement may be in order before passing on it as a builder. I couldn't have been happier with the way mine performed.
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Just an FYI, I am running a 500557 block in my car, runs like a banshee, bored .040, forged pistons, roller tip rockers. Used existing crank. Engine was built back in 2009, still running strong! Depends on what you want to do with it. On paper, motor is pushing 400 - 450hp.
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I think the 557 block has a much worse reputation than it deserves. Buttler Performance uses the 557 block in builds up to 450 or 500 HP, I don’t remember which. Obviously there a lot of variables that come into play when building an engine other than just the block. Probably just as important to have it done by a competent shop.
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Absolutely. Half the guys going around posting online about avoiding that block then source the other block and build their 250hp monster.
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Yea, I’m no engine guru but if butler comfortably builds a 557 to even 450hp I’d have to imagine they leave room for error to speak meaning those blocks will probably handle a little bit more. They wouldn’t build one to its absolute limit. Most street builds are less than that.
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I think the 557 block has a much worse reputation than it deserves. Buttler Performance uses the 557 block in builds up to 450 or 500 HP, I don’t remember which. Obviously there a lot of variables that come into play when building an engine other than just the block. Probably just as important to have it done by a competent shop.
The shop that did my motor work was aware of the 557 reputation. He said yes, it is a weaker motor but, he said, done right, he could push that block to run 600hp without issue. He said while you don't want to build a quarter mile beast with it, you can build a very nice street machine.