Thread: 454 2bolt hi-po question

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Hello all, I am new here.. I had a good question that is irritating the ever living hell out of me. Hopefully I can get some good insight and knowledge from you more experienced mechanics.

I am currently rebuilding my 454, Now I checked the casting number through Chevy and the block casting came back as a 1969-1973 block year 454 engine.
I sent my block to a machine shop a few days ago and I had just recently called the shop back, and they told me I actually have a 396 bored .030 over... Now that cant be, because the pistons I pulled out where 454 pistons stamped with a .010 over bore... I was told that some 396 blocks were cast with the same casting number as the 454 in that year range.. But still the piston size and bores just don't add up. Any ideas on whats going on? I personally think the machine shop is trying to pull a quick one on me and swap my block out for some block they had sitting around for ever. Now I did stamp a mark that only I know into a certain place on the block.. But still, Any ideas on the piston and block??

sounds like its time to take your pistons to the machine shop and look for your secret mark---------

I smell a rat.....

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Good one, Tech, yessindeedee.

Go ask to see your block and after they show it to you, tell them about your mark and watch their faces. I recovered a stolen manifold and set of carbs that way once; when I mentioned the marking I had done to the manifold and carb bases, the guy just about fainted.

I am going to the machine shop today. I have one of my pistons with me, and I will be doing some digging there. And yes I will be looking for mark.
Thank you Gents for responding, I'll keep you all updated.

double post due to slow internet...

So I checked the Casting number and the years are right, BUt what I got online through Chevy is wrong with what the Actual Book number has, SO it is a 396 bored.030 over too a 402. Its sad, I checked my mark and sure enough it was my block.
My heads on the other hand... Apparently they need to be reworked with the valve guides and seals..Because one head is loosing compression. But I never noticed an issue with power loss from that and that's more repair money I don't have. SO they will stay like that because I honestly don't think that is affecting my motor. I don't want to pull a pair from a yard as I like my Oval ports, and if I do pull a pair they will just have to be reworked anyways. Good news is they are 454 heads. Sooo time to save up some more money for an unexpected repair..

If you have to rebuild your heads, consider buying a set of new aftermarket heads instead; you might find you will be money ahead that way, believe it or not.

why not check out having your heads rebuilt??

nothing great about 454 heads on a396/ 402 you will need i big dome on the 396/402 to get any CR. what many did was put the small chamber 396 heads on a 454 with a flat top pistons worked out very well

I have slight done pistons, and I would love to get new heads, or get my heads redone, but that costs money annnd I spent the last of mine ordering rings, and Bearings.

If the money's not there then the heads wait, but know in the back of your mind that they're costing you power and efficiency by leaking compression and start saving a few $$ as you can for new ones, and watch your CraigsList religiously. You never know when someone might turn some loose whey they need a few bucks quick.

Is your avatar picture recent? Cute kiddo!

Originally Posted by Imbraced

I have slight done pistons, and I would love to get new heads, or get my heads redone, but that costs money annnd I spent the last of mine ordering rings, and Bearings.

396/402 most all had small dome on the 325 hp 396

What EXACTLY do you mean by losing compression??????head gasket leaking? valve leaking? cracks??


If your on a low $ budjet rebuild, have vales/seats refaced,maybe resurface deck surface---put it together and drive it---


Maybe post the casting numbers here and some pics of the piston or complete info as to numbers/manufacturer---seems like there's quite a difference in what you have compared to what you think you have----IE---you won't get a 454 piston into a 396 bore--------

Why not just sit back and wait on the heads??? Budget builds do not have to be done in a hurry, nor do high dollar builds! It usually works out far better to take your time, save up a few more $$$$$$, and do things correctly the first time!