Thread: 427-454 build

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Can I use a 454 block to build a 427?

According to my book they both have 4.250" bores. The 427 uses a 3.76" stroke crank, and the 454, a 4.00". So I guess if you used a 3.76" crank you could do it.
Hope this helps.

Yes... this is what I run...

Used 3.76" crank from 396 in 454 block (+.060" on the bore makes 439")

-Chris

So you use stock length rods? 454 or 427 pistons? When the piston is at TDC will it be at the deck's surface or a .250 below? I've always wondered how that works. I know that both blocks are 9.80 deck height. I'd actually like to know too what other combinations I could use, i.e. 4.5" bored block. I understand it would have to have the 2 piece seal. I have a nice 427 crank and other big block parts to do another build.

Originally Posted by MyChev

So you use stock length rods? 454 or 427 pistons? When the piston is at TDC will it be at the deck's surface or a .250 below? I've always wondered how that works. I know that both blocks are 9.80 deck height. I'd actually like to know too what other combinations I could use, i.e. 4.5" bored block. I understand it would have to have the 2 piece seal. I have a nice 427 crank and other big block parts to do another build.

the only block that gm made that can go 4.500 is a bowtie or 502 block a stock block could go 100 over or 125 but then they are all used up and not all stock blocks should be cut out this far

Yes, same stock rods all 396/427/454 use same 6.135" rod... Use a 427(+) piston... the wrist pin hole is higher in the 454 pistons... with 427 piston you will be at ~ 0 deck. As for 4.5" bore that's cutting it very close... going that far on bore sonic check is a must and even at that you would need to fill the water jackets with block rock... generally I've heard .100 over is about the most you can go safely without filling the water jackets and even at that sonic check is required... I have heard of instances of .125 over (4.375" bore) but you will be very lucky to find a block that has enough meat for that.... not to mention you're no longer looking at off the shelf pistons (.030, .060, .070, .100 over)

All this is supposing a factory block, not an aftermarket (Merlin, Dart, etc) which can handle much larger bore...

I'm definitely not the expert on this, many others on here can give you better info but this is my experience...

-Chris

SKIDS72
Thank you very much for the info. When I mentioned the large bore I was thinking after market. I'm just want to kick a few ideas around. Sounds like your engine works pretty well. The shorter stroke gives quick revs. I just built my 454 .030 over and will test it next weekend, hopefully I did everything right. I took my time and did a lot of research.