? Maximum Bore 454 Bow Tie Block
 

I have a Mark IV Bowtie Block 454 Hy Per Series 9.8000 Deck
Numbers on Block are:10051107
4 Bolt Main
9.800 Deck Height
Siamesed Cylinders,

Anyone know what the Max Bore Size is on this block.

GM Performance Parts books say 4.500"

I had one that I bored to 4.600. Thinest cylinder wall after sonic check was .385". 4.625" is max safe.

Mark

Have on thats 4.625 thats limit

I don't think i would even try to take it out that far i had one and we bored it out to 4.460 and went thru on one cyld. and the four corners went to 4.500 .
so we went back sleeved them and i got another set of pistons and redone it .

Wow I think I'd sell it and get a Big M or Merlin that is already 4.5 then you have room for some rebuilds. JMO

you will be taking away the shelf life of that sbc if you go boring it to the max.If I were you if you want big inches,go big block.FISHMANJOE

hmm a bit confused a gm bowtie block is used as much as dart/merlin around here for 540 + builds and tall decks are very common to use for 632s for ts/td guys. The block is good and less money then a dart.

Nevermind I misread the post. :oops:

I have the same block and casting number, but mine started as a 502 and now it is a 540. How much hp can these Bowtie blocks handle?