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ashbros 02-03-2009 07:15 PM

? 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.

nofear57 02-04-2009 11:56 AM

GM Performance Parts books say 4.500"

coloradoracerguy 02-04-2009 04:11 PM

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


hammertime 02-04-2009 06:23 PM

Have on thats 4.625 thats limit

RonOwensRacing 02-06-2009 08:23 PM

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 .

Tod74 02-07-2009 12:26 AM

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

fishmanjoe 02-08-2009 07:37 AM

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

hammertime 02-08-2009 08:12 AM

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.

Tod74 02-08-2009 08:34 AM

Nevermind I misread the post. :oops:

tcarda 02-08-2009 10:39 AM

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?

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