gm bowtie sportsman block
 

any one here have or used a gm # 12480174 bowtie sportsman block with good results with a new modded full rebuild ?
they are a single rear main seal block and have siamese bores that can be bored succesfully and safely out to 4.155 " if needed.
there quite expensive though by the look but iv got a new 3.75" forged lite weight s/crank and canton 7 qrt race pan also both to suit 1 prms.
iv got some probe forged lite weight flat top pistons .60" over size to take it out to a 388 c.i.


tia

I ran some 400 blocks with siamese bores & had to drill the heads for steam holes.
They are about 40# heavier than a standard 350 4 bolt block.

I have a fresh 400 block ready to go if your interested. Bored .030, decked to 9" & line bored. Its a 2 piece rear main seal block. Use main bearing spacers or bearings designed for a 350 journal size arm in a 400 block if you want to go that route. Its 377 cu in with a 350 (3.48 stroke) crank. Will include a new set of flat top pistons for a 350 stroke crank.

406 cu in with 3.75 arm.

700.00 OTD.

I am using one, and my engine builder who is on this forum has used them many times. They are known to support over 1000hp.

My motor isnt done yet, but I certainly have no concerns with that block. It's pretty kick azz!

I bought mine for about $1500. I didnt think that was a bad price for what you are getting. I believe they weigh about 30-40 lbs more then the factory block.

thanks for your offer and info but im happy with the parts i already have.:thumbs:

mseven just built one, came out pretty nice.

ok then,cool.

http://forums.corvetteforum.com/show...112&highlight=

nice buildup

This is from John Lingenfelter's book:

"The major Bow Tie block improvements over stock involve the use of high nickel content cast-iron, thicker cylinder walls and deck surfaces as well as a number of other changes that make the difference between compromising with a production block and using the casting that championship drag racers and NASCAR stock cars win with every weekend. How strong are these Bow Tie blocks? I've been able to coax over 1400 hp from a Bow Tie block with no durability problems."

We have machined a few of the GM Sportsman blocks and they seem to be really a good peice good chioce:thumbs:

thanks fellas :thumbs:

It's definetely a good block and I am a fan of a 1 peice rear main. I think msot of it depends on what you ci. you are building and your budget, as there are some other good choices out there.