For Sale: (1) Bare Standard Bore 4.1 Block

[RealestVIN7]

Right on joe_schindler. Thanks for clearing some of that up. I second the vote that someone should have fun with this block.:biggrin:

I have standard bore 109's for $225 plus shipping as stated above.

Thanks.

-Andrew

 

[fbodlovr]

I wish someone could tell me the advantages/disadvantages of both a 109 and a 4.1 block. Im not trying to hijack his thread, I want a block, just dont know which one I would want.

Can this block be machined so that you can put 4 bolt mains in it?

 

[RealestVIN7]

You don't need 4 bolt mains. Just do billet main caps and a girdle. You might be able to splay the caps though. I really don't know. It's up to you man.
-Andrew

 

[joe_schindler]

If; you start with a 3.8 109 block:

Advantage of a 4.1-

You can’t bore a 3.8 up to a 4.1 –> more displacement = more power at not much cost increase (pistons may cost a few dollars more each). 20 cubic inches doesn’t sound like much when you say 20; but a 10% increase in displacement is significant.


Disadvantage of a 4.1-

If you have an ’84 or ’85 and your garage floor is littered with 14 bolt pan stuff -> no disadvantage.

If you have an ’86 or ’87 and your garage floor is littered with 20 bolt stuff -> you’re gonn’a have to find a pan.

If you’re looking for a weak link in the 4.1 or 3.8 over the other; they are the same design. The 3.8’s will crack at the bolt holes also; just not quite as often. The cylinder walls are about the same thickness; but I’ve found the 3.8’s are often a little thinner. Probably to reduce weight on production cars. 4.1’s went in Cadillacs and big Buicks where weight wasn’t going to matter. The 4.1’s might even be a little stiffer because of the additional cast in ribs.


This worked out for me because I had a floor littered with 25 years of Buick crust. I took my time and accumulated the parts I needed and had a good machine shop bore the block and balance the innards. I don’t push it too hard; and I have lots of fun. I know I’ll never make any money off of this engine at the tracks; but it is fun to embarrass the occasional Corvette with an old single exhaust Buick that needs a paint job.

If you’re planning a two year build; you might as well start with something big to begin with.