4.3 from a 291?

Joined
Oct 30, 2009
When I bought my car it was sold as having been bored out to a 4.3L. I figured that the owner was just mistaken (he wasn't the type to lie) and I call it a 4.1

It does have a 4.1 291 block.

I have decent records on the car. The motor has been rebuilt twice. Once when it was installed to replace the 3.8 and once when the guy I bought it from spun a bearing.

I have a receipt for 6 "4.1 +30 Buick pistons" from the first rebuild.

The second rebuild (at Conley's) is just listed on the invoice as "OEM rebuild" but there is also a "Crank-GM" listed @ $599. There is no info on pistons or bore. The guy I bought it from said he thought they were diamond pistons, but it had been 13 years since the rebuild so he couldn't recall.

Before I bought the car, I did the math (not an engine builder, but I am decent at geometry) and with stock stroke (GM crank implies stock stroke to me) there was no bore that would give me 4.3L

I bought it anyway. I paid less for the car than he spent in the two Conley's receipts.

I was reading my Kirban's guide the other day and I noticed that in Conley's section (pg 338) he states 4.1's can be bored and stroked to 272 ci (4.46L)!

So is it possible that I have a 4.3 with a GM crank?

I love it, whatever it is. After some major help from a local Buick club member, it runs like a raped ape and it sounds beefier than a lot of V8's :D

I know nobody can give a definitive answer, but I am interested in anyone's input.

Thanks for reading my lengthy post :D
 
4.0x4.0x3.48x6x.7854=262 which is a 4.3 for sure. And that is for the Chevy V6.
 
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