4 bolt mains?

[oldsub86]

Do any of the factory small block engines commonly used in I/O's have 4 bolt mains? If not, is it worth looking for such a block when replacing the original?
Appears to me that it would offer a bit more support to the crank. A marine engine will most likely run at a higher rpm than most car or truck engines most of the time so it seems to make sense to build a better one.

Randy

[Bond-o]

Nope,... and No....
SBCs rarely have bottom end issues, the 2 bolt mains are Plenty strong enough to support 350hp...

[86 century]

It depends on who you talk to that has been debated for a long time in auto eng anyway. I used after market splayed caps witch makes a two bolt a four. http://www.jegs.com/i/Eagle/356/C4102S/10002/-1

[concordsteve]

2 bolt is fine for a stock motor but if you want to build a high performence motor I would go 4 bolt for sure.

[bifflefan]

Nope,... and No....
SBCs rarely have bottom end issues, the 2 bolt mains are Plenty strong enough to support 350hp...

True as you can get.
2 bolts are great blocks. 4 bolts are over kill for most aplications. Factory 4 bolts are not as good as you might think either. A 2 bolt block machined for 4 bolt splayed mains is way better.

If you want a 4 bolt i think the casting number is 010. Im not sure as i havent messed with a factory chevy block for many years.

[zbnutcase]

Some of the factory Merc performance packages used 4-bolt blocks, the 010 block described is a pre-87 2 piece main seal dinosoar,and a lot of those were 2-bolts anyway. Yup a 2-bolt block with aftermarket 4-bolt caps much better. 'nutcase

[wca_tim]

that being said... and safer is always better... but a carefully balanced / blueprinted performance engine with a forged crank is good to go with 2 bolt mains to well over 500 horsepower...

[concordsteve]

If your going to build a 500hp plus small block you would be a fool not to use a 4-bolt or a 2-bolt block with 4-bolt caps installed. High compression engines for sure. The new LS series engine has 6 bolt mains and are almost bullet proof.

[fabrimacator21]

If your going to build a 500hp plus small block you would be a fool not to use a 4-bolt or a 2-bolt block with 4-bolt caps installed. High compression engines for sure. The new LS series engine has 6 bolt mains and are almost bullet proof.

Yup... 2 bolts are good to 500hp......

Stock,,,,,?


....well, your crank is more likely to snap before your caps give out.

[dan t.]

there is nothing harder on a motor than oval track racing, average life of a motor is 100 hours or less, I used 2 bolt main blocks with cast cranks in all my engines, never had a crankshaft related falure and these motors were spun up to 6500 on a regular basis