4 Bolt Main vs 2 Bolt Main

HuskieMobileMan · May 30, 2006

This may sound like a stupid question, but what is the difference between the two, what is it referring to, and how do you tell which your vehicle has? Thanks!

silveradoHO · May 30, 2006

This may sound like a stupid question, but what is the difference between the two, what is it referring to, and how do you tell which your vehicle has? Thanks!

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This refers to the number of bolts on the main bearings of crank shaft. 4 bolt mains are a little more heavy duty.

snoman · May 30, 2006

This may sound like a stupid question, but what is the difference between the two, what is it referring to, and how do you tell which your vehicle has? Thanks!

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This refers to the number of bolts on the main bearings of crank shaft. 4 bolt mains are a little more heavy duty.

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This is true but the need for it is kinda over rated for most consumer uses. Unless you reve past 6000 RPM a lot and are pull more than 400 HP at those RPMs too, the 2 bolt block will work fine. One other exception would be if you plan to boost it a lot with a super or turbo charger in which case it would be wisest to use a 4 bolt main block with a forged crank if you are building one up for this.

HuskieMobileMan · May 30, 2006

Thanks guys. How would I go about determining which my van has?

Supercop8100 · May 31, 2006

Engine block number.

enduro74 · May 31, 2006

well i'll take a 2 bolt over a 4 bolt any day.

Shocker · May 31, 2006

well i'll take a 2 bolt over a 4 bolt any day.

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Just curious, why? Are there some advantages of a 2 bolt over a 4 bolt?

snoman · May 31, 2006

Engine block number.

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Below is a link to a site that has a lot of info on GM casting numbers

http://forum.snoman.com/viewtopic.php?p=216

bigdogxx · May 31, 2006

well i'll take a 2 bolt over a 4 bolt any day.

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Your pretty much the only person ive ever heard say that.Like the other guy said why, i always thought a stronger bottom end of a engine was a good thing.

Are the new gen 5.3 blocks like the one in my silvy now 6 bolt mains i thought i remember hearing that about this engine.

silveradoHO · May 31, 2006

well i'll take a 2 bolt over a 4 bolt any day.

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I've never heard anyone say that before. While 4 bolt mains are not necessary for most street applications, they are definitely better for high hp motors.

Supercop8100 · June 1, 2006

That 2 bolt over the 4 bolt statement is rediculous. Do you know ANYTHING about engines? Why take a 2 bolt main block over a 4 bolt main block? Its the SAME block, ONLY STRONGER.

Duh.

Any heavy duty truck you find will 95% likely have at least a 4 bolt block.

HuskieMobileMan · June 1, 2006

In a somewhat related question, which type of rockers are better, roller or non-roller?

snoman · June 1, 2006

In a somewhat related question, which type of rockers are better, roller or non-roller?

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Roller because they can allow for more agressive cam ramp angles and higher spring pressures and they also marginally reduce internal friction as well.