Answered What Is A 4 Bolt Main Engine ?

XFIRE82

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You may of heard at some point in time the term 4 bolt main engine , so what exactly is it ? Some of you know , but for those who never seen one or know what to look for hunting at a swap meet here are some pics that give you a shot of what to look for. This is a 350 cube Chevy engine 1974 vintage. This is a bare block, but you can see 5 main bearing caps that would hold the crankshaft in place. If you look at the center 3 caps they have 4 bolts holding the cap down, the outside 2 caps have 2 bolts. If this was just the common 2 bolt main block then all 5 caps would have only 2 bolts each. But the stronger 4 bolt engine has the center 3 caps with 4 bolts each thus that much more holding the crank down in place.

IM003454.JPG
IM003453.JPG
 

hemicat

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LSx vs old school 350 differences

 
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Black 03 Z06

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Informative video Hemicat. Thanks for posting it.
 

LE BARON

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Excellent vid Hemi.
And here I had always thought that the main engine just had four bolts holding it and there was an auxiliary engine in the trunk for extended range.
 

Rruuff Day

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Excellent vid Hemi.
And here I had always thought that the main engine just had four bolts holding it and there was an auxiliary engine in the trunk for extended range.

:Funnypost:
Whats really scary Richard is when you rebuild a four bolt main engine and have five bolts, three nuts, four washers and two beers left over when you're done.
 

LE BARON

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:Funnypost:
Whats really scary Richard is when you rebuild a four bolt main engine and have five bolts, three nuts, four washers and two beers left over when you're done.
Yeah, having two beers left means you really didn't take enough time to do the engine properly.
 

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