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4 bolt main or 2 bolt main


Well-known member
Nov 17, 2002
81 dark metallic blue/camel leather
:confused Ok I have gotten several differant opinions on this:eyerole Does an L81 have a 2 bolt or 4 bolt main bearing engine;help We all know in 81 there was only one engine, so who knows the real answer? :CAC :Steer

The L81 has 2-bolt main caps. My original L81 block is in my garage with the oil pan removed. I can see that the main's caps are 2-bolt type. Also, I found in my 1981 restoration package (page 5) of the specification panphlet "No. bolts/main brg cap...2".
2 bolt or 4

thanks, I just came in from the garage wondering the same thing.

4-bolt main engines are appropiate for the increased RPM (6,500 - 7,000 RPM) and horsepower (above 500 Hp) they can withstand.

2-bolt main engines are suitable for engines producing up to 400 -450 Hp and do not see operation near the 6,000 rpm mark commonly.

And by the way, I am not trying to initiate a debate. There are plenty of exceptions to this general rule.

This still well above of what most of us would like ;) for a motor in our daily drivers or even sunday cruisers; however, once the Horsepower fly bites you, then you'll find yourself constantly trying to increase the horsepower count in your engine.

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