when does this become a need? im building a 396 and need to know if i need it or not.

whats the extra machineing cost?

can i have my caps machined or do i need to buy some milidon or some other brand? thanks guys

 

When you want/need to turn over 7k rpms when racing or on a fairly regular basis is when 4 bolt mains will become a necessity. I'm not sure of the machining costs, but some of the machine shops around here don't have the tools to convert a 2bolt block to 4 bolt. But the least you can do is use ARP bolts throughout the engine. That alone will strengthen the bottom end some.

Jason

 

I would do 4 bolt splayed mains if you were doing a power adder like nitrous or a blower.

I have 2 bolt mains on mine which are fine for N/A applications.

I think it costs about $400-500 u.s. for the machining and parts.

 

can i just machine my caps or do i need to buy aftermarket ones?

 

There are a number of people who prefer straight 4-bolt caps to splayed when used on a stock block.

Yes, the 4-bolt caps are new, not 2-bolt caps with extra holes drilled. If you look at http://www.sallee-chevrolet.com/Chev.../10185047b.jpg you will see straight 4-bolt caps on the 3 center main bearings. At the end is a 2-bolt cap. You can see how the 2 bolt and the 4 bolt are quite different. 2-bolt caps are used on the ends and 4-bolts may be used on the 3 middle positions. Here's a splayed 4-bolt and q 2-bolt intermediate cap. http://www.flatlanderracing.com/gm/14011072.gif, http://www.flatlanderracing.com/gm/14011052.gif.

I use straight 4-bolt caps.

Rich Krause

 

thanks a lot Rich. this may be a stupid question but can i not use 4 bolt caps on all of them or do i have to use 2 bolt on the ends? i may end up going over board for what i want but better safe than sorry.

 

With a stock block the end caps use 2 bolts and the three middle main caps may be 2 or 4-bolt.

Rich Krause

 

I could be wrong but I beleave the 2 bolt blocks have to use the splayed cap and not the straight ones. This is because the 4 bolt blocks have additional material on the web under the outer bolt for the bolt hole.

 

All LTx blocks are the same. The blocks in Corvettes had iron 4-bolt caps installed at the factory. But the blocks are identical to the blocks installed in F-bodys with 2-bolt mains.

Rich Krause

 

A buddy who has a 73 Camaro with a strong 355 was doing some research and heard that older Chevy small blocks with factory 4-bolts had more material in the web area and that converting a 2 bolt block over to 4 could actually weaken the web area. So this is not true of the LTs? I am planning on running the straight 4 bolt caps but was worried after hearing that info. Thanks!

 

A number of different castings have been produced over the years. I am no expert on classic Chevys, so I can't comment on the old blocks. But the LT1/4 castings all appear the same.

Rich Krause