Quote:
Originally Posted by burnin oil
You can either reuse the stockers or switch to standard 5.7 rods as mentioned. I would let budget and piston selection guide this. The difference is only .05", 5.65" vs 5.7".
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I think you missed a number there didn't ya.. 5.565" not 5.65 There just slightly over 1/8" longer, but that's 1/8" at top, at bottom and the sides. With the 3.75" stroke and even some stock 5.7 rods you will be spending time with a carbide burr making clearance for things to rotate.
Issue with the 5.7 or 6" rod in the stock 400 crankcase is clearance inside the block, AND clearance between the rod bolt shoulder to the cam lobes depending on which cam / rod combination.
There are engine 'builders' and engine 'assemblers'
When you start changine and mixing strokes / rods etc... I'd highly suggest you consult a engine BUILDER. To be CLEAR!!! I don't mean this as a slam to anyone,, any post or anything mentioned here... but simply put,
You will find the engine 'BUILDER' in his machine shop,, the engine 'assembler' in his backyard. The beauty of the SBC is parts and pieces from 50 years of configurations will 'fit' in a donor block. The bad part of the SBC is 50 years of mis-matched parts and pieces will fit in a donor block. Be cautious, KNOW exactly what every component is that your dealing with, and ASK QUESTIONS if your not perfectly clear on what you have and what your doing.
All that said,,
Your FIRST step is to get the block to a COMPETANT machine shop and have it checked 10 ways from Sunday! 90% of the stock 400 castings are nothing but scrap metal.
Cracks from the bolt holes to the bore are very VERY common, and many times can only be seen after the block is decked.
The 400 casting is a thin wall casting to begin with. Anything that is already + 0.030 is ALL DONE!!! +.040 and .060 on a production 400 block is total FOOLISHNESS
Main webs for the 3 center main bearings are notorious for cracking. A HUGE problem in the 4bolt blocks (is why GM discontinued the 400 in 4bolt configuration in 72) but the 2 bolt blocks are not immune by ANY means.
I've pulled numerous 400's apart that had cracks in the lifter valley up against the sides (coolant jackets) Was typical when someone ran them low on coolant to overheating, then pulled into the filling station and poured cold water in the radiator.
All that just to say there is lots of inherant issues with the 400 that you don't readily see without a THOROUGH inspection by a competant machinist.
Have it baked clean, jet washed, inspected, mag'd, and I always pressure check the block before spending one red cent of machine work, or wasting dreams on a parts list.
If you want a guarenteed 400 casting,,, break the penny bank and look into a SHP / Motown or LittleM block. THEN you have a solid platform to build on,, but the budget gets busted all to crap!!!