Autopendium :: stuff about old cars

Tags: engine oversize pistons rebore rebuild

I finished off the disassembly of the 350 two-bolt on Friday, and took a bunch of measurements (rough ones, since it was only with a pair of callipers) to try and get a better idea of what I was dealing with.

Over the weekend, I then had a look through the two books I was using to check out the measurements and what to do next (a very old copy of How to Rebuild Your Small Block Chevy and a slightly less old copy of How To Build The Smallblock Chevrolet. For the record I found the older book explains the background a bit better, but the newer one was better as a step-by-step).

The upshot, confirmed by the machine shop today, was the the block had been already bored out to 0.040" oversize, and would need further boring out to put it in a good way. The crank main journals seemed to be about 0.010" undersize, ditto the rod journals, and though the crank could be reground, it'd probably be more expensive than finding a good condition used one (i.e. one that didn't need regrinding), assuming one's available (and we think it might be).

So next step is to order a set of 0.060" pistons and rings, together with the bits for the valve train, then we're good to go. One the plus side, the heads have now been disassembled, and seem OK, and I've decoded the cam -- a Comp Cams Magnum 280, which is not bad at all, particularly as it seems in good condition.

One thing I should mention, I decided (somewhat arbitrarily) to try to keep the budget for the rebuild to £500 (including shop-work and parts). Two reasons for this -- one, the cost of the Amazon, which left the budget behind on the start line some time ago, and, two, it would be an interesting test to force me to use elbow grease and ingenuity rather than cold cash.

It's going to be tight, but so far there are good signs, not least my plan for a crank (more on that if it works out). However it does mean I'm going to do some hard manual work degreasing the heads and block rather than paying for it to be hot-tanked. A false economy? Time will tell.

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