i just took my block to a local high performance machine shop. the guy said my cylinders were fine except that they were tapered .005 an inch below the ridge. The ridge cannot even be caught on a fingernail, so theres not much ridge. Will this require boring to .030 over or can i just do a light hone and use the stock standard sized pistons?

thanks

 

You should be able to just light hone it and use stock bore pistons.

 

i don't have a manual sitting here but i beleive the spec is .003 taper or out of round, so if that's the caes you need overbored. the size of the ridge has little to do with the condition of the holes, other than being a wear indicator, or in other words the ridge isn't why you over bore. then again if you leave a ridge the top ring will crash into it when the piston comes up. if i don't bore a block i at the very least use a reamer on it to get the ridge out, and that's not 100% effective.

 

.005 is way too much wear, it nees to be bored oversize, but you may be able to only go .010 or .020 and save the .030 for a future rebuild.

 

I agree with deepstage69. Give it a good hone job and save your money. And by all means get what little ridge you might have out before installing the pistons.

 

If it's all apart and you have any uncertainty about the cylinders I would go ahead and just bore it--chances are you won't every have to do it again.

 

It's good to know the taper, but what about out-of-round? Typically, tapered bores will have roundness issues too.

0.005" taper is way out of spec, and you'll likely have some slap on a cold start. Personally, as long as the case is at the machine shop, I'd bore it to the next nominal oversize and enjoy the extra cubes. Ask them to use a torque plate when boring.

SBC pistons (and ring sets) are available in 0.005, 0.010, 0.020, 0.030, and even larger oversizes. 0.010" seems to be a common selection, and cast piston sets aren't that expensive.