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Discussion Starter · #1 ·
What is the going rate in your areas for SBC to be line bored not honed it does not have original main caps. Im in north georgia and have been quoted from 150 to 300?
 

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What is the going rate in your areas for SBC to be line bored not honed it does not have original main caps. Im in north georgia and have been quoted from 150 to 300?
It really depends on how much time fitting caps. You may have to go through quite a few rear caps to find the correct one as GM does not machine the same hole twice in the same spot That being said its time consuming to say the least. The rear cap has to be pretty much a perfect fit or you will have a rear main seal leak.

Same with the center caps its hard to find to fit as side to side seem to be different between blocks or should I say when the registers are cut.

If the block is a special block the best bet is to install billet caps on the first 4 locations.

The finish should be line honed not line bored.

Before you spend a lot of money on machining caps you should have it sonic tested for cylinder wall thickness and go from there.
 

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Discussion Starter · #3 ·
The rear cap is original it was the only one on the block when I got it. I had it sonic tested,pressure tested and cleaned everything was good there. The guy at the machine shop said there was a few pits in the cylinders he was worried it would not clean up but to 60 over but wouldnt know till he tried. I hit all the cylinders with a hone when I got it back and the pits do not seem very bad at all to me cant really measure tho I would thank 15 thousands would clean them up but thats just a guess. I have another set of main caps for it but I thought to fix the caps they machined some off the bottom of the cap then rebored or do they actually just go oversized with the main holes?
 

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The rear cap is original it was the only one on the block when I got it. I had it sonic tested,pressure tested and cleaned everything was good there. The guy at the machine shop said there was a few pits in the cylinders he was worried it would not clean up but to 60 over but wouldnt know till he tried. I hit all the cylinders with a hone when I got it back and the pits do not seem very bad at all to me cant really measure tho I would thank 15 thousands would clean them up but thats just a guess. I have another set of main caps for it but I thought to fix the caps they machined some off the bottom of the cap then rebored or do they actually just go oversized with the main holes?
GM main caps are all over the place as far as center line and from side to side is the biggest problem it may take a few sets of caps to fine the right ones as far as height and side to side.
 

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I took apart a zz4 with about 40k on it front mains showed copper on the drivers side, rear mains on the passenger. Engine ran decent, just needed freshened. Align boring cost me 120 when I had it in a reputable shop while doing the rest of the machine work. I went with new slugs and bearings, but getting the crank centered was worth it while I had it apart.
 

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I took apart a zz4 with about 40k on it front mains showed copper on the drivers side, rear mains on the passenger. Engine ran decent, just needed freshened. Align boring cost me 120 when I had it in a reputable shop while doing the rest of the machine work. I went with new slugs and bearings, but getting the crank centered was worth it while I had it apart.
Line honing is far more accurate for finish as most line boring machine cant line bore all five journals in one set up. Line honing bring out the imperfections of line boring, seen that to many times over the years.
 
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