The Ford Barn

55blacktie · 07-09-2023, 05:31 PM

I know this has been addressed many times, but I need to hear it again. How big can I go on the cylinder bores before the walls become too thin or core shift could be a problem? It's already .060 over and in need of a rebuild. I'm considering using 3.825 pistons (312 + .025), which will put me at .075 over the standard 292 3.75 bore. Hopefully, no more than .015 will be needed to clean up the bores.

paul2748 · 07-09-2023, 07:32 PM

Can't really answer your question, but the only way to find out is to have your block cylinders sonic tested. This will tell you what is left and the tester should be able to tell you what is the minimum needed .

Some blocks have serious core shift when they were cast so there is not one answer that fits all.

dmsfrr · 07-09-2023, 08:12 PM

Check on the availability of pistons in that size range, don't assume they're on a shelf somewhere.

The last few years have seen suppliers closing, parts shortages and poor quality replacements.

miker98038 · 07-09-2023, 10:27 PM

I’ve had a number of blocks sonic checked, and a good thing. Both the ones I built got a little less bore than I wanted, one we moved the center over a bit for the boring bar to maintain wall thickness.

Both were supercharged engines, and I was being cautious. But better safe than hole a block under heavy load or detonation.

The other interesting thing I had happen was align boring a 312. It had been done before, and the new timing chain was loose. Wasn’t a big deal, the guys in AU who did the timing chains would build a custom one with gears to take up the slack. But I think they quit doing those, so now it would be a problem. Sonic check and measure everything before you start the machine work.

55blacktie · 07-10-2023, 04:20 PM

Miker, I have a new Rollmaster timing chain set (still in package) that I bought several years ago. It seemed to be the best choice at the time (hopefully still is). I did read that you don't want to pry on the chain during installation/removal.

I most definitely will have the bores sonic checked before any work is done and will hold off on buying pistons until then.

darrell · 07-11-2023, 06:20 PM

Sponsored Links (Register now to hide all advertisements)

some engines have loose chains.i had one with 1/2 inch slop no amount of line honing will give you that much.these are faulty blocks.theres a guy over on facebook with one now.

55blacktie · 07-12-2023, 11:51 PM

I've been talking to an E-Bird owner. Years ago, he and his father had the 312 rebuilt/w +.080 Jahns pistons. Recently, he went through the engine, cleaned up the bores, and reused the pistons. So far, he's had no problems.

Knowing that Ted Eaton has taken 292 blocks to +.110 and that +.060 312 pistons are readily available, I have to conclude that the 292 & 312 blocks are the same casting; the final machining of the blocks determined whether they would be 292/312. 292 standard bore of 3.750 + .050 = 312 standard bore of 3.800. + .060 = .110 over 292. The OEM 292 piston skirts were too long to clear the 312 rods, due to the longer stroke. However, 312 pistons can be used in a 292/w the longer 6.324 292 rods.

I will still have the block sonic-checked before buying pistons; it's cheap insurance.

dmsfrr · 07-13-2023, 10:50 AM

Quote:

Originally Posted by 55blacktie

... I have to conclude that the 292 & 312 blocks are the same casting; the final machining of the blocks determined whether they would be 292/312. ...

Yes you are correct...

"292 and 312 Blocks were machined from the same castings with the same markings."
http://ford-y-block.com/Block%20identification.htm

"312's can have the following block casting numbers ECZ-6015A, ECZ-6015B, ECZ-6015C, EDB-6015E, B9AE-6015F. Of these ECZ-6015A and ECZ-6015C are by far the most common 312's and are likely to be a 312. Some 312 replacement blocks were C2AE-6015C.
Any of these numbers can also be a 292."

http://ford-y-block.com/identify312.htm

.

07-09-2023, 05:31 PM	#1
55blacktie Senior Member Join Date: Aug 2020 Posts: 442	1956-57 292 ECZ-B Block I know this has been addressed many times, but I need to hear it again. How big can I go on the cylinder bores before the walls become too thin or core shift could be a problem? It's already .060 over and in need of a rebuild. I'm considering using 3.825 pistons (312 + .025), which will put me at .075 over the standard 292 3.75 bore. Hopefully, no more than .015 will be needed to clean up the bores.

07-09-2023, 07:32 PM	#2
paul2748 Senior Member Join Date: May 2010 Location: Midland Park, NJ Posts: 3,982	Re: 1956-57 292 ECZ-B Block Can't really answer your question, but the only way to find out is to have your block cylinders sonic tested. This will tell you what is left and the tester should be able to tell you what is the minimum needed . Some blocks have serious core shift when they were cast so there is not one answer that fits all. __________________ 48 Ford Conv 56 Tbird 54 Ford Victoria

07-09-2023, 08:12 PM	#3
dmsfrr Senior Member Join Date: Aug 2012 Location: Abq, NM Posts: 3,607	Re: 1956-57 292 ECZ-B Block Check on the availability of pistons in that size range, don't assume they're on a shelf somewhere. The last few years have seen suppliers closing, parts shortages and poor quality replacements.

07-09-2023, 10:27 PM	#4
miker98038 Senior Member Join Date: Mar 2013 Location: Kent, WA. Tucson, AZ Posts: 1,398	Re: 1956-57 292 ECZ-B Block I’ve had a number of blocks sonic checked, and a good thing. Both the ones I built got a little less bore than I wanted, one we moved the center over a bit for the boring bar to maintain wall thickness. Both were supercharged engines, and I was being cautious. But better safe than hole a block under heavy load or detonation. The other interesting thing I had happen was align boring a 312. It had been done before, and the new timing chain was loose. Wasn’t a big deal, the guys in AU who did the timing chains would build a custom one with gears to take up the slack. But I think they quit doing those, so now it would be a problem. Sonic check and measure everything before you start the machine work.

07-10-2023, 04:20 PM	#5
55blacktie Senior Member Join Date: Aug 2020 Posts: 442	Re: 1956-57 292 ECZ-B Block Miker, I have a new Rollmaster timing chain set (still in package) that I bought several years ago. It seemed to be the best choice at the time (hopefully still is). I did read that you don't want to pry on the chain during installation/removal. I most definitely will have the bores sonic checked before any work is done and will hold off on buying pistons until then.

07-11-2023, 06:20 PM	#6
darrell Senior Member Join Date: Dec 2010 Location: p.e.i. Posts: 1,060	Re: 1956-57 292 ECZ-B Block Sponsored Links (Register now to hide all advertisements) some engines have loose chains.i had one with 1/2 inch slop no amount of line honing will give you that much.these are faulty blocks.theres a guy over on facebook with one now.

07-12-2023, 11:51 PM	#7
55blacktie Senior Member Join Date: Aug 2020 Posts: 442	Re: 1956-57 292 ECZ-B Block I've been talking to an E-Bird owner. Years ago, he and his father had the 312 rebuilt/w +.080 Jahns pistons. Recently, he went through the engine, cleaned up the bores, and reused the pistons. So far, he's had no problems. Knowing that Ted Eaton has taken 292 blocks to +.110 and that +.060 312 pistons are readily available, I have to conclude that the 292 & 312 blocks are the same casting; the final machining of the blocks determined whether they would be 292/312. 292 standard bore of 3.750 + .050 = 312 standard bore of 3.800. + .060 = .110 over 292. The OEM 292 piston skirts were too long to clear the 312 rods, due to the longer stroke. However, 312 pistons can be used in a 292/w the longer 6.324 292 rods. I will still have the block sonic-checked before buying pistons; it's cheap insurance.