Engine build

[thomasso]

Gentlemen;  I have a 292 block bored to 3.80 ( 312 ) size.  No one seems to make .50 over pistons for a 292. Question is can I use 312 standard pistons with the 292 rods, I know the rods are different lengths. Also, how did Ford effect the various compression ratios as all the heads seem to be the same and all pistons are flat topped?  Thanks.  Tom

[hiball3985]

I don't think you can use the 292 rod with 312 pistons. Why did you bore to .050 over rather then .060 over and use .060 over pistons? The compression ration between 272,292,312 vary due to cylinder volume.

[thomasso]

Yeah. A friend gave me the block already done.  Might have to hone it out 10 thousands.

[mustang6984]

Marc might know the answer. He was a wealth of information for me on my 292...which turned out to BE a 312.

[cos]

Pretty sure you can. Compression height same, rod length is different between 312 and 272/292. Also think(?) skirts are shorter on 312 piston don't know about weight. Go to Mummerts site for more info.

[Marc]

Thanks for the kind words Hugh. It's not so much that I know the answers. More often than not I just know where to find them 
I'm not sure there's any reason you can't use 312 pistons in a 292. As Cos said, compression height is the same. 292 rods are a little longer than the 312 rods.
Different compression ratios were achieved by varying the combustion chamber size.
If you're buying new pistons, 292 pistons are less expensive than 312 pistons, and offer a better selection of rings.
To be sure it wouldn't hurt to call John Mummert or Ted Eaton.

[Hoosier Hurricane]

As to bore size, for several years I have been using 292 blocks bored to 3.830 in my supercharged drag car.  F engined '57  Ford that has turned as quick as 11.63 at 118 mph in the quarter.  No cylinder wall issues yet.  I used 292 rods with the 312 crank by machining .070 off the piston tops.   Jphn

[thomasso]

So. 312 pistons can't be used with 292 rods without cutting piston tops.  Oddly my 57 service manual shows 292 and 312 rods to be same length.  other sources show 312 rods 0.72 shorter, hence the confusion.  I still don't know why they bored the block 0.50 to 312 size, maybe they were planning to use turned down 312 crank and 312 rods and pistons.  Thanks for your replies.