As Charlie pointed out, a core shift in your block, not uncommon,, could make a 312+ .060 overbore a dicey situation. And even if it is feasible, that might be the limit.. no cleanup re bore available. Apparently Ford only supplied pistons up to a 0.040 overbore for 312s... that equates to aprox 319 cu inches.    


Paul

Be sure to check the oil ring groove depth on the pistons against the oil ring width.  The set I got from John where slightly undersized and forced the oil ring into the cylinder walls at temperature.  I had to buy a different set of oils rings to corrent the problem.
Bob

Thanks for the tip, Bob.

MplsMike
'56 Parklane
Minneapolis, MN

Hi Bob,

I was thinking about your post. I assume you must have discovered the ring-piston mismatch after your engine was assembled and run. I'm not a builder, but is there anything that can be done to detect the problem you described during assembly? Did the mismatch cause any damage?

MplsMike
'56 Parklane
Minneapolis, MN

Mike,
Yup, we discovered the problem the first time that the engine was run on the dyno.  As the engine came up to temperature during the break in, there was a noticeable drop in engine rpm.  The run was terminated and post run tear down revealed some odd scoring on the cylinders.  It was caused by the oil rings being pressed into cylinder walls by the expanding piston.  The engine was cleaned,machine work was freshened, and reassembled.
You need to measure the depth of the oil ring groove in the pistons with a caliper and measure the wide part of the oil rings with the caliper. Subtract the piston measurement from the ring measurement to get the actual gap.   I am not sure what the gap needs to be (maybe Ted can chime in with the value) since my engine builder did the work.
Bob

what happened to rebuild

The wheels of progress move slowly! I just picked up the heads - cleaned and "roughed in" - and dropped them off at Jerry's house for porting Wednesday night. It's always fun hanging out there. He has a lot of cool stuff and I always learn something. He is starting to build a new engine for the t-bird he races. They'll go back to the machine shop once Jerry is done with them.

The engine shop is just starting on the block next week. When I dropped off the block, he wasn't busy but I hadn't accumulated all of the parts. When I got all the parts together, he was busy. Oh well. I'm going to use 40 over pistons versus the 60 over I suggested previously. The input I got including that from the builder nudged me that way.

I was hoping I would be able to enjoy the new engine this year, now I am hoping it is in the car by the time I store it this winter! Winter comes early in Minnesota!

MplsMike
'56 Parklane
Minneapolis, MN

I picked up the block from the machinist and dropped it off at Jerry Christenson's house last Friday. He is busy with his own project - building an engine for this year's Engine Masters competition. He will get to the assembly stage on my engine after that.





The heads should be done sometime next week.

Time to think about a carburetor. Any advice for this build? I am also thinking about whether I should rob parts from my current engine (like the exhaust manifolds) to use on the new one.

I still hope the engine goes in this year but am beginning to think it may be in the spring.

MplsMike
'56 Parklane
Minneapolis, MN

How about something to start the conversation. Jerry C seems partial to Holleys and he thought something around 500 cfm would work - I found a Holley street avenger online, 570 cfm. Here is the link, what do you think? What other options to consider?


https://holley.com/products/fuel_systems/carburetors/avenger/street_avenger/parts/0-80570

MplsMike
'56 Parklane
Minneapolis, MN

I have the 570 and like it a lot. It's a more modern Holley that comes with lots of great features.  It's probably not best for my combo, though.

It is intended for stock or very close to stock configurations.  If you use a cam with 220s or higher @.050", the 670 will probably work better.

The best thing you can do is tell the carb manufacturer all of the details about your combo and take their suggestion.  If I had asked Holley first,  they would have suggested the 670 for mine.



Lawrenceville, GA