How much has to come off the pistons? I'd think not many are thick enough to handle even .100 ", and getting too close to the top ring groove could also be a problem. Clearance of the skirt to the crank counterweight when near BDC may need to be checked too.
The stroke is different on those 2 engines. The pin placement in the piston must be known to do a proper calculation.
There has been a couple people built them. Scott Foxwell at Foxwell motors for one has built a couple.
the stroke difference is mostly made up by the rod length why Ford didn't use a a piston around 1.60 and the 352 rod only Ford knows
Nothing wrong with piston coming proud of deck. Thick fellpro head gasket and there are probably enough clearance.
No, but we had a truck 360 at the dealership that had a bad rod, the pin on the crank was bad so we ordered a crank and bearings from the local NAPA. The mechanic put it back together and it started and sounded like a diesel. He came and asked me if you could put a 390 crank in a 360 and get it to turn over. Since I was kind of the Ford guru at the Dodge dealership, I told him that I didn't think it was possible. Well it is possible. Called NAPA and their machinist said it wasn't possible. We pulled one head and measured the stroke, then the machinist measured the stroke at least 3 times. They sent us a correct crank and paid the labor bill.
I knew a guy that replaced a rod and piston in a T-Bird, had the wrong parts, ended up with the piston sticking out of the bore. No problem, he used a body grinder and ground it down flush with the deck, and put it back together !
The 352 has a 4" bore. A 390 is 4.05. The difference in stroke is .284. One half of that is the difference in compression height if the rod length was the same. The .052" difference in rod length leaves .09" in compression height difference in the pin location. A 360 is the same bore as a 390. Is that the piston you are wanting to use?
The 352 rod Length 6.54 compression height 1.816 The 390 rod 6.488 compression height 1.77 The idea is to take a 352 bore it to standard 390 ( I have a set of NOS dished pistons) use a 390 crank zero decking it by cutting the tops of the pistons to reduce the dish for compression
Given a nominal deck height of 10.17, you would have to cut 0.040" off the top of the piston to get it back to 0 deck, when using the longer 352 rod and standard 390 piston. 6.54+1.78+(3.78/2) = 10.21" Depends on the piston as to whether or not that is feasible, but I would be concerned about the strength of the ring land after hogging that much off the top.
A 390 truck/410 piston has a 1.66" compression height, correct diameter, for 10.09", .080" below deck.
What is the dimension from the top ring land to the top of the piston? Are they cast, forged or hypers?
I know this is an old thread about a 390 with 352 rods, but there's a current 352 rebuild that has this subject at the top. I want to link this info over to that current thread. Mostly because this has a solid thread title. My calculator shows the stack height in your example at 10.21" for .040 out of the hole. Pistons I'm looking are for the 360 FE and they have 1.760" deck height. That would go 6.54+374+(3.78/2) = 10.19 for .020" out of the hole. Seems much more feasible than skimming seventy thou off of any piston. The other issue frequently raised with FE rebuilds is getting a 352 piston anywhere near deck. This addresses all those issues. I researched this b/c I bought a $50 360 and a $45 390 crank and was curious.
Yep, looks like I mathed my math wrong and it should have been 0.040" off the top, much more feasible than 0.070". I corrected my previous post. I agree, if you can get your hands on 1.76" compression height 360 pistons, that is even better, assuming 0 deck is your target.
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