Originally Posted by cliff tate
if you are useing a older catelog the 361 edsel had a higher pin to top.power house in bakesfield show 390 and 360 use the same piston, that is car to lite truck. cliff
NOPE, all current within 4-5 years, however they do correspond EXACTLY with the older ones I have also. Just for general info...the 360/390 use the same head...Soooo a 360 WOULD have a lower compression with the exact same deck height( which usually is within several thousands) as a 390 because there is less to compress..pretty simple logic. Your measurements must be from the top of the pin bore and measured with a ruler because they are no where near specs. Plus, the measurements you gave were opposite of the real world...the 352/360 have a higher pin height than the 390 and you have them the reverse.
In a 2002 Silv-0-lite catalog, one I randomly grabbed from the files...a '68-'76 360 ( much later than the Edsel 361) piston # is 1131 with the 1.76 pin height, a '68-'76 390 uses a 1139 piston with a 1.66 pin height..once again your numbers don't add up. Finally Ford's part numbers are different with the 390 using a R suffix and the 360 using an A suffix, so what you are saying is that even Ford uses a different number for the same piston...you'll have to do better than that. I suspect that you put a 390 crank into a 390 you thought was a 360 and that's why the pistons were the same.
I will look at my piston cross reference catalog, although you didn't mention the manufacturer the number is a pretty standard number, I'm willing to bet your parts guy is very uninformed. I hate it when I have to get out my parts catalogs, but that's one thing nice about being a machinist for years...I have them. There is NO catalog that list them the same, Sterling(395P for the 360 and 304NP for the 390). The Federal Mogul book listed as one 360 option a piston with similar characteristics as the 390, but tstated the compression would be lower than 8-1, and it too had a different number than the 390. I couldn't locate the number you posted so there may be a company that sells the same one for both applications, that doesn't haowever mean that they are the same.. at least from Ford and that is what I am referring to and many piston manufacturers make pistons that are unique to each engine. As I mentioned earlier, you can use the same piston, but because of the difference in pin height the compression will be much less and cause a lack of power if used in a 360 instead of the correct ones.
The pin height is not the same in all the catalogs, however they all show a taller one for the 360. Some of that is a result of a variance made for oversize pistons to keep the compression from escalating when bored. You will find that most aftermarket (stock replacement type) pistons have a little lower compression height for each oversize they go up. That helps allow for head/block milling as well as the increase in displacement.
Just to convolute the issue some The 352 has a taller pin height than the 360 being 1.8xx( depending on which model it varied some). So technicly if you could get an oversize piston for a 352 that you could use in a .010 360 block, you'd have a lot more compression than what Ford was even building them. Of course the 360 served most of it's life in a unleaded age and gas was getting lower in octane.