Piston Discussion (Was - Re: Building my 360/390 for towing)

[fomocoguy]

one ? or mabey two...Can you use the 352/360 rods along with the 390 crank? And just mill piston tops to get propper deck height? would that lighten the bob weight to much trowing the ballance off? I guess thats three

I know that the rods are weaker but for a truck engine under 5000 rpms they should be fine. I was just thinking that the longer rods would help build torque.

I wouldn't just because I wouldn't want to compromise the tops of the pistons. I don't claim to know much about the thickness of 360 piston tops but they are under an awful amount of heat and pressure and it would make it much more vulnerable to burning a hole in one under the right or wrong conditions I would think. You could have a good machinist check and see if there is enough material there for you, but I think you could buy all the proper parts for less than it would cost to have all the pistons machined. As for the stroke, that is dictated by the throw of the crank, so the longer rods wouldn't really affect it. Wether you have a longer rod with a shorter piston or a shorter rod with a longer piston, the overall rod+piston length will be the same.

Ooops sorry about that I was trying to edit the last post

[JEF199]

Well I have 390 rods also, but I know that in the 302's they get more torque with a longer rod/shorter pistion. and was wondering if it aplied here?

I don't know if the pistons are coated or hardned but I was thinking on a dish piston the edge would only have to be cut .080 leaving the center untouched. But like you said.....better to get the right ones I guess.

[fomocoguy]

Well I have 390 rods also, but I know that in the 302's they get more torque with a longer rod/shorter pistion. and was wondering if it aplied here?

I don't know if the pistons are coated or hardned but I was thinking on a dish piston the edge would only have to be cut .080 leaving the center untouched. But like you said.....better to get the right ones I guess.

Stock 360 pistons aren't dished, but they do have valve reliefs cut into them. I suppose if you didn't have to go any deeper than the valve relief cuts it would be ok, but it seems like a lot of work when you can find new sets of aftermarket 390 pistons for around $100 all day long on ebay, but it would make a goood conversation peice!

[DuckRyder]

one ? or maybe two...Can you use the 352/360 rods along with the 390 crank? And just mill piston tops to get proper deck height? would that lighten the bob weight to much trowing the balance off? I guess thats three

Pippen on the FE Forum did that (I don't recall exactly why he chose to do it that way) you might try searching there for details.