360 / 390 Pistons vs Deck Height
Thread Starter
|
Senior User
Joined: May 2004
Posts: 280
Likes: 0
360 / 390 Pistons vs Deck Height
Well, I am sooooooooo confused but the light is on at the end of tunnel. If I have figured this right, using the present .030 over 360 pistons, in combination with the 390 crank and rods, I should have a deck clearance of .030, down from the stock stuff at .112. What will this do to compression ratio and can I run with this. These are cast (I think) Pistons, aftermarket. Is it worth it to use these or should I purchase new?
Cargo Master
Joined: Aug 2000
Posts: 2,931
Likes: 12
From: SW Michigan
deck height
Az, I think you are off to a good start. If you are .030 down the hole, add your gasket thickness to that and you'll know whhat your quench will be- normal FelPro gaskets (1020s ? ) are .041 thick. That would give you .071, a little on a the big side. Quench works better if the distance is .060 or less. But there are gaskets available that are .035 and .020 and .017 thick. What are the tops of those 304NP pistons like ? What is the casting number on your cylinder heads ? It sounds as if you are well on you way to a nice engine with 8 1/2 ~9 1/2 to 1 compression. DF, over at his father's house
Thread Starter
|
Senior User
Joined: May 2004
Posts: 280
Likes: 0
Thanks DF, the heads are C8AE-H units. I am planning on rebuilding them with SS 2.09 and 1.66 valves, per recommendations found here of course. The tops of the pistons are very similar to the 410's, being cut with that eyelid for the valves and dished a little. As for the thinner head gaskets, are they as effective as the thicker ones? The point my be moot because when all is said and done there may be some decking done onthe heads or the block, who knows. Thanks again:-)
Cargo Master
Joined: Aug 2000
Posts: 2,931
Likes: 12
From: SW Michigan
390 build
Az, might those pistons be H304Ps ? That is a 390 piston that gives 8 1/2 to 1 or so with steel shim gaskets that the factory uses. I think they are also hypereutectic. Yeah, the thick gaskets seal just as well. But the quench will be better with the thinner ones. You could mill a light .010 off the block and then use the thicker gaskets- they are usually easier to find. DF, @ his Dad's house
Thread Starter
|
Senior User
Joined: May 2004
Posts: 280
Likes: 0
Only marking I can find is 304NP on the skirt of each one. Cosmetically they look quite different from the 410's that I found in the 390, cleaner looking sorta. With a cross hatch pattern cast into them from the top of the skirt to the center of the wrist pin. Gonna get the block hot tanked this week. What other parts should I get done? Can I bead blast the pistons?
Thread
Thread Starter
Forum
Replies
Last Post
greentruck72
FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428)
27
Oct 4, 2016 03:47 PM
Boss9F100
FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428)
47
Jan 30, 2016 06:41 PM
67 428 Fairlane Ranchero
FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428)
5
Jan 30, 2003 08:12 PM
