Does anyone make a high compression 402 piston for open chamber heads? All I can find are for close. Best I can find are the KB hypers.

Should I just change heads..........maybe to a set of 98cc ovals?

Thanks everyone, Kevin

Have to use the 396/375 pistons and trial fit the pistons to the heads. May require a little bit of clearancing on the sides of the heads. All depends on the deck ht. and how much the block was bored out.

TRW made a piston L2337F for 396's with floating pins for 114 cc cylinder head. If I remember right it is 11.9-1 compression ratio. I found a brand new set from a warehouse in Lansing, Michigan. They haven't been made for quite a few years but there are some new sets out there. With 118cc heads and an .039 head gasket,and .005 deck height I came up with about 11.0-1 and with my cam the DCR is about 8.0. I have all the figures at my garage so I'm estimating. there is a set that is hardly used with rods on Ebay, $245.00 it's the 3rd time he has listed them. I found the set I have by sending emails to people listing pistons on Ebay and asking them to check there old stock. They also had a first and second design. the first design took 2 c-clips on each side of the pin and the second only took 1 on each side. I'll post the weight of my pistons and a picture.

Ebay link for these pistons
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=7911442147&category=33623

Summit also carries 11.2-1 396-375 pistons in all the over size sizes,,

So those pistons will work with open chamber heads with no modifications? I looked for info on them but came up with nothing.

With my 402 3993820 casting heads (113 cc) think I would come up with a cr I could run on anything other than race gas?

My block and heads are pretty much virgin (heads may have been decked once........any idea what I would end up with a thick gasket?

Thanks again, Kevin

here is a picture of my pistons
http://www.chevelles.com/showroom/ricks_67/pistons2.jpg

The best and only way to do this is build the shortblock with the pistons you intend to use [the TRW's listed are probably the best bet - contact the guy on Ebay and tell him you want to buy these on a contingency that they have to be checked by an engine machine shop first before you will pay the whole fee - offer to pay 50% up front, the balance on inspection - if he balks, ask him what guarantee can he give you ]. Anyway, install the pistons in the block, either with or without rings, mock up the tops with clay, bolt the heads down - loose at first (do 1 cylinder to start with) and check for clearance. Then do either a liitle machining on the piston or preferrably, open up the combustion chamber a little for clearance with a die grinder. This is prett much standard procedure for any high comp motor anyway.

There is another TRW piston that might be easier to find. L2287F-30 is listed as 11.88-1 with 106 cc cyl.head with a .508 dome. It's made for a closed chamber head with a higher dome and with your 113 cc head You might wind up with arround 11-1 or less with a thicker head gasket and depending on your deck height. I was looking at a set of these until I found the 2337's I have about 500 miles on my motor and have no problem with 93 or 94 octane with 11-1. Here is a link for Flatlander listing but you might want to check other places before buying TRW's from them http://www.flatlanderracing.com/ I paid 350.00 for the set I have, here is the name and info on the place where I got My pistons. Johnsons Speed Warehouse there hours are 9-6 m-f 800-248-0480

Originally posted by ricks_67:
TRW made a piston L2337F for 396's with floating pins for 114 cc cylinder head. If I remember right it is 11.9-1 compression ratio... Anybody got any solid figures and/or info on these pistons?? Maybe a website or something...I can't seem to find anything of real value...Help :confused: ??

This is beginning to be a growing problem. With the huge BB's being built these days it is very hard to find anything for a 396/402 engine. Of course you can always get Ross, or SRP to custom forge some, but other than stock replacement the off the shelf pistons are becoming a thing of the past for these engines. :(

Here is a link for Weisco piston kits for 402, 408 BB motors.
http://www.pistons-online.com/protru.asp?make=Chevy&st=12&end=12

Be real carefull with the 820 heads. They have a chamber that is different from everything else. I have not tried anything else but the old factory 10.25 to 1 closed chamber piston. They worked but the compression was very low.

I have the 820 heads and use Speed Pro L2242 forged pistons. They are the replacement pistons for a 65-69 375 hp 396 and have an aprox 36cc dome. I had them flycut .040 on the intake side (factory notches are shallow) and the block is notched for the larger valves installed. I ended up with a 10.1 CR with a .005 deck and .039 gasket.

I've been giving this alot of thought............not sure if I'm making the right decision, so somebody stop me if I'm wrong graemlins/waving.gif

Given the condition of the engine when I opened it up (suprisingly good), think I'm gonna find a set of close oval heads and sell my opens.

I "think" the stock pistons will work with close heads and yield 9 something with steel shim gaskets?

Put it back together and see how it runs.

What do ya think?

I think you are on the right track AND will save yourself a hassle!! Try reworked -206 or -215 heads and they should do you fine..

AS for pistons, has anybody tried getting a set of good .060" over, 283 or .030" over 302 pistons lately???

They are really becoming a pain to find too, imho...

pdq67