I found out that my engine in my car is a Goodwrench 350 with part number 12513151 it was swapped in the car in 1996. What type of pistons are in this engine, are they flat tops with 4 valve reliefs? What is the compression ratio of this engine? Is it a roller block? Is it 2 piece or 1 piece rear main seal? I would greatly appreciate some help here. Thanks.

 

It's an L05 Caprice replacement engine. Crap swirl port TBI heads (worse than the L98 heads) - 64cc. 9.5:1 compression, roller cam. Single piece RMS.

It's your basic 200 HP smog era 350.

GD

 

Ok cool I thought it had a flat tappet cam. Do you know if the pistons are flat top or dished? I just bought Brodix 180cc 64cc chamber heads for it, and I'm going to mill them down to 58cc to increase my compression ratio. It will also have a comp 282hr cam.

 

Probably has valve relief dished pistons but not sure. Look in a cylinder with a bore scope. Why does it matter? It has 64cc heads. You can back-calculate the piston volume from the head volume and compression ratio. But at the end of the day the piston dish/dome doesn't really matter. If you change the heads and cam it's going to make relatively the same power regardless of piston shape. I had dished/valve relief stock Vortec pistons in my 350 and made 325 RWHP. I swapped them to much larger dished forged pistons for 8.5 compression with a supercharger and still make 300 RWHP in NA form.

GD

 

Ok sounds good. Looks like my build will be fine.

 

If it is a TBI Caprice engine it will be flat top pistons with 6cc worth of valve relief. With a 65.3cc swirl port head they were 9.6:1 advertised compression ratio. Use a thinner head gasket because those pistons will be around 0.025" down the bore at TDC.

 

Well the engine is a TPI engine right now. The original owner blew up the original engine and his local dealer put in this goodwrench 350 brand new replacement in 1996. This engine was never in a previous car, but from what you guys say it should be a similar engine to what the caprice had. Also, I am going to use a .015 head gasket to put my piston to deck height clearance at .040.

 

Also, if it is 9.6:1 compression and I mill the heads to 58cc do you think I will have enough piston to valve clearance? Obviously I will check ptv clearance but I don't want to have any clearance issues.