You need to look at the overall picture, like what heads you are going to use and piston dish. The heads can easily be changed while in the motor but the pistons cannot, so first figuring out the compression ratio that will suit your needs is ideal before putting the motor together. Pistons that are domed will usually cause increased compression; dished inward will decrease the compression ratio. Cylinder heads have what is called combustion chamber. This is the space on the underside of the head around the valve area and usually measured by the manufacture or engine builder. Depending on what piston you have is a factor that determines the compression ratio compared to the combustion chamber on the heads. If the cylinder head chamber is 64 cc and you have a dished-style piston of 16 cc you will have a lower compression ratio, about 8.5:1 to 9.6:1 depending on other variables. If you had a domed piston with that same 64cc head your compression will be higher, 11:1 and up depending on other variables. The same domed piston and a larger combustion chamber head of 74 cc will lower the compression ratio. I could have used a slightly smaller D-dishedtype piston to increase the compression, but with a set of RHS 64cc heads (PN 12053-02) and other things considered that should bring me up to a 9.6:1 compression ratio. Also when using aluminum heads a rule of thumb is that you can get higher compression without the worry of detonation. I am going to play it on the safe side when pushing the compression envelope. Look into building the motor you already have; that way it is built for your needs and can handle the type of driving you put it through. CT

Parts List

Junkyard block: ’88 Chevy 350
Eagle Specialties 383 kit: PN B13052L030
COMP Cams Extreme Energy Camshaft: PN 08-432-8
COMP Cams timing set: PN 2136
COMP Cams lifter hardware w/thrust plate: PN 08-1000
COMP Cams 10W-30 oil: PN 1594
COMP Cams two-piece cover: PN 210
TCI Crankshaft Balancer Rattler: PN 870001
Summit Racing water pump: PN SUM-312449
Summit Racing fuel pump: PN SUM-250000-1
Summit Racing fuel pump push rod: PN 134-8701
ARP engine bolt kit: PN 534-9802
ARP four-bolt main bolts: PN 134-3701
ARP crankshaft bolt: PN 134-2501
Milodon oil pump: PN 18755
Milodon oil pump pickup: PN 18311

1863 Eastman Avenue
CA  93003
Westech Performance
11098 Venture Drive
Unit C
Mira Loma
CA  91752
Comp Cams
3406 Democrat Road
TN  38118
VW Paradise And Machine Shop
Summit Racing