Dish Piston top volume??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

OrangeCrush1970 · 06-05-2012, 08:30 PM

I have a stock '77 350 with cast aluminum dished pistons w/ 4 valve reliefs. What is the piston top volume? I've looked all over the internet and I get so many conflicting answeres any where between 12 and 15cc's. Im trying to calculate my static and dynamic compression ratio.

cableguy0 · 06-05-2012, 08:53 PM

They are conflicting because there were variances. Without knowing exact deck heigh and head cc as well as head gasket thickness you cant accurately find static or dynamic compression ratio. Stock heads usually vary chamber to chamber on size. If the heads have ever been surfaced that changes it as well. Without the engine apart to measure and properly CC everything any numbers you come up with are a guess.

OrangeCrush1970 · 06-05-2012, 10:09 PM

To clarify, I am lookgin for the piston top volume for the stock dished pistons that came in at stock GM 350 truck engine. I know the other measurements that I am working with.

Bore = 4.00
Stroke = 3.48
Head Gasket Thickness = .041
Deck Height = .025
Piston Top Volume = ??????????
Combustion Chamber = 64cc

Scotty-D · 06-06-2012, 02:50 AM

13cc's will get you in the ballpark. I've always heard thats what they are, but I've never measured one. I did measure a stock vortec dish piston once and it was 12cc's. If I'm not mistaken the dishes on the earlier motors are a touch bigger.

Either way, as cableguy mentioned if you are not cc'ing your heads, 1 or 2 cc's here or there is not going to make any difference as combustion chamber volumes on factory heads can vary much more than that.

I don't know exactly what my compression in my 383 is. It 9.4ish, but I didn't cc my heads or pistons so I don't know exactly know. I just knew that 9.4ish would work and I didn't see any need to cc.
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06-05-2012, 08:30 PM	#1
OrangeCrush1970 Registered User Join Date: Jun 2007 Location: Smyrna, GA Posts: 709	Dish Piston top volume??? I have a stock '77 350 with cast aluminum dished pistons w/ 4 valve reliefs. What is the piston top volume? I've looked all over the internet and I get so many conflicting answeres any where between 12 and 15cc's. Im trying to calculate my static and dynamic compression ratio. __________________ *Rottenwood Garage* 1970...71...72 C1500 aka Orange aka Sideshow Bob 540 BB Straub Roller Cam, AFR Magnums, XP 950, TKO 600 2 Tons of Fun

06-05-2012, 08:53 PM	#2
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,950	Re: Dish Piston top volume??? They are conflicting because there were variances. Without knowing exact deck heigh and head cc as well as head gasket thickness you cant accurately find static or dynamic compression ratio. Stock heads usually vary chamber to chamber on size. If the heads have ever been surfaced that changes it as well. Without the engine apart to measure and properly CC everything any numbers you come up with are a guess. __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

06-05-2012, 10:09 PM	#3
OrangeCrush1970 Registered User Join Date: Jun 2007 Location: Smyrna, GA Posts: 709	Re: Dish Piston top volume??? To clarify, I am lookgin for the piston top volume for the stock dished pistons that came in at stock GM 350 truck engine. I know the other measurements that I am working with. Bore = 4.00 Stroke = 3.48 Head Gasket Thickness = .041 Deck Height = .025 Piston Top Volume = ?????????? Combustion Chamber = 64cc __________________ *Rottenwood Garage* 1970...71...72 C1500 aka Orange aka Sideshow Bob 540 BB Straub Roller Cam, AFR Magnums, XP 950, TKO 600 2 Tons of Fun

06-06-2012, 02:50 AM	#4
Scotty-D Registered User Join Date: May 2012 Location: Perry, Oklahoma Posts: 157	Re: Dish Piston top volume??? 13cc's will get you in the ballpark. I've always heard thats what they are, but I've never measured one. I did measure a stock vortec dish piston once and it was 12cc's. If I'm not mistaken the dishes on the earlier motors are a touch bigger. Either way, as cableguy mentioned if you are not cc'ing your heads, 1 or 2 cc's here or there is not going to make any difference as combustion chamber volumes on factory heads can vary much more than that. I don't know exactly what my compression in my 383 is. It 9.4ish, but I didn't cc my heads or pistons so I don't know exactly know. I just knew that 9.4ish would work and I didn't see any need to cc. Posted via Mobile Device __________________ 85 Scottsdale LWB 383 227/235 105 lsa Howards Roller TH350 by Jakes Performance, Sanger TX



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