eddy heads to low cc for me??

[mopar_persson]

hello i have a 408 smallblock with probe flat top pistons,
I currently have 596 cylinder heads with 72cc,
and I got hold of 2 Edelbrock 63cc cylinder heads for a good price that I want to put on the engine, but now I wonder if I'm going to get to high compression with these Edelbrock cylinder heads?

what will the compression be with these eddy heads?

piston info:
Brandrobe Pistons
Manufacturer's Part Number:13746-030
Part Typeistons
Product Linerobe SRS Forged Pistons
Summit Racing Part NumberBP-13746-030

Bore (in):4.030 in.
Piston Style:Flat top, with two valve reliefs
Piston Material:Forged aluminum
Compression Distance (in):1.460 in.
Piston Head Volume (cc):+5.50cc

eddy heads info:
edelbrock 60779
Cylinder Head, Performer RPM, Aluminum,
63cc Chamber, 171cc Intake Runner,
2.05 Intake Valve
1.60 Exhaust Valves

the current cam is a Mopar Performance Purple
P4120231
484 484 lift
Duration:284

 

[IQ52]

Without knowing for certain the deck height and the gasket thickness, best quesses would be, 11.0-11.4:1 compression ratio. Right now you are at 10-10.3:1

 

[krazykuda]

Install the pistons in the engine and measure the volume above the piston to the head deck as shown in this how to thread:

http://www.forabodiesonly.com/mopar/showthread.php?t=278215


Then measure your head gasket compressed thickness and diameter.

Then check your heads with the cover plate as described in the how to check compression thread, and then we can help you figure out where you want to go.

With the head combustion chamber cc's and the volume above the piston to the head deck, we can try to pick a head gasket to suit your desired compression.

The only way to tell you, is to see where your parts are at. You don't know if they've been recut or where they fall within production tolerances. Did your machinist have to reface your block and heads to true them up? The only way to know exactly where YOUR engine is is to measure YOUR parts.

"Book" numbers can be misleading....

 

[hemi446]

Without all the exact numbers it is going to be hard to tell but one good thing is the aluminum cylinder heads will absorb more head and you can run a little higher compression without any problems. Just make sure to check piston to valve clearance by using and old head gasket and some modeling clay. Bolt one for the heads on. Set the valve adjustment and rotate the engine slowly by hand after the engine has been rotated remove the head and check your valve clearance if it good I would run the heads. Good Luck

 

[JBurch]

A loose rule of thumb is that a 10 cc reduction is worth a point of compression, there for, what ever your comp ratio is with the iron heads would go up 1 point with the Eddies. YOU, gotta figure out if that's too high; or higher that you would like.

 

[autoxcuda]

...

eddy heads info:
edelbrock 60779
Cylinder Head, Performer RPM, Aluminum,
63cc Chamber, 171cc Intake Runner,
2.05 Intake Valve
1.60 Exhaust Valves

...

60779 heads from Edelbrock have 2.02 intake valves. Are your modified by an aftermarket company.

I cc'd my new out of the box Edelbrock 60779 that are advertised at 63 cc's actually at 65 cc's. Most others have measured this same amount.

The Edelbrock "65 cc" head measures out is 67cc

That helps you out a tiny bit.


http://www.forabodiesonly.com/mopar/showthread.php?t=217291&page=3

 

[krazykuda]

Here's what we have so far:

Bore = 4.030"
Stroke = 4.000"

Volume = .7854 x (4.030)**2 x 4.000 = .7854 x 16.24 x 4 = 51.02 cubic inches

Convert to cc:

51.02 x 16.39 = 836.3 cc

This is your swept volume (sv) which is the volume that is changed when the piston moves.


clearance volume (cv) = volume above the piston at TDC - this includes head combustion chamber volume, head gasket volume, and volume above the piston to the head deck.

To calculate the rest, we need to know:

head gasket compressed diameter and thickness

Head cumbustion chamber volume (of both heads)

volume above the piston to the head deck of the blosk.


They can be found by following this thread:

http://www.forabodiesonly.com/mopar/showthread.php?t=278215

 

[flyfish]

The chambers on my Edelbocks, after port work and being cleaned up were 68cc.....then I had to cut them down to 57cc....long story, but the short version is I should have ordered pistons AFTER I knew the exact size of the combustion chamber :violent1:.....live and learn I suppose.

 

[autoxcuda]

The chambers on my Edelbocks, after port work and being cleaned up were 68cc.....then I had to cut them down to 57cc....long story, but the short version is I should have ordered pistons AFTER I knew the exact size of the combustion chamber :violent1:.....live and learn I suppose.

Which edlebrock part number heads did you start out with?

 

[flyfish]

The 60779 head. If I recall correctly (it has been a while) they were 65-66cc prior to the de-shrouding and chamber cleanup.