HI all
is there a way to figgur the compression ratio with this set up?

302 cu.
74 block (not decked)
D2 head (not milled)
D3 head (not milled)
(I know but that's what came on it stock)
the heads were just taken apart and tanked and re-assemabled lapping in the stock valves..
gasket mached and exhaust bump out. HO I am going to clean up the chamber as to cut down on possiable Octain knock.. (WHAT SHOULD I USE TO POLISH THE CHAMBER?)

HERE'S THE PISTON INFO.

Bore (in) 4.000 in.
Bore (mm) 101.600mm
Piston Style Dome, with a trough
Piston Material Hypereutectic aluminum
Compression Distance (in) 1.608 in.
Dome Height (in) 0.200 in.
Piston Head Volume (cc) -2.60cc

Thanks
Tim

you cant total a race car
you just get tired of fixing it.

Tim,
Here is a link to a compression ratio calculator, this will give you an idea of what info you need to get an accurate answer.

http://www.diamondracing.net/cocalc.htm



Joe
3-'63 Fairlanes
'72 Gran Torino Sport (Q code)
'79 F-150 4X4

Thanks Joe

you cant total a race car
you just get tired of fixing it.

My calculator
http://raceabilene.com/kelly/hotrod/compression.html
I'll assume .039 x 4.1 for the gasket (FelPro) and 58cc for the heads. you also need the deck clearance, I'll use .012 which is maybe close in my experience. And might be WAY off with the parts used. You will need to measure it. [it needs to be zero to get the most out of the assembled parts BTW]

Comes to 10.32:1, more or less

To polish the chambers, start with 80 grit cartridge rolls with the ends broken lose to make flap rolls, then go back with 120 grit.


1967 Falcon 4 door 351C-4V
1970 Mustang 351C-2V
http://raceabilene.com/kelly/hotrod
Owner built, owner abused.

Thanks Faclon67
the calulator was asking stuff I didn't know or could measure.. So I was just going to ask my machinest when he balanced it...
Well 91 octain be ok or will it need more?
Thanks
Tim

you cant total a race car
you just get tired of fixing it.

That depends. 10+ with a lot of deck clearance usually means less resistance to detonation. Typically you want to keep the deck to under .050, tighter if possible. The 302 I have picked up about 20HP just from cutting the deck clearance from .012 to zero to end up at 9.5:1. It runs fine on 91 with a 216 intake duration and a 110 lobe center. My 10.5:1 351C requires 93 octane to keep it off the hairy edge. That's with about 230 intake duration and a 108 lobe center cam. you'll need to keep an eye on the plugs and fiddle with the total ignition advance.

Typically Good to reduct detonation - tight deck, long intake duration, tight intake duration (lower number, more overlap)

Typically Bad for detonation - lots of deck clearance, small intake duration, wide lobe center (builds cylinder pressure)

1967 Falcon 4 door 351C-4V
1970 Mustang 351C-2V
http://raceabilene.com/kelly/hotrod
Owner built, owner abused.