Just Bought a 360
Hum, I'll have to break out the calc. A zero deck with a 72cc chamber (My J heads) worked out to be 9.8-1.
What gasket are you useing? Bore, thickness?
And how many cc's your J's are?
I've cc'd the heads and I'm getting about 72. I've plugged everything into a calculator using these numbers.
Heads 72cc
Bore 4.030
Stroke 3.58
Gasket bore 4.15
Gasket thickness 0.54
Valve reliefs in piston 5cc
Deck height -.006 (This is per the seller, I haven't received the block assy. yet. He said "...approx .006" positive above deck height")
All of this gives me a compression ratio of 9.53 to 1. Will I be safe there? I hope it sounds reasonable for the street with pump gas.
The block is a 91 which is set up to use the LA heads & a factory roller cam. The car has an 8 3/4 rear with 3.91 gears. I have the options of the original cast iron trans (huge ratio change from 1st to 2nd & ball & trunion front joint, along with limited selection of speedo drive gears available), an aluminum case close ratio trans (already rebuilt with the 66 & later tailshaft for a standard front U joint), or an 833 OD (again, the huge rpm drop but more evenly spaced ratios overall. This is a truck trans so I'd have to swap the tailshaft or adapt it to fit the car).
Anybody have any ideas for a cam? Should I cam the engine for good torque & use the OD trans or go for something else & use the close ratio box? I'll probably keep it under 5500 most of the time & I doubt it'll ever see a strip, but you never know. With the 8 3/4 rear, I could always keep the close ratio box & swap to a different rear ratio for a long highway trip (I'm leaning towards this). I'm also still undecided as to whether to use my fenderwell headers or fix the fenders (I have the panels) & run a set of 340 Hipo manifolds that I have.
When looking at roller cam specs I have to keep in mind that the rollers are spec'd with the magnum 1.6 ratio rockers & my LA heads will have 1.5s. I was told that I also need the long snout on the cam for the fuel pump drive. I kinda' want a lopey idle. I'm a bit old school. Maybe a custom grind from Hughes?
:burnout: