Building up a holden 308 with early cast heads with a camshaft of around 250@.050,want to run around 10.5-11.0 using 98.What CR are you running!
mram,
Feb 2, 9:14am
Have you cc'd your heads! Flat top pistons! typical CR with early red heads and flattops was 9.5-10:1 depending wether pistons were zero-decked and standard cc'd chambers
skin1235,
Feb 2, 9:32am
what are you doing to the breathing, 10.5 - 11 is gonna be hard to achieve without some substantial work ports and valves, and damn hard to maintain it's getting pretty close to CI, and thats not a good effect on a 308
extrayda,
Feb 2, 9:36am
geez thats a big cam for a motor that small.What is it going to be used for! I had a 244/252 @ 50 in a 383 Chev and it was quite lumpy. I ran 10.0:1 CR, which in theory was a bit on the low side, but the cam worked very nicely, probably helped by a few extra cubes.
elect70,
Feb 3, 12:44am
Gonna need some serious milling &deep eyebrows in piston crownswith thatbig stickor,bang,race engine !
hollyx_,
Feb 3, 6:57am
57 cc,zero deck height,heads been ported to make 450 hp @.550 lift,torque power manifold,650 dp holley may go a bit larger,full msd etc.Just a weekend car.
quickbuck,
Feb 3, 1:49pm
Might be all it lasts!
extrayda,
Feb 3, 6:47pm
The only issue I had as far as fitment went was clearancing the rods to not hit the cam lobes (due to high lift).Mine was a crane cam.Chev motor, so clearancing might be quite different in a 308.I assume either manual or high stall, with suitable gearing!I ran with 3.0:1 for the first few 1000 k's, then went to 3.83 (somewhere around that), which woke it up quite a bit :-)
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