am rebuilding a 400 small block chev, with flat top pistons. I want to use chevy bow tie heads casting number 14011049 , with 55 cc combustion chambers, and 1.52 roller rockers with an eldebrock 5002 cam. -Any clearance problems with the valves contacting pistons-?
I can't tell you of clearance, but I can tell you with 55cc chambers you will have some rather EXTREME compression. I run a 68cc chamber (on a 406/400+.030) with 11:1 flattops and have around 10.5:1. (Can't recall exact figure) Anyways; most people usually run something between 64 to 72cc to keep comp.ratio within bounds of reason, although with aluminum heads you can usually figure to be safe up to 11-11.25:1 before detonation (pre-ignition) becomes too much of an issue. Just my opinion but if I were you I'd look to stay within that range of chamber-size. Also consider runner sizes as well. Probably 180cc intake runner would be minimum,210-220cc maximum, with 190-210cc being optimal for MOST 383-412ci. applications. Just some thoughts to ponder, but someone here can probably give the exact answer as to clearance issue-although I'm sure it would help to know if your deck height is stock (9.025") or not, and wether or not you know how far your pistons sit "down in the hole", and lastly; what thickness of headgaskets you plan to use. (Don't forget steamholes if building for street use). Good luck with your shopping/assembly/etc...
am rebuilding a 400 small block chev, with flat top pistons. I want to use chevy bow tie heads casting number 14011049 , with 55 cc combustion chambers, and 1.52 roller rockers with an eldebrock 5002 cam. -Any clearance problems with the valves contacting pistons-?
Won't work. Calculating 6cc's of piston eyebrows, 6cc's of piston deck height and 9cc's of gasket, you'd be at 11.96:1 static compression ratio. The cam you're looking at would work well at 10.0:1, but at 11.96 you will encounter detonation unless you run the motor on race fuel in my opinion.
Also, there are too many variables for someone to give you an answer on valve to piston clearance. Each motor is an individual case and must be measured on its own using a clay strip method or dial indicator method.
If you hadn't already done so, you might want to read this related thread, and use the link mentioned by F-Bird for an alternative head choice (but skip the milling-down part). Anyways; here is the thread if
you hadn't already read it: 305 heads on 400, questions .
With that cam choice you probably would want to stay within the 10.0 to 11.0:1 c/r range, (UNLESS OF COURSE YOU CAN AFFORD THE RACING GAS) and have heads and valvetrain that breathe well into the 6500 range to make best use of it's characteristics.{190-220cc Intake runners} You can tweak active rpm range of cam's powerband a small amount by advancing or retarding the cam install , and valvelifts by choice of rocker ratios (1.5/1.6/"mixed",etc..)but the Edlebrock site states to use only stock [1.5:1] ratio for that cam. Anyways; ...Happy reading and hope this helps you out some.-Jim
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