To much cylinder head?
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On The Tree
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To much cylinder head? Can you have to much head for a particular engine?Enough that it would rob horse power from an engine?Ive got a 355 sbc with a holley street dominator single plane intake and my cam is .488 lift with 234 deg duration @ .050 and 114*lsa....right now it has a set of stock 64cc heads....it makes great power up to about 4500rpm then its having a hard time breathing....im looking a set of a world products sportsman 2 heads a guy has for sale cheap...200cc runners and 72cc chambers with 2.02,1.60 valves....do these heads have to large of runners for what im doing here?Im also running a set of speed pro flat top pistons.what kinda compression can i expect with the bigger chambers?I dont think it would hurt my power seeing how they should be flowing so much more that the stock ones but i dont know...any help would be great.
TECH Apprentice
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Can you have to much head for a particular engine?Enough that it would rob horse power from an engine?Ive got a 355 sbc with a holley street dominator single plane intake and my cam is .488 lift with 234 deg duration @ .050 and 114*lsa....right now it has a set of stock 64cc heads....it makes great power up to about 4500rpm then its having a hard time breathing....im looking a set of a world products sportsman 2 heads a guy has for sale cheap...200cc runners and 72cc chambers with 2.02,1.60 valves....do these heads have to large of runners for what im doing here?Im also running a set of speed pro flat top pistons.what kinda compression can i expect with the bigger chambers?I dont think it would hurt my power seeing how they should be flowing so much more that the stock ones but i dont know...any help would be great.
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thats good to know it does well up top cause mine just falls on its face....the engine is wanting to rev higher but it just doesnt make anymore power....im planning on running a 100 shot of spray with these heads so it should like that pretty well on top id guess.
I would run a little more cam, the large runners will kill port velocity and make it sluggish off the line. Another thing to consider is the compression drop going from the 64cc up to the 72cc Sportsmans. If you have flat tops your at about 11:1, moving to the 72cc will put you at about 10:1, im only guessing on the pistons. I have no clue what done or dish you have if any. You will lose approximately a full point in compression.
On a 350 non-decked motor with the 64cc heads and a stock head gasket you are looking at 9.43:1 compression. With the 72cc heads, things would only be 8.72:1 compression. This is a poor mixture of parts to be used in my opinion. I'm not trying to be rude or cruel, but just telling you a few facts.
P.S. Speed Pro also quotes their compression ratio's with one of their competition head gaskets. These gaskets have a different than stock compressed thickness and/or bore diameter.
Last edited by 1997bird; Aug 14, 2008 at 08:34 PM.
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Verdad Gallardo Not only that but the single plain intake manifold kills tq badly on a lower compression street motor, unless you have a 421 or larger cubic inch motor. The Performer RPM Air-gap style intake is the best choice for this build.
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well i bought the engine from a guy i know very well....he built it for a nova he had.the intake was just one he had laying around...but it has a scat 4340 crank egeal rods and speed pro pistons and he likes that particular grind of cam for a street engine so thats what he put in it....i bought the whole engine ready to run carb to pan for $600....im thinking about going with a set of heads from summit racing...they have 67cc chambers 2.02-1.60 valves and 165cc runners....how well would those work with what ive got?would it be worth buying a dual plane intake to run in it?
I would get the Air-gap style intake and a 200cc intake runner head from either RHS or Dart with a 64cc combution chamber. While you have the motor pulled down that far I would also change the cam out as well.
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Im looking for a about a 350-400 hp engine and still be very streetable.i like to drive my car....i do plan on running nitrous on it here soon but no more than a 100 shot....is that cam capable of making that kinda power? 6000 rpm is the max im running the engine up to......ive got 3.73 gears with a th-350 trans and a 3000 stall in a 3400 pound car just for refrence of what its pulling behind it.
What heads are on it now double humps? It sould like you have some other problems, mine would turn 6500 with a stock set of doulbe humps and a solid cam, even with what you have it should go 6000. The cam will work but its just a poor design and you will be leaving 20 or so Hp on the table.Nitrous does not need a wide lobe center unless you are shooting well over 200shot. I would spend some money and get some good heads thats where all the power is.
I would use the intake that I mentioned above with the heads that I recommended as well. As for the cam, I prefer custom grinds myself, but there are two cams off of the shelf that I have used that work very well. The first is a Comp Cams # 12-242-2 and the second is a Lunati # 60103.
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No they arent double humps or anything special....just stock plain jane sbc heads like you'd find on a pick up truck....so yeah they are killing me in the power department and i know they are....id really hate to pull the cam out and have to go through getting a new one degreed in right...it seems to make good power and it revs like crazy but it just cant breath well enough with those heads.
Last edited by 1994t/a; Aug 20, 2008 at 02:51 PM.
No they arent double humps or anything special....just stock plain jane sbc heads like you'd find on a pick up truck....so yeah they are killing me in the power department and i know they are....id really hate to pull the cam out and have to go through getting a new one degreed in right...it seems to make good power and it revs like crazy but it just cant breath well enough with those heads.
Then it doesnt have 64 cc heads on it more like 76cc and low compression.
