notched pistons AFR heads
02-02-2008, 06:26 PM
#12
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Join Date: Aug 2006
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Posts: 943
RE: notched pistons AFR heads
The intake valve chases the piston. I agree lift not always causes piston to valve clearance issues, it's cam timing in realtion tothepiston'spostion in thecylinder. Either way in my opinion a stage 1 Trick Flow isn't big enough cam to take advantage ofa head with 180+cc intake volume. He is going to have to have a custom ground camfor his set-up, notch the pistons, get Twisted Wedges, ora head with smaller intake valves.
02-02-2008, 07:20 PM
#13
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RE: notched pistons AFR heads
ORIGINAL: OnyxCobra
Yeah they say you'll have to notch the pistons with the AFR 185s because usually you'll want to run a cam with much more than .499 lift to make optimal use of the 185 heads. Depending on your plans the AFR 165s could be just fine, the flow isn't majorly different between the two.
Yeah they say you'll have to notch the pistons with the AFR 185s because usually you'll want to run a cam with much more than .499 lift to make optimal use of the 185 heads. Depending on your plans the AFR 165s could be just fine, the flow isn't majorly different between the two.
02-03-2008, 12:20 AM
#14
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Join Date: Sep 2007
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Posts: 798
RE: notched pistons AFR heads
ORIGINAL: OnyxCobra
It could be, all depends on the overlap of the cam. Wouldn't you want the intake valve open before the piston starts going down to maximize your intake stroke?
It could be, all depends on the overlap of the cam. Wouldn't you want the intake valve open before the piston starts going down to maximize your intake stroke?
The intake valve opens just a few degrees before TDC, and some open up at TDC, and some open up after TDC. It says open several degrees after the piston begins the compression stroke to keep that inertial airflow to keep packing in.
Look at the Trickflow Stage 1 camshaft. It opens up just 3* BTDC, but closes 38* ABDC. Of course many camshafts are designated with a BTDC opening just before it reaches BTDC to get a jump start, but that has nothing to do with peak valve lift. Peak valve lift should be an issue taken care of with the valvetrain, not piston to valve clearance.
Peak lift is not an issue. The piston is darn near 2 inches down in the bore. So take a valve lift of .500", and the piston is 2.00" away from TDC. I wonder if it will hit?[8D]
Take a stock camshaft at .444" lift. With some high (steep) ramp rates, and some early intake openings and late exhaust closings could cause it to hit. Then again, many run .600" on stock pistons.
02-03-2008, 12:44 AM
#15
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Join Date: Nov 2005
Location: Rochester, NY
Posts: 8,467
RE: notched pistons AFR heads
ORIGINAL: Joel5.0
Why?......or does any of the valves is at full lift during the overlap of the cam?.... the peak lift spec of any cam has nothing to do with the possibility of PtV problems. If "the flow isn't majorly different between the two."...... why would you choose one over the other?
ORIGINAL: OnyxCobra
Yeah they say you'll have to notch the pistons with the AFR 185s because usually you'll want to run a cam with much more than .499 lift to make optimal use of the 185 heads. Depending on your plans the AFR 165s could be just fine, the flow isn't majorly different between the two.
Yeah they say you'll have to notch the pistons with the AFR 185s because usually you'll want to run a cam with much more than .499 lift to make optimal use of the 185 heads. Depending on your plans the AFR 165s could be just fine, the flow isn't majorly different between the two.
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