need help with valve to piston clearance?
03-17-2007, 12:58 PM
#1
Thread Starter
Join Date: Oct 2006
Posts: 21
need help with valve to piston clearance?
big valves, stock pistons
I'm putting heads with 1.94 intake valves on a stock 94 mustang shortblock. I'm just wondering if I need flycut pistons. Any advice would be appreciated. I am putting a cam(magnum 280H) in the car also. Thanks
03-17-2007, 01:48 PM
#2
2nd Gear Member
Join Date: Jan 2007
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Posts: 213
RE: need help with valve to piston clearance?
If your talkin about the magnum 280HR with .560/.598 lift, 224/230 @.050 durationI think it would be safe to say you'll need to fly cut the stock pistons. How much is another story, your gonna need to mock it up and see to get an idea of how much you'll need to cut. Remember the rule is .080" PTVclearance for the intake and .100" for the exhaust.
03-17-2007, 02:27 PM
#5
5th Gear Member
Join Date: Jan 2006
Location: Puerto Rico
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RE: need help with valve to piston clearance?
Lift numbers won't matter for PtV.....the 280HR has a +3° overlap @.050 and the 280H has +10°...even with the lower valve lift spec, the 280H will have those valves closer to the piston when it counts....@exhaust TDC....when the valves are at full lift, the piston is +1.5" below the deck......OH!...and don't forget to check the PtV radial clearance as well, with larger valves you will need to ensure .050" around the edge of the valve and the pocket.
03-17-2007, 02:29 PM
#6
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RE: need help with valve to piston clearance?
that cam has retarded lift that isnt going to make you any power.
as far as OTS cams go. A steeda #19 with 1.7 ratio rockers would probably be a better choice... I could look around and recommend something better.... but seriously, you dont need .600 lift on your exhaust valve.... thats just silly
as far as OTS cams go. A steeda #19 with 1.7 ratio rockers would probably be a better choice... I could look around and recommend something better.... but seriously, you dont need .600 lift on your exhaust valve.... thats just silly
03-17-2007, 06:05 PM
#8
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Posts: 213
RE: need help with valve to piston clearance?
I'm sorry I was under the mistaken idea that a stock 94 Mustang shortblock used a roller cam...hmmmmm. The 280H is a hydraulic flat tappet camshaft. Somethin dont make sense...[sm=smiley24.gif]
03-17-2007, 06:10 PM
#9
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RE: need help with valve to piston clearance?
ORIGINAL: Chitown racer
I'm sorry I was under the mistaken idea that a stock 94 Mustang shortblock used a roller cam...hmmmmm. The 280H is a hydraulic flat tappet camshaft. Somethin dont make sense...[sm=smiley24.gif]
I'm sorry I was under the mistaken idea that a stock 94 Mustang shortblock used a roller cam...hmmmmm. The 280H is a hydraulic flat tappet camshaft. Somethin dont make sense...[sm=smiley24.gif]
