Valve Clearance?
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Pro
Joined: Apr 2005
Posts: 591
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From: Batavia IL
Valve Clearance?
I am putting together a 383 and had a question about clearance for the valves. I am considering using a mechanical roller cam that has about .580-.6 lift. I am almost positive that there will be issues with the valves hitting the pistions due to the unconventional layout of the valves in my heads. My heads are Trickflow twisted wedges. What I wish to know is, is there a tool I can use to grind proper valve reliefs into my pistions so that I will have enough clearance? such as a cutting bit the same size as the valve and bolt the head on and lower it onto the piston to grind the reliefs. maybe I can just sharpen a valve and use that as my cutter. Is this a smart way to do this?
Drifting
Joined: Dec 2005
Posts: 1,360
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From: NORTHEAST
Originally Posted by Tumarr
I am putting together a 383 and had a question about clearance for the valves. I am considering using a mechanical roller cam that has about .580-.6 lift. I am almost positive that there will be issues with the valves hitting the pistions due to the unconventional layout of the valves in my heads. My heads are Trickflow twisted wedges. What I wish to know is, is there a tool I can use to grind proper valve reliefs into my pistions so that I will have enough clearance? such as a cutting bit the same size as the valve and bolt the head on and lower it onto the piston to grind the reliefs. maybe I can just sharpen a valve and use that as my cutter. Is this a smart way to do this?
It would be a good idea and call the piston manufacturer to see how they can be cut and a engine shop that does this type of work would be your best bet on doing a good job.
Drifting
Joined: Jun 2005
Posts: 1,824
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From: Middleboro Massachusetts
Originally Posted by Tumarr
I am putting together a 383 and had a question about clearance for the valves. I am considering using a mechanical roller cam that has about .580-.6 lift. I am almost positive that there will be issues with the valves hitting the pistions due to the unconventional layout of the valves in my heads. My heads are Trickflow twisted wedges. What I wish to know is, is there a tool I can use to grind proper valve reliefs into my pistions so that I will have enough clearance? such as a cutting bit the same size as the valve and bolt the head on and lower it onto the piston to grind the reliefs. maybe I can just sharpen a valve and use that as my cutter. Is this a smart way to do this?
Put about a half inch dollup of modling clay on the intake and exhaust valve head. Bolt the cylinder head on with the old gasket (if you have one) and 4 head bolts. Turn the crank over by hand through one revolution to cycle the valvetrain. You must use a solid lifter, or a checking valvespring, so the lifter does not collapse and give you a false reading. Remove the head and measure the depth of the clay by plunging a micrometer through the thinnest portion. It should be more than .120" on the exhaust valve and .090" on the intake valve, or you will need reliefs cut into the pistons. Do not use playdoh or it will give you a false reading due to its memory.
Last edited by zo6vetteman2003; Feb 28, 2006 at 07:01 AM.
Melting Slicks
Joined: Apr 1999
Posts: 2,010
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From: Moon Twp. PA USA
Originally Posted by Tumarr
I am putting together a 383 and had a question about clearance for the valves. I am considering using a mechanical roller cam that has about .580-.6 lift. I am almost positive that there will be issues with the valves hitting the pistions due to the unconventional layout of the valves in my heads. My heads are Trickflow twisted wedges. What I wish to know is, is there a tool I can use to grind proper valve reliefs into my pistions so that I will have enough clearance? such as a cutting bit the same size as the valve and bolt the head on and lower it onto the piston to grind the reliefs. maybe I can just sharpen a valve and use that as my cutter. Is this a smart way to do this?
, we used to take a valve that we wanted to use, and put an edge on the face. We then put it in the head, bolted it down, and used a drill to spin it and cut a relief in the piston. Check your HOT ROD mags from the '50s.It worked back then, should work now.
Drifting
Joined: Jun 2005
Posts: 1,824
Likes: 1
From: Middleboro Massachusetts
Originally Posted by glen242
Way back before electricity was invented , we used to take a valve that we wanted to use, and put an edge on the face. We then put it in the head, bolted it down, and used a drill to spin it and cut a relief in the piston. Check your HOT ROD mags from the '50s.
It worked back then, should work now.
, we used to take a valve that we wanted to use, and put an edge on the face. We then put it in the head, bolted it down, and used a drill to spin it and cut a relief in the piston. Check your HOT ROD mags from the '50s.It worked back then, should work now.
Melting Slicks
Joined: Apr 1999
Posts: 2,010
Likes: 3
From: Moon Twp. PA USA
Originally Posted by zo6vetteman2003
The valve was used as the drill bit you are saying? If so very cool. So you mean a valve exactly like the one you are going to use.
Drifting
Joined: Dec 2005
Posts: 1,360
Likes: 3
From: NORTHEAST
Originally Posted by glen242
Yes, a valve exactly like you were going to use. As I said, this was in the dark ages, but should still work today.
HMMMMMM
