Valve to Piston Clearance?

rojo · Feb 2, 2008

What's your opinion on the these clearances. I'm hoping to cheat a bit.

Intake .087 .....recommended min. is .100 (.013 off)

Exhaust .112 ....recommended min is .110 (okay on this one)

These were checked with a dial gauge using a solid lifter and a test spring so I'm pretty confident in the results.

4.060 bore x 3.562 stroke .002 in hole .041 gasket compressed

Cheap cast pistons.

BillK · Feb 2, 2008

Robert,
As long as you are not going to be turning it 7000 rpm you should be ok. Just putting on the real springs will probably get you another .005" or so. Also, make sure when you adjust the valves that you use very little preload, probably 1/8 turn or so. That way if the lifters pump up for some reason you wont have a problem.

rojo · Feb 2, 2008

Thanks Bill (again). I'll keep it below 6k. Ya know when you push down on the rocker to check the clearance .087 sure looks like more than it sounds.

BillK · Feb 2, 2008

rojo said:
Ya know when you push down on the rocker to check the clearance .087 sure looks like more than it sounds.

Ain't that the truth ! By the way, I would really suggest that you check the clearance with some modeling clay. I have found that most pistons have enough depth on the cutout, but a lot of them do not have enough diameter, especially around the intake valve. The ONLY way to see this is with clay. You might have enough depth but as soon as the engine starts and you get a little piston rock, the valve could hit the edge of the valve relief.

rojo · Feb 3, 2008

I did the clay to start with. I thought it looked okay but to be honest I'm not sure that I paid attention to that aspect. I guess I'll find out. :yes:

Valve to Piston Clearance?

rojo

BillK

rojo

BillK

rojo

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