TR2/3/3A TR3 valve clearance settings

prb51

Luke Skywalker

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• Nov 17, 2008

• #1

What do you set and why? I know the .010/.012....010/.010 by the book depending upon year/mods but it seems the more TR3 guys I talk to set differently. .012/.012 on a latter car for example.
We're talking normal cam profile here.

 

TR3driver

Great Pumpkin - R.I.P

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• Nov 17, 2008

• #2

I've always run 10/10 (since all my engines have the aluminum rocker pedestals). But I doubt 12/12 would make enough difference to argue about; just a bit more noise and a bit less peformance.

 

angelfj1

Yoda

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• Nov 17, 2008

• #3

It depends on the cam. If it's original, set it per the book. if not, the cam mfg will state the proper clearance.

 

T

trfourtune

Jedi Knight

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• Nov 19, 2008

• #4

it's not just the cam (but that is definitly the biggest factor). I don't know what the original valves are made of but stainless steel expands more than carbon steel. So new stainless valves may have a higher expansion rate than the originals which would require more clearance.Just a thought.

 

rlandrum

Jedi Trainee

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• Nov 19, 2008

• #5

I have an aftermarket cam, but I don't have any specs on it, and I didn't bother degreeing it. I used the factory settings, even though during disassembly I noticed zero lash, which I know is wrong (or rather, is most probably wrong, at least with flat tappets cause they need to spin...).

 

T

trfourtune

Jedi Knight

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• Nov 19, 2008

• #6

rlandrum,
you definitely need clearance or you will have a set of burned valves very soon, as well as no power. You may be throwing away as much as 5 hp by not degreeing your cam. the stock sprocket can be installed in a few different ways to optimize the cam timing without going to a vernier cam sprocket. I know that every additional hp usually costs some major bucks but this one is cheap.
IMHO
R

 

rlandrum

Jedi Trainee

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• Nov 20, 2008

• #7

Actually, it was timed straight up. I didn't bother removing the the timing sprocket, so I'm not worried. As for the HP, that's not really an issue, since I pretty much replaced the TR4 engine hi-flow intake/exhaust with low-flow TR3 versions, mostly to appear correct.

 

T

trfourtune

Jedi Knight

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• Nov 21, 2008

• #8

actually, timed "straight up" does not mean it is timed. Unless you check it, you do not know what you have. If it is an aftermarket cam, as you say, then you are trusting that the guy who first put it in knew what they were doing. Putting it in "per the timing marks" means nothing.
If it is a reground to stock specs cam, use the stock clearance numbers. Why do you need clearance?-as the engine heats up, the clearances close up because of thermal expansion of the valves-they get longer. the exhaust gets hotter than the intake so it usually has more clearance setting.
Rob

 

W

Wyndell

Freshman Member

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• Mar 10, 2019

• #9

I just had a valve job on my TR3A. Putting the head back on, I backed off the adjuster screws but there does not seem to be enough clearance for the valve adjustment. Do I need another set of pushrods, or what?

 

TR4nut

Yoda

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• Mar 10, 2019

• #10

Did you happen to skim the head pretty heavily? Either that or possibly having valve seats cut in deeper than stock might give you the problem you have. Shortening the pushrods, or adding shim stock underneath the pedestals can be cures, but I’d check back with your machine shop to see if you can determine the main cause.

 

glemon

Yoda

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• Mar 12, 2019

• #11

Wyndell, sorry if you are way ahead of me here, but are you checking clearance with the "rule of nine". Valve 1 fully open check clearance on 8, valve 2 open check 7, etc.?