Calling all T Gurus

[Flyingpiper59]

Forum Chums
First, I would like to thank all the people who have responded patiently to all my questions regarding cam shafts…. your insights have all been invaluable as I try to learn more about the model T…..I am slowly getting my engine through a “refreshing”… operative term… SLOW!
I spend a lot of time on the road flying airplanes…. This whole making a living thing can be a pain in the backside, eh? lol.

I believe I have come up with a way to check the lift on my stock Cam without first taking it out of the engine!

First off, I want to find the backlash on each valve, utilizing piston position, and make note.
Secondly, I’d like to measure the “valve” lift on each lobe with a dial indicator.
Lastly, I will add in the individual backlash of each valve to get true “cam” lift from step one.

Is the Cadet’s logic sound?…..thoughts?…..Did I miss anything?

Thanks in advance and Cheers!

[Adam]

No need to find lash and do any calculations. Shove a nickel or something similar that removes all gap between the tappet and valve, then crank the engine and check the lift with a dial indicator.

[TrentB]

Adam’s suggestion should work.

Alternatively, create a dummy valve by grinding/turning down an old valve’s head so that it is only about 1 inch in diameter, and it will completely clear the valve seat. Remove a valve, spring and keeper, and clean the guide and top of the pushrod, if you have not already done so. Put in the dummy valve and set up your dial indicator. Crank the engine over two full turns and watch your dial indicator.

You may want to do this on several different valves both in front of cylinder #3 and behind cylinder #2 in order to check for uneven cam lobe wear.

You may still have wear in the cam bearings that may be detected by measuring the lift on numbers 1, 2 and 3 cylinders exhaust valves both with and without the valve springs and keepers. The rear camshaft bearing does not seem to wear much in normal use.

Respectfully submitted,

Trent Boggess

[Flyingpiper59]

Trent and Adam….Thank you!

Adam…brilliant idea about the nickel…. even though the nickel will bring the valve up from its seat, the subsequent lift of the cam doesn’t change…
You just saved me a ton of needless ciphering…. Nicely done!

[Mark Nunn]

Edwin, I did what Adam suggested a few weeks ago with success. My head was off the engine to make the process easier. However, when I adjusted my timer, I made an offset tip for my dial indicator where I replaced the normal tip with a properly sized piece of wire. The wire was bent in a Z shape. The tip goes through the sparkplug hole and against the top of the piston. I could see making a smaller Z that could rest against the valve with the head still on. It is worth a try if you have not removed your head.

[Scott_Conger]

Anyone wishing to make a custom tip for a drop indicator will need a 4-48 plug and bottoming tap, as that is the standard thread for these things.

[Dan Hatch]

Here is how piston position was found back in the day

[Mark Nunn]

Thank you, Dan. I looked for that photo you posted a while back but could not find it. I can see how one of the offset parts on the right could be used to measure valve lift too. I made one for my dial indicator.