Newbie Valve Adjustment

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Model T Ford Forum: Forum 2015: Newbie Valve Adjustment
Top of pagePrevious messageNext messageBottom of page Link to this message  By John Aldrich Orting Wa on Saturday, December 19, 2015 - 03:09 pm:

Never adjusted valves before but I am thinking the attached photos show valves opening entirely too far.
Also... valves 6 and 7 have dimples in the top whereas the others have tiny holes. What's the difference?

Your thoughts?




Top of pagePrevious messageNext messageBottom of page Link to this message  By Dennis Plank - Three Way, TN on Saturday, December 19, 2015 - 03:44 pm:

Depending on what cam you have, the valves should open about 1/4". The valves with the two little holes are probably 2 piece valves and should be replaced. The valves with the dimple look like one piece valves to me and should be OK.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Aldrich Orting Wa on Saturday, December 19, 2015 - 05:03 pm:

1/4 inch measured from the edge of the valve to the block surface?

They are all one piece adjustable valves. This is a stock 1915 rebuilt with .060 over-sized pistons. I do not know what cam is in there.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Saturday, December 19, 2015 - 05:16 pm:

If they all close properly and have a lash of at least 0.010" (inlet) and 0.012" (exhaust) - then you're probably OK. More lift than std 0.250" is good for power :-)
Some very early blocks can have trouble with .280" lift in a new cam, the lifter may touch the block from the underside, but if you haven't got any annoying sounds, then it's very likely OK as is.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tony Bowker, Ramona, CA on Saturday, December 19, 2015 - 05:23 pm:

The original camshaft had a lift of 0.250", and with the specified clearance of 0.030, the lift at the valve will be 0.220. Now over the last 90-100 year the camshaft have worn a little and the camlift can be as low as 0.220.
These days, most are looking for more performance and install modified camshaft with lifts from 0.250 to 0.280. In addition, with more accurate grinding, we tend to reduce the valve tappet clearance to 0.010 to 0.015.
Now we can look at the valve lift on your motor and estimate what is in your block, the maths are easy, so make your measurements and if you need more help, let us know.....


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Aldrich Orting Wa on Saturday, December 19, 2015 - 07:41 pm:

I measured all the valves and they were all just a hair over 1/4" lift. Satisfied with what I have read here I finished cleaning all the surfaces, put a new head gasket on, re-assembled, and actually had to choke it to get it started!

I didn't do any primer cranks so I guess that was my own fault. Cranked twice, choked and cranked twice more, let off the choke and the next crank she took right off. Runs smooth.

Couple of friends said I have low compression since it is so easy to crank. Makes sense to me.

While I had it apart I put oil in all cylinders to the "crown" of each piston.

I had no leaking or bubbles of any kind after 2 hours.
How well did I test the rings this way?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hap Tucker in Sumter SC on Saturday, December 19, 2015 - 08:14 pm:

John,

The oil sitting on top of the pistons won't leak past the rings nearly as easy as the combustion gases under pressure. And you will not see bubbles as the oil drips past the rings into the crankcase and the air that is displaced in the crankcase would exit the breather cap. There is not pressure to push it up through the oil. Finally I would assume you had all 4 pistons about equal distance from the top of the block. But that means they are half way down their stroke. And the most wear is often at the top of the cylinder. (ref: http://www.aa1car.com/library/ring_end_gap.htm ) So if you have the piston half way down in the bore it normally will have better sealing there than at the very top of the stroke.

A better way to check the compression is to use a compression gauge and turn the engine over. Your 1915 & probably doesn't have a starter but the other three may. Even without a starter you can have someone spin the crank with the spark plugs removed and get a compression reading. See: https://www.youtube.com/watch?v=0W0kQeTvURU For a Model T Ford you will need an adapter for most modern compression gauges. If you have the type that seals with a rubber cone you can remove the porcelain from a spark plug. Screw the base of the plug into the cylinder. Have all the other plugs out. Throttle open. Keep hands and tools away from moving parts. Car in neutral, wheels chocked. Hold the rubber cone in the spark plug base. Have someone else spin the engine over (hand crank or starter). And record the readings. Higher numbers are better. Numbers for all 4 cylinders close to one another is better. See: http://www.mtfca.com/discus/messages/29/29023.html?1178459412 where they discuss that as low as 35 psi will run but not very strong and 40 to 45 is good. Also if you do the check at sea level verses the top of Pikes Peak the same engine will have different readings.

There is also a differential cylinder check that is used on general aviation engines. That would give you a more accurate reading but it is a Model T Ford engine so the first method mentioned above should work fine for you. For more on the other method please see: http://www.eaavideo.org/video.aspx?v=2363274331001

Good luck with your engine.

Respectfully submitted,

Hap l9l5 cut off


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Sunday, December 20, 2015 - 10:50 am:

The 1/4 inch is the amount of movement of the valve. Use a dial indicator to measure the lift.

Your valves appear to be carboned up and in need of at least a lapping in. The valves are sitting proud of the block, which shows the valves and valve seats are not badly worn.

I would remove the cam and valve springs, and then clean all the valves with a wire wheel. Then lap them in with some Clover compound.

Then check your cam lobes for uniformity. They should be the same maximum and minimum measurement on each lobe. Any lobe out by .010" from the rest would merit replacement of the cam with a new one.

Finally set the valve clearance. I have had good luck using .015" on the intake and .018" on the exhausts. Someone mentioned .030" which is crazy talk - the engine would be very noisy and down on power if that dimension was used.


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