Valve timing with high compression pistons

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Model T Ford Forum: Forum 2015: Valve timing with high compression pistons
Top of pagePrevious messageNext messageBottom of page Link to this message  By Daniel M. Chapasko on Wednesday, January 21, 2015 - 12:33 am:

What is the correct way to set valve timing in my newly rebuilt 1927 engine? Would there be a gauge for valve timing for the taller aluminum pistons? My new engine runs great, but I would like to adjust the valves a little better. Thank you guys.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Wednesday, January 21, 2015 - 10:30 am:

What cam do you have? Adjustable lifters? New valves?
In any case I would just set the gap and forget about the travel method.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Wednesday, January 21, 2015 - 11:17 am:

If you have a reground or new camshaft, follow the manufacturer's instruction. in other cases, try adjusting the gap at a common clearance such as 12 or 14 thousandths. Then check to see whether the valves open and close at or nearly the same piston position. If so, you are good to go. The important thing about piston position, is not necessarily the best power, but the smoothest operation. If they are all close to the same, the power will be even on each cylinder causing it to run smoother. The piston position method was intended for older cars with worn camshafts using original grind and pistons.

Most engines in operation today are not original, such as yours which has been "rebuilt" (means different things to different people)Already, you know the pistons are not original.

Why do you want to adjust the valves "better". Is it because of noise, or smooth running? If the compression is even, and it were mine, I would just keep driving it.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By G.R.Cheshire on Wednesday, January 21, 2015 - 12:12 pm:

Since the valves are off to the side in a flathead engine a taller higher compression piston would make no difference as long as it doesn't hit the head! Valve / Piston clearance only comes into play for overhead valves ... or have you converted your engine to a rajo?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Daniel M. Chapasko on Wednesday, January 21, 2015 - 12:37 pm:

Thank you guys. I will adjust the valves in a simple manner and go driving. Dan C. Loveland Colorado


Top of pagePrevious messageNext messageBottom of page Link to this message  By Glen Chaffin on Wednesday, January 21, 2015 - 01:55 pm:

Dan, If you are using an original cam just set valve clearance. If you are trying to use the old piston travel method your valve clearance will be all over the place. If you are using a new cam use the clearance recommended by the manufacturer. In either case just set the recommended valve clearance


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Wednesday, January 21, 2015 - 08:27 pm:

Might want to read the service manual on valve adjustment to understand what is meant by piston travel method. It has nothing to do with an over head and has to do with having all the valves open and close at the same place during the pistons travel. With worn lobs, pistons machined at different heights or rods not bored the correct distance between centers or all of the above you would set the valves to open and close at the same place for each cylinder. This could give you valves gaps of .030 plus and very noisy engine.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Glen Chaffin on Wednesday, January 21, 2015 - 11:44 pm:

Mark, When I rebuilt my 1913 roadster for the first time. I did not have any new 280 cams to use so I used my original cam. Indeed every lobe was worn different but I set the valve clearance to 0.015 and the car ran beautifully You would never have known it was a worn cam and all of the cylinders were performing differently. But it was quiet and ran good. So so much for adjusting by piston travel. Bruce McCalley would turn over in his grave as he published many articles about valve adjustment by piston travel. After rebuilding the engine using one of my new 280 cams I did notice a significant improvement in performance but that was because I was using a non worn , better designed cam. But my point is you will get a quieter cam that will perform just as well if you simply set the valve clearance so they are all the same.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dale Peterson College Place, WA on Thursday, January 22, 2015 - 08:17 am:

It would seem that no matter which Pistons you have you should be able to set the valve timing by travel. Set one valve to a predetermined clearance, then build a gauge with that piston position measured at the tallest point, then adjust all other valves to open at the same point.


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