Is my valve timing gear index mis-marked?

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Model T Ford Forum: Forum 2014: Is my valve timing gear index mis-marked?
Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Anderson on Friday, October 10, 2014 - 05:30 pm:

I measured when my #1 intake valve closed and it was (with .012 clearance) 62 deg after bottom dead center. I read that it should be about 50 deg with a stock cam. I checked the gear timing marks and they appeared to be correctly aligned with the Ford logo, see pic. I then advanced the big gear one tooth and checked again. It is now 48 deg abdc, much closer to 50 deg. Am I missing something? I hope this would explain why my engine really struggled after the low to high transition.

timing gear mesh index marks


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Friday, October 10, 2014 - 05:40 pm:

It might just be the angle of the photo, but to me the key way on the crank gear looks to be 1/2 a tooth out.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Friday, October 10, 2014 - 05:43 pm:


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Anderson on Friday, October 10, 2014 - 05:57 pm:

Frank, as best as I can see, your crank gear and mine look like they have the same marking locations. Could my big timing gear mark be off?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Friday, October 10, 2014 - 06:21 pm:

OK, your cam gear doesn't look like a Ford one, try this, a ruler on the left side of the 2 dowels and you get 1-1/2 teeth to dot.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Anderson on Friday, October 10, 2014 - 08:09 pm:

It matches up like yours.
I installed a large nylon gear that has the 7.5 deg advance option. I advanced it one tooth and found the valve opening at 43 deg abdc, which is close to what it should be. If I installed it so the timing marks match up, it would be retarded even with the advanced setting. Maybe there is something goofy about #1 intake cam; I should check the others.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Anderson on Friday, October 10, 2014 - 09:00 pm:

FYI I measured the cam heel to top of lobe to be 1.030"
The lift was (including .012 clearance) .241"
I havent been able to find any specs on what these should be, but a warn lobe might explain the retarded timing?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Friday, October 10, 2014 - 09:08 pm:

Unless you have a brand new cam and brand new gears, and bearings you will find problems. That is why they re-grind camshafts and place new gears and bearings. Anything worn would retard the opening of the valves.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Larry Young on Saturday, October 11, 2014 - 01:11 pm:

Wear should not cause any appreciable change to the cam timing. The greatest effect is on the lift, since the nose is where most wear takes place. You first need to confirm whether you have a stock cam. The specs are given at the Tulsa website. - http://www.mtfctulsa.com/Cams/design_stock.htm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Fred Miller, Sequim WA on Saturday, October 11, 2014 - 03:03 pm:

Maybe a bad Camshaft Regrind or an aftermarket replacement.


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