Rattling timing gears

[wensum]

I know this subject has been covered ad infinitum, but it has driven me crazy.
My motor is bored 100thou oversize so must have done a lot of miles. It also has a reground touring camshaft and oil pressure fed main bearings (25lb pressure relief valve in valve chamber)
At idle the motor is perfectly quiet, but under load there is a loud clatter coming from the timing gears.
It had an aluminium timing gear that was mildly noisy so I fitted a matched set of Dam McEachern Bronze timing gears and the noise has been considerably worse.
Suspecting a weak plunger spring (new) I packed behind it to provide more pressure, but no change in noise levels.
I wonder if it's a combination of worn bearing faces in the block and the more severe camshaft profile causing oscillation at the gears?
I'm tempted to fit a new Stipe touring camshaft which might have a better ramp profile than a reground cam and an original type timing gear?
I'm also tempted to provide an oil supply directly to the gears?
Any suggestions?
Keith

[Patrick L.]

Have you checked the gear lash ?

Should be in the .003-.005" range. They'll rattle at .010".

[Chuck Sea/Tac]

Check your crank pulley. Is it a two piece? Buying another cam isn't going to solve this problem . I'm curious as well, of how much play is in your gears.

[quickchange]

Keith have you measured the clearance ? use 4 rolly papers between the gears , should just cut them . 4 thou. If too loose run a o/s fibre one , it will see you out,

[wensum]

Unfortunately, I've just put it all back together, but I'll have to have another go at it shortly.
In the meantime I think I'll try installing a jet to spray oil directly onto the gears and see it that helps?
It does sound very metallic.
Certainly a fibre one might be the end result at this stage
Thanks
Keith

[Patrick L.]

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Chuck makes a good point. The 2 piece pulleys can be a problem.

Running the engine with the timing pin pushed against the gear face will usually take the noise out of the gears, but, probably not the pulley.

[Flathead]

Dan's gears are well liked. Possibly there is too much backlash which could be caused by the previous rebuilder not getting the cam and crank centerlines right when the babbitt was machined. The aluminum gear you replaced may have been oversize to compensate for this.
That could account for the increase in noise when putting in Dan's gears which would be sized for a correctly machined motor. As was previously suggested, try checking the clearance between the gear teeth. This is one possibility to explore YMMV

[V4F]

if it is a metal cam gear , does it lessen as the motor warms up ? mine did

[H. L. Chauvin]

Hi Keith,

Some of the perfectionist engine re-builders who offer replies on this Forum will agree that after one or several engine re-builders and/or machinists provide work on Model A engines, and there are problems, it is not always a question of "what" was done; but sometimes "who" did what?

Maybe try making a sound video with a cell phone and send same to Mr. McEachern.

With years of timing gear problems and questions presented to him, his looking at and listening to this video will not be his first observation of a difficult and mysterious bull riding and bucking horse timing gear rodeo ...... plus you will meet a compassionate gentleman who cares.

[hardtimes]

Originally Posted by wensum

Unfortunately, I've just put it all back together, but I'll have to have another go at it shortly.
In the meantime I think I'll try installing a jet to spray oil directly onto the gears and see it that helps?
It does sound very metallic.
Certainly a fibre one might be the end result at this stage
Thanks
Keith

Hey Keith,
Have you checked (drained) your oil and checked for metallic chips of any kind ? No chips=good. Bronze chips=wear. Silver chips=not good.

[wensum]

Originally Posted by H. L. Chauvin

Hi Keith,

Some of the perfectionist engine re-builders who offer replies on this Forum will agree that after one or several engine re-builders and/or machinists provide work on Model A engines, and there are problems, it is not always a question of "what" was done; but sometimes "who" did what?

Maybe try making a sound video with a cell phone and send same to Mr. McEachern.

With years of timing gear problems and questions presented to him, his looking at and listening to this video will not be his first observation of a difficult and mysterious bull riding and bucking horse timing gear rodeo ...... plus you will meet a compassionate gentleman who cares.

Thanks for that suggestion. I'm not a cell phone user (hate the things) but I'll find some way of following up the suggestion.
Keith