1935 221 timing gear lash

V

Vince1962

New member
Hello all, I've got a 221 with (many) issues. The block has been converted to insert mains, and a late modified crank has been installed. Currently I am fighting the timing gears. This engine was a fresh rebuild (unknown builder) that failed shortly thereafter. When the engine came in the fiber cam gear was destroyed, with multiple teeth missing. An aluminum NOS was sourced and installed (press on style). My problem is with the crank gear installed I have ZERO lash, in fact its so tight it binds the crank and will damage the aluminum gear. I am concerned the cam centerline is off, as the bores have repair sleeves installed. The other possibility is the gears don't actually match. I am told there is a difference between an early and late crank gear, but nobody has been able to tell me what the difference actually is. Currently its a "2704" which is the early style. Is it possible the NOS aluminum gear is profiled for the "new" style despite being the old press on center? Does anybody have any insight on this issue?

I have posted this on AACA and The Hamb already
 
First of all, welcome aboard!

The only difference I am aware is a very obvious one on the 49-53 flatheads in that the angle of helical gear is opposite direction so that the thrust of the camshaft was opposite of the early (32-48) engines.
 
Zeke3 said:
First of all, welcome aboard!

The only difference I am aware is a very obvious one on the 49-53 flatheads in that the angle of helical gear is opposite direction so that the thrust of the camshaft was opposite of the early (32-48) engines.
Click to expand...

There is also a 32-33 crank gear and matching cam gear.
 
Zeke3 said:
First of all, welcome aboard!

The only difference I am aware is a very obvious one on the 49-53 flatheads in that the angle of helical gear is opposite direction so that the thrust of the camshaft was opposite of the early (32-48) engines.
Click to expand...

There is also a 32-33 crank gear and matching cam gear. Top set in pic is 32.
 

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Is your cam gear oversize? They made several different oversized.
 

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Oversized cam timing gears are around…..as the pictures show, they are clearly marked with the particular oversize dimension. I would confirm that before jumping to the next level, which might be that the cam bores/sleeves weren’t aligned correctly.
 
The number of teeth on the early timing set, versus a bit later (still press on) is way different. You couldn't install the wrong cam gear (with a wrong tooth size/count) and fit it to the early gear and visa versa. As noted by a few, it could be that the cam gear is oversized.

It could also be that whoever did the "main bearing conversion" messed up the centerline distances between the cam and crank - with the crank moving closer to the cam. Or they screwed up the 'sleeves' in the cam bores. Given the sleeves in the cam bores, is this a 32 block that didn't come with cam bearings . . . and now it does???

Truth be told, I am betting you have a problem with the centerlines of the cam/crank being off - that is what I'm going to guess, as the fiber gear was all chewed up as well.

If that is the case, I'm not aware of any easy way to "fix it" - depending on how the conversion was done. It would take a total tear down, diagnosis and then determination if a fix was possible -> and the costs would probably be ridiculous, versus finding another engine to work from.

What year engine is this?

Edit: I missed that you said it was a 35 engine. Going to a 36 LB engine with insert mains would be a great place to go - as long as you can find bearings for it.
 
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there is a fix if the centres are not correct,
I had the machinist bugger up my old A engine,
I then had them rebore the cam bores out .125 oversize then made up some centric bushes .
That engine has boy 25K miles on it and its still as quite as.
A lot of fancy machining required though
Lawrie
 
I would suggest that it is possible, if the crank mains were line bored that the crank is a little higher up. Any machine shop with a hand held laser scanner would be able to diagnose your problem. Plus if they have a CNC machining center they can re-machine the cam gear that you have to suit your specific dimensions. It's quite simple and not as expensive as you might think.
 
69a said:
I would suggest that it is possible, if the crank mains were line bored that the crank is a little higher up. Any machine shop with a hand held laser scanner would be able to diagnose your problem. Plus if they have a CNC machining center they can re-machine the cam gear that you have to suit your specific dimensions. It's quite simple and not as expensive as you might think.
Click to expand...

The challenge is that somebody has to make an accurate 3D CAD model, apply tool-paths to it, etc.. This all takes time and this sort of labor is not cheap. The biggest issue will be finding somebody who even wants to screw with a one-off job like this.

Me, if I found the centerlines were off, I'd consider going back to babbit mains and having the centerlines fixed, or building a new engine.
 
You don't need to build a model! I know someone who had a aluminum timing gear (not Ford) with 4 teeth smashed out of it. He had it welded up and re-machined. This was 6 years ago.
 
Try Dan McEachern he makes gears for T and A and can make gears for your centerline distance on those,I don’t know if he does V8
510-532-8228
but yo will he to figure out your centerline distance or how much undersized you need.
 
69a said:
You don't need to build a model! I know someone who had a aluminum timing gear (not Ford) with 4 teeth smashed out of it. He had it welded up and re-machined. This was 6 years ago.
Click to expand...

In regards to CNC: I don't know how much involvement you've had with CNC, but in every modern machine shop I've been involved with, we use 3D CAD models as the basis for tool paths for any complex geometry and sometimes 2D models for very simple stuff.

Yes, one can program a toolpath "by hand", but in this day and age I haven't seen that being done for more complex geometry, like gear teeth.

Your experiences may differ. :D
 
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