MTFCA Forum

I am dry fitting this side cover and generator to check out the generator gear lash with the timing gear. I have one gasket in there measuring .010" thick. This crank, cam and generator gears were all meshed together in a running engine when it was torn down. I'm keeping this fiber timing gear as it was in good shape and a new camshaft can't be had anyway. None available. How does one tell looking at the gears whether that generator gear fit with the timing gear will be happy or not?

There should be a little wiggle between The gen & cam gear. The "gasket" is not, its a shim. Add more if necessary.
Check @ all points around the gear, not just one point.
NO WAY I ever run a fiber gear. There were good quality gears made in the past. If you dont know its the better one you are taking a chance of being stranded sometime in the future. Your choice, your risk.

I see 2 No-No's in your photo, first the fiber gear and those brass oil pick up's on the big ends.

I’ve been running fiber cam gears for close to 50 years in multiple engines. The key factor is good gear mesh. They must Not bind. Probably about.002-.005 clearance is good. The same applies to the generator gear

Frank, this fiber gear and copper oil dippers have been in this engine for many miles. The gear isn't worn or chipped and the dippers are tight. This engine had original cast pistons in it but they were knurled once and worn. So it got a new field coil, magnets charged, and bored to .40" over with new pistons and rings and 4 intake valves. I'm just looking for a good fit on the generator gear since I didn't mic the gasket shim that was in there on tear down. I would have liked to put a new cam with a new gear. No cams. Kind of a sad thing in the T hobby right now. Why should a guy tear that fiber gear off a used cam. I have those fiber gears in my A's, yes I know they aren't driving a gear generator. Any other thoughts or ideas on fit. My machine shop said my cam he'd have no problem reusing.

I'm not smart enough to tell which is good and which is bad, so I'll pass.

I don't get to see the ones that people have good runs out of, as an T engine builder, all I get are the ones that fail. Striped teeth and those big-end pick-ups lying in the pan.

There are fibre gears and then there are fibre gears. The one Steve's photo shows is the usual type to fail. It is made of chopped fibre and some kind of binder.
The one in your engine is not one of those and may be quite adequate.
The best of them were made with laminated fibre. It has been a long time since I have seen one of those.

Allan from down under.

One thing often overlooked when checking generator gear backlash is that the generator bracket must be mounted parallel to the front cylinder cover surface of the block. The generator bracket is a sloppy fit if you rely only on the bolts. Mount the cylinder cover on the block and then mount the generator bracket, using the cylinder cover as an alignment plate, then remove the cylinder cover and check the gear mesh.

I believe the Model A and V8 cam gears were made of many die-cut pieces of cloth cut to the gear blank's profile and then impregnated with Bakelite and pressed together under high pressure, then baked/cured. After all that the gear blank was machined and the teeth cut. They were very durable.

OK, so bullshitting with Linda this morning over coffee about this fiber cam gear. Suppose it's the good fiber gear, but now I wonder if it has just been lucky not to fail. Linda says, and I had to laugh out loud. You have how many hundred of dollars into the engine, why don't you just let the snowball continue to roll down the hill. Okay, now let me open this can of worms further. There's no way in hell I'm replacing that good crank gear. I have a proper cam nut removal socket and the front plate alignment tool. What economical aluminum gear should I buy? Before I'm done the block, crank and cam will be the only original left unless someone has a reground cam and gear they want to part with.

Steve

if you were ever wondering, Linda's a keeper

If you always have a trouble truck following you, go ahead and use the fiber gear, but if you drive alone, be sure to have a cell phone along in case you need help. Fiber gears are unpredictable.
Norm

Linda and I have been together for 38 years. She is a sweet little Polish girl. She loves rides in my old Fords in the country and she prefers the T rides over the A's, she don't like my Model A Huckster. I need to get past this timing gear thing though to get this 25 coupe on the road again. So advice on what aluminum gear to get would be helpful. I'm to assume I don't need an oversize, just standard.

I think a McEachern gear will serve you well.
He makes both aluminum and bronze, and other quality parts.

IMO Your best timing gear is one manufactured by Dan McEachern. That would be bronze. The bronze gear has the least expansion when hot, so it can have less gear lash which equals quietest.

Depending on the alloy used in the aluminum gears, expansion can be quite large & require more clearance. How would you know? I once answered the question by measuring the gear cold then after coming out of a boiling water pot. The growth was shocking, but it provided an idea for a safe gear lash.

As far as gear size: Depends on the accuracy of the crank location in relation to the cam. & crank gear wear. Did your babbiter/line bore get it right.
If you can precision measure the centerline between the 2 you would have an idea if an over or under size is needed (Sorry, its one of those unknown variables) Absent of that, start with a standard gear & check the lash.
Not to scare you but, I recently had a motor with an off center ground crank. That varied the gear lash to .006 - .010. Another unforeseen issue.

You wouldnt think selecting/fitting a gear would be such a hassle, but it can be.

It’s a good idea to install a new cam gear to replace the fiber gear. There is plenty of information on how to set the lash and undersized gears are available if needed. That said, if you don’t change the crank gear you may still get some unwanted noise. Perfect world, new cam and crank gears from Dan set up to the proper backlash.

Andy

This engine had beautiful main and rod babbit with shims left so I don't think I have a center to center distance to worry about. This engine had the original cast pistons in it that were knurled once, don't think the fiber gear put much wear on the crank gear. I was looking at Chaffins aluminum gear with the advance. Any thoughts on a it with this used stock cam? Tried both landscape and portrait close up pictures again without success. I wouldn't give this site an A rating in this regard. Nothing personal to those whom set this up. Lots of hard work I imagine, just a spades a spade.

Steve

your question regarding an advanced cam gear, with a standard cam really begs for it's own thread. Do yourself a favor and start one: there is good information that will come out which will advise FOR an advanced gear and AGAINST an advanced gear depending on a number of factors.

I run one and love it, but I did it when there was a plethora of cam choices to match to the gear to achieve a particular type of performance that I was seeking.

Steve, I'm using an S10 Samsung camera phone. I used it to post the earlier pictures in this thread. Seems like when I attempt to do a close up in either landscape or portrait, it will show a file size of 1.9 or 2 mb and shows a caution diamond and won't give me the place in line option to upload. Also in keeping this original thread updated, Brendan Doughty at Plank Hill Garage has an Aluminum cam gear for me. I'm putting this in and keep moving forward. I appreciate the advice of using the front cover to square the side and check lash. Trying to do this well enough to be acceptable, trying to avoid any obvious pitfalls but not make it into a drawn-out year process.

If you're replacing the timing gear, you should also replace the generator gear. In your one photo it appears well worn. Running a worn generator gear against a new timing gear will make for a noisy mesh.