The Stovebolt Site Forums The Shop Area Engine Shop Urgent - Timing gears not sitting flush

I am finally getting around to installing my new camshaft and lifters on my '58 235 but have hit a snag.

I pulled the old crankshaft gear off and installed a new one (by heating it and driving it on till it bottomed out). I had a machine shop heat and press on the new aluminum gear for the camshaft. I checked the gap with a feeler gauge and it is within spec (.005").

I just slid the camshaft in and now the camshaft and crankshaft gears are not sitting flush. From what I can tell the camshaft gear is sitting out about .040" compared to the crankshaft gear.

Pictures of the problem:
http://i51.tinypic.com/2uz5nnr.jpg
http://i53.tinypic.com/35n81eh.jpg

Can I just pull on the crankshaft gear a tiny bit to get them flush? Or will it be alright to run it the way it is?

If you have used any gasket between the Thrust Plate and the block front end plate it might be too thick. Just a thought.

Nope, didn't use any gaskets.

Is there to much end play in the crank letting the crank shift to the rear?

The trust plate for the 235 is similar to the 250/292 plate but have a different thickness. I don't remember which one is thicker.

There shouldn't be an issue with setting the clearance if you use the inside spacer ring. Push the gear on until it hits the ring and the clearance is set.

I don't know who these guys are, but they have nice pictures of their products and include the ring.
ChevyHotRod6 Thrust plate

Just checked the end play per the instructions in the shop manual. I have .007" So within spec (just)


The thrust plate is brand new from The Filling Station. I had a auto machine shop press it on and I checked the spacer gap and it was fine (.005").

A 235 plate should be .187" thick. A 230-250-292 is .130".

I just measured .19" on the new one. The old one measured .189". I pulled the camshaft out a bit to double check my measurements. There definitely is a .005" spacing between the plate and the bearing.

What it looks like:
http://i53.tinypic.com/10gzatg.jpg

The only thing I can think of is that the crankshaft gear went on too far. But it should have just bottomed out so I don't how it could have gone beyond that?

It can never be easy, can it?

Anyone have any ideas? I am debating whether or not to just run with it. I have a feeling I might come to regret that decision. Thoughts?

Thanks

Is it possible that the rear block plug for the cam galley is set in too far?
Admittedly, I'm reaching in the dark here.

Hy Ferndale53, did you do comparative measurements of the thicknesses of the old and new gears? This may be the "normal" installed relationship between these new gears when installed. I would call the manufacturer, and explain that you're concerned about the relationship between the gears when installed. The only concern I have, is that if the manufacturer says the two gears should sit flush to one another when installed, and yours do not, then you have changed the camshaft timing either advancing it or retarding it relative to the crankshaft. When I used to build blowers for Detroit Diesel engines we timed the blower rotors by placing shims between the ends of the shafts and the gears, this would change the in/out relationship between the two gears and thus change the timing of the two blower rotors, hope that helps.

They are supposed to sit flush so I am still trying to figure this out.

Is it possible that the crank gear deformed from me heating it and driving it on? I heated it to 220 for 10-15 minutes and drove it on with a large socket (that fit over the snout of the crank) and a 16 oz hammer.

I didn't need to hit it all that hard but I guess it is possible. I guess I am going to have to pull the crank gear. Which since the replacement doesn't have tapped holes that isn't going to be fun.

Hy Ferndale53, I doubt very much that you could have deformed the crank gear by your installation procedure.

Hey Ferndale, I think there have been some good points made. I'm in the process of building a 261 and have just installed the cam and crank gears. I went through 2 cam gears as I had too much play between the thrust plate and cam shoulder. I pulled the gear and realized the spacer was upside down (even though the old spacer was also installed upside down). If both gears and the thrust plate are the same thickness as the originals, I think that DrewP makes a good point— the cam galley plug could be too far in. From memory the manual says to seat it flush to 1/32" in. Worth checking anyway...

If it were the cam galley plug, I wouldn't be able to push the camshaft in all the way. The camshaft goes in fully, and the thrust plate sits flush against the front of the block. I know for a fact that the play between the thrust plate and the gear is .005", I had the gear pressed on by a pro, and I checked it again.

Since the camshaft goes in fully, and the play on the thrust plate is .005", it seems like the camshaft is installed right. That leaves only the crankshaft, but I don't see how just driving on the gear I could have screwed it up.

There is one other thought I had.
What is the thrust area of the crank was welded up at one time and reground with the crank shifted to the rear. It is common practice to weld up the thrust.
I will see if I have an engine I can take a measurement from the crank gear to the timing plate, or maybe someone else can post this.

If you could get a measurement that would be great.
When I pulled off the original gears they were even with each other, but I don't know if the crank gear was on the crank all the way. I guess its possible at some point the engine was "rebuilt" and to get the gears to line up they just pulled the crank gear back slightly until it lined up.

I know this is an old thread, but I'm having the same problem with my 235. Any word on why yours was doing that?

The above poster hasn't participated in over 4 years- - - -not likely you'll get an answer. I'm not really sure how critical a few thousandths fore or aft on the timing gears is, but if it's something that bothers you, try fabricating a shim to fit behind the crankshaft gear and align the teeth in the same plane. Once the crank gear is pressed or driven into place, it's not likely to move, so a shim won't be in any danger of coming adrift. I believe a few manufacturing tolerances have stacked up to allow a minor error in gear placement.
Jerry

Thanks for the input Jerry! I talked to the machine shop that pressed on my cam gear along with a few gear heads at work. Everyone is just telling me to run it. And stop worrying about that....