Front end of camshaft noise

[LizardsA]

I'm busy rebuilding a '30 Pickup engine, and while it is still on the engine stand, there is a knock as I turn the engine. I have only just installed the crankshaft. The camshaft is in the engine.
1. The timing cover is NOT on the engine yet
2. The timing gear is on really tight
3. With the side timing cover off, the noise appears to be right in the front end of the camshaft, in the block.

What could be causing this noise?

Mike
Johannesburg, South Africa

[Marshall V. Daut]

Check the lash between the teeth on the camshaft gear and the crankshaft gear. It's supposed to be 0.003"-0.005", with an absolute limit of 0.008" (too much for me). I measured the "Engine from H*ll" mesh because I couldn't locate a knock up front, either. Turns out there was almost 0.011" backlash! I suspect that because the Babbitt in the block is so worn, the crankshaft sits higher up, thus increasing the mesh gap. When testing the mesh and rocking the crankshaft, I definitely heard a clicking noise between the gears. Imagine that at speed inside an assembled engine! "Knock, knock, knock!" I think this was ONE of the knocks inside this POS engine.
I just installed a .005" oversized timing gear and have acceptable mesh now. I will find out today or tomorrow if this solved the problem. Check your gear mesh and see if that might be your problem.
Marshall

[d.j. moordigian]

Originally Posted by LizardsA

I'm busy rebuilding a '30 Pickup engine, and while it is still on the engine stand, there is a knock as I turn the engine. I have only just installed the crankshaft. The camshaft is in the engine.
1. The timing cover is NOT on the engine yet
2. The timing gear is on really tight
3. With the side timing cover off, the noise appears to be right in the front end of the camshaft, in the block.

What could be causing this noise?

Mike
Johannesburg, South Africa

It's the cam shaft "snapping" back an forth because of the valves. But more
important is the clearance on the 3 cam shaft main bearings,....loose(too
much clearance) will also do the same thing..

[Jim Brierley]

Likely what d.j. says but not having the front cover and thrust spring on may be part of the problem

[LizardsA]

Thanks Marshall and DJ, seems I need to get that timing gear off to get the camshaft out.
DJ: How does one fix too much clearance on the camshaft?
Jim: This engine made the same noise with the front cover and thrust spring on, but we could never find the source of the noise - now I think we are a lot closer to finding the problem

[d.j. moordigian]

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Pull the cam and measure the cam and block,..I'd think that .002"-.003" should be right.
The center one controls the oil flow..

Fixing the problem is a costly adventure,...new cam or align boring the mains for bushings
or cam cam bearings. I think it's been mentioned here on the Barn about which after
market cam bearings they use..

Let us know what clearances you come up with..

[LizardsA]

Thanks DJ, much appreciated

[art ebeling]

Mike, Do you have a fiber or metal timing gear? I had the same type of noise with a metal gear.

[BILL WILLIAMSON]

"Probably" just "normal" sounds, when turning the engine SLOWLY!
Bill W.

[LizardsA]

Alright everyone, took the engine back to the engineering works, and they found two problems:
1) not enough clearance on the timing gear / crank gear;
2) timing gear was loose on its centre mounting

We replaced with a new timing gear, and the noise has gone!

Thanks for all the help.

[CWPASADENA]

It is good to hear that the problem was found.

AS you know, it is best to find out what is going on before proceeding.

Let us know how the engine runs after you finish the installation.

Chris W.