Main Bearings and Cam Gear help!
 

Ok, so I have a knock issue. hear is a little history of what I have done. well when I bought my 29 roadster there was a slight knock, so we checked the rods, they where ok. but I notest that the cam gear was bad so a few months later I replaced it with a aluminum one. the knock was a little better but not much. so I figured that mains where loose, so out comes the motor.

a finely got the mains adjusted. I don't see how you can do that in the car, but that's another story.

while i was cranking over the motor to see how it felt I can hear the cam gear clunk. I pulled off the timing cover and cranked the motor over with the crank, the clunk goes away. put the cover back on , back comes the clunk. I have the motor on a stand upside down. so what do you guys think, please help, thanks Brendan

P.S. also when I originally replaced the cam gear I replaced the pin and the spring

Re: Main Bearings and Cam Gear help!
 

do the cam and crank gear match up good. Is there a tooth broken on the crank gear?Have you checked your oil pump drive gear to the cam?

Re: Main Bearings and Cam Gear help!
 

the noise is coming from the front of the motor. also the crank gear is good, tomorrow I will pull the side cover off the cam cover. thanks, Brendan

Re: Main Bearings and Cam Gear help!
 

Brendan, the reason for checking the drive gear and distributor is, if the distributor or gear gets tight or the bushings in the distributor are tight it will cause the cam to walk and snap back causing a knock. Make sure all the parts turn freely to make sure none of these are the problem.

Re: Main Bearings and Cam Gear help!
 

Measure the clearance between the cam gear and the timing gear. Measure at 3-4 points around the cam gear. Should be .003, .004 max. Cut the end of a feeler gauge down with scissors so it slides in between the crank and cam gears. Sounds to me like there is too much clearance.
Contrary to popular opinion, the metal gears will make noise if the clearance is too much. Hand cranking is not a good test because you can't crank it fast enough to get a backlash bounce. You may need an oversize cam gear. Dan McEachern makes them.

Re: Main Bearings and Cam Gear help!
 

I checked the clearance between the teeth, its .005, is that too much?

Re: Main Bearings and Cam Gear help!
 

Yes, too much. Metal gears will rattle at that clearance, though the softer fiber gears may not. Check with Dan McEachern [email protected] He has the oversize metal gears. Email is probably best initially, he is hard to get on the phone. His number is 510-523-8228, 6-9 PM Pacific time during the week, all day Sat. Very nice guy, very helpful.

Re: Main Bearings and Cam Gear help!
 

Dan McEahern says to set the metal gears to .005 thousandths, and that is what I have been using for spec's many years.

Fiber cam gear we use .003 clearance.

Herm

Re: Main Bearings and Cam Gear help!
 

Check the camshaft cover plunger and spring. Make sure they are in position in the front cover and pack it full of heavy grease. Also, if you have a two piece crank pulley, check to see if the in-board piece is seated as some of the 2 piece reproduction pulleys may need a washer under the hex bolt to seat the pulley all the way. If it isn't seated it can cause a knocking sound.

Re: Main Bearings and Cam Gear help!
 

I have a good used .003 oversized aluminium cam gear $20.00 shipped to you if interested p.m. me

John

Re: Main Bearings and Cam Gear help!
 

the clunk is caused by the valve spring rotating the cam as it goes from pushing up on the valve to pushing it down, a normal thing exaggerated by excess clearance.