I changed my timing cover on my 350 engine in my 1978 corvette.I have P.J. gear drive when i was done i started my car up and the gear drive made a strange noise for a few minutes.It almost sound like the gears where touching the timing cover .The cover is a edelbrock and is made for a gear drive.the noise went away.Do the gears have to set them selfs up.Seems to be ok now but just woundering what it could have been.

Those Dam things will raise hell, you did check all of your clearances?

I agree with roys63, most sbc really should have the block machined. I had problems with mine and so did a few others that I know. I checked mine at least 6 times before I finally put everything back together, and still had a problem. I put on a Cloyes true roller instead, and so did the others. go to www.compcams.com and the have all the specs on all valve trainsystems.
LOL
George

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on most of the gear drives i have installed, you have to modify the idler gear axle on the back side or cut the block. but if you only knew what a gear drive does to a cam and valve train you would get it out of there.

I'm just curious, what kind of damage they do? I have a gear drive in one of my motors with about 50,000 miles on it, it's been in there since day one. It's a Dyna Gear from PAW (PAW brand), I just followed the instructions, and didn't have to machine anything. I would think that after 50k miles I would notice something, I did notice that the sound changed pitch a little after the first few hundred miles, but is still tight as when first installed. I will be tearing into this motor to freshen it up this winter (and do a few more things too ), but was wondering what to look for as far as evidence of damage.

bestmech the gear drives transfer all of the vibration, harmonic and mechanical to the camshaft and it in turn transfers to the push rods and up to the rest of the valve train, you may thing this is nit pickey, or trivial but you don't see gear drives in grang national or top running roundy cars,they use jessel belts, that setup isolates the valve train and keeps the upper half together better.,,if you could see a computer readoutor watch a computer simulation of the valve train running with a gear drive you would not even touch one. they are by far the worst timing setup you can use. the valve springs and rocker arms actually ring from the vibration and the spring coils look like a tuning fork.

I kinda like the gear drive, it WHIRS like a kitten. Only have it on one sbc, a 69 327, haven't had it apart since rebuilding it.

Just another opinion about gear drives to confuse everyone more than they already are. All Chevy straight 6s have used gear drives for decades and they seem to run ok.

Also, it may be beginner's luck but I installed an 'extra noisy' (sounds like a blowr belt) Edelbrock gear set and Edelbrock front cover on a 350 Chevy V8 in my friend's '42 Willys pickup. Instllation went perfectly and engine has been a sweet runner for at least 50,000 miles.

This is the first bad news I have heard about gear drives.

Willys is correct, straight six Chevrolets and some other engines did have gear driven cams, BUT they used fiber gears which are just slightly stronger than wood. They go work great for 110 hp engines turning 3000 rpm max and 100 lb. valve springs.
Will also echo some of the earlier sentiments relating to gear drives. They transfer all of the combustion forces from the crank, through all of the valve gear and right into the distributor. This is why just about all of the serious drag cars utilize belt driven cams and crank trigger ignition systems.

Granted, most Chevys used the fiber gear for quiet operation in passenger cars. Some Chevy 6s used aluminum cam gears that allowed a 'souped up' engine to live. Aluminum gears are available for all Chevy 6s now.

Smokey Yunick said in his book "power secrets", that all he used was two gear (no idler/s) and a reverse rotation cam. Ford 300-6s had steel (cast iron) gear drives (most anyway), although they have a helical cut they still have the potential to transmit the harmonic frequencies you talk about. Even some Chevy truck motors came with this set-up. I will find out for sure myself this winter when I tear into that motor. I know it has seen 7,000 RPM short bursts, and 5,000 RPM from Phx. to Tuscon AZ. (haulin ***** ). It has about 50,000 miles, and with the way it was driven, I should notice anything when I tear into it.

most of the chevy truck motors with gear drive were designed as governed engines with a very low rpm limit, dump trucks etc. the 2.5 GM iron duke also has a gear timing setup but they, like the chevy six were not intended for high performance work, as for Smokie he was damned good but his day was a long time ago-before the days of hi-tech, and 7second street tired 1/4 mile cars.and jessel belts etc.

Well, if Smokey used a gear drive in his 209 cu.in. sbc (wich he did) that produced over a 1,000 hp. and turned 8-10,000 rpm in the Indy 500. Than I think it will work fine in my comparatively mild motor. Don't take me wrong, I hear what you're saying, and I will check it out. Do you know of any web-sites that have any info on this subject? Thx.

Yes, a lot of us had trouble with gear drives,
one thing you must remember Smoky had GM Engineering behind him and didn't have any idel/s gears on his setup.It could be the different manufacture's and combination's that we use.
I still wouldn't reccommend one. We use gear to gear on our race cars. I hit the web search here is the main site, it has alot of sites to surf thru.LOL

<a href="http://search.msn.com/results.asp?RS=CHECKED&FORM=MSNH&v=1&q=camshaft+gear+drives" target="_blank">http://search.msn.com/results.asp?RS=CHECKED&FORM=MSNH&v=1&q=camshaft+gear+drives</a>

[ October 28, 2002: Message edited by: 1BAD80 ]</p>

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right! there is a lot of difference between a $100.00 gear drive and the generous motors mega buck setup.