Gear Drive Question

[Double Trouble]

Is a gear drive in my engine OK? I heard that a double roller would be easier on the engine running the boat with a jet drive. Or doesn't it matter? My Project (http://www.geocities.com/cougar_mtr/photopagestars.html)

[Dennis Moore]

I have never heard of a GOOD reason to run a gear drive in any V8 engine. You need to run an idler gear to keep the camshaft rotation correct and I don't think this added complexity makes up for any gains in performance or durability.
Crankshaft harmonics (the pistons bending the crankshaft during each firing)works against gear reliability and a jet pump may add more harmonics to the crankshaft. Harmonics has no effect on timing sprockets and a chain.
The balancer, on the front, and the flywheel, on the rear, help to cancel crankshaft harmonics but many people run jets without a flywheel (using only a flexplate). A flexplate only cancels harmonics if it has a torque converter attached to it (like in a car or truck).
Dennis Moore

[HOSS]

A gear drive is much more accurate with engine timing. I`m sure its also causes less stress on cam and main bearings. The gear drive probably has a longer service life as well.
I also doubt that harmonics have anything to do with a gear drive nor timing chain setup.

[Liberator TJ1984]

Running one for 5 yrs. now no problems or excessive wear on gears...chains tend to stretch , and teeth will wear out faster than a gear drive...just my 2*

[Double Trouble]

Thanks for the info, I used a gear drive in my blown Corvette years ago. I am new to boating and want to science it out before next spring on a new motor.
Appreciated.

[Danhercules]

Dose it matter on what motor? IE. Ford 460, Cheby 454, 502??

[powerplay230]

I put a gear drive in the 454 in the Chevelle last time motor was redone. Love the sound and I have had no problems. I have been told by more than one source that with gear drives are prone to break camshafts as they can directly transfer any vibrations from the crank. Don't know if there is any truth to that and with the 50 miles a yr that go on this car was not a concern. Now the Boat that might be a different story...
R

[GofastRacer]

Well, I may as well put my .02 for whatever it's worth!. I put a gear drive in 25 yrs ago after an expensive chain broke. The way I see it, chain stretches, timing retards, chain breaks!!..Sorry, I'll stick with a gear drive!. wink :D

[DEL51]

There are different gear drives available and some are louder than others.If you rebuild a boat engine after 400 hours would it make a difference? I agree with Dennis on the harmonics issue and have learned something.I did not know that a Flex plate needs a converter to dampen harmonics.I did know you can order a neutral balance flexplate or your plate may need to be balanced for an external application. Does it matter if the engine is internaly balanced or external? I think mercruiser uses a plate with a large rubberlike hub. Do cam builders use a setup with this on their test stations? Maybe not but maybe merc does.I think a jet pump under load has a dampening effect.There is a smooth application of power and vibration is less than if more gears were involved.I know that a straight cut milodon in a 327, 62 Impala is loud.Either way, it is cool.

[Danhercules]

Dose it matter on what motor? IE. Ford 460, Cheby 454, 502??

[powerplay230]

I have put on big block chevy that runs 7500 rpm for very short time periods over the course of a month and have had no problems at all. Think I would take several peoples' advice and add a quality fluid dampner to help keep things together. As hard as marine engines run I would definately check outfluid dampners and the effect on flexplates. They do make some noise though even though it is possible to quiet them down without a negative effect (to a point)

[flat broke]

Then what about a belt drive as an option? They should totaly neutralize harmonics, have less drag, etc, but can they stand the R's for extended duration? I've only seen them on drag boats. But that doesn't mean they couldn't be a viable alternative in other applications.
Just a thought.
Chris

[Dennis Moore]

The belt drive works nice, most of us have cars with belt drives. The V8 would use a relatively short belt drive compared to the OH cam engines in our cars, but I would I would still worry a little bit about durability with big valve springs on the engine.
Dennis Moore

[FastRat1]

Danhercules...u can run a gear drive in most any motor...its advantages..as Hoss says..it keeps the timeing much more accurate..and no chain stretch to worry about..i ran one in all my drag cars and also run one in my boat..n/p ever..i also run a flex plate on my motor with n/p..perhaps a flywheel (alum/steel) in a drag boat might work to some advantage..but i dont think the average boat needs one..belt drives are nice in a car/truck application (quiet--reliable)..but i dont know about there overall reliablety in a high rev application...just my 2 cents
Ron