gear drive or chain?

[gunslinger]

557 cid chevy blower motor. Which is better and what manf?

[FastTimmy]

Don't use a gear drive.
I would only use a gear drive for a drag application that I was doing on a budget. even now there is not that big of a gap between a gear drive and a belt drive costs.
The gear drives tranmit to much valve train harmonics down the the main and rod bearings. The end result is premature wear or failer of the rotating assembly.
I have used rooler chains for years up to 950hp and up to 700in of gross valve lift with out any failers. I can not atest to true hores power lost due to fluctuating cam timing but I have always made the numbers.
If you have the bigg bucks I would say use a belt drive..
Just my .02
Timmy

[gunslinger]

Anyone else care to make a suggestion?

[Liberator TJ1984]

I'm running a full roller setup with a Pete Jackson Quiet Geardrive for approx. 5 seasons now with no problems....454 8/71 .623 lift

[Infomaniac]

Blower belts absorb a lot of harmonics.
I have run street type gear drives without any problems on pleasure boats.
A good chain system works well.
Belt drives are the best.
My 4 opinions

[GofastRacer]

I been using a Jackson(same one) for 15 years without a problem, I turn 7500 r's and no probs with harmonics!...
My experience with GOOD chains= chain stretches, timing retards, chain breaks, end of motor!!..
Belt drives are the shit, just have to keep an eye on the belt for wear like any other belt system!..
Blown motor, I'll go for a Milidon single idler gear drive!..
Just my worthless opinions!.....

[DogHouse]

I've been running an Erson fixed idler gear drive for a few seasons now. Hasn't caused any problems that I'm aware of. It was a very cost effective way to get reliable timing and a two piece cover that allows cam changes without dropping the pan. Only drawback as far as I'm concerned is the noise.
I've heard people refer to the harmonics issue but have never heard a good explanation of exactly what that is. I can see the alternating loads of the valve springs causing slight deflections along the length of the camshaft, but if that was going to affect the cam bearings then it wouldn't matter what system was driving the cam. I also couldn't see the deflections being great enough to overcome the lash in the gear drive and cause any sort of transmission of radial load to the crank gear. I could maybe see the crank gear transmitting a shock load to the valvetrane each time a cylinder fires, but a chain under tension would do the same thing. I guess I don't understand the issue, must be something else I'm missing?

[GLWBEAR]

I've used chains, gear drives and now the Jessel Belt drive system. The Jessel system is quiet, accurate and bullet proof. I run a pair on a set of 572 CI 1050 HP Teague Blower motors and they work great!
Gary
408-842-1400