Timing chain or geardrive

I am trying to get some opinions here, I know everybody has one. I am building a 283 with a roller cam, roller rockers, ported heads, 3 two's and an MSD ignition. I should spin about 7000 rpm.I am trying to decide between timing chain and timing gears. Lets hear about your experiences. The gears sound cool but I am not sure how well they would be for the street.

 

I have a 'quite' one in a 'tree fidty. I like it. It is not obnoxious. Really cool sound upshifting from L1-D.

 

if you go gear drive...buy a good one...i know a few horror stories

 

Yep.. if you go gear drive be sure and get the quite one.

 

Go with a noisy gear drive, and run straight pipes, unless it's gonna' be a daily driver.
Hot Rods are supposed to be Loud.
.

 

Are you planning on doing 7K rpm on the street? If not, personally I'd spend that extra money and effort on something a bit more useful. But then again, judging by your sig. line, you're probably looking to do the opposite. But, that's hot rodding.

 

What you you believe a gear drive would do for you that a chain wouldn't? A good quality chain and sprockets is plenty durable. A gear drive that is comparable to a good chain is very expensive. If you decide on a gear drive don't use one that has a floating idler gear or gears. Get one with a fixed idler. Due to machining variations in the block the fixed idler must be adjustable to achieve proper gear mesh, some aren't. Even on endurance racing applications the need for a gear drive is questionable for most engines. All things considered, I suggest you go with a premium chain and sprockets. That means a steel crank sprocket. If you want to save a few dollars, a less expensive iron cam sprocket doesn't give a lot away to a steel one.

 

I've been in the engine building business since the sixties. I try to keep up with the latest poop on engines. So I attend many seminars and classes on the subject.

Since the late eighties a well known cam grinder shows a film clip about gear drive use on Chevrolet engines. Once viewed you would never use one on any engine.

Gear drives transfer any imbalance/harmonics from the crank/rotating assembly directly to the valve train. Stop action and computer simulation shows some amazing problems.

The pushrods vibrate like tuning forks. The lifters and cam also vibrate at different frequencies. Not what you would want in a reliable engine.

The best setup is a belt, second is a double roller chain.

 

yes , a good quality double roller and you will be fine

 

Use a good double roller chain and spend the rest of your time / money controlling the cam thrust / end play.

 

i bought a used engine that had a floater on time.it came thru the cover at a 6000 shift.torn that engine all to shit.ive also built a few with fixed iders. didnt really need them but then it was the thing to do.ive been using a good double roller chain in the engine lately and i can shift in one of mine a 9000.i dont do it much but i have done it and its still together..lol.well except a roller rocker that came apart once..unless your building a screamin high rpm motor a good double roller will do you ggreat.

 

I've had a gear drive in my SBC 355 for over 6 years now.2X4s
and a 4 speed. Have never had a problem.You have to love them
or you hate them !!!!! LOL

 

First off, what makes you think you're going to turn 7 grand?

I race a 408 sbc and don't hit that mark. What are your dyno numbers saying is your peak power and torque rpm's?

Secondly, gear drives are useless and counter-productive. They rob power, are not good for engine harmonics and have been known to be tough on blocks. Go with a double "true" roller.

If you want the best for timing, go with a Jesel belt drive.

If you want that annoying noise, stop being a poser and buy a "real" blower.

 

There are pros and cons. Provided the dynamic issues you mentioned can be avoided, gears are potentially the most reliable option. At the same time, gears cause more drag than a belt or well oiled chain. Belts and chains both have some harmonic issues of their own. Thje elasticity of a belt results in less precise timing than a properly guided and tensioned chain. Last I knew, those guides and tensioner were not available for old SB Chevys. Although belts have become pretty reliable, all things being equal chains are more reliable. A good timing chain will normally last the life of a street engine, a belt won't. Premium car engines generally have chains instead of belts, and to keep customers happy more and more manufacturers are switching from belt to chain.

 

Tensioners???

What tensioner?

 

Gear Drive Yeah! I got one in my Model A 4-Banger.

 

I basically had the same engine, but with a hydraulic cam. headers, short pipes with glass packs under my seat. I cummuted 45 minutes to work every day. It was a hot rod, loud and obnoxious. I loved it, except for the gear drive, which drove me crazy. It sounds cool, but for daily use, go with a chain. You love them or you hate them, and at this point, I have 2 sitting on the shelf with no plans to use them.

 

I had a pete jackson quiet gear drive in a 327 and I loved it for the first month. Then it got to the point that I could not stand listening to it or any other car with one. I will never have one again for the street.

 

I had a dual idler geardrive that wore out the fit between the idlers and their axle shafts. The engine seemed to run ok (down on power), but the slop allowed one of the gears to force itself between the crank and cam gears, causing the front cam bearing severe wear. Net result was the cam being retarded about 20 degrees when running, cranking compression was down to around 65psi.

I've heard of bent cams caused by the dual idler geardrives, but mine was fine and fixed by swapping the geardrive for a chain/sprokets.

 

Would not run a belt system like that on the street unless it had a sealed cover over it. Normal dirt and crud will eat that belt up and an errant rock will ruin your day.

 

Currently trying a Milodon fixed idler gear drive....extremely quiet, timing absolutely unchanging. Cup engines commonly use gear drives .....at least for 500mi, but still 9500???

 

i had a "quiet" one years ago in a 302 i built. it was neat for about 200 miles then i got sick of it. personally i think that kind of noise should come from a blower. just my two cents.

 

good double roller chain. That's what I'm running in a 327 with a small solid roller cam.

 

Every time I read about someone asking about running a gear drive on the street I think of a friend of mine's white Chevy sedan delivery that had a LOUD gear drive that you could hear and recognize before you could see the car. You knew you were about to meet him on the road before you could ever see him. That ended any desire I might have had for a gear drive on the street.
I don't think I personally know anyone who has put one in a street car for the added accuracy of the cam timing or the possible longevity of gears over the chain setup, It's always been about the "cool noise" with the guys around me that run them.

 

Why would anybody think that "gear drive noise" is freakin' cool?!?!

Tell me what's "cool" about it!

 

...and I wanted to run the Pete Jackson noisy set on a 283 I'll be building in the future

Resonance can't be good for the valvetrain.

 

W#haddya care you call me a poser for running one? Do something here besides post.

 

Well I guess my answer to this pleasent post is........

Yea and I do exactly what so many others on here do!!

 

Gear drive noise is great for others to have. I don't like the engineering issues that they bring up, too. Go chain or belt.

 

I run a chain a cloyes chain at that. So I guess I have two things going against me?

Gear drives are OK a fixed idler is the only way to go if you run one. Used to be that rodders ran straight cut gears because they had less drag than helical cut gears but now it is just for noise because they have made some improvements to quiet gears and the way that they are cut.

I used to run a power steering pump that I had put Type F transmisson fluid in for the whine. Man there is nothing like the sound of a whining power steering pump.