Timing chain or Gear Drive?
Thread Starter
Safety Car
Joined: Jul 2002
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From: St. Charles IL
Cruise-In 5-6-7-8-9-11-12 Veteran
A CI-6 Car Show Winner
Timing chain or Gear Drive?
My engine builder talked me out of installing a gear drive for my SB. Instead he recommended the double row timing chain. Last night I talked to a local hot-rodder, he says the timing gears are much better, won't stretch out like the chains do after a few hundred miles. Which one is better for performance?
Drifting
Joined: Oct 2000
Posts: 1,825
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From: Shawano WI
Re: Timing chain or Gear Drive? (Big Fish)
Gear drive transmit all the crankshaft harmonics to the cam and valve train. Because of this you will find that valve springs go away faster with a gear drive. I would not recomend a gear drive to a customer unless it is absolutely nessecary such as extreme high RPM (8500 RPM and up) or extreme valve spring pressures such as those needed with a inverted flank roller cam with ultra-fast ramp speeds.
A good quality true roller will transmit considerable less harmonics to the valve train helping to make the valve train more stable. Good quality tru-roller chains will go a long time before stretch is a problem.
If it is in the budget I would recommend a belt drive by Jesel/T & D/ Comp Cams. It is the best of all worlds. It will eliminate just aboult all harmonics to the valve train, has less horsepower loss than a gear drive or chain, and you can make cam timing adjustments without taking anything apart.
[Modified by Pete79L82, 7:55 PM 8/1/2003]
A good quality true roller will transmit considerable less harmonics to the valve train helping to make the valve train more stable. Good quality tru-roller chains will go a long time before stretch is a problem.
If it is in the budget I would recommend a belt drive by Jesel/T & D/ Comp Cams. It is the best of all worlds. It will eliminate just aboult all harmonics to the valve train, has less horsepower loss than a gear drive or chain, and you can make cam timing adjustments without taking anything apart.
[Modified by Pete79L82, 7:55 PM 8/1/2003]
Team Owner
Joined: Apr 1999
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: Timing chain or Gear Drive? (Pete79L82)
:iagree: Everything Pete said is true. I use the Crane billet gear and timing chain. It's probably one of the most expensive to buy, but i can verify that it's one of best. I run my motor pretty hard and when i had to reresh my motor because of Solid roller lifter failure I still had nearly Zero slop in the chain. That was 20,000 miles with .600+ lift and 200+ pounds of spring.
The ware would be more than a H-flat cam could do in 100,000 miles.
Just buy quality chains & gears
The ware would be more than a H-flat cam could do in 100,000 miles.
Just buy quality chains & gears
Le Mans Master
Joined: May 2003
Posts: 5,642
Likes: 1
Re: Timing chain or Gear Drive? (Big Fish)
So did i screw up? my crate came with a cloyes double roller, but I had it swapped out for a pete jackson gear drive. I was under the assumption the it would have more accurate timing and ble less likely to jump with nitrous.
Pro
Joined: Dec 2001
Posts: 708
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From: Renton Wa
Re: Timing chain or Gear Drive? (munday)
All I have herd was that the Gear drives cannot handle high rpm.
What about the reliability of the belt drives? To me it seems like they would snap alot sooner than a chain Gear drives worry me cause they can float back and forth across the surface of the grears. "nothing to keep it in place except for the timing cover and block. which infact does hold it in place, but just doesn't seem all that practical. Then there is the gear drives that are bolted to a housing that acts as a timing cover it's self. Those look pretty cool.
I love the sound of a grear drive. and was pretty saddened when I was strictly told to keep with a double roller. :sad:
What about the reliability of the belt drives? To me it seems like they would snap alot sooner than a chain Gear drives worry me cause they can float back and forth across the surface of the grears. "nothing to keep it in place except for the timing cover and block. which infact does hold it in place, but just doesn't seem all that practical. Then there is the gear drives that are bolted to a housing that acts as a timing cover it's self. Those look pretty cool.
I love the sound of a grear drive. and was pretty saddened when I was strictly told to keep with a double roller. :sad:
Drifting
Joined: Oct 2000
Posts: 1,825
Likes: 56
From: Shawano WI
Re: Timing chain or Gear Drive? (WashingtonRacer)
What about the reliability of the belt drives? To me it seems like they would snap alot sooner than a chain
A belt drive is much stronger than a chain. In 15 years of using belt drive on motors I have never has an instance of a belt failure. I have had many chains break. All Nascar motors (Cup, Busch, Trucks) use timing belts. Sprint car motors use gear drives and turn 8500 to 9000 RPM all day without failure, (but they are harder on the valve springs) so gear drives do hold up at high RPM. Sprinters are slowly converting to belt drives. (old habits are hard to break)
I have never heard of an instance were N²0 has made a quality timing chain to jump a gear or break a chain. (sounds like advertising propaganda form a gear drive manufacturer). Also gear drives have the greatest amount of timing fluctuation. As the block heats up and expands the clearence between the gears increases and causes greater timing fluctuations.
All three systems are good but each has distinct advantages and disadvantages. You have to decide which fits your circumstances best.
Pete
[Modified by Pete79L82, 11:31 PM 8/1/2003]
Safety Car
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From: Pearland TX
St. Jude Contributor
Re: Timing chain or Gear Drive? (Pete79L82)
Just out of personal experience I would say *NO* to the gear drive timing set-up. I had a set of Pete Jackson gears shatter in a doorslammer(Super Gas) that I had and it wasted the engine with parts sucked through the system. Not even close.... double roller chain is the way to go.
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Thread Starter
Safety Car
Joined: Jul 2002
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From: St. Charles IL
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A CI-6 Car Show Winner
Re: Timing chain or Gear Drive? (Big Fish)
I really appreciate everyone's input on this. I am getting the impression I will be just fine with the Cloyes double roller chain I installed, but the belt sounds like the way to go on the next engine I build. Transmission of harmonics and tolerance changes with temperature changing does seem to make the gear choice a little questionable.
Intermediate
Joined: Jul 2003
Posts: 31
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From: Winnipeg MB
Re: Timing chain or Gear Drive? (Big Fish)
If Gear drives were the answer I am sure the auto manufactures whould have installed by now. Note they have gone away from chains to quiter rubber Belts.
Race Director
Joined: Apr 1999
Posts: 11,520
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From: CORVETTE 77 385 C.I. TEXAS
Re: Timing chain or Gear Drive? (Pete79L82)
We have covered this before. Pete's right. Get a high quality roller set.
The timing chain is very short in Chevy V8s compared to an overhead cam(s) setup.
The timing chain is very short in Chevy V8s compared to an overhead cam(s) setup.
Drifting
Joined: Jul 2001
Posts: 1,418
Likes: 1
Re: Timing chain or Gear Drive? (Ganey)
The Cloyes # 3100 is prestretched .
The gear drives with the dual idlers gears will cost you around 10hp up top.
Gear to gear is the only way to go but requires a reverse ground cam but again,should be reserved for racing only and not the 1/4 mile type :lol:
The gear drives with the dual idlers gears will cost you around 10hp up top.
Gear to gear is the only way to go but requires a reverse ground cam but again,should be reserved for racing only and not the 1/4 mile type :lol:
