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why cant I use gear drives on marine engine?

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Old 12-05-2003, 06:25 PM
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Default why cant I use gear drives on marine engine?

i ve installed ger drives instead of timing chain,no special reason ,i used to see that part for along time just wanted to use it and bought one.Then Strip told me that its not a good idea to use it on a marine engine but i dont know why!?!?

why cant I use gear drives on marine engine?
does anybody have any idea?
thnx
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Old 12-05-2003, 07:37 PM
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One word that means they SHOULD NOT be used on ANY engine. - HARMONICS

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Old 12-06-2003, 12:04 AM
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I personally have used Pete Jackson dual idler gear drives in my engines for about 25 years with no ill effect.
Chains stretch and get sloppy, when this happens valve timing becomes inaccurate. In a offshore powerboat you are constantly on and off the throttles, that stretches timing chains. Gear drives whine.
This is just my opinion, with what I have experienced.
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Old 12-06-2003, 12:29 AM
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Just because I said so.

Email a harmonic balancer co. and ask about the harmonics . ask some of the gear drive company's. Ask some of the tech depatments WHY??

This is what I have beed always told ,in theory sounds right .The cloydes hex a just is a top of the line chain , I would not have any quams using them. and have on the marine engines.

A pete jackson has a floater style set of gears that when you let out it takes up the slack. the One gear idler gear is a better design. .
The pete jackson is the cheapest on the market.No offense CigaretteFirefox.

I would think the offshore race engines would have the belt drives, like Nascar and all the shonuff drag cars.

On my Chevelle I have a B&M gear drive 1 gear idler gear . you can spin the gear that is fixed in the timming gear housing it spins freely ,but can feel and here the needle bearing in the gear when you spin it by hand.some thing to think about?.The pete jackson has 2 gear with bearings in them.that just float ,not fixed in the a cast aluminum housing?Just my opinion
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Old 12-06-2003, 01:01 AM
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Well you should definitely not use one on any engine that is EFI and uses a knock sensor. You will get false readings. However anytime you use a geardrive with the floating idler you MUST MUST use a reinforced timing chain cover. Not the stamped steer or composite (plastic) covers. Personally I would rather use the true roller double roller timing chain. Although more expensive I have seen 20-HP gains at 6000-RPM over a run-of-the-mill double roller chain and gear drive. However the most efficient as Strip poker stated is the belt drive. It needs to be inspected more often.

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Old 12-06-2003, 08:35 AM
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20 horsepower gain? sounds like a lot to me,maybe on a big HP engine. also the frequency in sound that a gear drive operates at is different than the sound of detonation, I have used and have friends that have gear drive setups [that are set up correctly] on newer EFI cars with no problems, I have hooked my snap on 2500 scan tool on newer GM cars and it takes a pretty good tap to make the knock sensor kick in and retard timing, but like the old saying goes, anything is possible,
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Old 12-06-2003, 09:54 AM
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[QUOTE]Originally posted by Strip Poker 388


A pete jackson has a floater style set of gears that when you let out it takes up the slack. the One gear idler gear is a better design. .
The pete jackson is the cheapest on the market.No offense CigaretteFirefox.

No offense is taken. Speak your mind, that is what learning is all about.
Pete Jackson used to be about $100 more...That is before Edelbrock started copying his piece.
I don't have any experience with the single idler so I have no opinion yet about their durability.
Jesel belt drives are quiet, probably soak up vibes, eat a minimal amount of horsepower. But, I would have to experience their durability to recommend them for the stressfull Offshore Powerboat environment.
High performance Powerboats really test Big Block Parts.
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Old 12-06-2003, 10:09 AM
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Quote:
Originally posted by H2Xmark
20 horsepower gain? sounds like a lot to me,maybe on a big HP engine. also the frequency in sound that a gear drive operates at is different than the sound of detonation, I have used and have friends that have gear drive setups [that are set up correctly] on newer EFI cars with no problems, I have hooked my snap on 2500 scan tool on newer GM cars and it takes a pretty good tap to make the knock sensor kick in and retard timing, but like the old saying goes, anything is possible,
The comparison was between 2 double roller chains. The true roller (which you can roll the the links with a ballpoint pen) and the regualr double roller (which links are solid) This was on a stroker 383. The belt drive won out though only marginally beter than the true roller.

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Old 12-06-2003, 10:38 AM
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Belt is best. Longevity, timing accuracy, and dampens harmonics.

Cheap chains and plastic sprockets are the worst for durability when combined with performance valvesprings.

Double roller a good compromise.

Gear drives vary in style and manufacturing tolerance, but the fact remains that you are running thru gearsets that are even multiples of each other (2:1, regardless of what ratio your center gear is) and that creates harmonics.

Granted, chains deal with harmonics also, but the centrifugal forces on the chain tend to dampen the harmonic some whereas the gear is a direct link with no cushion.

Properly shimmed, a quality gear drive is not a bad deal, but that in't what you get out of the Pete Jackson box.

Quality gear drives are as expensive as a Jesel Belt system and are not in the same league as the adjustability and durability of the belt, so that's why you just dont see them on top notch hardware.

A good true roller is the budget man's best friend here.
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Old 12-06-2003, 10:47 AM
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thnx for ideas. but the problem here is;
i installed tehm ,dont have any other alternatives for the moment.i drive this boat maximum 100 hours in a season.do you think i go with them or change them immedetaly?
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