engine builder says gear drine
11-20-2006, 08:33 AM
#11
Re: engine builder says gear drine
I have run belt drives for the last couple of yrs with no problems.
I think some people are trying to over think the situation. There is reason merc swithed to the belt drive on their 900sc and continues to use them on the 1075.
I think some people are trying to over think the situation. There is reason merc swithed to the belt drive on their 900sc and continues to use them on the 1075.
11-20-2006, 09:07 AM
#12
Registered
Re: engine builder says gear drine
Just my thought on the belt drive system, in a car or drag car, there is usually no oil, water or lack of air flow around the engine. On a boat there is little air flow around that area and usually water and oil floating around in there, plus the cost of replacement belts, around $90. The safe bet would be the well proven and reliable chain type. I also change from a jesel belt drive system to a chain type when i bought my boat.
11-20-2006, 10:06 AM
#13
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Re: engine builder says gear drine
I had a Jesel belt drive on an old 632" motor and it was great......until the belt delaminated and (3) valves got bent.....the only "lucky" part about the who deal was the motor was idleing in gear when it delaminated and I had just been turing 6500 about 1 min before..... 
Motor only had ~60hrs on it when it happened.
I went to a Cloyes chain after that with no issues. Jesel is probably fine if you change them every year, but I choose not to mess with on a go forward basis. It's interesting your builder thinks a "gear drive" is the most precise...I've always been told they were the worst due to the mesh and wear....
Motor only had ~60hrs on it when it happened. I went to a Cloyes chain after that with no issues. Jesel is probably fine if you change them every year, but I choose not to mess with on a go forward basis. It's interesting your builder thinks a "gear drive" is the most precise...I've always been told they were the worst due to the mesh and wear....
11-20-2006, 11:31 AM
#14
Geronimo36
Gold Member
Re: engine builder says gear drine
Gears are the cheap way to fool your friends into thinking you have a blower under hood cause of the gear whine! 
No joke, I know a guy who did it on his hotrod just so he could have the gear whine...
No joke, I know a guy who did it on his hotrod just so he could have the gear whine...
11-20-2006, 12:35 PM
#15
VIP Member
Re: engine builder says gear drine
Originally Posted by bobkatz
Just my thought on the belt drive system, in a car or drag car, there is usually no oil, water or lack of air flow around the engine. On a boat there is little air flow around that area and usually water and oil floating around in there, plus the cost of replacement belts, around $90. The safe bet would be the well proven and reliable chain type. I also change from a jesel belt drive system to a chain type when i bought my boat.
If someone had oil or water floating/splashing up on the front of the motor.They have bigger problems than a belt.
I also run a chain,I would stay away from a gear drive ,Is it worth taking a chance?
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11-20-2006, 03:07 PM
#16
Registered
Re: engine builder says gear drine
I've used the Jesel belt drive for 10 years. Jesel says the belts are good for 250-300 hours. I just replace mine when I rebuild the valve train at 175-200 hrs.
11-20-2006, 05:01 PM
#17
Re: engine builder says gear drine
I don't know what would be the best, I've been running the Milodon gear drives since 97, over 900lb spring pressure, up to 7500 rpm, knock on wood no problems yet. The timing mark sits rock steady, works well with EFI.
11-20-2006, 05:09 PM
#18
Re: engine builder says gear drine
Originally Posted by GPM
I don't know what would be the best, I've been running the Milodon gear drives since 97, over 900lb spring pressure, up to 7500 rpm, knock on wood no problems yet. The timing mark sits rock steady, works well with EFI.
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The Only Time You Have To Much Ammo Is When Your Swimming Or On Fire.
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The Only Time You Have To Much Ammo Is When Your Swimming Or On Fire.
11-20-2006, 06:14 PM
#19
Registered
Re: engine builder says gear drine
Originally Posted by Reed Jensen
The problem with gear drives is they impart an opposing load on the cam and crank... Simple terms.... the crank and cam are pushed away from each other... A chain pulls the two together.
If that is indeed true, which it seems it would be, then it is actually better for the camshaft bearing oiling. Having the cam pushed upwards would let the oil get out of the oil hole and allow the bearing to "draw" the oil around it as it turns, creating a hydrostatic wedge of oil for the camshaft to run on. This is really how bearings are supposed to work. In reality though, I doubt that the force of the gears would counteract the force of the valve train pushing down on the camshaft.
The oil port is not on the bottom because of the load from the chain. It just so happens that is how the big block is designed. If you look at a small block the oil hole in the bearing is at about 2 oclock and it works fine.
11-20-2006, 06:46 PM
#20
Re: engine builder says gear drine
Originally Posted by Strip Poker 388
You said Over 900psi on a marine motor?I guess that would be in the upper 800 lift also
