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Gear drives

Muddytazz said:
I just installed a noisy gear drive in my new built SB350 and with the radio going, and the 40 series flowmasters and headers, and tires, the gear drive is hardly noticable.
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Ditto, but with a 454.
 
Hello,
I think I am going to install one. I am after a loud truck but I think with true dual flowmaster 40's, headers, a cam that is going to give my 350 a choppy/rough idle the truck might be a little to loud. I think next year I am going to get to know the cops pretty good :doah: . But what ever I am playing with the idea of buying a truck Chevy gaser or Ford diesel and keeping the k5 as a play truck.
Thanks
Adam
 
I put mine in my 350 a few months ago when I was putting my cam in. After seeing my old timing chain after only 50,000 original miles on my truck, I was amazed it was still running. Gear drives are much better to me in theory, my long term test is still in the process but so far its doing great. I got the noisy Pete Jackson set and at first it was noticeable but, maybe its just me, but it seems to have quieted down after everything broke in. It has never bothered me. With headers and a 3 inch Flowmaster exhaust, the exhaust is usually heard over the gear drive. I like to mess with people and tell em I have a supercharger because it sounds similar to the gear drive lol. The only time its really noticeable is if youre outside the truck standing in front of it. If you have a healthy motor and any decent exhaust it wont be very noticeable.
 
ProJunkRacing said:
hmm if you got it in a few weeks i just might how loud is it and how worn >?
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It came on my supercharged 400sbc and the previous owner just installed it so it should have less than 5k on it. I haven't heard it but he said it was kind of loud.
 
Beast388 said:
While many will tell you to avoid gear drives because they "transfer harmonics to the camshaft", that theory has never been proven. How does one explain the fact that many engines came with factory timing gears.....many GM straight 6's for example?
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The difference is that the OE gear drives are helical spur gears while the drag race stuff are all (to my knowledge) straight cut spur gears. That is a huge difference in how much noise is generated.

And, not that most are lacking on power, but if it makes noise it is consuming power. Same is true of tires. Ever noticed that A/T's tend to get slightly better MPG's than the same sized M/T's? So you're paying a small MPG penalty for that noise. Probably not a lot, but is there and measureable.

The "nasty harmonics" show up in the oil system more than in the cam and lifters. What happens is that those vibes cause cavitation at high RPM's b/c the cam is 'chattering' back and forth btwn each successive pair of gear teeth. That chatter is transmitted to the oil pump's gears. So now they chatter too.

Ever pulled down a high mileage hi-po BBC (w/ or w/o a gear drive) and noticed how clean the oil galleys are? The reason is that the oil pump has more teeth than an SBC. Those extra teeth put the vibe frequency up into the UltraSonic range at high rpm. Appearantly when you get into UltraSonics it causes cavitation in oil pumps. This is the reason that BBC oil pumps are no longer the hot set-up in an SBC. So the oil pump is effectively ultrasonic cleaning the oil galleys. Which wouldn't be bad except for the AIR bubbles that are in the oil. Air isn't a very good lube.

What I've seen the most on recent drag engines are cogged belt cam drives. Those have a couple advantages. The belt acts as a damper so that the drive "noise" isn't transmitted into the cam. And the belt systems are outside of the engine (even on an SBC) so cam timing is much simpler to change.
 
ntsqd said:
What I've seen the most on recent drag engines are cogged belt cam drives. Those have a couple advantages. The belt acts as a damper so that the drive "noise" isn't transmitted into the cam. And the belt systems are outside of the engine (even on an SBC) so cam timing is much simpler to change.
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Also a much wider range of cam degreeing. Just move a teeth on one of the cog belts. I believe they make some that are enclosed and could be used by us... don't quote me on that though.
 
Those that I'm familiar with use a Vernier adjustment btwn the cam sprocket and the cam sprocket hub. I have seen some with a cover for dirt Sprint car use use, but I've not had one in my hands.
 
ntsqd said:
Those that I'm familiar with use a Vernier adjustment btwn the cam sprocket and the cam sprocket hub. I have seen some with a cover for dirt Sprint car use use, but I've not had one in my hands.
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Can't seem to find the setup my teacher has. I can't remember if he has a custom made cover for his or it came that way. I know it is a Jesel but don't see an enclosed system on their site. His is a Jesel enclosed setup on a Dodge Nascar block. Everything seems to be the adjustment you are talking about either. Take that piece of info I "knew" and forget it, ha.

Another issue to consider, gear drive and knock sensors. Have never confirmed but have heard the harmonics of the gear drive will set off false knock signals. No good for engines with EST or fuel injection.
 
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