Big cams and springs don't necessarily increase drag on the cam, as the spring pressures balance out on both sides of the lobes. Don't believe it, try rolling the engine over with just 1 rocker arm on. If a gear drive wears cams out so quickly, how come IH engines used direct gear to gear cam drive for 50 years (or more) and those engines last more miles than just about any other? I agree that the floating "dog bone" idler setups are not the greatest, but I've seen good quality single idler drives on race engines for 10+ years with no problems.
My 37 V8 60 and My 47 lincoln V12 both have gear drives,factory even,lol...helical gears set with proper clearance will not whine, those damn straight cut gears on gear drives and blower drives will.A street car needs a gear drive like I need another car/motorcycle project.
Fact: Gear drives rob power! Anyone who actually races or anyone who has actually delt with a "professional" engine builder (that really knows his ****) will tell you that gear drives rob power because they've proven it. To anyone out there: If you want the sound of a blower just so you can be cool and all your buddies can hear you comin'.... then pony-up and buy a blower!!!!!!!!
when i was a young gun i run gear drives. i thought it was needed for a really high horse street engine. and it sounded cool. now im older i aint about to run one on the street. i like to hear any new tick my engine might make and i cant hear it over that damn gear noise.ive built some crazy hp sbc and ive run them all with a quality double roller chain.and no noise.lol but i do like to hear a blower whine.go fiqure!
Increasing the load on the lifters does not make a cam harder to spin? Do you think it's some kind of magical zero friction situation? That line of thinking might lead you to believe that a cam with 2 lobes would take less power to spin than one w/ a single lobe. Remember, there's friction anywhere two parts are interacting with one another. Side loading in the lifter bores is often overlooked, but even friction thru needle bearings increases with increased load. Fixed idler or 2 gear drives do not have the problem, it's the floating "dual idler" drives that wear out cam bearings.
I should have said "increase drag on the timing set", but I stand by my point. My big-block runs a .765 lift roller, and the springs are about 230/700lb. With the plugs out, it pulls over by hand like a stocker...really. And no, I don't believe in some magical reversal of the laws of physics...1/2 the lobes are always on the closing ramp, so the force from the springs is counter-acting the effort to push the other valves open. Yes, in certain parts of the rotation it is MUCH easier to turn a cam with 2 lobes than 1...
#@$%!..lol can't us poor guys with tunnel rams have a little fun by making our engines sound like we can afford a blower? now you guys have me thinking second thoughts on running the Pete Jackson setup I recently picked up.
one of my race engines had that setup,never had any problems and we changed it when the motor was freshened about every 1200 laps...it was built by Draime out of M***ilon,Ohio and I guess they like them more than a gear drive for 700hp.
I think the reason most people install a gear drive in the first place is they think they are going to have blower whine without the expense. But to me they sound nothing like a true blower and kinda label the car as a wannabee. Probably more people pull them back out than actually leave them in. Don
Belt drives are your best bet but very costly. Unless you buy a cheap one, then you're only playing with fire. B.T.W.: Don, I like your "wannabe" label! It's soooo true!
Don't worry about what the other computer chair hot rodders think. There are several pros and cons to a gear drive set up. Might be the trailer park redneck coming out in me but I like the whine of a gear drive... - Mayor
Let's see ..gear drive for the cam or cams,just about every purpose built race engine,heavy duty truck engines,motorcycles,and of course 10's of millions of Chevy 6 cylinder pushrod inline 6's..... Sounds like a gear drive offers better reliability and timing or it wouldn't be used at all. Stuff like Italian engines with many gears to the DOHC V engine make a lot of noise but a properly designed gear drive on a pushrod V-8 can be pretty quiet.
Computer chair hot rodder??? I'm on the couch with a wireless keyboard and viewing the H.A.M.B. on a tv screen...
I bet it takes more power to spin your roller big block's cam at 7000 than it takes to spin a stocker at 5500. My point is the more load put on a dual idler drive, the harder it tries to wedge one of the floating idler gears between the crank and cam gears (typically the one on the right side of the engine). Put one on a stock engine, it might live. In my limited experience with an sbc that sees north of 8k regularly, the dual idler drive may have lasted longer than 2500mi, but after finding out that it was allowing the cam to retard almost 20 degrees from the bearing wear it caused, it was pulled from service and replaced with a double roller chain setup. The bearings were not changed, now the cam only retards a few degrees with the chain. The car picked up about 4/10ths in the 1/8th just by swapping to a chain. This isn't heresay, but actual personal experience. YMMV... I still have the drive and it looks just fine at first glance, but the side plates are severly worn inside the bores where the idler axles fit. Not sure if that is a cause or an effect, but it's not something i want to see inside my engine. Once again, this is not a problem on factory style drives that have a fixed idler or 2 gear drives that have no idler at all. It's only a problem with the dual idler drives that allow the two idler gears to "float".
Not all gear drives are created equal. Every OEM gear drive I have seen has angle-cut gears. By design, these will be quieter than any with straight-cut gears.
If you want the noise of a gear drive. Just run a bad power steering pump. Its way easyer. Besides im running one on my 454 with a 4 speed behind it. I cant notice it. But every one else said they can hear me comen.
There are some "quiet" gear drives available,.... I believe Speedway still offers a choice of noisey, or quiet. Speaking of cam drives, has anyone used one of the belt drives? 4TTRUK
Well Don I agree with you 100% here but it is a 20 dollar cure for a 10 cent problem. If you want people to think you get a blower under your hood you put type F ****** fluid in your power steering pump. It won't be long until that ****er is a whiny son of a gun. I think that there are pros and cons to running a gear drive, you can even get them with helical cut gears that are moderately quiet. I still run a chain and have most of my life and am happy as a duck in mud.
Every one knows some one running a gear drive is a blower wannabee. Why else would anyone listen to that annoying sound? I'd rather not be thought of as wannabee. Five minutes after installing one I was sorry. Why is it some posters say double roller chains stretch? Don't they think the gear drive wears as well?
Some guy named Yunick found out years ago that timing chains on racing engines did most of their stretching very early in their lifespan. The gear drive was not invented just to be annoyingly noisy (which they are...).
Cam timing accuracy,No stretch to worry about....Hmm I can't hear the whine over my exhaust and rear end anyway! Plus it was laying on the shelf!!! But guess I'm just a blower wannabe!
Pete Jackson is in mine and its been in there for years with no problems. Not a wannabe as others have said just a christmas gift from my son because he thought I would like it so we put it in and I like it..............
Hey Mayor, from a previous post weren't you going to provide us with info you had that a gear drive provided more precise cam timing? I'd like to see it.
had a 64 chevyII that ran a gear drive on a sbc with a 671blower, hemi 4speed with straight cut gears that was hooked to a franklin q/c out of my old modified on the street and track for quite awhile. with the aluminum interior and marginal exhaust i hardly noticed the gear drive sound.
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