Anyone care to share pro's/con's on gear drives for BB? Compared to a timing chain, are they worth the extra dollars. What about longevity in a race only world?
Which one, Pete Jackson or Milodon gear drives or who's timing chain, and why?
Thanks, Brian

I use Donovan gear drives, never had an issue.

Keith black should be on that list and at the top of it!!!

pete jaksons eat horse power. Milodons are expensive.
I have always just used double rollers.
i have heard good things about rollmasters for the price on hear though i havent personaly used one. I think the last one i used was a engine pro i have had no promblems with it. I think i will give the roll master a try on the engine im building now

Have been using milodon for 25 years,never really had an issue.If I were to buy new,would get a KB.They need the biz

I like the Donovans myself, I'm sure the KBs are fine. Never had a real issue with the Milodons.If you go for a Donovan, it will be their " pro " series now. Very stout pieces.


I dont necessarily subscribe to the notion that gear drives eat up horsepower. The junk ones may.

Stable timing may increase horsepower. That being said, a good quality timing set can do a lot of work in the average race engine. All these things come down to making the proper selection of the correct parts for your application. They all are different.

Stay away from all "dual-idler" systems. The only gears drives I ever had breakage with were dual idlers.

I considered a geardrive for a moderate 496. Reading all the posts over time I concluded 1) gear drives are best for medium race RPM engines with really stout cams say up to 7500 RPM 2) At really high RPM a belt drive is better... the gear drives can create/transmit their own harmonics 3) At my level there was little benefit to a gear drive. 4) The Pete Jackson type has several drawbacks. I ended up buying a good $100 chain - .010 short to fit to my line bored engine - and saved the $3-400 extra for a gear drive.

Quote:

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Reading all the posts over time I concluded 1) gear drives are best for medium race RPM engines with really stout cams say up to 7500 RPM 2) At really high RPM a belt drive is better... the gear drives can create/transmit their own harmonics

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i've posted this before take it for what it's worth

not saying belt drives aren't good (i have one as well as a milodon) but i wouldn't consider this a "medimum RPM" engine. i'm pretty sure these guys had some insight into race engines and they were OK with a gear drive.

I have a Milodon here. Can't speek about the others, KB, Donovan etc. I'm sure they are all good quality. Stay away from a dual idler.

Now I probably could tell you about many timing chains.

Gear drives, buy it once, set it and forget it. Wear out the motor and put it on your new block. Or just keep buying timing chains.

The kid has a PJ in his 413.Been in for ten years and many street and strip miles.No problems ever.Rocky

Thanks for the comments guys. One reason I'm thinking gear drive is because it seems that I buy a timing chain & gears, put them on and the're "tight", then next time I check it, its loose. Tired of spending $100 each, and them not lasting very long.
Who sells Donovan and/or Keith Black gears and how do they stack up against Milodon price wise?
Thanks again, Brian

You can buy Donovan and KB direct, expect to pay approx. $300 more for those over the Milodon.

I love these endless debates that always pop up. The theme is always the same.

So here is an alternate view. I have a couple thousand passes on a 25 year old PJ dual idler setup. 451/440-1. 330# seat pressure, 700+ open load, with a hilborn cam drive pump. Shift @ 7300, 7600 peak. I'm going to change the thrust washer while I have it down for the first time in 4 years.

I think Frieburg(sp) did a dyno test awhile back on every type of cam drive and found very little difference.

Do your own thinking. Trust but verify!!

RIP

milodon here ! u should have a gear drive or belt drive on a roller cammed motor all that spring pressure tends to strech the chains also if u aline hone the block u may have to get a chain that is 2-4 thousands smaller to compensate for the crank moving toward the cam during the machining of the block !!!

Per Pete Jackson ...

Fiction mixed with fact : Gear drives create harmonics

Fact : Every rotating part that contacts another, or part that is stressed under load in an engine ( crank, cam, valve train, gears, chains etc. ) creates a harmonic ( frequency ) . Some frequency are harmless, a simple matter of unavoidable friction , while other are percussive & concussive, and are capable of creating damage in very short periods of time. Gear drives, chains ( yes chains ) and most valve train components create frequencies which are a simple matter of friction and rendered harmless by simple lubricants (oil). An unbalanced or improperly balanced crank , ( especially if the harmonic balancer is removed ) create the percussive and/or concussive types which can over a period of time ( if severe very short ) cause damage , above and beyond anything considered normal wear . Gear drives absolutely do not create these types of harmonics .