Pete Jackson Cam Gears Opinions Wanted

[dandyZ]

I have a sbc in a '71 240Z. I'm not sure I like the sound of the gears and wonder if the benefit of precise timing is worth the annoying whirr of these cam gears. It makes the engine sound very different and is annoying to me on any drive over an hour or so. So, I'm thinking about a timing chain set-up. What do you guys think??? Any input is appreciated.

[dr_hunt]

IMO there is nothing better. The sound you speak of is really minimal compared to most exhaust notes of today's mufflers. I doubt you'd even notice it.

[rsicard]

dandyZ: The small amount of noise on the quiet Pete Jackson Gear Drive as stated by Doc will be overrun by the exhaust noise. There is nothing better than this gear drive to eliminate distributor spark scatter. Just now running a 383 SBC with the Gear Drive on a test stand and the muffled exhaust is louder than the noise from the Gear Drive.

[BillZ260]

Personally I like the 'noise' the accurate timing was a side benefit

[grumpyvette]

http://www.petejacksongeardrives.net/index_files/pjgdfaqs3.htm

 

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=430

 

if you correctly install the quite cam drive per the instructions youll have zero problems, but in most cases a CLOYES CHAIN DRIVE is a lower cost option

[NewZed]

Dandyz, are you saying that your 240 with sbc already has a gear drive, and that the noise is annoying as you are currently driving it? You are considering removing the gear drive and replacing it with a chain?

 

I wonder if motor gear noise is transmitted through the chassis like differential gear noise when you go to solid or urethane mounts on the "moustache" bar. Does anyone know? Could the engine noise be better isolated with different motor mounts?

 

I like precision but don't like noise either. Don't have a hybrid yet, but plan to eventually.

Edited January 20, 2010 by NewZed
Remove thumbs down icon...

[DavyZ]

I have a sbc in a '71 240Z. I'm not sure I like the sound of the gears and wonder if the benefit of precise timing is worth the annoying whirr of these cam gears. It makes the engine sound very different and is annoying to me on any drive over an hour or so. So, I'm thinking about a timing chain set-up. What do you guys think??? Any input is appreciated.

 

If you are driving over a half an hour at a time, just how high performance is your motor currently? If you have a relatively mild performance motor, then having a gear drive is a bit overkill, but that's my opinion.

 

OK, so you don't like the noise and it sounds like you may have the "noisy" version vs the "quiet" version of the Pete Jackson gear drive. The "quiet" version is hardly noticeable, and a good double roller timing chain is going to be that much quieter as well. Try out a timing chain since they are cheap.

 

Davy

[sweetride2go]

I used to have a gear drive, but in my most recent rebuild I opted for the timing chain. I got tired of the gear whine. Especially when I was trying to listen to something in the engine compartment...

 

Cheers

Ryan~

[lazycat5]

I ran a noisy gear drive and hated the noise. Chainged to the double roller and was much happier with it. If you have the funds a belt drive will give you the timing benefit of the gear drive without transmiting the harmonics to the valvetrain. Engine guys, please correct my if I'm wrong.

[grumpyvette]

every time I hear that (GEAR DRIVES CAUSE VALVE TRAIN HARMONICS REPEATED) I would LOVE to find ANYONE who has any data to prove it, in fact for 40 plus years Ive looked, and have YET to find conclusive PROOF, even smokey yunick used gear drives in many engines and took lots of high rpm photography, and advised the use of gear drives in some applications

Edited January 21, 2010 by grumpyvette

[lazycat5]

I didn't say it caused them, just transmited them.

[dr_hunt]

I didn't say it caused them, just transmited them.

 

Simply not true. There is play in the gears which is required to run properly, that play is the reason why they will not transmit harmonics of the crank.

 

Also there is nothing more durable than a gear drive, just ask CAT, Cummins and Detroit! Anyone who thinks otherwise is absolutley positively wrong! Chains do break and any HD application especially industrial, uses gear drive for simplicity and durabiltity. I know of several Reher-Morrison BBC's that had tchain and gears and the chains gave up, destroying the engines.

 

I have run them in several of my personal street engines with over 100K miles logged and zero problems. The sound may delay your detection of engine sounds will in no uncertain terms prevent you from finding it.

[dandyZ]

Thanks for all of the input guys. I have the noisy version put in by the p.o.. Maybe I'll go with the quiet Pete Jackson gears. This is a street and back roads prowler. I'm not trying to be the fastest or noisiest car in town. Just like the power on demand. Love the Z!!!

[lazycat5]

Simply not true. There is play in the gears which is required to run properly, that play is the reason why they will not transmit harmonics of the crank.

 

This is a quote from Pete Jackson Gear drives Q&A section.

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 .

I never said they cause harmonics nor did I question there reliability. All I said is a belt drive may do the job with out the harmonics (transmited) by a gear drive.

[rsicard]

dandyZ: Just to reinforce what Grumpyvette has said, I wanted to acoustically record the gear whine at the Knock Sensor location to characterize the frequencies emitted by the gear drive. The knock sensors are piezo electric devices that are tuned to output a voltage at certain narrow band of audio frequencies. I think it was Smokey Yunick that said if you could see a worn timing chain you would see it flapping all about and it would be alarming to the trained observer. This is one, if not the primary cause, of ignition spark scatter in the SBC engine. The whine is a byproduct of the straight cut gear set they use. I used the Pete Jackson quiet type and it is noticeable but not overwhelming. Secondarily, I went to a Big Block oil pump because it will cause less spark scatter than an SBC oil pump. You add up the FACTS then make your decision.

[dr_hunt]

Simply not true. There is play in the gears which is required to run properly, that play is the reason why they will not transmit harmonics of the crank.

 

This is a quote from Pete Jackson Gear drives Q&A section.

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 .

I never said they cause harmonics nor did I question there reliability. All I said is a belt drive may do the job with out the harmonics (transmited) by a gear drive.

 

Belt drives don't have the durability that chains or gear drives have. Simply to say, they are without a doubt the most inferior of the three. If the belt drive is so good at removing harmonics then it also is the least accurate of the three also as the belt is stretching. Belt drives come in wet and dry versions. never run a dry belt on a street car or you run the probable chance of shredding it by debris entering between the belt and gears. Wet belts you can't see and you have to disassemble the engine to inspect unless your running a cloyes 2 piece or similar cover. For logetivity accuracy and durability, your better off with a billet roller chain or gear drive.

[rsicard]

dr_hunt: With all that has been said, belts and chains are not as good as gear drives. Smokey Yunick recommended gear drives for driving the camshaft. Enough said.

[Phlebmaster]

Sweet thread!! I just purchased one for my sbc. I will post pics and a video of the install, and maybe help with some questions about installation.

 

I pick it up today and will install it by next weekend if I can find the time or do it when I pull the engine to rebuild it after the first of Feb.

[tyler031734]

I came across a magazine article a about two years ago with 5 different engines on dyno's testing crank HP between chains vs. gears. In all 5 there was (as they stated) a five percent decrease in hp running a gear set. These where all mid 400 to 500hp motors. So it would seem to me the only reason to run a gear over a chain is having a motor powerful enough to brake a recently new chain, or to lazy to change em every 100k... this was found doing research for a 72 Chev Cheyenne I was looking to buy with a built sbc and noisy gears that overwhelmed the headers 6'' of pipe to short cherry bombs out! (at idle)

 

My theory is chains are more efficient, HP and probably MPG with everything said. Unless a chain isn't strong enough gears are a waste, besides im on the sleeper kind of things

 

.02

[grumpyvette]

I came across a magazine article a about two years ago with 5 different engines on dyno's testing crank HP between chains vs. gears. In all 5 there was (as they stated) a five percent decrease in hp running a gear set. These where all mid 400 to 500hp motors. So it would seem to me the only reason to run a gear over a chain is having a motor powerful enough to brake a recently new chain, or to lazy to change em every 100k... this was found doing research for a 72 Chev Cheyenne I was looking to buy with a built sbc and noisy gears that overwhelmed the headers 6'' of pipe to short cherry bombs out! (at idle)

 

My theory is chains are more efficient, HP and probably MPG with everything said. Unless a chain isn't strong enough gears are a waste, besides im on the sleeper kind of things

 

.02

 

IVE found over the years that magazine dyno test results depend a great deal on the company that's paying for the testing to be done and the components they sell, seldom does the company's products come out looking badly,Ive had very good results with BOTH CLOYES chain drives and JACKSON cam drives, and ID doubt theres a two hp difference between them on an honest dyno test., to say theres a 5% reduction in power for a gear drive (thats 25hp on a 500hp engine) is ludicrous, but its also easy to "PROVE" a chain drive OR a cam drive is superior with a skilled dyno operator doing the testing