Pete Jackson Gear Drives

[88trailblazer]

Wish I could hear a side by side comparison it's kinda hard to tell in a single video. I do hear a whirring sound I take to be the gears.

Thanks for the post though, it's the first one I've heard

Here is another vid with the gear drive,...


And here is the same motor after the rebuild with a timing chain,...

 

[tRustyK5]

1. Yes,… it is now what is considered by many to be a "Mild-Built 350". Like I said in the 1st post, the video was before the rebuild and it now has bigger pistons, cam, intake, ARP fasteners and aluminum rockers (and a timing chain).

2. I never claimed to be the Automotive Encyclopedia that is "tRustyK5". SShultz just asked if anybody had experience/opinions and I gave mine.

Re-read what I wrote...

I said "I'm not sure how relevant your experience or your mechanic's opinion is"

A) Your experience is with a small block, not a 6.2 diesel. These motors are dis-similar enough that I'm unsure of the relevance of your personal experience with the PJ in a small block.

B) Seeing as this is the diesel forum it should have been a given we were discussing gear drive opinions from those that have gear drives in a diesel.

C) Lose the attitude

Rene

 

[88trailblazer]

Touche'

I have to admit when i'm in the wrong. It seamed like you were talking smack. Shows me for checking this site before coffee.

I would still imagine that, while gas and diesel motors are different in many ways, the timing systems should be the same. The only difference IMHO between my old PJ in a gas motor compared to a diesel would be that noise from the diesel motor would cover up some of the noise from the PJ.

 

[jac6695]

But the 6.2/6.5 diesel has so many other noises that it is doubtful the gear drive would be noticable at all.

 

[tRustyK5]

The sbc timing set is behind a thin tin cover. The 6.2 timing set is buried behind a cast aluminum cover with a waterpump in front of that. Add the diesel clatter and I doubt you'd hear it much if at all.

If I recall right, the PJ gear drives for small blocks were offered in a noisy version as well as a quiet version.

Rene

 

[tRustyK5]

Touche'

I have to admit when i'm in the wrong. It seamed like you were talking smack. Shows me for checking this site before coffee.

I would still imagine that, while gas and diesel motors are different in many ways, the timing systems should be the same. The only difference IMHO between my old PJ in a gas motor compared to a diesel would be that noise from the diesel motor would cover up some of the noise from the PJ.

Thanks for that. I try not to come off as a ';know it all' here or anywhere, but this medium can be unforgiving sometimes. I don't do so well without my morning coffee either...

i'd love to hear from some guys that have been deeper into a 6.2 than i have whether cam walk is an issue. Same for an SBC. For the life of me I can't recall what keeps the cam from walking on a small block. If your gear drive was rubbing the inside of the cover it sounds like the cam was able to walk forward a bit.

As far as timing goes, it's a lot less critical on a gas engine than it is on a diesel. There is probably 8 degrees on either side of the sweet spot where a gas engine will still run. The range for a diesel is about 1-2 degrees on either side of the ideal. Deadly accurate timing in a diesel translates into more power...

If i had a concern with a gear drive in a diesel, it would be whether or not the timing set is burly enough to take the pounding. Velocity spikes during each ignition event are quite pronounced. OTOH those same spikes would be apt to wear the chainset faster than on a gas engine too.

Rene

 

[MaxPF]

Thanks for that. I try not to come off as a ';know it all' here or anywhere, but this medium can be unforgiving sometimes. I don't do so well without my morning coffee either...

i'd love to hear from some guys that have been deeper into a 6.2 than i have whether cam walk is an issue. Same for an SBC. For the life of me I can't recall what keeps the cam from walking on a small block. If your gear drive was rubbing the inside of the cover it sounds like the cam was able to walk forward a bit.

You rang? Since the 6.2 is a roller motor there is a retainer for the cam that controls forward movement. Rearward movement is controlled by the cam gear rubbing on the front of said retainer. On my PJ gear drive there is a bronze thrust washer between the gear and the retainer - I don't remember what the stock chain sprocket uses.

SBC/BBC's with flat tappets controlled rearward movement by the cam sprocket rubbing on the block face. The lobes of a flat tappet cam have a slight taper built into them that gives the cam some rearward thrust, so there is no need to retain it against forward movement. On old non-roller blocks that have had a roller cam installed a thrust button is commonly used between the cam sprocket and the timing cover to limit forward movement. Factory roller blocks have a retainer similar to the 6.2/6.5.

I agree that if the gear drive was rubbing it was probably installed incorrectly. I would have liked to seen pics.

As far as timing goes, it's a lot less critical on a gas engine than it is on a diesel. There is probably 8 degrees on either side of the sweet spot where a gas engine will still run. The range for a diesel is about 1-2 degrees on either side of the ideal. Deadly accurate timing in a diesel translates into more power...

If i had a concern with a gear drive in a diesel, it would be whether or not the timing set is burly enough to take the pounding. Velocity spikes during each ignition event are quite pronounced. OTOH those same spikes would be apt to wear the chainset faster than on a gas engine too.

Rene

I wouldn't run a gearset in a SBC unless it was a race engine, and then I would run a Milodon type since the PJ type isn't really suitable for high RPM use. As Rene said, the diesel is more critical with regards to timing insofar as having it slowly retard as the chain stretches and wears. There is also a lot more load on the diesel's timing set. I think the gear drive is definitely a better setup in this case. I would prefer a fixed idler setup or a counterrotating cam that needs no idler, but the PJ seems to be proven and long lasting in these engines.

 

[tRustyK5]

Yeah, I did ring...

Thanks for adding the detailed tech this thread needed.

Rene

 

[Goose]

Thanks guys, that's some good tech info.
BTW, there are $251 on Summit.

My water pump is leaking, so I'm thinking of doing the PJ at the same time.