351C Gear drives, anybody use these?

[ponydrvr72]

The parts for my top end rebuild are almost assembled,I am conscidering a gear drive instead of the timing chain.i'm leaning toward the edlebrock accu drive noisey.Now most of these drives say minor machining to the block may be needed, does anybody know what this machining entails? Please give me your opions on these drives

 

[Dirky]

Not worth it IMO.

Gear drives, especially the "dog-bone" type of gear drive will transmit more engine harmonics though to the camshaft, which of course will shorten camshaft life... Timing chains/belts absorb some of that vibration. The "dog-bone" style idler is where many gear drives fail.

I personally would NEVER use a gear drive, but in any case, a gear drive should only be used in extremely high HP applications where high spring pressures are present, or when fast cam swaps are needed.

If you have to have a gear drive, make sure its a Milodon, stay away from the Pete Jackson garbage.

Double roller FTW

Danny-Bee belt drive @ 800+ HP

 

[dragogt]

After doing some reading on sbftech.com Ive come to the conclusion that there not worth it..

From Jay Allen:
My colleague Joel Torres has a thread on degreeing a cam that I will be posting in soon enough. But cam degreeing goes right back to the heart of this thread.

The first is simple, NEVER under any circumstances that I can foresee, use a gear drive. The amount of harmonics transmitted is absurd and the fact that they may or may not be accurate than a chain is irrelevant. But typically the average enthusiast does not take enough precautions to help reduce harmonics anyways. Poor cam core choices, poor valve springs, springs run too far from coil bind, cheap push rods, all of this will play into harmonics along with an assortment of other factors.

When selecting a chain, there are reasons there are 90.00 sets and then there are 45.00 sets. This is where the "budget" or grass roots mentality will bite you. I use the Comp Cams 8138 timing set now on all of my own engines. Yes it is 100.00 more. But I will install the cam dead on where it needs to be. And when I take into account chain stretch, I'll tell a person where to install the cam so when the cam does retard 1.0* - 1.5* it is where I want it.

All chains will stretch. This is a fact. But before you get your panties in a wad over chain stretch, what about the crank index? What about the cheap cam core? How about the way that cam was ground and the specs are not even close? What about the FACT that your crankshaft is NOT the "exact" stroke you think it is. These are FAR bigger concerns in regards to correct valve timing vs a chain that is going to stretch. But again, if the cam comes from me, I "try" to take this into account.

And hence yet another reason why the "Lift at TDC" is MILES more accurate than the ICL method to install a cam.

And just incase the thread is viewable. http://sbftech.com/index.php/topic,22783.0.html

Also the comp timing set Jay mentioned. http://www.compperformancegroupstor...=CC&Product_Code=8138&Category_Code=AdjTiming

 

[TexasNomad]

If they are so destructive to the engine why do so many people use them??

 

[dragogt]

Dont know any better... At least thats my guess.

 

[Dirky]

If they are so destructive to the engine why do so many people use them??

Who uses them?

 

[ponydrvr72]

Thanks for the input guy's, I guess i'll just have to be satisfied with the whine of the cam shaft.

 

[ponydrvr72]

I got my timing chain today, summit was backordered on cloyes, so i got the edelbrock true roller, dual steel sprockets,should work very nicely.Thanks again for all the good advice, scott

 

[dragogt]

Cool. luk how it turns out.