[Schroeder]

I read somewhere on here that the BOP distributor gear should b ran with cams from SD performance. Stock dizzy gears should be used during the cam break in. why is that? Why cant I leave a stock dizzy gear in the engine? What is the benefit of the poly gear?

[Hooter]

They should be ran on billet roller cams. For a hydraulic or flat tappet, run the stock gear.

[Schroeder]

I have the road paver and am running the comp cams hydraulic lifters 857s. WHY do the billet cams need them?

[b-man]

The materials are not compatible, the steel roller cam will get eaten up by the factory distributor gear.

Your only choices are either the bronze or the poly gear if you use a roller cam.

[Schroeder]

What kind of roller? Do I need this gear for a HYDRAULIC roller cam like the road paver?or do I just need it for a BILLET roller? Should the hydraulic roller be broken in with the stock gear? Is the bronze or BOP better?I had s BOP bought I think and can't seem to find it. I cant belive theyre $125.

[1969GTO]

I have the poly gear on my Stump Puller cam, as per SDPERFORMANCE/HYD ROLLOR

[Schroeder]

Will a melonized one from summit ($62 compared to $125) work?

[Don 79 TA]

i have been using the BOP gear on the last few billet rollers i have been using
no problems with it either on the MSD dist.

you want to check with whom ever made the cam as to what gear to use just to be safe

[Steve C.]

The 'Old Faithful', 'Road Paver' and 'Stump Puller' cams use steel billet roller cores. Thus the use of a bronze gear or BOP gear is necessary.

More often than not all Pontiac Hydraulic roller cams or solid roller cams have a 'dash' 9 in their part number. The -9 designation is for a Steel Billet Roller. There are exceptions but if memory serves me right they involve roller cams with a 4/7 swap.



.

[Tim Corcoran]

Flat tappet cams are made from a cast iron casting. Most roller cams are made from a steel alloy. The type of material that the roller cams are made from are not compatible with the factory cast distributor gears and they may fail. Before there was a composite distributor gear available for Pontiac the only choice was a brass gear and they are sacrificial and small particles of brass will contaminate your oil. Today the best, and in my opinion the only choice is a composite gear with a steel roller cam. Just make sure the gear on your cam has no sharp edges or they have been removed with a stone prior to installation.

[mach flyer]

Hey Tim!!!
I have heard both you and Sun Tuned now refer to using a stone to remove any rough edges. Can you describe the procedure and what kind of stone that you use?????

[lust4speed]

Originally Posted by Schroeder

Will a melonized one from summit ($62 compared to $125) work?

Interesting question. Don't have an answer, but my guess is that it would work after reading the description of the gear. Flat tappet cams are cast iron and normal distributor gears are steel. Now we seem to reverse the metals, hydraulic roller cams are steel, and the melonized gear is ductile iron. Sure seems like it would work. That said, I don't see a listing for a Melonized Pontiac distributor gear so it seems to be a moot point.

Any run time with similar metals would gall both the cam and distributors gears, so you don't want to do it. Even the 20 minute break-in time would corrupt the gears.

I finally retired a brass gear that has survived an embarrassingly long time - measured in decades. The cam and the gear got along really good and there just wasn't any noticeable wear on the gear. I've seen other gears that showed more wear after coming off the break-in stand. I have also adopted taking a stone to the gear teeth on new cams because it does definitely seem to help.

On another front, I finally got around to checking the BOP gear on the Cruiser's hydraulic roller - a little over 16,000 miles and the composite gear looks like new.

[shaker455]

Originally Posted by Schroeder

I read somewhere on here that the BOP distributor gear should b ran with cams from SD performance. Stock dizzy gears should be used during the cam break in. why is that? Why cant I leave a stock dizzy gear in the engine? What is the benefit of the poly gear?

Jordan,
You run the BOP gear right from the get go.

As mentioned, steel to steel will wipe out the gears.

That Poly BOP will out last almost anything and not deposit any metal in your engine.

Kind of a no brainer,

I have a Crane hyd roller in my combo that has a cast iron dist gear installed on the cam so you can run a stock dist gear.

All others get the poly gear.

[Tim Corcoran]

Some cam manufactures don't always have the best quality control these days, if they did there would be no reason to de-burr a new part. Prior to installing a new cam get a small hand stone or a rotating stone and remove any sharp edges on the gear teeth edge prior to installation. If the edge is smooth already then no need to dress it. This is for any distributor gear, brass, polymer or cast.

[Schroeder]

sounds good. thanks guys.

[Steve C.]

Stated- "I finally retired a brass gear that has survived an embarrassingly long time - measured in decades. The cam and the gear got along really good and there just wasn't any noticeable wear on the gear. I've seen other gears that showed more wear after coming off the break-in stand."

We have had similar experience with bronze gears in the past, distributed by MSD as their materials are top quality. Unlike some off brands.

One of the key issues can be the instillation. Set up properly a bronze gear should last quite awhile, and yes they are designed to be sacrifical.... no big deal ! Some find with experiance a bronze gear can get real sharp from wear. Which brings up the question or thoughts about not being properly matched and set up. Articles from MSD will point out the effort that goes into a ring-and-pinion installation. Yet many don't think twice about the distributor gear/cam gear relationship unless performance starts to suffer. How the dist gear and cam gear mesh is just as important as the quality of the metals involved. MSD states the excessive clearance between the gear teeth shouldn't be fixed by shoving the distributor farther into the hole; this screws up the proper wear pattern. They also mention that if a CAM gear is poorly made, the first bronze gear may destroy itself deburing and reshaping the cam gear, but the second bronze gear should wear in faster, work more smoothly, and live longer. And they remind you to remember to check ignition timing; as the bronze distributor gear wears, the timing will retard.

++++ If using a bronze gear remember do not beat on the motor before the oil's hot ++++


In the last few years we have also switched to the BOP composite gears with no issues.


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[Skip Fix]

I have read that the Chevy factory HR cams use a melonized gear. Not sure if they use a special gear on the cam itself to be able to do that.