Timing issue

CopperNick · Thursday at 12:17 PM

I think that I would be taking a pencil flash and using it to take a good look look down into the distributor hole to see what the cam gear looks like. After that I would be pulling the oil filter and filleting it to see if there is any glitter in the pleats. And even if the filter is clean, change the oil, jic.

As has been noted, that drive gear is showing wear to a degree that could be more than normal. Is your cam a flat tappet unit or a roller and is it a cast piece or a billet? Why? The cast flat tappet cam is normally comfortable with the stock gear on the dizzie. With rollers usually being a billet, it will want either a mellonized gear or a bronze gear; they do not like the steel gears as they are steel themselves. The basic relationship is usually that one gear of the pair has to be softer than the other for them to get along; typically that is the distributor gear simply because it possesses the ability to be changed if/as needed. If in doubt, pay a visit to the website for whoever manufactured that cam and ask the tech page WTF?.. If the tech say all is well, then change the gear anyway, and maybe add a shim or two between the bear and the housing to tighten up the vertical movement of the shaft a little.

And just as a Q. here, is that distributor Made in the USA or is it a chinesium knockoff?? Think quality here.

Nick

Coltrane · Thursday at 12:24 PM

CopperNick said:
I think that I would be taking a pencil flash and using it to take a good look look down into the distributor hole to see what the cam gear looks like. After that I would be pulling the oil filter and filleting it to see if there is any glitter in the pleats. And even if the filter is clean, change the oil, jic.

As has been noted, that drive gear is showing wear to a degree that could be more than normal. Is your cam a flat tappet unit or a roller and is it a cast piece or a billet? Why? The cast flat tappet cam is normally comfortable with the stock gear on the dizzie. With rollers usually being a billet, it will want either a mellonized gear or a bronze gear; they do not like the steel gears as they are steel themselves. The basic relationship is usually that one gear of the pair has to be softer than the other for them to get along; typically that is the distributor gear simply because it possesses the ability to be changed if/as needed. If in doubt, pay a visit to the website for whoever manufactured that cam and ask the tech page WTF?.. If the tech say all is well, then change the gear anyway, and maybe add a shim or two between the bear and the housing to tighten up the vertical movement of the shaft a little.

And just as a Q. here, is that distributor Made in the USA or is it a chinesium knockoff?? Think quality here.

Nick

I'll be picking up a borescope tomorrow when I'm free to get a look inside and will be changing the oil/cutting the filter as well. It's a comp hydraulic roller, and the distributor is an msd pro billet. It was an oversight on my part when ordering the million parts for the motor that I left the stock iron gear on there, when the roller wants a melonized gear.

CopperNick · Thursday at 12:45 PM

Coltrane said:
I'll be picking up a borescope tomorrow when I'm free to get a look inside and will be changing the oil/cutting the filter as well. It's a comp hydraulic roller, and the distributor is an msd pro billet. It was an oversight on my part when ordering the million parts for the motor that I left the stock iron gear on there, when the roller wants a melonized gear.

U-huh. Mellonized or bronze. Either option is compatible. In this case the compatibility includes the ability to absorb the shock of contact during rotation and not shed metal in the process. Yes, they will wear, it is their duty to die on a controlled basis to protect the rest of the system from damage but they do so very slowly and don't contaminate the oil system in the process. As mentioned above, you do have to keep track of them or just put a note on the maintenance calendar to change them once a year, just as you would keep track of oil or grease jobs or plugs or whatever.

Nick

melloelky · Thursday at 6:50 PM

This's after a year's worth of driving.

spongbob · Friday at 12:40 PM

Oil pumps are the primary ( main load) with those gears I don't beleave the dizzy it's self would merret any fast wear .adding High volume pumps ? /ect with tight bearings . Its just my opinion that the gears mentioned might last significantly longer and just chew oil instead of metal if it weren't for that oil pump and what pressure...what say yee?..huh"...

Sweet_Johnny · Friday at 7:00 PM

spongbob said:
Oil pumps are the primary ( main load) with those gears I don't beleave the dizzy it's self would merret any fast wear .adding High volume pumps ? /ect with tight bearings . Its just my opinion that the gears mentioned might last significantly longer and just chew oil instead of metal if it weren't for that oil pump and what pressure...what say yee?..huh"...

Interesting points... While the oil pump is the load driven by the dizzy, the two add up to resistance at the cam gear driving them. With the cam being fully supported and driven by chain the only slop is the cam endplay and distributor endplay, the latter accounting for slight changes in manifold/gasket height. The gear design also allows things to "climb" each other a bit, also changing spark advance and causing wear. Excessive tolerances or ill-fitment are guaranteed to cause issues.

I once purchased an Accel HEI for a fresh 350 rebuild with nice parts, and the gear ate itself. It looked as if my block had been decked or the manifold had been milled but neither were true. The gear wasn't melonized or bronze, and one was not required. I bought a Mallory Unilite and the weight mechanism came loose, stood vertical, and ruined the distributor. This engine had very tight tolerances as well as a high volume/ high pressure pump. I bet you're onto something here because tight bearings and the pump I chose were a poor match.

It may be loose distributor tolerances, maybe poor gear manufacturing that day, maybe a tight tolerance engine with a dragging oil pump. I agree that the oil pump could be a factor but also think it might have little to do with the excessive wear.

Ernest · Friday at 7:59 PM

When replacing the distributor gear, heres a good bit of info on the subject when it comes to proper alignment.

My aftermarket mechanical distributor has an off center dimple from the roll pin hole, i aligned that side with a tip of the rotor, no timing issues whatsoever.

EDIT: Examples of my distributor gears, both aftermarket, spectrum premium/wai(pic 1) and blueprint engines(pic 2), you can see where the dimple was placed, blueprint is where its expected to be, the other, offset, some care, others dont.

Distributor Location and Timing

www.camaros.net

Coltrane · Saturday at 4:04 PM

Ernest said:
When replacing the distributor gear, heres a good bit of info on the subject when it comes to proper alignment.

My aftermarket mechanical distributor has an off center dimple from the roll pin hole, i aligned that side with a tip of the rotor, no timing issues whatsoever.

EDIT: Examples of my distributor gears, both aftermarket, spectrum premium/wai(pic 1) and blueprint engines(pic 2), you can see where the dimple was placed, blueprint is where its expected to be, the other, offset, some care, others dont.

Distributor Location and Timing

www.camaros.net

Thanks for that info! Just got my new gear in and noticed this - the side with the dimple has the pin hole lined up in between the teeth, but that side is opposite (not exact) of the point of the rotor. Should i disregard what’s currently on there and put the dimple side closer to the rotor, or match up whats on there now?

Coltrane · Saturday at 4:28 PM

Coltrane said:
Thanks for that info! Just got my new gear in and noticed this - the side with the dimple has the pin hole lined up in between the teeth, but that side is opposite (not exact) of the point of the rotor. Should i disregard what’s currently on there and put the dimple side closer to the rotor, or match up whats on there now?

Here’s what I mean…this first pic is the one that’s currently on the distributor (came like this) with the pin on the side closest to the point of the rotor, right on a tooth:

And here is the new melonized one, with the dimple lining up with the pin hole between the teeth:

Ernest · Saturday at 6:12 PM

Line up the tip of the rotor with the roll pin hole thats between the teeth.... thats the correct way.

EDIT: Heres a full length shot of my mechanical distributor that shows correct orientation of the rotor and gear.. the pin between the teeth.

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Timing issue

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