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While rummaging through my storage unit the other day I came across something I forgot I owned. It's a cheap/Chinese(?) Knock-off HEI dizzy for an AMC v8. I must have got it back around 2008 and after hearing the horror stories of the cheap dizzies eating cams and ruining motors, I just squirreled it away. Got to thinking... As the issue seems to usually be due to incorrect hardness of the drive gear, why not swap it for the one on the dizzy that is in the motor now? Anyone had any luck making the swap and it work out ok? Just curious.

Yeah, the cam eating is because of mismatched gears, or a dizzy gear that is mismatched and too hard. You should be able to use the gear off your current distributer with out issue.

Thanks Stuka, I figured your wisdom would come into play.


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I disagree. Bronze gears used to be made for racing applications when these engines were more common, even. In every case I researched with sufficient info (including my own) showed that the timing set was replaced prior to the dizzy gear failure. Nearly all replacement timing sets have mismatched oiling pathways and/or multiple oiling slots for the chain. Both of these deprive the dizzy gears of sufficient oil flow that results in their failure.

REDONE wrote:I disagree. Bronze gears used to be made for racing applications when these engines were more common, even. In every case I researched with sufficient info (including my own) showed that the timing set was replaced prior to the dizzy gear failure. Nearly all replacement timing sets have mismatched oiling pathways and/or multiple oiling slots for the chain. Both of these deprive the dizzy gears of sufficient oil flow that results in their failure.

Interesting point.
As I'm not going to be changing the timing set, I think swapping the drive gear seems a near effortless task for a lil piece of mind. One that's in it works. No idea about the Chinese version.


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Fair enough. It's just a roll pin so go for it. I'm just trying to squash a myth. If gear hardness was the issue, the harder gear would survive at the softer gears expense. This is not the case:



This problem is clearly a lack of lubrication, since even if they were different hardness, the lubrication boundary would protect both. These were both stock gears, after installing a summit double roller and correcting the oil pathway. I didn't fill the extra oiling slots and this happened less than 2000 miles later.

Matt, I see your point(s).

The bronze dizzy gear is still available, MSD 8006 for example. I see no reason why most of us Jeepers would ever need it though.

I installed a new Mallory HEI with original dizzy gear off the Prestolite in Krista's Wag in 2009. The gear still looked almost new. 6 months later, it was running like crap and the gears looked just like the ones you pictured. We were lucky to get home from AZ that November. The timing set was still original with around 105K miles. When I get new gears, they are MSD 8005 and 8007.

I believe there are multiple factors that can affect cam and dizzy gear failure, including inadequate lubrication.

Yeah, I agree. there most likely was/is multiple causes. Poor lubrication due to oil holes that were either not drilled at all, or drilled poorly are probably up there as the most common.

A dizzy gear that is way to soft could also cause some bad issues. Once it gets eaten into, it can start to damage the cam gear. Either way, I have just stuck with re-using the OEM gears, haven't had an issue yet.

As I sit on the side of the road in my suburban I'm drawn back to this thread. Why? Driving along, running good as usual (for an old suburban) and suddenly it shuts off going up hill. Turns over, can hear the fuel pump working but no start. Tried spraying some carb cleaner in the intake but nothing. Best guess is...
Distributor.
Once I get out of the road I'll check it out and hope it's easy. Maybe the module? Though I noticed the heater fan isn't working now either... Possibly a fuse?


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It might be a Chevy thing. I don't know anything about old Suburbans. Maybe a fuse link (if GM used those)? Good luck getting back on the road.

I have an opinion about HEI distributors. I like the one wire solution. Uses all the same parts inside as a GM unit. Parts are easy to find. I tried a couple Mallory units and found they can fail like anything else so I decided the Skip White el cheapos would be sufficient. I can buy 2 for less than what I paid for a Mallory. Yes, it is preferred to take the original distributor gear and put it on the HEI if it is in good shape. Currently running a Skip White on one 401 and a Mallory on another. Bought two Skip White to put one in another 401 and then have a spare. Parts is Parts.

Well, fingered it out. The dizzy module was bad. $38 bucks later and it fired right up.


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