rmchrgr
Skate And Destroy
After literally years and years of searching, I finally got myself a Sun distributor tester! It's a 500 model from 1963 and it works. Incredibly, I got a pulse amplifier with it which enables me to read magnetically-triggered distributors like our electronic units. Those are hard to find in themselves and when they do pop up on Ebay or forums, they go for big bucks. The guy also had the original cart that went underneath it but instead of taking the cabinet I took the P.A. instead. I didn't need the box and would have nowhere to put it anyway. All in all a great deal for a somewhat reasonable price and no shipping to contend with - cash and carry right into my garage.
So it works but it needs some fixing. Presently, the tach is not operational which is a little annoying. Plotting an advance curve without an accurate tach is guesswork at best. Sure, I can infer what I am looking at but I'd rather have it working. I've traced the problem to the AA battery holder that powers the gauge. It had some corrosion where it connects to the wiring that seems to be causing the issue - it basically crumbled when I handled it. BTW, the tach is a 4,000 rpm (crank speed) unit. The 500 model normally came with a 3,000 rpm tach. For now, I am able to use my cheapo Sears tach dwell meter but it only goes up to 2,000 rpm crank speed.
Second thing that's bothersome is that it's pretty noisy at lower RPMs. I have found through research that this can be attributed to the drive wheel. There is a hard rubber idler wheel behind the drive unit which can get flat spots or wear out which causes the noise and excess vibration. Seems like what I have going on here as it smooths out at higher speeds.
Lastly, at higher RPMs, there is a flutter in one of the strobe signals. Initially, I thought it may have been a wobble in the distributor that was occurring at higher speeds but I tested two different units back to back (one brand new) and the same thing occurred both times.
If you're familiar with these things, you'll probably know of Mark/Paramount Distributor Co. He repairs/sells parts exclusively for these things. I spoke to him about some of this stuff, including the high rpm flutter. He said that sounded like a problem with one of the springs under the drive unit cover that can bind and need to be stretched a little. Hopefully that's all it is.
Basically, he can sell you a fix all the common problems that these 50+ year old machines have. He offers a new idler wheel and bearing kit, new capacitors, battery holders etc. His stuff is not cheap by any means but the parts are available if needed. Sometime after the holidays I'll probably be placing an order for an idler wheel/bearing kit, possibly a capacitor kit and a battery holder.
So far, I've run a few distributors I have on hand and it was really cool to do. I especially wanted to run the one that was currently in my Duster to see where the curve was at. When the car was running last year, I looked at the timing with a light and I wasn't exactly sure what I was seeing. Based on where the mark on the damper was, it seemed like the initial advance was almost 30 degrees which was basically turned out to be true. It was only advancing about 11 degrees and was all in by 2,000 RPM.
Just for fun, I took apart the distributor and saw the advance plate was indeed marked 13 which x2=26 degrees initial so seeing 30 degrees in the car was not unrealistic. Someone had tapped the ends of the advance slots with a center punch to limit the advance but not by much. There was no welding or anything. To double check, I measured the slots with a dial caliper and I got .044" = 13 degrees. The OE damper that was on the car was shot and was probably slipping a degree or two and the center mark on the timing cover scale was marked with white out - not exactly precision engineering. so having it out and apart kind of confirmed what I was seeing but the machine definitely helps to visualize it a little easier.
In any event, the distributor has a total advance of 35 degrees; 26 + 11 which is right where it should be. Obviously I can adjust it in the car a little if necessary but at least I know where it's at beforehand.
I also have an older MP tach drive 'race' mechanical advance distributor which has a really quick advance curve from the factory - it's all in by 1,200 RPM. This is essentially like having locked out timing. The reasoning behind that is 'race' cars usually idle over 1,000 RPM and you're at WOT off the line with no real concern for part throttle drivability.
I wanted to see if I could slow the rate of advance with a heavier spring to be able to use it on the street. I swapped the super light spring on the tach drive for a heavier spring out of a regular electronic distributor I had on the shelf. Success! The advance rate slowed several hundred RPM but the amount of advance stayed the same. It was still all in by around 2,000 but that's a lot different than 1,200. I have to say this was very easy to do on the machine and would have been a real PITA on the car. I can just imagine doing this job while bent over the fender, reaching over the back of the block and potentially dropping the little spring between the header tubes - forget about it.
So yeah, I'm pretty excited about this thing even if it will only see limited usage. I guess it was just one of those things I wanted. If any one local wants to have their distributor set up, let me know!
Here's the unit. Note tach on top left is disconnected.
Here's the pulse amplifier. I made a connector from a parts store trailer harness to work with the Mopar pickup. Works good.
So it works but it needs some fixing. Presently, the tach is not operational which is a little annoying. Plotting an advance curve without an accurate tach is guesswork at best. Sure, I can infer what I am looking at but I'd rather have it working. I've traced the problem to the AA battery holder that powers the gauge. It had some corrosion where it connects to the wiring that seems to be causing the issue - it basically crumbled when I handled it. BTW, the tach is a 4,000 rpm (crank speed) unit. The 500 model normally came with a 3,000 rpm tach. For now, I am able to use my cheapo Sears tach dwell meter but it only goes up to 2,000 rpm crank speed.
Second thing that's bothersome is that it's pretty noisy at lower RPMs. I have found through research that this can be attributed to the drive wheel. There is a hard rubber idler wheel behind the drive unit which can get flat spots or wear out which causes the noise and excess vibration. Seems like what I have going on here as it smooths out at higher speeds.
Lastly, at higher RPMs, there is a flutter in one of the strobe signals. Initially, I thought it may have been a wobble in the distributor that was occurring at higher speeds but I tested two different units back to back (one brand new) and the same thing occurred both times.
If you're familiar with these things, you'll probably know of Mark/Paramount Distributor Co. He repairs/sells parts exclusively for these things. I spoke to him about some of this stuff, including the high rpm flutter. He said that sounded like a problem with one of the springs under the drive unit cover that can bind and need to be stretched a little. Hopefully that's all it is.
Basically, he can sell you a fix all the common problems that these 50+ year old machines have. He offers a new idler wheel and bearing kit, new capacitors, battery holders etc. His stuff is not cheap by any means but the parts are available if needed. Sometime after the holidays I'll probably be placing an order for an idler wheel/bearing kit, possibly a capacitor kit and a battery holder.
So far, I've run a few distributors I have on hand and it was really cool to do. I especially wanted to run the one that was currently in my Duster to see where the curve was at. When the car was running last year, I looked at the timing with a light and I wasn't exactly sure what I was seeing. Based on where the mark on the damper was, it seemed like the initial advance was almost 30 degrees which was basically turned out to be true. It was only advancing about 11 degrees and was all in by 2,000 RPM.
Just for fun, I took apart the distributor and saw the advance plate was indeed marked 13 which x2=26 degrees initial so seeing 30 degrees in the car was not unrealistic. Someone had tapped the ends of the advance slots with a center punch to limit the advance but not by much. There was no welding or anything. To double check, I measured the slots with a dial caliper and I got .044" = 13 degrees. The OE damper that was on the car was shot and was probably slipping a degree or two and the center mark on the timing cover scale was marked with white out - not exactly precision engineering. so having it out and apart kind of confirmed what I was seeing but the machine definitely helps to visualize it a little easier.
In any event, the distributor has a total advance of 35 degrees; 26 + 11 which is right where it should be. Obviously I can adjust it in the car a little if necessary but at least I know where it's at beforehand.
I also have an older MP tach drive 'race' mechanical advance distributor which has a really quick advance curve from the factory - it's all in by 1,200 RPM. This is essentially like having locked out timing. The reasoning behind that is 'race' cars usually idle over 1,000 RPM and you're at WOT off the line with no real concern for part throttle drivability.
I wanted to see if I could slow the rate of advance with a heavier spring to be able to use it on the street. I swapped the super light spring on the tach drive for a heavier spring out of a regular electronic distributor I had on the shelf. Success! The advance rate slowed several hundred RPM but the amount of advance stayed the same. It was still all in by around 2,000 but that's a lot different than 1,200. I have to say this was very easy to do on the machine and would have been a real PITA on the car. I can just imagine doing this job while bent over the fender, reaching over the back of the block and potentially dropping the little spring between the header tubes - forget about it.
So yeah, I'm pretty excited about this thing even if it will only see limited usage. I guess it was just one of those things I wanted. If any one local wants to have their distributor set up, let me know!
Here's the unit. Note tach on top left is disconnected.
Here's the pulse amplifier. I made a connector from a parts store trailer harness to work with the Mopar pickup. Works good.
