Okay, so I've got one of the small cap F-body distributors that's going to be going into my car. Tonight I was inspecting it, and gave it a slow turn. At one point there was a small catch/grind, and less than a quarter turn later a longer, more noticeable catch/grind.

It doesn't take much (if any) force to push it past this point, as a matter of fact, I can't tell the force difference. I just happened to feel the grinding sensation, so slowly turned it a few more times to see if it was consistent, which it is.

Obviously the rotor cap wasn't on there.

Is this something to be concerned about? Should I buy a new one?

 

Are you sure it's grinding and not just the magnetic attraction of the reluctor poles?

 

Definitely, the event happens when the points are furthest from each other in one case, and starts again just after turning away from a point in the second case. If you're looking at the distributor with the ignition module plugs pointing at you, the first, short catch would be at 5 o'clock (point is at 6), stopping before it reaches 6.

The second starts just after the same spot on the rod starts to turn away from the point at 9 o'clock, but continues till 10/10:30.

I hope that makes sense?

 

I'd replace the distributor then.

 

Thanks Apeiron.

I was worried that might be the case, so I started looking up distributors last night, using a 92 Firebird 350 as my search criteria on Summit, and ran into a catch -

I'm going to be using the 7730 ECU, do I want a distributor with a computer controlled advance, or "stock" (not sure what the "stock" advance controller is on a 92 Firebird), and I'm assuming the "Trigger style" should be Magnetic?

Thanks!

 

"Stock" and "computer controlled" will be the same thing. Summit isn't real smart about equating what different manufacturers say.

 

Thank you for the clarification! Does the same go for the magnetic trigger?

 

You can take yours apart, clean and inspect it. I have pulled one out of one of my cars and the shaft was slightly bent and doing what your describing.
You can buy just the parts you need, if you want.

 

Stock triggers are all magnetic, and anything that uses a stock module would have to be too.

 

Hey TTop350,

I didn't know that! I always figured they were press-fitted/assembled in such a way that the most you could tear them down was, well... to what I already have!

I started searching for information on how to break it down further. So far what I found (on another forum via google) is to very carefully hammer out the pin that's through the gear at the bottom of the dizzy, and then everything else should just slip off/out? Is that all there is too it?

If not - is there any good tutorials or threads you can point me to on how to break it down further?

 

They're a piece of cake to take apart, but I don't know that it's worth it unless you've got other cores to rob parts from.

 

Gotcha, I'm not at home to play with it right now, hence the Googling/asking.

No, I don't have any cores - I was hoping I could find the part(s) inexpensively online. Though if all else fails, Summit has a remanf. one from "Cardone" for about 90 bucks that I was eyeballing.

Thanks again guys. I'll toy around with it tonight when I get home.

 

the parts ad up quick to rebuild these the shafts usually crack on the poles.

gm/acdelco 10467353

 

Thanks for the part number, tuned!

Yeah, I see what you mean, the cost for that shaft alone is around 90 bucks. Though that Cardone stuff seems seriously hit or miss, so I scratched that off my list.

There seems to be a plethora of distributors from Delphi on ebay... part number CZ20001... priced inexpensively, and listed as "new" (other sites have them for 2-3 times the ebay price).

Maybe I'll snag one of those?

 

If it was me I would get another stock one used for 20-25 or the cardone and take that chance. Don't buy the cheap chinese ones on ebay. I got one several years ago the icm was dead. bought a new icm and 2 months later was getting a miss and the cap had oil in it the bushing fit was jacked up on the upper bushing.

 

Thanks! I didn't realize the Delphi distributors were poor quality.

 

The parts do add up fast but if you already have a new ICM and a pickup coil you could just grab a new shaft. (if thats your problem)
I bought a new complete Dizzy for a GM smallblock EFI and it cost me around $225. I think retail is higher.

 

Yup, I'm weighing the options. I have a new coil. The distributor is used, so the control module is likely used - I was debating on replacing that, which is why I'm on the fence now of buying that shaft or getting another used one (either to use or part-swap with) or getting a whole new shindig.

Going through the for F/S section of the boards now.

 

If all your stuff is older and "used" your better off with just getting a whole new one if you can swing it.
Make sure you use the proper gear for the cam you have.

 

Good suggestion.

This is all stuff I'm collecting to ditch the carb and go to a HSR. When I do the actual swap, will I be able to take the gear off my existing large cap distributor and pop it onto the small cap one?

 

I don't think so. I think the large cap has a lil bigger shaft than the small cap. I ran into this when I put a plastic gear on my small cap HEI dizzy.
Comp makes 2 sizes and the small cap runs a smaller shaft than they make.
I had to make a metal sleeve to get it to work.

 

Thanks again.

Here's the distributor I'm currently running http://www.summitracing.com/parts/SUM-850001-1/

It has a steel gear on it, the distributor itself is what was suggested to me by the shop that built my engine.

So when you say to make sure I get the right gear, is there anything else I need to worry about besides gear material?

 

Well, working on taking my distributor apart. Noticed something interesting, that the shaft has a hint of vertical play in it, and when I hold the distributor upside down and turn the gear, the catch/grind is gone. So I'm wondering if there's just some crap in there that needs to be cleaned out. Here's hoping!

 

While you're at it you can pick up a set of distributor shims to take out a lot of that vertical play.

 

Vertical play is bad. Got it. Thank you! I would have thought it as "normal" and not even asked about it! First I'll make sure it's just crud that's causing the issue. If not, new distributor!

Trying to get the damn pin that's through the gear out... using a nail punch and a hammer. Not having much luck yet, but I don't want to really lay into it and miss or something. lol

 

Also the gear has a lil dimple and it is supposed to line up to the rotor point side of the shaft.

 

Vertical play is normal. You need some to allow for the different rates of expansion in the steel shaft and aluminum body. The problem with having too much is that the helical gears translates every .013" of vertical movement into a degree of variability in the timing. Given that stock endplay can be around .060", your timing can vary about 5 degrees. Shimming the clearance down to .010" brings the variance to within a degree.

 

Got it. I did not measure how much play is in it, so I don't know how close to the tolerances listed it falls. I don't have a fine-measuring device to do so, guess I'll have to pick something up!

 

Feeler gauges would be the way to do it.

 

That's a great suggestion, thank you. I was sitting here looking up the prices on calipers.. man, your way is much cheaper. Thank you again!

And thanks for putting up with all my beginner questions. I've never done much outside of basic maintenance.

 

Not unusual for grime to build up on the shaft. Best to use a carb cleaning gum cutter (2+2 works good). After the gear is off spray it into the bottom of the distributor and work the shaft back & forth until it may be removed.

Apeiron is correct about the end play. Although, I tend to set it between .014" and .015" (cold). As the distributor heats up the body expands more then the shaft, which tightens up the clearance.

When I rebuild GM CC distributors, it is usually: replace the shaft with a new one, install new pickup coil, use the OEM GM ignition module. Cleaning everything and using new heat sink compound under the ICM.

Note that I only replace the shaft if the magnets in the star wheel are cracking and flaking. Every now and then one will be OK and doesn't require a new shaft.

I've also been known to add an additional heat sink to the outside of the distributor. This is located directly under the module. There is a thread on the V6 board here where I posted pictures and such of it. That thread has recently been bought to the top.

RBob.