Thought of something else too. I've occasionally heard of distributors that the vacuum advance allowed them to advance too far. Wonder if the problem might be a bad vacuum advance? Also wonder if your distributor has the ability to set the amount of advance? If it does, you usually put a allen wrench in the vacuum port, and turn a screw in the port to limit the amount of full advance.

 

I'm really starting to wonder about this distributor myself. I believe there was something in the instrux about adjusting the advance with a small allen in the vacuum port. My problem is that I wouldn't know how to set it anyway. Of course I can't find the paper that came with the distributor. Honestly, there wasn't even a manufacturer name for this thing. I hate not knowing if there's possibly something wrong with this distributor. It was the first part ever bought for this engine project 4 years ago. I remember it having a lifetime warranty and Skip White boasted about ZERO FAILURES with it. Stupid mistake not buying a MSD but I figured with that kind of warranty and failure rate, how could I go wrong?


What I can't get off my mind is how well the engine started and idled today when it was showing 45 of the tape. It made the headers glow real quick but again, the only time it ever ran on it's own immediately after starting it.

 

I am not positive what Skip White is selling but if I had to guess it was an off shore HEI clone. Do you have your old one? It should light it off. I have read horror stories about those things. Things like excess shaft play and even exploding while running. I think its either a weight hanging up and holding the timing high or the vacuum can is pulling a bunch. You can leave the can unplugged and keep it that way for a short term trial and error. My dizzy doesnt even have a can! But its a race dizzy and needs to be replaced soon.

 

What the heck, connect the advance to the full vacuum port on the carb and see what happens, it can't hurt. The "disconnect the vacuum advance before setting timing" is a throwback to the pre-emission era when the distributor was hooked up to full vacuum. I have yet to run into a ported vacuum connection that made a difference in idle timing connected or not. There could be rare instances where it could, if the carburetor design puts an idle circuit at or slightly below the throttle blade line, or if you have the blades cracked open at the curb idle adjustment. The vacuum can on post emission factory and aftermarket distributors are designed to be connected to ported vacuum. But not knowing what you have, switching the vacuum source is worth a shot.
You wanted to know what the distributor and advance does, give this a thorough read: http://www.camaros.net/forums/showthread.php?t=150344
Also: http://www.camaros.org/pdf/timing101.pdf

 

If you don't have the instructions, then just wing it. You can try various allen wrenches (metric I bet!) until one fits into the port screw. Then fire the engine with the vacuum hose off and the end of the hose plugged. Put a timing light on the engine and start to slowly turn the wrench and see what the timing does.
Skip White sells the Pro Comp junk, and I doubt he'd really tell anyone about complaints on that junk. A quick google search for Pro Comp reviews will turn up a ton of bad reviews and complaints. If SW doesn't get any, it must be akin to a miracle!

 

Great read Chuck, thanks very much for the link sir. From what I read, manifold vacuum is the ONLY option to use. I understand the advance more now but that also makes me have more questions. Ported/timed vacuum sounds as though it should never be an option since it doesn't even operate the vacuum advance at idle? When else are you going to have/need vacuum since there's little/no vacuum as the throttle opens? Ironic that just about everything you read or are told by instructions, Edelbrock installation videos etc. is wrong according to "this one guy." I also read that the ported vacuum was designed to increase exhaust temperature, interesting. You said yourself that you've never seen a difference using ported vacuum, unless the throttle plate is slightly opened. Brings me to another question. If I'm adjusting the idle up high (over 2000 rpm) it's still considered "idling" but at what point would adjusting the idle higher begin to open the throttle plate? I've not checked yet (actually need to get a vacuum gauge) but I'm assuming vacuum will be low with the cam I'm using. If the throttle plate is open I'd have little/no vacuum right? I could go on and on and all of this wondering is really more for knowledge gain but it just seems like a lot of what I'm experiencing coincides with the article writers reasons for not using ported vacuum. What sticks out the most to me was reading about how it would constantly change the timing readings because of the changing vacuum, without using the throttle I mean. So, I'm going to try again today using manifold vacuum and from what I read, stay with manifold vacuum. With that said, what will I need to do so the trans modulator line can still be connected to manifold vacuum? Just get a T fitting?

 

I get what you're saying Vall, I'm fully aware that Procomp (name has been changed to Speedmaster btw) is not top quality stuff. But that certainly doesn't mean, nor do I believe that everything they sell is broken or inoperable right out of the box. It's not worth spending a single minute debating, but if the distributor is bad the only way I'll know this is to replace it. Actually, I'm certain this distributor is not Procomp, I remember seeing the manufacturer name of Highline somewhere on the listing, but it was bought back at the beginning of 2012 so I can't go back and get details from the same listing. Either way - same thing only different.

 

The car may be sitting still, but 2,000 rpm is NOT an idle. Plus if you raised the rpm's by opening the throttle, vacuum has been dropped. It's also very likely that your distributor is at full advance at that point, and your readings point to that as well. Your distributor out of the box, wasn't designed to run on full manifold vacuum. You need to use a different type of vacuum advance canister, and alter your advance plate inside the distributor to limit it's travel. I had a link to that somewhere, lemme take a look. A t-fitting will work, or you can hook up the advance to the other side of the carb that has a full manifold port.

 

Understood, that's why I was wondering about having the idle set so high. I'd need a T fitting regardless, other port is used for the brakes.


For what it's worth (not much) here's a link to the same type of distributor I bought back in 2012, just a red cap and mine's clear. Read the listing, it was a compelling sales pitch when I was first getting started. Lifetime warranty, "the last distributor I'll EVER NEED TO BUY!"
SBC BBC Chevy 65K Red Hei Distributor 6501 R | eBay

 

It's the last one you'll buy, until you smash yours with a sledge hammer out of frustration! lol