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I’ve used the PC91 on several project engines it has a good reputation.

However, my findings is that it’s putout is weak on 12 volt systems it really works best off a CDI box.

I use it on my own DD 350 without a 6AL or any other CDI box right now and with ProComp/Speedmaster 7000 small cap distributor and their module with the PC91 coil. I use Taylor Spiral Wound wires and Accel spark plugs gapped .030 inch with this but they are just part of my typical street performance set up. The heads, intake and distributor are independently grounded because some ignition combos tried on this engine used the 6AL box, the current setup doesn’t simply because this is a experiment to see how good the basic PC/SM distributor is, the answer is it is a fine system the engine runs well from idle to redline it’s been on there for three years. Induction is an 800 CFM Edelf rock, AVS I, Thunder on a GMPP LT1/4 intake, cam is GMPP LT4HOT straight up.

Bogie
 

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The ProComp/Speedmaster module is a 4 pin module but arranged a bit different that GM‘s HEI module. Mounting and harness dressing is a bit better with ProComp/Speedmaster module. I used one and observed very good spark, equal to or better than GM’s. But I found the module short lived and died with in a week. I was using a Ford pickup and GM‘s “E” core coil. I have not found much information on the ProComp/Speedmaster product nor any reviews out side of Bogie’s post. I had one of the ProComp/Speedmaster distributors but the quality of the machining was poor and wobbled installed in the engine as it ran even with screw tightened down. So now it is a decoration on the work bench.

The ProComp/Speedmaster distributor is their rendition of GM’s HEI in a small diameter.
The advance mechanism sucks. No real way of modification. And no spec’s supplied as to ramp up. And access to it is NG, everything has to come apart. Adjustment of the pickup is a joke ....just move around till gaps are even. When new out of the package one side was tight and the other was a wide gap. Bogie must have got a good one or I got a real POS.

I‘m not intending to bad mouth ProComp/Speedmaster product but beware of off shore products. I’m assuming this is a china product but I could be wrong as no indication on package.
 

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Back in the shop days I avoided ProComp parts till a growing contingent of customers either requested or brought these parts in. I found that compared to similar parts from domestic sources the failure and quality defect rates not to be all that much different. When you see a lot of this stuff you get a different view of quality. It doesn’t require too much reading to see users complaining about goof ups pretty much across the board of part makers. It didn’t take long with ProComp Chevy heads to see a different approach with the cam was needed to tweak their output, but of SBF’s they were a bolt on and go with a conventional cam pick but for the Chevy you want to look for more lift and less duration if you want to work the head hard without spending a lot of flow bench time to pick up the low to medium lift flows where the high lifts on these heads are pretty decent.

For my distributor situation as I converted permanently to a carb the 350 in my GMC S15 (like a Chevy S10, but a real truck). The engine is backed right to the firewall with no space for a big cap HEI, The MSD I used to use during various tests wasn’t mine and went with the partner that owned it when we all went to retirement. I contemplated buying a new one but my budget rejected the idea so I thought I’d try the PC 7000. Now there may be variations but mine uses pads on the module not pins so the GM style module is not a drop in. Since I spend time in the mountains and out in the desert where getting parts is not as easy as in the big city, I ordered up a couple of extra modules, caps and rotors and carry them around in a zip lock freezer bag. So far they are just gathering dust and grime under the seat. A surprise I hit was the distributor gear unable to get a satisfactory answer as to whether the PC gear was Melonized or not and running a roller cam I wanted to be sure to protect the cams distributor gear but with the PIA of a bronze gear and its street wear that drives fairly frequent replacement, so I grabbed a GM Melonized gear since PC uses the GM .491 inch shaft. But on assembly I discovered that PC uses a larger diameter roll pin to secure the gear to the shaft than does GM. This lead to setting the gear up on the drill press to do a properly aligned hole through the gear so it would fit the PC pin. The other thing was finding the PC91 E core coil without a CDI box was not up to firing .050 plug gaps at WOT with my 10.7 SCR. So I regapped the plugs to .030 and it’s been happy ever since. Eventually I’ll put CDI back in but first I wanted to get some performance analysis without stupefying electrical jolts to the plugs.

Bogie
 

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Bogie, how do you handle the advance curve. I couldn’t even find any spec’s on it let alone modify it. I found it was too much for the little it was in the car. But all that for me is water over the falls since because of the wobble I’m not going to use it anyway.

The tuning you had to do is nothing out of the ordinary for products today. The module on mine had spade terminals all in line. A nice configuration but it only lasted a week. I see there is somebody selling those modules on ebay. Nothing on reliability or performance anywhere that I could find. Thank you for reply.
 

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Discussion Starter · #66 ·
Yes, the PC91 coil and RTR distributor worked just fine for several thousand miles. My only heartburn with it was the non adjustable mechanical and vacuum advance. Both are too much at 20 degrees. So I got the bright idea of going to an electronic distributor with the adjustability I wanted. That is what started this whole mess. I just never know when to leave well enough alone, I guess.
 

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Discussion Starter · #67 ·
Well, I remembered this thread and thought I would provide the ending. I bought a Pertronix Flamethrower Ignitor III complete distributor with the recommended coil. Installed it and the darn thing runs perfectly. What fixed it? Who knows! Maybe it was adding a grounding system from frame to heads, manifold, and distributor. Maybe I had a bad coil. Now it only has about 100 miles on it. So I can't speak to the longevity. I have become gun shy of electronic distributors, so I joined AAA just for the emergency service.:) They had a special. $49 for 3 years. Cheap insurance. I'm not getting stuck on the road again without a plan.
 

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What I have learned about the ProComp/Speedmaster 7000 distributor is it is a Bosch design used by Ford of Australia in the V6 and V8’s engines and GM in the V8 Holden 256 - 308 which is an offshoot of the American SBC design, not exactly the same but the family resemblance is unmistakeable. The PCE/Speedmaster module has a direct Bosch replacement often called the 021 module, its Bosch p/n is 9222 067 021 or sometimes marked as BIM024. Bosch best I can tell stopped manufacturing these back in the late 1990’s or early 2000’s. I assume that PCE/Speedmaster picked it up for the aftermarket hot rod community.

If you hotrod a GM 4 pin module into this beast Bosch module wiring is pin 3 is negative timing sensor; pin 7 is positive timing sensor; pin 15 is positive 12 VDC to module from coil positive terminal; pin 16 is coil negative. I find the color codes of the wires can change across the years so mark you layout before disassembly.

Inside the the 7000 you will find it’s built a lot like the old Ford points distributor with the mechanical advance system in the bottom under all the sensing/timing parts. It is a complicated design rather typical of Bosch. It shares a lot of old Fordish distributor design characteristics with the advance system close to the upper bushing under the timing mechanism, the spring clip snap on cap, etc.

The module will burn out if you have a condition where the engine is not running but the ignition is left on,,,personal experience! There are some variations where the older housings use a screwed on bracket to mount the cap’s clips, the later models cast this retainer as part of the housing, I’m not crazy about this improvement as it can let the clip come off then you have to go hunt for it whether it’s stuck in grease and oil somewhere, landed in some inaccessible place or if your luck holds is on the garage floor. I solved this by drilling a 3/32 hole (if you do this you’ll see where) then inserted a 5/8 long roll pin through the bottom of the roll pin attachment coil and this little bulkhead that forms the attachment of this cast on T shape fitting. Now the clip cannot escape. The other thing to watch for is the drive gear uses a larger roll pin than Chevy to secure the gear to the shaft and the shaft is the Chevy .491 dia not the aftermarket .500 so MSD gears will not fit the shaft and GM gears need to be drilled for the larger pin. PCE/Speedmaster sells their own bronze gear, they may have changed their supplied gear to a Melonized piece but I’m unsure of what their sales wording really means. For those that I installed on street performance engines with roller cams I redrill the pin hole on a Chevy, Melonized gear.

Attached is a PDF file that is not mine but is out in the ether. I suggest you burn a copy or print it while it’s available.


Bogie
 

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Well, I remembered this thread and thought I would provide the ending. I bought a Pertronix Flamethrower Ignitor III complete distributor with the recommended coil. Installed it and the darn thing runs perfectly. What fixed it? Who knows!
Thanks for reporting back. I'm also using a Pertronix distributor and like it a lot; no issues!
 

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Discussion Starter · #70 ·
I'm also using a Pertronix distributor and like it a lot; no issues!
Yep. Pertronix is pretty proud of them, but it is a nice piece. I set up the curve I wanted according to the instructions before putting it in . It was perfect. Set it and forget it. I hope. I am, however, reserving judgement on the longevity issue.
 

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Jaw22w, which Pertronix distributor did you settle on?

FWIW, I installed a Pertronix "stock" look with Ignitor III module in my bucket-t. I needed a small cap due to clearance issues. Except for hard acceleration it works good. But, the mechanical advance is not adjustable. So, my full advance is around 40-41 degrees. All Pertronix says is "sorry".
 

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Discussion Starter · #72 ·
I called Pertronix before I bought mine. They told me that the mechanical advance was not adjustable on the stock look distributors. I wanted to be able to set up my own ignition curve, so I bought the D7100700. Billet Body. It has a different mechanical advance limiting system than I ever saw before, but it works well. What surprised me was that the directions showed how to set it up for my desired 18 degrees of advance. When I put it in and checked it, it was right on the money at 18 degrees. As I said before, they are pretty proud of them but they do work well.
I am pretty sure you could do a little modification to the stock look distributor to limit the mech advance.
I use to put a spot of weld on the advance slot to limit the mech advance on stock distributors. Adjust by filing the slot. IT's a pain in the butt, but it can be done.
 

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Sorry. This might end up long. Electronic ignitions. SBC. I have posted on this topic a couple of times before.
Background: Started out with points system in my '26 T coupe. Points needed replaced at about 10K mile or so. OK. Pretty normal. With the difficulty and high price of obtaining good quality points and condensers, I decided to try a Pertronix. The kind with the whirling magnetic disc under the rotor. Worked fine for about 2-3K miles. Then started acting up. Rough idle/ backfiring. Went back to points until a buddy gave me a chinese RTR small cap HEI distributor. It has worked ok and got probably 5k miles on it. Problem with that RTR distributor is it is not adjustable for mech or vac advance. Set at 20 degrees for both. Made my engine ping if I wasn't careful. I rebuilt the engine and wanted to change the distributor out. Bought an RTR Summit small cap distributor. 15 miles later had to be towed home. Back in goes the chinese RTR distributor. Still not convinced, I bought another Pertronix. This time the Ignitor II lobe sensor model. I got it installed, got it running well enough to back out of the shop to continue the timing process without gassing myself. Backed it out, went to timing it. The idle started kind of fluttering, then the motor died. Would not start. Check spark. NO SPARK!!!. 5 minutes. I couldn't hardly believe it. So I like to keep my T coupe going all the time. Put the chinese RTR back in. Runs just fine for a couple days. Then yesterday I started it to leave in it and it is banging and popping and carrying on. I'm sure it has spark because it runs. Just very badly. I'm positive it is the ignition. Now I have to put together a points distributor just to get it running.
So what the heck is going on??? It must be the way I am holding my mouth. There are only 2 wires in the car's system going to the ignition system. The 12+ from ignition switch to coil and tach feed. It has a good heavy ground engine to frame.
An HEI won't fit due to firewall interference problems. So not an option. In one of my previous posts 57nomad posted info about converting a points distributor to chevy HEI. I really don't want to attempt this conversion myself. It looks like a science experiment. He also suggested a fella named Dave that does that conversion. I contacted him, but he is out of commission due to a brown recluse spider bite on his right hand.
I really would like to have an electronic ignition in this car (obviously, judging by how persistent I've been). But there's gotta be something wrong somewhere to cause 4 different ignition systems to go bad. I know....I am the only thing common to all 4 failures, but I really don't think it's me. Karma?
Somebody enlighten me, PLEASE!
i would go with a ready to run msd makes one and other company as well and use a new coil. that may be your problem
 

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i would go with a ready to run msd makes one and other company as well and use a new coil. that may be your problem
I called Pertronix before I bought mine. They told me that the mechanical advance was not adjustable on the stock look distributors. I wanted to be able to set up my own ignition curve, so I bought the D7100700. Billet Body. It has a different mechanical advance limiting system than I ever saw before, but it works well. What surprised me was that the directions showed how to set it up for my desired 18 degrees of advance. When I put it in and checked it, it was right on the money at 18 degrees. As I said before, they are pretty proud of them but they do work well.
I am pretty sure you could do a little modification to the stock look distributor to limit the mech advance.
I use to put a spot of weld on the advance slot to limit the mech advance on stock distributors. Adjust by filing the slot. IT's a pain in the butt, but it can be done.
Thanks for the info.
My original error was asking Summits tech help and not Pertronix. Normally, Summit's guys do good but not this time.
Your right, I'm going to try to modify this one before spending more money. Nothing to lose. If I have to buy one, just by what's available, Pertonix and MSD is on the short list.
 

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Well - tell you what I did. I don't think point systems are all that bad and I have this little 355 engine with a mild hydraulic in it, Edlebrock intake and unfortunately one of the Edlebrock carbs - I just don't really like them. Now, you're correct - 10k - 12k or so is about the limit on a set of points but for the most part that's about a year of use for this engine. I found me a brand new, regular old points distributor that was complete from Rock Auto. Just checked and the price right now is $71. Yes, I had to tune the mechanical advance on it to suit the vehicle but that is all I have done to it. I also installed a MSD blaster coil for a bit more hit and some MSD plug wires. Simple, easy to repair if needed and it fires up and goes down the road. I don't have to worry about some whiry-twirely magnet failing or a CD box going puke on me in the middle of no where. At worst, I have found my old points file but have yet to use it.
 
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