I know you wouldn't know it, (because I haven't told you) but for 2+ months I've been wrestling with my HEI trying to dial it in. I finally gave up and sent it to a professional (heretofore known as "The Distributor Guy") who has a Distributor Testing machine, the proper know-how to figure out why my advance isn't fully coming in and an S TON more
patience than me.
This post will be one of those "what not to do" type posts. You'll see why.
You know what is apparently being added to the latest list of unobtanium? Genuine GM HEI advance weights. Maybe I'm late to the party and they've been off the market for years, but I'll tell ya, there are none on this forum, and none in any of the 20 GM groups I'm in on Facebook. Pretty astounding considering the amount that were made available from the factory and the amount of people these social sites reach.
Don't get me wrong, the journey has been interesting - got a chance to talk to Rocky Rotella on weight and curves. (If you don't know the name, you're probably fuel injected. ) Man, what a nice guy!! But still no weights.
Got a few folks that said they could help - even willing to go with 139 weights - but I must have ticked them off or something, because they ghosted me in short order. I guess I have a way of doing that.
Enough about that. Lets get to the reason you're all here. My awesome photography.
My big cap HEI is really just a distributor of spark - the 6al does all of the heavy lifting; the dizzy just tells it where to go. No modules lefts to fry, it was strictly the magnetic pickup and the advance mechanism. Simple. Years ago my Distributor Guy even made an advance bushing to limit the curve and dialed it in perfectly, even with the crappy curve kit I had in it.
But if you read any dizzy threads at all, they all have one thing in common - the aftermarket weights and cams are junk. Its true more so today than ever before. Most serious curve guys buy for the springs and throw the rest away.
Whats wrong with my distributor? I don't really know to be honest. All I know is it limits me to half the advance Id expect to see regardless if I use new weights, or the old proven good ones. Yup, all greased, spins freely, shimmed identically as before and doesn't feel odd in any way. Oh, and it ate a bronze gear in 90 minutes of run time.....
....and put a ton of carbon under the rotor in the same timeframe. Yup, I said 90 minutes.
Something ain't right Scoob.
Maybe the shaft bent when I dropped that roller lifter waaaay back at the front of this thread? Remember, that oil pump got pretty hot.
So given there are apparently no genuine GM weights left in the world, and my dizzy has gone off to the great carousel of spark in the sky, what options exist before one goes completely fuel injected?
Another Dizzy or a Crank Trigger.
You know, I tried to buy a distributor to make my life easy, maybe get me running this year, but of course, MSD no longer sells a Pontiac HEI distributor. Very annoying.
Since my mantra has always been to upgrade when a part breaks, I figured the crank trigger would give me the most flexibility going forward - either in a switch to FI or just making more power and requiring more stable spark. Take that advance weights!!! Try and squeeze me, huh? I'll show ya.
I had the trigger delivered to see if I could mount the wheel to my old Fluidamper. MSD support isn't allowed to share tech drawings (go figure) and at the same time, couldn't tell me the exact size of the center hole so I had to find out myself. I thought my biggest battle was won when I unpacked and found a removable center allowing the wheel to register on different dampers. Well played MSD.
When it all bolted together perfectly with my odd Fluidamper 4 bolt 3.3" bolt circle, I thought I was in the clear. (seems like a good timing pun could be used here, doesn't it?)
Yeah, no.
I now know what the phrase I've read on this board so many times actually means, at least partially:
"I've gotten an MSD crank trigger modified to work on the Pontiac". I was hoping those were old statements said against old versions of the part and any "issue" that needed correcting was done with future iterations. Wrong again I was.
For those that aren't familiar (and I'm likely the last to ever attempt this because there are far more modern ways to get accurate ignition timing today) here is a rundown of "the problem" Ive got with the trigger. If you're looking for a solution, I will let you down.
If you're running a 4 bolt damper, such as the Fluidamper, the likelihood one of the 4 magnets in the wheel aligning with the pickup is slim. Take a look.
This picture is with total timing at 29 degrees BTDC. As you can see, there is no aligning the two, at least not at 29 degrees. (The pickup is at the end of its upward travel). I didn't measure, but it looks to be about 10, perhaps 12 degrees off, so its basically sitting at a starting point of 40 lets say, with no option but to advance more.
You see, MSD instructs one to find TDC on #1 on compression stroke, set engine for the total desired timing, align magnet with the center of the non-magnetic pickup and attach the wheel. Maybe with a 3 bolt damper you can get a magnet to align with the pickup somewhere on the slider, but not when the damper is using 4 bolts. The bolt circle and the magnets have the same relationship. (do not believe the MSD tech thread that says this trigger will work with 4 bolt balancers. Not without extensive modification it wont)
Rotating the wheel to the next spot it bolts to the damper, yields the following:
And because the slider can only travel up in this photo, that would no nothing but retard timing starting at 29 and continuing downward.
Yeah, I could modify the slider to work - this is hot rodding after all. There is a lot of material on the adjuster I could mill to get more travel, but I'm just not that sure I want to go this route just yet, especially since I'm likely to have to buy a new dizzy anyway.
Back it goes.
I'll talk to my Distributor Guy - Maybe a DUI is in my future.
More news as it becomes news.