HEI woes...

[Grim 82]

My 82 was equipped with a manual transmission, which is why I think that it didn't have the vacuum switch on the firewall. That may be for an auto trans, I am not completely sure. The ESC control box on mine was mounted on a bracket directly above the gas pedal. It was a shiny metal box about 4"x6"x2" or so.

If I remember right I am using one light and one medium spring, and I used the center plate and weights in the moroso kit. MSD recommends running a bigger plug gap with the hotter coil. I am running Delco CR43TS plugs gapped at .045 and some heavy Performance Auto wires that cost almost as much as the dist. Good luck, I think you will like it.

[jlane1820]

Thought about gapping mine to about .050 after I dropped in the new dist...I think stock is .045 IIRC.
Yes I have a TH350 auto, so the switch may be for that, but like I said I ran that switch without vacuum for years and never noticed anything at all. There is already a vacuum to the tranny, so I think it's getting what it needs as far as I know.
But thanks for the advice on the ESC box...didn't look above the gas pedal so I will check that later today. I want rid of it if it does exist. I know it's to help with ping on the higher compression 305, but I have played around with timing enough to eliminate any pinging. At one time (when I first bought the truck, before I tinkered with it) it would ping really bad under load, so the ESC obviously didn't help that if it is there.
Oh and I have heard of running the light/medium spring combo as well and considered this. MSD says the StreetFire is set at about 20° advance at 4000 rpm, which is a little late for a truck that rarely sees over 3000. So I will experiment with spring combos...thanks for the input on that as well!

[Grim 82]

Could you have a TH350C? That switch could be the low vacuum switch for your TC lockup. Does it have wires going into the trans?

[jlane1820]

Could you have a TH350C? That switch could be the low vacuum switch for your TC lockup. Does it have wires going into the trans?

Pretty sure it does...I am running vacuum now to that switch and have been for a while, well, since my last tune-up. But if this controls a TC clutch of some kind, and it wasn't engaging, I wouldn't think it'd really be a big deal, right? Maybe cause me to run at a few rpm's higher than normal and maybe a little more sluggish but that's it?
The wires from that switch go into the firewall though...seems odd they would pass through the cab to get to the tranny. Again, when I get some more time I will be inspecting this switch and the routing of it's wiring. 

[jlane1820]

So Grim...I'm looking to remove the ESC now before I drop in the new dist. You mentioned yours was right above the gas pedal. I looked there and saw what looks to be a grey box with a harness of several wires going to it. I looked online for a replacement so I could get an idea of what I was looking at and found this...
http://www.oreillyauto.com/site/c/detail/BOR0/ESC16M.oap?year=1982&make=Chevrolet&model=C10&vi=1030802&keyword=control+module&pt=01603&ppt=C0334

Is that what yours looked like? Also, the pink power wire that goes to the BAT terminal of the cap has a pigtail that plugs into that same group of wires that goes to the mystery vacuum switch, is this for the ESC?

[Grim 82]

Yeah that's pretty much what mine looked like. You can unplug the pigtail for the pink BATT wire, find the wire that goes to the knock sensor (in the block above and in front of the starter,) and that bunch of wires will go through a grommet in the firewall. I had the dash out of mine at the time so I followed the wires back and removed everything up to and including the box. The wires can be stubborn, they are in behind the defroster duct work and there are metal tabs that are bent to secure them. When you get the new dist. in, just plug in the remaining BATT wire and you should be good to go. As far as the vacuum switch, mine never had one so I can't say for sure, but if it's wired up with the rest of the ESC harness I would *guess* that it could also be removed.
I think that if the vacuum switch in question was for the TCC it would be on a seperate harness that would also include wires that you could trace back to a switch above the brake pedal. Some of the guys here with more experience with automatics might be able to help out with that one.

EDIT: I went back and read that article that I linked to earlier and it sounds like that switch gets filed away right next to the control box and the wiring.

[jlane1820]

Much appreciated on the advice! I think I read somewhere the vacuum switch for the ESC is used on models with automatic transmission, so it could be for that too, but could also be the TCC. Of course I will follow the routing of the wires from the module and the vac switch to make absolutely sure before I go removing any of them. But even though you may not be as knowledgeable with autos, your experience with this really helped! 

[Grim 82]

Glad to help. I have been kicking around the idea of adding the CDI box to the setup, but I'm not sure how much of a difference it would really make.
http://www.street-fire.com/cdiignition.html

[jlane1820]

Glad to help. I have been kicking around the idea of adding the CDI box to the setup, but I'm not sure how much of a difference it would really make.
http://www.street-fire.com/cdiignition.html

Funny you should mention that, Grim.
To update my progress, I installed the StreetFire HEI and gutted out the ESC crap...but took it a step further and purchased that very box. Now I can't say my issues would/wouldn't have probably been solved with the new SF Dist. alone, but the idea of multi-sparks at low RPM and an external spark control that won't have the heat saturation issues of the regular internal HEI module sounded good to me. I also wasn't looking for anything too high-end for racing applications, where a Mallory, Comp or MSD 6AL would be a better choice, just reliability. Besides, this has a dial-in rev limiter, of which may be more of a benefit to trucks with manual tranny. So I gave it a shot and installed them both at the same time using the internal HEI coil that came with the SF dist., wiring the SF box into the module wiring with the supplied harness, and using StreetFire low resistance 8mm wires to send the spark to the motor. I also dismantled an older HEI module to cap wiring harness and rigged up the CD box's wiring to it so it would plug into the cap the same way as stock. I also opened the gap on the plugs to .050.

The result...

Off the bat, I noticed the truck fires in less than 2 cranks of the starter every time, cold or hot, and idles MUCH more smoothly. After some carb tuning (because my previously set idle speed jumped way up), it was good to go! This was my desired goal, and so far it seems to work very well. I also like the dedicated tach wire, which will be useful when my tach gauge cluster arrives. I wasn't expecting huge gains in performance, nor have I really seen any, at least judging by seat of the pants dyno. I know I could have probably went all out on a small cap billet dist. with a better CDI and external coil, but for around $200 bucks for both the new dist and the CD box, the starting issue seems to be solved, it idles more smoothly, and I am one happy camper!

[Grim 82]

Awesome. Did that vacuum switch end up being part of the ESC?
Where did you mount the box? (pics?)

Next time you have to drop the coolant for any reason you can spin that knock sensor out and put a pipe plug in it. What is your timing set to now? Maybe advance it a bit and you might see some more performance.

[jlane1820]

Awesome. Did that vacuum switch end up being part of the ESC?
Where did you mount the box? (pics?)

Next time you have to drop the coolant for any reason you can spin that knock sensor out and put a pipe plug in it.

Yes it was part of the ESC, so I took it off. And it left just enough space on the firewall to mount the StreetFire Box in it's place (with a few additional holes drilled). The SF box is noticeably smaller than an MSD 6AL, measuring only about 6" W x 3.5" H so it was the perfect size for this location. I also made some DIY anti-vibration mounts using 4 rubber wiring grommets sandwiched between the box and firewall. I will take some pics this weekend and post them.

And I did leave the KS in place after unplugging it. I have taken them out of my Buick several times, but I've heard that these in the ESC Chevys are easy to break so I left it in as a simple plug. Good to know a pipe plug will work if I ever remove it.

But thanks to you and everybody for all the help in sorting this out!

Oh yes, my timing. Well I did replace a spring in the dist. advance...I put in one heavier spring and left one that came with it, in hopes of it beginning the advance at around 1200 rpm, topping out at around 12° @ 3500rpm. My initial timing at idle is set to about 14° advanced. My StreetFire dist didn't come with an adjustable vacuum advance, but a stop plate instead, which I've installed to stop it at about 12°. My goal was about 38° total advance...does that sound about right? Think more advance would be beneficial? It's hard for me to check my advance right now at anything above 1200 rpm because that's all my handheld tach will read, but like I said, I have a tach gauge cluster coming soon that will allow me to check timing at higher rpms.

[Grim 82]

Your distributor is not equipped with the vacuum advance canister?

[jlane1820]

Your distributor is not equipped with the vacuum advance canister?

It is, just not an adjustable one. Funny because I know the Street Fires did come with an adjustable advance at one time because I downloaded the manual before I bought it and it includes instructions on how to adjust it with an allen wrench. On the one I got however, the instruction sheet was revised in the vacuum advance section, and the adjustable advance instructions were removed and replaced with how to install the stop plate. Plus, I could not insert an allen wrench and find a screw. It's just a standard canister. I have an adjustable canister from my old dist., but figured the stop plate would do the job and limit it to what I needed and to prevent any ping.

[Grim 82]

Adjustable or not, I would scrap the plate and use the vacuum advance.

[jlane1820]

Adjustable or not, I would scrap the plate and use the vacuum advance.

Hehe, I'm assuming your Street Fire came with the adjustable vacuum advance and no such plate. So I'll send pics of mine...
It's not a block-off plate, like what you'd use to gut out the vacuum advance altogether in a racing distributor. The advance canister with full vacuum from the carb is certainly being used. The plate I'm referring to is simply a stop plate, sort of like the one that comes with a Crane vacuum advance kit. It basically mounts behind the vacuum advance inside the distributor, but has 4 different 'claws' which limits the full movement of the vacuum advance shaft to your choice of 4 different advance degree settings. I chose the claw which limits vacuum advance to 11-14°. So I am using vacuum advance, but once it opens enough to hit the stop 'claw', it will advance no further. So the way I understand it, if my vacuum advances 12° at say 2500 rpm, which was my theoretical vacuum advance limit, but I needed to open the throttle further, the vacuum advance shaft would be at the end of it's travel due to the stop claw and therefore would only see 12° vacuum advance from there on out, instead of advancing further and potentially causing detonation and power-loss under more load. The centrifugal advance would do the rest at higher rpms. I thought it was a pretty good idea to prevent over-advancing at the vacuum which would lead to pinging, without the hassle of having to adjust and readjust a screw that I can't see.