HEI Firewall Clearance Issues

[69TowRig]

I searched around and could not find my specific concern addressed.

A long while back I bought a used GM HEI distributor with an ACCEL Super Coil cap/coil assembly. I just finally got around to installing that yesterday and it is wedged against the firewall with zero clearance for anything, including spark plug wires!

So my question...what are you 4x4 and Blazer guys using for cap/coil assemblies? From pictures I have seen online it looks like I might have the big bertha of HEI setups, so anything else might be smaller.

Looking for suggestions of brands that leave a bit of clearance, I don't need anything fancy for my half-dead 307, just something I can get at a local store that will not break the bank.

Thanks in advance.

[MiniD]

I could not use the ACCEL Super Coil on my Blazer's HEI either. The HEI should fit with a regular coil on it, though.

[69TowRig]

Thanks, so what kind of coil are you using?

[Long Roof]

I had a stock HEI coil on my cap. I think MSD and others make hiperformance coils that are the same size as stock.

Aaron

[Yukon Jack]

I'm using a stock hei on my 70 Blazer and it fits put is very close. If you want to spend the dough, an MSD Ready to Run distributor will fit and have plenty of clearance.

[Jtrux]

I've got about an 1/8 inch clearance between my stock cap and firewall.

[69TowRig]

Thanks guys, I went to the parts store and bought a generic coil and cap, it fits (REALLY TIGHT) but now the truck will not crank properly/start. I probably should start a new thread but I hate wasting board space:

When I turn the ignition key the engine cranks for maybe 1/2 a turn then the courtesy lights go dim and the starter bogs down something fierce. If I disconnect the +12V lead it will crank normally but of course will not start because it has no spark. It seems like it is getting a huge voltage drop/short from the HEI but I have no idea what would cause that.

I have the +12V plugged into my unfused ignition plug on the fuse block. Tach is hooked up, and will start to read something when I try to crank it. Had to "create" a ground strap because it was missing from the cap (and none of the replacement cap, coil, and cover parts came with one). I scraped the paint off the core for the coil at the two screws nearest the plug, landed the coil ground and the plug ground strap. I have not cut out the wire that runs down to the starter; it was past 1AM when I gave up last night (and will not be able to mess with it until Monday now). I am using the original style alternator with the external regulator, but I have never heard that to be an issue with HEI nor would I see how that would effect the ability to start the engine.

Thanks in advance for any tips/suggestions?!?!??

[Jtrux]

Where is the wire from the starter going? In your original setup with points there should of been a wire going to the positive side of the coil to the starter to provide the system with a full 12-14 volts during startup. The ONLY wire going to the HEI distributor should be the one coming from the fuse panel (10 or 12 guage preferably, and it's a good idea to run an inline fuse holder in there too with a 30 amp fuseo or 25). Timing doesn't seem like an issue concerning the bogging down of the starter since it only bogs down with power (it would bog down all the time if it was timing). It think that wire going to your starter is the culprit. Where on the distributor is it hooked?

[69TowRig]

Originally Posted by Jtrux

It think that wire going to your starter is the culprit. Where on the distributor is it hooked?

It is not hooked up to the distributor at all, the original wire going to the distributor is taped off at the moment; the other yellow lead that is factory spliced is still going to the starter. The HEI +12V is hooked directly to the fuse panel and that is all. Hopefully this evening I will have time to mess with it again.

Thanks for the help, anyone have any other suggestions?

[Mike C]

Are you sure you are OK on the timing? Sounds kind of like too much advance.

[69TowRig]

Originally Posted by Mike C

Are you sure you are OK on the timing? Sounds kind of like too much advance.

I fail to see how timing would make the entire electrical system act like it has a huge short and everything practically goes dead. I will probably disconnect all the spark plug wires to see if it will crank over.

I was not able to mess with this last night, maybe tonight instead.

[chiggly626]

Originally Posted by 69TowRig

I fail to see how timing would make the entire electrical system act like it has a huge short and everything practically goes dead.

With too much initial timing your starter can't overcome the pressure inside the cylinder. This will cause the starter to bog down and stop, acting like an electrical short.

[MiniD]

Originally Posted by 69TowRig

I fail to see how timing would make the entire electrical system act like it has a huge short and everything practically goes dead. I will probably disconnect all the spark plug wires to see if it will crank over.

I was not able to mess with this last night, maybe tonight instead.

He's right and that's most likely your problem. I know this from experience.

[Long Roof]

If you are changing from a points dizzy to a HEI then the rotor tab should not have been installed in the same location. If you look at the cap on a points dizzy the #1 plug points to the #2 cylinder on the engine, in a HEI it should point almost directly to the #1 cylinder on the engine. I believe this would give you to much advance.

If all else fails bring the engine up to compression on the #1 cylinder, lining up the timing mark up on the timing tab (both valves should be closed) then set the rotor tab to point to the #1 cylinder which should correspond to the #1 plug wire location.

Just did this myself over the weekend and everything worked fine.

Aaron

[69TowRig]

I'll try all the suggestions, I wish I had more time to mess with it looks like it won't be until Sunday now. Travelling jobs suck when you can't drag your projects along with you.

Thanks guys, I will update.

[Jtrux]

Originally Posted by chiggly626

With too much initial timing your starter can't overcome the pressure inside the cylinder. This will cause the starter to bog down and stop, acting like an electrical short.

Agreed, have had problems with this in the past. Just turn the dizzy clockwise to retard it a little at a time and see what happens.

[69TowRig]

Originally Posted by Long Roof

If you are changing from a points dizzy to a HEI then the rotor tab should not have been installed in the same location. If you look at the cap on a points dizzy the #1 plug points to the #2 cylinder on the engine, in a HEI it should point almost directly to the #1 cylinder on the engine. I believe this would give you to much advance.

Okay, I had been pondering over this for two weeks while I was out of town: I had remembered reading somewhere to put it in the same position. I found it in the FAQ:

http://67-72chevytrucks.com/vboard/s...ad.php?t=17403

I quote: "Remove the old distributor. After lubricating the HEI distributor gear and installing a new gasket, install it so the rotor is pointing in the same position as the old one. "

That's fine and all, but of course mine doesn't work. So following y'alls suggestions (except for the little at a time) I clocked the dizzy about 20-25° and tried to crank it, after a stumble she fired up and ran fine. New problem, my harmonic balancer has apparently spun and I will have to manually find TDC and scribe a new mark on the balancer to do the timing. She is a little advanced (spark knock on moderate to heavy acceleration) but drives like a scolded dog compared to with the old points dizzy. I couldn't be happier, I feel like I swapped engines the change is so drastic and noticeable.

Thanks for everyone's help, I think I have the last bit figured out...

[Long Roof]

Glad to see that you have it running again. I see that its a 307. Thats what I put in my Jimmy and I like the little mouse.

It's not tough to change the balancer. I would think you could even rent the puller/installer tool from a local parts store.

P.S. Here is the diagram for the different dizzies. Maybe the FAQ needs to be changed.

Aaron

[69TowRig]

Well after looking at those diagrams it makes even less sense, since I turned the dizzy clockwise. According to those diagrams I should have had to turn it counterclockwise.

Ah well. Thanks again for the help. If I decide to mess with the Balancer (and I probably won't) I already own a puller for it, they are great for pulling steering wheels and (with the proper pieces of threaded rod) tone rings on certain semi-floating axle shafts...