[Elarson]

I started the day a fan of the HEI.
Ended the day never planning on using one again.

Eric

[Skip Fix]

Eric I have had real good luck with the DUI HEIs.

[mgarblik]

Originally Posted by Skip Fix

Eric I have had real good luck with the DUI HEIs.

Funny you should mention DUI ignition. The Supercharged Studebaker I posted about in another thread was on the dyno just before Eric's Pontiac. The Studebaker was a special GM DUI HEI grafted on to a Studebaker base. It worked fine until they turned up the boost on that engine. When they increased the boost above 8 PSI, they began to have some misfire and ignition issues. We decreased the plug gap to about .022" and it ran better but not as well as a point ignition Studebaker distributor they had as a back up triggering an MSD 6 with Blaster coil. Just don't think HEI has enough spark energy for boosted or high RPM operation. I could certainly be wrong, but the last two engines on the dyno have had HEI issues. Don't know the history of the Studebaker DUI, how old or how many miles on it.

[Half-Inch Stud]

I think HEI performance is inherently excellent IF the HEI is setup properly:

RELUCTOR:
Proper pickup coil winding (CW vs CCW) by wire color. No flipping coil over.
Proper magnet sense (N vs S) for proper voltage spike sense. No random magnet flip.
Inspection of RELUCTOR signal sense for proper triggering: going - then + vs going + vs -.

If you are already squeemish then go random with such (for giggles?) or sell your HEI.

4-Lead Module
Regardless of GM vs GM 990 vs aftermarket, or yellow vs White
You check for variable dwell function with your Dwell meter.
I've measured a batch of Modules and found 1 without dwell (chucked it), another with dwell vary too low, and interestingly 1 with more dwell variation than the GM Modules.

I have "remoted" the module with a heatsink onto Firewall for hot Summer posterity. No real benefit except i geek out about Silicon electron mobility and beta vs temperature. Boy a GaN HEI module would be SOA.

Button
Only use the low resistance button: about 3-10 Ohms. High resistance buttons. Are 3000-10,000 OHMs and will heat up super hot in our kind of use.

Plug Gap
0.035" to 0.40" ought to do. There may be better statements on this due to GND Lug design, side-gapping, aircraft 4-GND posts. I don't figure ANYBODY is using a recessed plug tip (scared turtle spark) like some lawn movers might use.

CAP
Brass posts for proper spark jump-Land. Rotor are always the proper metal for consistent spark jump.
AL posts corrode after each spark to allow the spark to land on various spots across the posts, for many degrees in variation per spark. AL post are/were stooopid bad for wver being let for Production.

Wires
I donta care what wire philosophy you got, just check the total resistance of each wire to be > 18,000 Ohms for the longk wires, and > 9,000 Ohms for the short ones. A fella might run "equal-length copper or nickel wire" wires for theoretically best spark delivery. Shielded aircraft wited & plugs would be best, but nobody achieves such best because unshielded is best-enough.

Dizzy GND; add a robust GND wire from Dizzy cup to Head. You'll get rid of troubles with the GND wire, and may save a dizzy gear from EDM.

Dizzy Power;
Yada yada use the copper wire 18-16 14? gauge wire to power source, I replace the fuse block wire with GM copper wire from some other used harness run. Supply wire matters for reliability, so dress the wire run to endure flexure and vibration.

Rotor Phasing
Make a spare cap with hole at post #6 so you can visually verify the spark jump tracks across the #6 post with advance sweep. If you don't then keep complaining about craap results. ADJ by slotting VAC Can mount to allow adv-ret walk of rotor-post phasing.

Mech ADV
I donta know about other's results, but my results involve the basic 139 weights and intentional Center post, mounted for Pontiac rotation. Must lay Post and weights down for PMD CCW rotation. I use heavy springs to mitigate ping on hi-compr, and continue than with my 9.0:1 deal. No idea if spark jumping around under hard accel. Many HEI images show Chevy weights setup for CW rotation...which be wrongk for PMD, and run poorly in CCW PMD. This is the Race section right, so you got this.

Vac ADV; i think the ADV range (or VAC level for max?) is stamped on the bracket. Usually too much ADV for high compression PMD combos. I zig-zag the Rod to reduce ADV range and attain rotor-post phase, as-needed. Have a selection of Cans. If in doubt run Ported Vac, and try Manifold Vac if the combo permits (think Chevy ran manifold vac). When I run Vac Adv, I run with Ported Vac.
Set TIMING
Race Section, You got this.

I wrote a Tech Paper (unpublished) for myself on the HEI build. Didn't refer to it herein, but avail upon request. So did some other PY guy (shurkey?) with a decent total capture.

[Half-Inch Stud]

Does the MSD-6 have variable dwell, for best coil charging vs RPM ?

I have held the MSD-6, et al, yet i find it difficult to inspect the build or repair. Who does?

[25stevem]

Many times it’s the basics that need to be insured.

Any HEI or DUI needs a voltage never less then 13.7 and as the rpms and or the charge in the cylinders gets denser the wire powering it better be of a gauge thick enough to provide 10 amps just to be on the safe side .
Wire resistance going up due to engine compartment heat or too small of a gauge will bite you in the hind quarters every time!

[mgarblik]

Posts #44 and #46 make excellent points about HEI and how to make them work properly. After bashing them in a couple of posts, I can point out 2 things I actually like about them. 1. When working correctly, the all in one design is kind of nice. 2. The huge cap in theory reduces the possibility of cross fire vs a small diameter cap. On the engine in question, the distributor was not carefully addressed like HIS spelled out. I did replace the pick-up coil with a new Echlin unit. It came assembled with the coil, housing and magnet. Green and white wires for CCW rotation. All I did was set the air gap. The springs and weights were cleaned and re-installed. I have no idea if any of those parts were correct or made for CCW rotation. The HEI distributor came out of a running Pontiac drag race car that ELarson bought. I assumed it functioned correctly. (Always Dangerous). No module used so can't comment about that. If nothing else, it proves once again you CAN NOT assume anything is going to be correct on a 60 year old engine. Everything must be tested and verified. Thank goodness for an engine dyno to track down and fix this. On a road course, this problem could have taken a really long time to find and fix. It was rather subtle and peak HP wasn't really effected. We were sure it was a fuel delivery issue initially but once again, data from the dyno proved that to not be the case. (air flow and fuel flow). Finally I should mention that battery voltage to an HEI or MSD for that matter is critical as mentioned. We typically have a charger on the dyno battery maintaining 13.2-13.4 VDC when pulling. We seldom run the engine charging system on the engine dyno.

[Formulas]

Not of great importance to original post but when i retro'ed in a HEI into my 1970 bird along with replacing the original coil resistor wire that i upgraded to a (12G) wire and also utilized the ignition post (12G) on the starter solenoid and T'ed into my new (12G) HEI power wire so during cranking there is a more direct under hood ignition power source from the HEI to positive Batt terminal

Plus i grounded the dist body and used a low resistance button reduced spark plug gaps, did all that in around 2004 not a peep of trouble and quick starts

[Tom Vaught]

As mentioned earlier in the threads, I never had good luck with the HEI parts and
I have had outstanding luck with a MSD/FORD SVO Box (POTTED NASCAR PART) for many many years under boost conditions.

Happy some have been able to get the things to work. My 1978 TA went thru several of
the pieces (UNDER WARRANTY) in the time I owned it.

Tom V.

[Half-Inch Stud]

Toughest HEi looksy for me is assuring the Magnet sense is correct for PMD. See, either you need a good compass, or a known-PMD HEI magnet p-Reluctor assy and go by the impressions on the magnet.

BTW the china compasses will re-magnetize after checking them a few times and start showing South for North. Toss em!

So, it greatly helps to have a PMD specific reference reluctor laying around to sort out the build parts. Otherwise, a geek-out effort with a scope or voltmeter to identify/assure the pos or neg going pulse, and the Ref needed for the Module's specifiec pulse sense. The pulse goes neg then Pos, or goes Pos then Neg, so a visual scope is best.

[Dragncar]

Once you are using a MSD 6AL, 7-AL triggering them with points works great. Simple, not much can fail as long as you have a good set of points and they last a very long time.
You can get the big caps for them if you like.

[Skip Fix]

The DUIs I have used have all been shifted 6500-7000 max(7000 on my RAIV 400 when it had a big UD solid in it), so maybe not high rpm and NA. My pump gas 455 in the 78 We dynoed against a MSD with a &AL box on the dyno and no difference but granted if no missfires there would not be.

I do know I learned about them form one of my old NMCA buddies form Amarillo. He said the dyno shop up there kept one for SBC around and often it worked better in some of the SBC dirt track motors than whatever the owner was using.

[Elarson]

If we would have been able to spend more days on the dyno, we could have dug into diagnosing the HEI problem, and possibly learned some interesting things. Locking out the centrifugal advance, trying different pickup coils, etc.

We ran out of time and had to take the win with the MSD distributor.

Eric

[Tom Vaught]

Originally Posted by Skip Fix

I do know I learned about them from one of my old NMCA buddies form Amarillo. He said the dyno shop up there kept one for SBC around and often it worked better in some of the SBC dirt track motors than whatever the owner was using.

I should not really blame the HEI design when the issue was a bunch of bad HEI Modules from the factory.
I had Proper Grease on the contact area for the HEIs each time that failed.

My "POTTED" SVO FORD MSD box has never failed me and is spot on for the RPM (once I surveyed a few MSD Chips and found ones that were same as the rpm range quoted).

Tom V.

Really do not care that it says "Ford Motorsports" on the outside of the part.

[Half-Inch Stud]

Back to the Road Race Engine !

[Scott Stoneburg]

Is that a 4 or 5 speed trans? I'm not a manual trans guy so I can't tell by looking at the pic.

[Elarson]

Super T-10 4-speed. Rugged transmission, true to Firebird roots and I had no need for an overdrive 5-speed.

Eric

[sdbob]

Rear suspension you are using? Stock modified?

[aaronman]

Congratulations on a well designed and executed build. Thanks for taking the time to share it so we can all learn.

[Elarson]

Originally Posted by sdbob

Rear suspension you are using? Stock modified?

Leaf spring with 2" drop springs from Detroit Speed, aluminum/Delrin spring bushings from Global West, 9" Ford axle assy, Herb Adams VSE 1" sway bar, QA1 shocks, Wilwood 13" 4-piston disk brakes.

Eric