HEI Ignition Tips for Your Engine

Nothing proves engine theories or new parts like a little dyno time. Horsepower Monster decided to take a closer look at ignitions in general and the ever popular HEI ignition in particular. We also tested a stock unit against a high-performance unit from Performance Distributors, and the dyno proved that all HEI ignitions are not created equal.

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[hmayerv]

All well and fine for high performance engines. Seriously the stock points system and thereafter the stock GM HEI is the perfect distributor for stock engines. They've run these on millions of American made cars from 70s onwards. Time tested perfection.

[Dannysoutherner]

For the average street motor an off the shelf HEI is perfect. They are dirt reliable unlike the Ford Durafail system. If you have the misfortune of losing an ignition module they can be gotten pretty much anywhere. Walmart used to carry them. I have made the mistake of using esoteric fancy gear and having it die on me leaving me on the end of a hook. Edelbrock carb and HEI is a bulletproof combination for daily use.

[ViewThis.]

On my supercharged engine I first used a regular distributor and separate coil. I later changed to HEI 50, 000 volt and it made a huge difference, especially in the strength of the idle while in gear with my foot on the brake.

[michaelstarr]

Since I started driving with a vacuum guage on my dash, it's gone from from 10mpg to 14mpg! Simply installed a brass T adapter and ran a hose though the firewall. Then just keep vacuum in the optimum zone while accelerating.

[jayhagsrc]

I'm pretty sure the vacuum advance advances timing because at part throttle the air and fuel in the cylinders isn't as dense as wide open throttle, therefore it takes longer for the mixture to burn. Vacuum advance isn't going to make a difference doing wide open dyno pulls. Vacuum advance is done for driveability. If you have too much vacuum advance the motor will "ping".

[braddenning]

I built a GMC 292 inline 6, no expense spared in the build, about 11.5 comp. forged 60 pistons, floating pins Major headwork, Lump ported, 175 rollers, ALL BEARINGS COATED, THE LIST GOES ON ! I bought the DUI distributor, basically it sucks. First thing is some of the module screws were loose, and for the inline 6 they give you a 2" adaptor that goes on the end of the main shaft to reach the oil pump, rather then having a dedicated shaft for this application, Now you have to carefully file the adapter on the one end so it fits TIGHT with no play and is then held in place with a tiny roll pin, you have to "V" out the recess but on an angle this is precision work and no room for any tolerance. . the slightest bit of play will cause the adapter to vibrate and damage the distributor gear, Beside other shit first Dyno pull was 366HP, We swapped out the DUI coil with an Accel coil and picked up 10 HP !! 3 times we did this. Ended up building my own distributor with parts I had, Never will I recommend DUI !!! and made another 9 HP !!! side by side it is exactly the same as an E-BAY special !!! That two piece distributor shaft not only stupid but was incorrectly machined, ebay HEI with a accel coil and MSD module beat the DUI IN HP, Quality and cost .

[doncroswe]

The experts in my area, told me to not use the vacuum advance at all, instead set the timing that they suggested, in my case it was 38° before top dead center ☆ my motor is a 440 mopar thats some what modified * headers, cam & such ☆ its mostly street driven and go's to the drag strip once a year ☆ When i go to cruise ins, people want to know why my vacuum advance is blocked off with a pastic plug ☆ i tell them, thats where where it runs the best 😊, they usually walk away is disbelief ☆ however, these folks do not run their car's at the strip ☆ in ending, , i will say this, im completely satisfied with the with the performance of my car, street or strip 😊 thanks for listening ♡

[joealbert]

I don't understand why the timing had to be reset when you connected the vacuum advance. Vacuum advance only adds timing under low load conditions (high vacuum). It has no effect on high load applications such as a dyno pull. The maximum timing under these conditions is controlled by the mechanical advance. The real purpose for vacuum advance is part throttle fuel economy. That's the way most vehicles are driven.

[frankzito]

I ran 6.80s in the 1/8 with a fairly strong solid roller 11 to 1 327 in a vega with at th400 and a 4.56 12 bolt.
Stock gm hei. Shifted at 7000 rpm. Absolutely bone stock distributor. Switched to a DUI and didn’t pick up any et or mph.
Ran 38 degrees total on both.

[bobstephens]

I use vacuum advance on full manifold vacuum to help my engine idle better with a big cam, also keeps plugs cleaner.

[pauljanssen]

You bring your engine up to 10 degrees before top dead center on the firing stroke either by watching the valve train or compression you'll see the trigger wheel on HEI is pointed citizens points lineup and you go a hair father that's when the spark will happen you can literally shut your engine within 1 to 2 degrees by this method you won't even have to re-time your engine I've built many engines with this method knowing where the distributors fire I really have to move them after checking with a timing light basically I learned it from timing VW engines and mg midgets always Prime the engines with a dummy distributor before you 🔥 them up and it's not hard to build a oil priming tank out of an empty R134 tank just have to weld A fitting on the bottom and put some oil in it and a cap with the Tire valve to pressurize the tank

[SteveXNYC]

Since resistor type plugs actually “resist” some of the spark energy, non-resistor type plugs actually deliver a more powerful spark. It is for this reason that most racing plugs are non-resistor types. However, in most automotive applications, a resistor plug is required for proper vehicle operation.

[MiguelSanchez-stpv]

Just got a dui dizzy for my ski boat excited now 😁

[susanhenderson]

Seems like lots of folks commenting on here dont understand base timing, totatiming advance and vacuum added timing

[jayleno]

i like their stuff DUI rev limiter live wires and mini VIP on, y 355 7000 plus no issues and the vip was what made power over anything else i used

[timokuusela]

GM has different coils for the HEI. The standard one uses normal plug gap. The stronger one uses different plugs that have over 2 mm, about 0, 08 gap. I used to have a Buick -84 with 307, and it had that coil and plugs from the factory. When the coil failed, I went with it to the local speed shop here in Finland, and the guy looked at the coil wires and said "oh, it is THAT coil" They are of different color or something. I have a Ford Taunus (Taunus not Taurus, google Ford Taunus -82) that used to have a Pinto type 1.6 L four in it. I put a 302 to it, but bought a Hei with the Ford style base, Ditched the Ford strange ignition system. One + wire and good to go.

[ABsnova]

8 years and I literally have NEVER seen another sbc with the same heads/intake as me until now

[sidecarbod]

I don't think you guys fully understand what the vac advance system is for or if you do it was not clear in your video. You have established that the engine wants 36 degrees at WOT and that is what it is always going to want. The vac system should be setup to add more timing above this figure of 36 degrees to allow extra advance when the throttle is just cracked open (regardless of the RPM), the extra advance allows for the fact that the flame speed is low when the VE of the engine is low. Your total timing may go up to something like 50 degrees but only under very light throttle settings.

You guys seemed set up the vac system then pull a WOT run on the dyno, of course it is not going to make any difference with that sort of test.

[whirlwind]

manifold vacuum to the distributor only ... wot timing should be set and then lock the distributor, small springs on the weights ... you want to launch advanced .. then taper off to mechanical timing all in at wot... and always use mechanical secondaries for better response

[rockinbass]

you guys should make a video explaining how to tune the vacuum advance like how much to safely ad and how to tune when it drops out