In the mid-’70s, leaner mixtures demanded greater voltage and more spark energy to kick off combustion. The HEI distributor is still an inductive-discharge ignition, but exchanges points for an electronic device called a module. Since this system produces more voltage and amperage output than a point-type ignition, it requires a larger-diameter cap to prevent voltage crossfire inside the distributor cap. The large cap also offers extra space to host the coil, making the HEI distributor self-contained. All you have to do is to apply a volt hot lead to the distributor and you’re ready for the road. Early HEIs were infamous for giving up at speeds above 5, rpm-so many avoided them. This was true of the early-model distributors, but it didn’t take GM long to modify the modules and coils to offer greatly increased spark energy at higher engine speeds. These days there’s a plethora of aftermarket high-performance modules, coils, and complete ready-to-run HEI distributors that can be added to a high-performance engine that’ll provide excellent spark energy and rpm potential well in excess of 7, rpm.


It features a high quality, fully adjustable mechanical advance and an accurate magnetic pickup trigger. The CNC-machined aluminum body and hardened steel shaft, guided by a sealed ball bearing on top and a sintered steel bushing on the bottom, ensure stability up to 10, RPM. The dielectric cap features bolt-down and twist-lock capabilities. It has solid brass terminals and comes with a color-matched wire retainer.

fully adjustable mechanical and vacuum advances, meaning precision is a breeze. It has a high-output module, high-spark 65,volt coil, solid brass terminals, and an easy one-wire hookup.

I’m also pretty sure that a V8 with two cylinders blocked won’t be correct, either. You can easily recognize an odd fire distributer just by looking at the cap carefully, the cam if it’s “points” and undoubtedly the reluctor if it’s electronic. There is a wider space between every other two cylinders, due to the design of the crankshaft.

You can see this easily on a scope, every other two cylinders firing closer together, with a big space in between. There was a bunch or at least 3 of different caps and distributers–“they are NOT all the same. They were a torq’y little thing in the Jeeps though I don’t remember, but I’d be surprised if the GMC wasn’t “even fire. So far as the 4, you could use a V8, but ground the unused towers. I saw a few V6 compressors, where someone had replaced the head on one bank with a compressor head, and just cut off and grounded the 3 unused wires.

Also, the centrifugal advance may not “fit” the requirements of your tractor.

HEI Distributors – Fact Or Fiction

No one but wiring geeks will be interested in this post Use a little ‘Gorilla Snot’ weather strip adhesive on the cap adaptor to distributor joint. This isn’t a wear part, so you shouldn’t have to remove it but every K to K miles for a distributor rebuild or replacement. Use a bead of dielectric grease in the groove on the edge of the large Ford style distributor cap. When the cap meets the cap adaptor the grease will seal the joint from external moisture. This will make you a nipple for an air line to hook up to.

Jul 25,  · The advance weight kit and the vacuum advance will have instructions on how to install them. Follow those instructions carefully, and it all (hopefully) makes sense once you look at .

Dynatek developed its Classic Fuel Injection CFI system from the desire to combine the classic good looks of downdraft Weber IDA carburetors with the precision tuning and performance offered by electronic fuel injection. What kits are available? Dodge applications include the new 5. What extras or options are available? Options include ported intake manifolds worth up to 40 hp , a stainless braided fuel system including an adjustable fuel pressure regulator , and a complete conversion kit for retrofitting CFI in a vehicle originally equipped with carburetion.

Additional options include polishing, chrome plating, and powdercoating of the intake manifold and throttle bodies. How do I tune it?


Remove the distributor cap, right valve cover and the 4 cyl rocker arms and pedestal. Set up a dial gauge on the 4 intake push rod. Rotate the engine to TDC 1 cylinder. If the dial reads thousands, your valve timing is right. If the dial reads thousands, your valve timing is retarded or your chain is streched. If the dial reads thousands, your valve timing is to far advanced.

Lock out the mechanical and vacuum advance. Connect the distributor directly to a 7 or 8 pin HEI module that you mount in a weather tight box (like the inside of a gutted out motorcraft box). Connect that module to the computer and to your coil.

Nearly 22 years ago now. Today, it has 95, miles. A large percentage of that 58, mile difference has been off-road in the Pacific Northwest. The rest has been getting to and from the trail-head to leave the pavement. I traced this rig’s history and spoke to it’s original owner not long after buying it. He had purchased it as a dealer “demo” with 4, miles on the odometer.

He used and abused it hauling a 55gallon drum, hunting dog cages, and pulling a 12′ trailer before the Repo-man mercifully rescued her from him, returning her to a Mike Salta dealership in Portland.

TSP JM6511R AMC/Jeep 232-258 L6 HEI Distributor with Red Cap

Share this Tom Morr Our swap guide in the Sept. Here we have assembled a cross-section of professionally built engines to make swaps even easier for the weekend-warrior wrenchmaster ‘wheeler. Although more expensive than a home-freshened or junkyard-pulled engine, the ones shown here are assembled with builder-proven parts combinations; many also come with warranties. Alternately, many pro builders will assemble an engine to suit your specific needs, ensuring features like good off-idle vacuum for maximum braking power.

Most engines in this guide are assembled with all-new, brand-name components.

TSP’s HEI Distributor has everything you need, all under one cap. With a high-quality aluminum housing and hardened steel dual bushing construction, it is built to last. It features fully adjustable mechanical and vacuum advances, meaning precision is a breeze. It has a high-output module, high-spark 65, volt coil, solid brass terminals, and an easy one-wire hookup.

Reply I may the only person in the world that followed Holley’s suggestion to remove extra wires from 2 harnesses provided but now I find that I cannot go back. By that I mean originally I wired for a standard points system and since moved to a mag distributor and want the sniper to control timing. There is no information about color and placement that I can find. I have been on infinite hold trying to get the information and gave up. So I decided to post on the forum thinking that they would chime in but instead I got the usual ‘call tech support’.

Could you post a pic of both plugs showing color and location on the plugs. I would think it would useful information. Now, you already have a connector, but on that page are a picture of the connector as well as a list of the various signals and the pin letter into which they go. If you look very closely at the connector there should be a letter on each pin.

Between that and the picture you should have everything you need to be successful. Ken says he reloaded the setup a couple of times and the problem went away and everything runs great now. If you’ve had any experience with this please do add your comments!


It’s a little long, but has alot of good info on ignition timing and what is best for your application. I have made every attempt to present factual, technically accurate data wherever possible. If you find factual errors in this information, please let me know so I can correct it. Background The vacuum advance control unit on the distributor is intended to advance the ignition timing above and beyond the limits of the mechanical advance mechanical advance consists of the initial timing plus the centrifugal advance that the distributor adds as rpm comes up under light to medium throttle settings.

When the load on the engine is light or moderate, the timing can be advanced to improve fuel economy and throttle response. A control unit that responds to engine vacuum performs this job remarkably well.

Aug 13,  · The standard vacuum advance does’nt work with your is pretty common. Don’t know much about Holleys,but eddy carbs have a timed port vacuum,which is above the port has no vacuum in idle.

The rebuild never seems to last and some of the areas like leaking around linkage and dry gaskets are often not fixable. They are too complicated, too hard to adjust, and in a difficult place to work on. I have a new engine, is the old carb still correct for the heavy breather? With a closed loop control, this should be adjusted automatically.

I think basically, I hate carburetors. These are the parts to be added. Need to get under the wheel wells and do some work so it is suggested to raise the front of the coach. I feel safer with it up on blocks and this was enough height. This picture shows that it is necessary to put a block or stand under the rear of the GMC when ever you are under the rear. There is nothing lower than a GMC if an air line or bag breaks. Time to get rid of some of this clutter. Ready to remove carb, christmas tree, and gas pump.

It is interesting what you find when you go looking.

Sourcing Chevy Big-Block Parts: Distributors and Ignition Systems

July 9, Marty, I will chime in on this if you don’t mind. Proted vacuum comes from the carburetor and is based on the vacuum created by the air flow through the venturi. More air flow equals more vacuum. So my understanding is that the vacuum created by the increased airflow throug the carb anticipates and begins to advance the spark before the weights in the centrifigal portion can react to the increase in RPM.

You must have more fuel air befoe Rmps can increase.

May 31,  · Factory small cap electronic ignition systems also need a computer and a bunch of sensors to replace the centrifugal and vacuum advance functions. One of the conversion systems on the original point-type distributors using over the counter parts would be best instead of buying a proprietary system like Pertronix.

This is due to the simple one piece design, easy installation and performance enhancements over a stock ignition system. The all-in-one DUI replaces the weak three component system that came standard on the AMC engines and utilizes only one 12 volt hot wire for hookup. The DUI is equipped with an internal 50, volt coil, which will fire a spark plug gap as large as. Their high dwell Dyna-Module, located inside the distributor, increases spark duration for improvements in throttle response and low end power.

The DUI centrifugal advance system utilizes a high performance weight and spring assembly engineered for super smooth operation. The mechanical advance is then tuned using a Sun distributor machine to ensure a precise timing curve that will provide maximum power throughout the RPM range while eliminating engine damaging detonation. An adjustment free vacuum advance canister is selected to work with the centrifugal advance for better drivability and increased fuel mileage.

Ballast resistors are not required for the DUI as this system works best with full alternator voltage. These parts can be found at any local auto parts store. Please note that DUI Distributors may not be ready for immediate shipping. The attention to quality and detail requires us to build each unit per order, and due to this process orders can take several days to complete before shipping out. During our busy season March-September , build times can take slightly longer.

Electronic Fuel-Injection Systems – EFI For Any Car

Barnegat, New Jersey, Ships to: High quality brass terminals and a protective plastic dust cover that encapsulates the 65, volt coil. A new cast-aluminum housing featuring a machine polished finish contains new bushings, mainshaft assembly, and a hardened steel gear. Our HEI includes high-output module, centrifugal advance components, and adjustable vacuum advance canister.

A very good vacuum advance. I liked the fact that its adjustable. It lists a bunch of distributor part numbers and you adjust it based on your application or to your liking if you like to tweak things on the peformance side.

Distributor Vacuum Advance Control units Specs and facts for GM Distributors Background The vacuum advance control unit on the distributor is intended to advance the ignition timing above and beyond the limits of the mechanical advance mechanical advance consists of the initial timing plus the centrifugal advance that the distributor adds as rpm comes up under light to medium throttle settings. When the load on the engine is light or moderate, the timing can be advanced to improve fuel economy and throttle response.

A control unit that responds to engine vacuum performs this job remarkably well. Also, a GM V8 engine, under light load and steady-state cruise, will accept a maximum timing advance of about 52 degrees. Some will take up to 54 degrees advance under these conditions. Anything less than 52 degrees produces less than optimum fuel economy at cruise speed. The following considerations must be made when selecting a vacuum advance spec: How much engine vacuum is produced at cruise?

If max vacuum at cruise, on a car with a radical cam, is only 15 inches Hg, a vacuum advance control unit that needs 18 inches to peg out would be a poor selection. If the distributor has very stiff centrifugal advance springs in it that allow maximum timing to only come in near red-line rpm, the vacuum advance control unit can be allowed to pull in more advance without the risk of exceeding the degree maximum limit.

If the engine has an advance curve that allows a full degree mechanical advance at cruise rpm, the vacuum advance unit can only be allowed to pull in 16 more degrees of advance. Does your engine require additional timing advance at idle in order to idle properly? Radical cams will often require over 16 degrees of timing advance at idle in order to produce acceptable idle characteristics.

If all of this initial advance is created by advancing the mechanical timing, the total mechanical advance may exceed the degree limit by a significant margin.

Top VIdeos

Remove the coil, and coil bracket from the engine. Remove the vacuum hose attached to the vacuum advance canister. Read all instructions before starting installation. Flame-Thrower HEI distributors come with machined steel distributor gears which should not be used in applications with billet camshafts. Consult camshaft manufacturer for distributor gear compatibility. Before the original distributor is removed, several settings should be noted:

May 21,  · This is from the summit re-branded HEI directions: “The distributors mechanical advance is 6 @ RPM, 8 to 10 @ RPM and reaches a maximum of 10 to [email protected] RPM The vacuum advance provides 10 of advance.”.

Would you like to merge this question into it? MERGE already exists as an alternate of this question. Would you like to make it the primary and merge this question into it? MERGE exists and is an alternate of. The information here applies to various Buick V8 and V6 engines, so make sure you understand the details as they apply to your engine.

Your mileage may vary and your car may be different than mine was. The usual “Do this at your own risk” disclaimers apply. This is a pretty long and detailed page, so give it a good read before you start this process. Use common sense and if you mess things up, it’s not my fault.

HEI Distributor Installation for V-8s