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GM HEI 5 pin spark retard
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Author:  Slanty [ Wed Nov 06, 2013 1:46 pm ]
Post subject:  GM HEI 5 pin spark retard
Everyone here prefers the GM 4 PIN HEI module swap.Net for a, little more you can get a module that can retard ignition timing 10 degrees.A 5 pin module for an 1980 Oldsmobile 260.It's like a 4 pin module except that it has a small 5th pin that retards timing when grounded.Good for hard hot starts or ping issues on hills. 8)
Author:  Joshie225 [ Wed Nov 06, 2013 3:51 pm ]
Post subject: 
Hey, that could be the thing for guys running nitrous. Thanks for the info.
Author:  Ssg Pohlman [ Wed Nov 06, 2013 5:42 pm ]
Post subject: 
Or even turbo, once you go into boost have a Hobbs switch set up to ground it.
Author:  Slanty [ Wed Nov 06, 2013 7:31 pm ]
Post subject: 
Just use a pressue activated switch to ground it,or a toggle.
Author:  olafla [ Thu Nov 07, 2013 9:48 pm ]
Post subject:  Additional marine 8-pin modules with built-in advance curve
The 5-pin module came in 3 versions, they differ in type of input signal to retard the ignition. All the 5-pin modules are used with distributors having conventional centrifugal and vacuum advance mechanisms.
1. HEI/EMR Electonic Module Retard, this is the one described here, it originally used various input signals to an electronic controller, that provided a ground signal to activate the retard mechanism.
2. HEI/ESC Electronic Spark Control, uses knock sensor and an electronic controller to provide a voltage signal to the module to activate the retard mechanism.
3. HEI/ESS Electronic Spark Selection, uses signals from pressure or vacuum, temperature and distributor into an electronic controller to provide a voltage signal to the module to activate the retard mechanism.

8-pin module with built in advance curve
Not well known on the automotive scene, Delco also sold a marine HEI distributor kit to upgrade older boat engines to electronic ignition. The Delco Voyager Marine Distributor Ignition System was made for 4 cyl, V6 and V8 engines, and reportedly used the same module in all adaptations. These marine kits use a different 8-pin module, that provides a built-in advance timing curve, and works without using an ECM. The marine kit was delivered with a distributor without any mechanical or vacuum advance. The module could be an interesting alternative used with a Lean Burn distributor on a race engine. But there is of course no problem to use them with any distributor...

An 8-pin module for a car will not work, they have an externally adjusted advance curve, HEI/EST - Electronic Spark Timing provided by an engine management unit.

I have seen claims for 20-22° advance built into the marine Delco module, but in the curve I found, it starts on 11° and give 22° total advance. It may be incorrect, and it must be investigated further, because the engines the kit was intended for, all like around 30° total advance. I would guess that the curve shown is for a SBC V8.

RPMS/Advance
700/11
750/12.5
800/13
1000/15
1250/16
1500/16.5
1750/17.5
2000/18.5
2250/19.5
2500/20.5
2750/21.5
2800/22

There is also the Mercruiser Thunderbolt Ignition system, that has the same functionality. There are several ignition mudules available. See this site for info:
http://wolfiesenterprises.com/Ignition% ... 0Parts.htm

Here are advance curves for the ignition modules used in Thunderbolt TBIV and TBV systems (for carburetted engines):

http://www.mtboats.com/mercuryignitiona ... dules.html

Olaf
Author:  wjajr [ Fri Nov 08, 2013 6:33 am ]
Post subject: 
Quote:
These marine kits use a different 8-pin module, that provides a built-in advance timing curve, and works without using an ECM. The marine kit was delivered with a distributor without any mechanical or vacuum advance. The module could be an interesting alternative used with a Lean Burn distributor on a race engine

I have to agree in theory.

The thing about marine engines is they operate more like a stationary engine with long duration steady throttle openings, and constant load, unlike a passenger car engine encountering gear changes, constantly changing load (hills, stop and go, and velocity), and constant throttle opening changes requiring an ever changing timing change during operation. A dedicated drag race engine has more in common with a marine engine where it operates mostly with one set of parameters, WOT for ¼ mile.
Author:  olafla [ Fri Nov 08, 2013 6:23 pm ]
Post subject: 
I also thought that those who wish to have some advance in the ignition timing on a race engine, would see it as a bonus to be able to reduce the possible sources for failure, by eliminating some moving parts.
(and for at least one of you racers, some weight! ) :lol:

Olaf
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