Jump to content
6bg6ga

Make your own ignition module Onan?

Recommended Posts

Well, curiosity has gotten the best of me so I'm setting out to make my own Onan electronic ignition. Armed with the proper timing cover, sensor ring, and crank key will allows one to mount a stock ignition module. I will attempt to put together a working electronic ignition system simply because I hate anything that is a closely guarded secret and I hate scalpers that charge mega bucks for a part not worth $20.00  I will make a ignition module and an interface unit to provide signal to the coil.

 

My donor engine is my B43E that just received one new piston and rod assembly. This is a points type ignition engine.

Anybody have the patent number for the Onan ignition module?

  • Like 4

Share this post


Link to post
Share on other sites

Selection of the Hall Effect Sensor to be mounted to the timing cover. Picture of bare sensor with three wires. Black wire is ground, Red wire is 12VDC and purple wire is signal output.

 

Note the picture showing the sensor along with the timing cover. Many are asking what the insulator does and its real simple as its a heat insulator not an electrical insulator. The Hall effect sensor will have to be raised up approximately 1/2 inch in height. This means a simple spacer is going to have to be made with will accomplish two things. First to raise the height and second to provide a means to attach the sensor to the spacer and the engine.

 

Now, the sensor I selected will need to be within 3/4" of the magnetic ring that triggers  the hall effect sensor.

hall effect.JPG

cover with sensor.JPG

  • Like 2

Share this post


Link to post
Share on other sites

Now, I could make the rest of the ignition from discrete pieces but I chose to put together something I felt others might like to copy and try that would be both simple and easy.  The picture below is a simple "early type" HEI Solid State Ignition Module. The cost on ebay is roughly about $10.

 

The hook up will be simple  Looking at the module as pictured the top left terminal is the "W" terminal and it will be grounded. Below the "w" terminal is the "G" terminal which will receive the signal from the Hall Effect Sensor.

 

ON the right side of the module the top right terminal is the "C" terminal which will go to coil negative.  Below the "C" terminal is the "B" terminal and it will share the + coil terminal along with the Battery +

 

Now, there are two holes in the module in which to attach it to the distributor. Since it will no longer be attached to a distributor you will need to attach it to a piece of 6061T6 aluminum.  You will need to make some sort of bracket  that will mount to the engine. You will need to use heat sink grease on the bottom of the module and bolt the module to the heat sink. You will want to attach a ground wire from one of these mounting spots to the engine/chassis ground.

 

Wiring is simple.... attach the red from the sensor to the coil +.   Attach the Black from the sensor to ground.  Last attach the signal to the "G" terminal of the module.

 

In testing by hand it works fine and I have no reason to believe it won't work in a real time basis. I would however hold off until I get my B43E running with the ignition nd let you know.

 

Oh, Cost wise its about $25 for the sensor and the module.  Those wanting to change from points and want to utilize this system will need to put out for the timing cover, the magnet sensor wheel, a new crank key and the timing cover gasket.  The DIY ignition to me looks promising simply because I AM CHEAP and don't like to support the scalpers that with to charge mega bucks for the original module that on a good day is worth $25-30  

HEI.jpg

  • Like 2

Share this post


Link to post
Share on other sites

I'm following along...

  • Like 2

Share this post


Link to post
Share on other sites

Wouldn't the Ford TFI module also work? Would think that it should. Where did you get your sensor from? Application? My 520H has apparently lost spark. If it's the module, I'd like to try this.

Share this post


Link to post
Share on other sites

There are a number of different sensors that one can use depending on what your going to use for the other electronics. Its not going to be a 100% swap out. I haven't gone any further with mine simply because I have had some major projects at work and no time to devote to the ignition project.  Basically you will need a sensor that you can turn on and off with the magnetic ring. I chose the GM ignition module for simplicity. The Ford I assume could be used also but I haven't researched it so I couldn't tell you at this point in time how to wire. I can tell you that a spacer is going to have to be milled so it can attach to the timing cover where the original sensor sat. The aftermarket sensor will then mount to that pad and the mounting distance must be determined. I can also tell you that there is going to have to be the capability to move the sensor to obtain the correct ignition timing. Its not going to be a simple swap and walk away project. I would suggest that if you don't have the time available for this project the simplist thing would be to purchase the Onan module.

 

Digi-key and Mouser are a good source for Hall effect sensors. I'm not going to spell out any particular sensor simply because I haven't finished the project. Also, taking this shot in the dark I don't know at this point in time if there isn't a better hall effect sensor out there that might be better suited than the one that I chose.

 

With respect to your no spark condition....

I would suggest that you conduct the ignition module test to see if the module is indeed bad or the problem is the coil. The basis procedure is available I would assume by downloading the 520H files in the download information section in the forum. It will spell out the exact procedure to check the module and to check the coil. I never throw parts at anything. I like to know exactly why something isn't working first and then repair as needed.

  • Like 2

Share this post


Link to post
Share on other sites
Posted (edited)
5 hours ago, Indianajohn said:

Wouldn't the Ford TFI module also work? Would think that it should. Where did you get your sensor from? Application? My 520H has apparently lost spark. If it's the module, I'd like to try this.

 

I will post the PN

 

Mouser Electronics # 934-551103M02A  and the cost is about $9.50 plus shipping.  In looking up the Ford TFI module...it is for points operation not a hall effect sensor. Look for a different Ford module to use or go with the GM module that I pictured that will work with a hall effect switch. The Ford module would work well in an Onan points setup or ANY other points setups to prolong the point life and to provide a better hotter ignition.

 

I could write a page about why not to use or try to use it but instead I will simply post a link that will provide a usable cheap GM module. I believe I have posted the wiring and if not feel free to send a message and I will respond.

 

https://www.walmart.com/ip/NEW-4-pin-IGNITION-MODULE-Replacement-for-HEI-Distributors-CHEVY-GM-OLDS-PONTIAC/823382634?wmlspartner=wlpa&selectedSellerId=10002&adid=22222222222077334354&wmlspartner=wmtlabs&wl0=e&wl1=o&wl2=c&wl3=84043920257895&wl4=kwd-4587643547969467&wl12=823382634_10000010324&wl14=4 pin gm ignition module&veh=sem

 

The GM module is about $15 at the Walmart store check link above.

Edited by 6bg6ga

Share this post


Link to post
Share on other sites

The GM module is a good idea -- inexpensive and well-documented in uses like this. Keeping it properly mounted to a heatsink surface like you're doing is critical. As long as it can dissipate the heat, its current-switching capacity ought to be more than enough for small engine.

Share this post


Link to post
Share on other sites
Posted (edited)

Actually the TFI system is full electronic, using a reluctor wheel and pickup unit inside the distributor. It came after the EEC IV system which was Fords first electronic ignition system. That system used a box that was fender mounted, also with a reluctor and pickup in the distributor. The TFI came later and was mounted directly to the side of the distributor. I have experimented some with crank trigger ignition using both the original Ford module and the TFI, using an npn style prox sensor as described on Brian Millers site. I was trying to use it on the P224 on my skid loader, but never could get the timing where I needed it to be. Since I really needed to use the machine and was tired of fighting with it (and SWMBO was running out of patience), I finally bought good used stock parts from Boomer and gave up for the time being. I still have all the pieces laying around here and may try it again at some point. The only reason I tried it to begin with is that I already had everything on hand here except the pickup, and I was facing replacing both the module and coil on the P224. A lot of money that I was trying to avoid having to spend. Oh well......

 

This was my test bench when I was experimenting with the TFI unit.

IMG_2195.JPG

Edited by Indianajohn
Additional text.
  • Like 1

Share this post


Link to post
Share on other sites

Well that is good to know. I did a quick search on it and it came up as a points type ignition system and I didn't look any further.  Not taking time to do any further research or break it down internally I dismissed it as points only. I stand

corrected.  Maybe you would like to share the info you have collected on it with those interested here.

 

Looking at your sensor I'm wondering it that could have been the problem because that type is slower in that the part I posted. Your sensor is more suited as a industrial counting device.

Share this post


Link to post
Share on other sites

DuraSpark-I ignition system

This California only version of the DuraSpark system is very similar to the DS-II, with the following exceptions:

DY204 module (red sealing block, a.k.a. "grommet")

Deleted coil resistor

Low-impedance high-energy ignition coil

The DuraSpark-I system coil charging currents are higher than the DuraSpark-II, and designed to achieve better emissions and mileage through more complete charge burning, and improved ignition of lean air/fuel mixtures. To allow increased coil output, the coil resistor was deleted, and an electronic dwell circuit added to allow full saturation of the coil, yet prevent coil overheating. While the equivalent to GM's original HEI, it was limited to California-only as it was more advanced and expensive to produce. This high cost and limited availability is one reason the less-powerful DuraSpark-II conversions have historically been more popular. With the much greater availability in today's market, and prices reduced to DS-II equivalents, the DuraSpark-I is seeing a large increase in popularity for upgrades and conversions.

The large distributor cap designed for the DS-I to help prevent terminal spark jumping was also standardized for all DuraSpark versions to reduce long-term maintenance. While the DS-I is capable of firing over 0.080" spark plug gaps, the factory recommended gap was 0.055-0.060" in most models - much wider than the DS-II.

Ford part numbers for the DuraSpark-I module are D7AE-12A199-A1B, D7AE-12A199-A1E, D7AE-12A199-A2B, and D7AZ-12A199-A.

Ford part number for the low-impedance DS-1 ignition coil is D7AZ-12029-A. However, due to the special dwell circuit, many other high-energy coils may be used, such as the GM HEI external coil, the Ford TFI coil, and many aftermarket equivalents.

Ford models using the DuraSpark-I (California-only) include:

1977 Custom

1978-'79 Fairmont

1977-'79 Granada

1977-'79 LTD

1977-'79 LTD II

1977 Maverick

1979 Mustang

1977-'78 Mustang II

1977-'79 Thunderbird

Lincoln and Mercury equivalent models are similarly equipped.

 

Its been many years since I have worked with the Dura-spark Ford's first electronic ignition.  I remember I owned a Jet Boat with a 460 Ford engine in it and converted the points ignition to the Dura-Spark. It worked well.

 

I would have to play with it myself to determine if the Dwell circuit change is in the TFI portion or in the module section of the ignition. The GM module as I pointed out is already proven as a good workable device for small engine ignitions. The hall effect sensor I posted is a workable unit per its specifications and ability to reset very fast. It a copy of what others have used at a reduced price.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Recently Browsing   0 members

    No registered users viewing this page.

×