Ignition Help - Howell / Crane CD - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 09-20-2006, 06:21 PM Thread Starter
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Ignition Help - Howell / Crane CD

I have a mechanic trying to get the correct TAC signal from my Crane HI-6 CD ignition w/ E-core coil to my Howell TBI. For some reason the Crane's TAC signal does not have the same transmitting signal that the Howell TBI needs to receive a TAC signal. Does any body ever use this setup? Does anyone know what exactly is that signal. All I now is that is a 12v square wave that both manufactures said thatís what they need. Should I use MSD instead? We will be calling Howell tomorrow to see what works. I do not wont to back to the stock ignition but do I have a choice?

Any help would be helpful. This is very frustrating!
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post #2 of (permalink) Old 09-20-2006, 08:05 PM
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Re: Ignition Help - Howell / Crane CD

The Howell is just a stock GM with their wiring harness. The "Tech" guys there will say "I dunno." It just needs the same signal as a stock GM.

Call Crane - since they build it, they probably know how to make it work with a GM.
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post #3 of (permalink) Old 09-20-2006, 08:12 PM
 
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Re: Ignition Help - Howell / Crane CD

this is from the howell instructions from their website.


AFTERMARKET IGNITION SYSTEMS: If you are running an aftermarket ignition system (MSD, Mallory, Jacobs, etc.), you might not have a coil signal that will trigger our built-in tach filter. If your engine will not start, and you have one of these systems, contact Howell Engine Developments at Ph 810-765-5100 for assistance.
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post #4 of (permalink) Old 09-21-2006, 12:17 PM Thread Starter
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Re: Ignition Help - Howell / Crane CD

R Rich, You are right, Howell said we donít no, call Crane. Crane said, "we used to make a tack filter but discontinued it". They said "use a MSD tach filter part". We tried that, and again the injectors were not firing in order correctly. Seems that its reading the tack signal at full rpm's.

I am going to call Howell again and find out what C.D. ignition works with its unit. It looks like I will have to go back to the old stock Duraspark II ignition.

Question: Can a GM TBI work with a CD ignition system or not. It all comes down to what the tach signal is made of to both can work together.

Thanks
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post #5 of (permalink) Old 09-21-2006, 01:00 PM
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Re: Ignition Help - Howell / Crane CD

It may not ever work with a CD - at least properly.

Reason being is a "normal" Kettering ignition "lets go" of the coil when it fires the plug. Meaning the coil primary "sees" a negative going pulse - that's what the FI uses to trigger.
The CD doesn't first charge the coil, then "let go" like the Kettering - it fires "through" the coil like a transformer. So the negative going pulse would be AFTER the plug fires.

But - you might try a couple things before ditching an expensive Crane unit.

Radio shack - get a resistance subsitution box - I think the cheapies are less than $10. And get a capacitor, around .01 MFD - non electrolytic $.98?

Put the capacitor in series with the tach lead - try it.
Remove the capacitor - put the resistance substitution box in series with the tach lead. Crank it while trying various resistances.
Even try both.

It may not work, but it's worth a try.
It may run, but it may also double trigger - way too rich.

If not - I'd go with a GM HEI system, the Howell, being a GM ,should work perfect with that. And it's cheap and easy.

Look up stealth HEI here - there's lots of info about how to make a remote mounted HEI. Sometimes you have to filter through all the baloney, but they work great!
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post #6 of (permalink) Old 09-21-2006, 01:09 PM Thread Starter
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Re: Ignition Help - Howell / Crane CD

O.K. Called Howell. They said that the only C.D. ignition that they know will work 100% is 'DUI' (GM HEI) or 'MSD'. But the MSD you need to buy Howell's Tach Filter for $50. Now I wonder if that same filter will work with the crane? And what does this filter do that only Howell can provide?

I hate not knowing why one tack signal is not the same as the other.

We are going ahead a put back the stock ford Dura Spark II back in with the TFI coil just to get it too run and break in the new engine.

Sorry I left this out! It a newly rebuilt 258 for an 84 CJ 7

Thanks
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post #7 of (permalink) Old 09-21-2006, 01:18 PM
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Re: Ignition Help - Howell / Crane CD

I'd venture a guess that their filter is the same thing as the resistance box and capacitor.
I forgot to mention - after you find the right resistance, replace the box with a fixed resistor and make it permanent.
Theirs probably is potted in plastic so you can't tell what it is.

Maybe call MSD - ask if their CD works with GM TBI. Ask what adapter/filter they use.
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post #8 of (permalink) Old 09-21-2006, 02:28 PM Thread Starter
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Re: Ignition Help - Howell / Crane CD

Thank you RRich for explaining this. I thought this was going to be a very simple connection. Tach to tach. NOT!
I will try what you suggest.
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post #9 of (permalink) Old 09-21-2006, 03:36 PM
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Re: Ignition Help - Howell / Crane CD

He He - Uncle Murph and his Law never lets anything be simple or straightforward.
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