TCI Replacement 2020 It Works

[Its been a long time]

Thanks for this. The pick up looks perfect in there. My 77 650D is a conversion candidate once I get it running on the stock points ignition system.

I don't know if it's been tried, but will the Gonzo ignition box fire two stock coils connected in parallel? Obviously, that would be cheaper than buying a new dual output coil.

 

[DogBunny]

Outstanding!!!!!!!
Jack, hit me up if you want a couple of stock advance rods to play with.
I believe you are going to want a 6mm wing nut for the stock advance rod.
Obviously, the PITA part for you is installing the bushings for the advance rod. I might even have some of those somewhere.

Related note, I just took delivery of a few of the GN250 TCIs yesterday. Thirty minutes later, and I'm running one of them.

I've got some fancy 6-pin connectors on the way, but his works for now. Re-purposed a stator connector. Didn't look at the diagrams before I started, so I didn't realize that one of the pins isn't used. Wasted a female spade terminal. That was dumb.

The empty 6-pin connector to the right is my spare TCI which is zip-tied under the left-side cover.
I tuck the primary TCI behind the right side pod. Not strapped or tied down in any way. I've done it that way for decades on countless bikes. Never occurred to me until now that maybe vibration is a bad thing? But, it's a pretty snug fit, and I've never had any problems.

 

[Team Junk]

I don't know if it's been tried, but will the Gonzo ignition box fire two stock coils connected in parallel?

I haven't fired up and driven across the desert to El Paso and back to test them but yes both the HEI and the Gonzo are quite happy to fire the stock coils wired together on the bench.

On the chevy HEI the stock coil is less than 1 ohm. The Yamaha coils in parallel are still somewhere greater (somewhere around `2 ohm I believe.). I have let the Gonzo run for over a hour on the bench in that setup with no problems so should be ok.

 

[DogBunny]

On further reflection, you are going to need to lock the advance rod to the camshaft somehow. This is done with the advance mechanism on points bikes. Great if you have an advance mechanism, otherwise, something else you need. I can give you one of hose too if you need.
And, I'm wrong about the 6mm wing nut. You need a wing nut that will slide over the 6mm advance rod end, not thread onto it. So that you can adjust it, and then tighten it down with a 6mm nut. As you surely already know.

 

[gggGary]

seems like this is begging to made into a complete "for sale" kit.
hint for points bikes; a trigger that fits the shaft, location pin where the cam now sits.

 

[DogBunny]

Further reflection, you don't need an advance rod. Just tighten any old threaded rod to the camshaft. Never installed a Boyer, but I think that's what they do. As you surely already know.

 

[Team Junk]

And, I'm wrong about the 6mm wing nut. You need a wing nut that will slide over the 6mm advance rod end, not thread onto it. So that you can adjust it, and then tighten it down with a 6mm nut. As you have surely already know.

My thinking is 6mm wingnut with washers and copper washers between the nut and the shaft to space the wingnut on the threads to line up the wingnut. The stock method of adjusting the timing with the backing plate comes into play also.

Welcome to the Cult of Sparkulators. Glad the Gonzo worked straight out of the box.

 

[Team Junk]

Further reflection, you don't need an advance rod. Just tighten any old threaded rod to the camshaft. Never installed a Boyer, but I think that's what they do. As you surely already know.

My shopping list for today includes 3/8 allthread 3/8 fender washers and 3/8 x 1/2 rubber plumbing washers to center the rod in the cam.

What a wild ride it's been. Never expected to be putting up post #1440 on this thread.

 

[Its been a long time]

I haven't fired up and driven across the desert to El Paso and back to test them but yes both the HEI and the Gonzo are quite happy to fire the stock coils wired together on the bench.

On the chevy HEI the stock coil is less than 1 ohm. The Yamaha coils in parallel are still somewhere greater (somewhere around `2 ohm I believe.). I have let the Gonzo run for over a hour on the bench in that setup with no problems so should be ok.

Thanks. That's really good to know. Only issue I can see with me doing this conversion is the difficulty in finding a Chevrolet HEI trigger over here in the UK. Things like that tend to be difficult to find and very expensive when you do find one. I am minded to think a standard industrial spec proximity probe will provide a suitable trigger signal. However, I don't know what is required to feed a trigger signal to the Gonzo box. As in I don't know what signal a Gonzo box expects to see.

 

[Team Junk]

Only issue I can see with me doing this conversion is the difficulty in finding a Chevrolet HEI trigger over here in the UK.

The pickup is a Chrysler part. I'm sure Jeep parts are somewhat expensive in the U.K. but that would be a possible source. I can't say for certain but I think I have seen this pickup used in some Bosch FI systems. I'm pretty sure the Chrysler system was made by Bendix and Bosch also licensed some of the Bendix stuff.

This should work if it fits under the cover. https://www.amazon.co.uk/Hlyjoon-Replacement-Accessory-Scrambler-Sportsman/dp/B08FD5VPMV/ref=sr_1_9?crid=3ETGXABO0ZD5D&keywords=rd350+pickup&qid=1706713406&quartzVehicle=1553-11917&replacementKeywords=rd350&sprefix=rd350+pickup,aps,256&sr=8-9

 

[Team Junk]

The good news is that Amazon.uk has the HEI module pretty cheap.

 

[Team Junk]

Good info from Chrysler on how the system works. The GM HEI module acts pretty much the same as the Chrysler box.
Skip to 14 min in for pickup info

 

[Its been a long time]

Thanks very much for the information, highly appreciated.

 

[Jim]

Be curious to see what kind of advance numbers you get with locking the trigger to the cam. The Gonzo's supposed to give about 25°. In reality that's about 15-20° using the TCI trigger. Since the cam is at half speed relative to the crank, that's only gonna be about 5-10° advance. don't mean to rain on anyone's parade but I don't think that'll be enough.
Here's hoping I'm wrong. Good work Jack.

EDIT: or am I backwards (as usual) and that's gonna give more (doubled?) advance being cam driven?

 

[Team Junk]

Won't change because there are 2 pulses pre turn on the cam instead of the one per turn on the crank.

 

[Jim]

Not sure I'm following Jack.... why would 2 pulses have an affect on advance?

 

[Jim]

'K... through the dense fog that is my brain... managed to work out that 10° at the cam is 20° at the crank. So basically it's gonna double the amount of advance. Don't think that'll be a problem... as the Gonzo isn't really giving all the advertised advance it's supposed to anyway (with the TCI trigger).

Since the advance relies on the leading and trailing edge of the trigger to determine advance (that's my theory anyway), you could always vary the thickness of the wingnut to reduce it if it's too much.

Never mind me... I'll jus' be on me way...

 

[Team Junk]

The advance curve is exactly the same.

600 rpm = 600 pulses from TCI trigger on chrank

600rpm at crank =300 rpm at cam

300 rpm cam speed x 2 pulses = 600 pulses at 600 rpm crank speed

 

[Jim]

Just reread the last few days Jack and thinking I may have confused the issue.....
Are we talking the Gonzo box here or the Mopar box... with the wingnut?

 

[Team Junk]

Case A

Stock points bike.

Use points to trigger a GM HEI modual.

Advantages

Less erosion on points. Rubbing block wear wont affect dwell time on coil. Hide the hei mod and everything looks stock.




Case B

Stock points bike.

Replace points with Mopar pickup- HEI module and wingnut retain stock advance system.





Case C

Rip out points-advance rod and advance mech.

Gonzo box (for advance) Mopar pickup and wingnut on all thread.