Reproduction TI Amp Issues

[Richard M.]

Re: Reproduction TI Amp Issues

To my amazement the car started (no R terminal jumper) so I think the TI amp isn't fried. Rich, your initial instructions were perfectly clear. I was just being stupid.

However, it still isn't anywhere near right. I've cleaned the connection from the ignition switch and the pink wires at the distributor like Doug said. They appeared clean and well connected.

So I took some additional voltage measurements:

- Battery voltage before cranking: 12.94V, during cranking and 10.97V measured at the battery terminals
- +coil with jumper from battery+ to the two pink wire/white wire to distributor during cranking: 4.9V and 6V with ign switch ON
- +coil no jumper: 4.5V cranking and 3.5V with ign switch ON
- at the two pink wire/white wire to distributor during cranking: 9.5V and 7V with ign switch ON

The attachment should be an illustration of the same measurements.[ATTACH]116432[/ATTACH]

I'm thinking the 9.5V at the pink wires versus 10.97V at the battery during cranking suggest a new solenoid? This is the same voltage I initially measured at the R terminal. To add to this I tried starting with an R terminal jumper and based on one attempt it started easier than without a jumper.

The circuit board screws are the same ones that came with the K&B amp. They do have the K&B washers.

Thoughts? I've got a solenoid ready for pickup in the morning.

Scott, Glad the board is ok.

Since it started without the Solenoid R jumper, I'd think you have other issues. Likely intermittent. Your voltage readings are a bit low without the jumper, but even though the battery is at a 12.9v level, it could be marginal during Crank under high load. TI is very needy during crank.

It's possible your solenoid is marginal, but the best way to prove that is in a no-start condition, then try the jumper wire.
I wouldn't change it yet, but maybe have it on the shelf if you need it.

I'd run it for a while to get the engine to temperature and try to get it to fail. Tough to speculate when it doesn't fail.

When you had the no-start problems before, did you ever actually pull one plug wire and test for spark, and see a good arc?

Rich

[Doug M.]

Re: Reproduction TI Amp Issues

Scott,
Good that you cleaned distributor connection.

You should also trying unplugging and cleaning the bulkhead wiring connections. They are on the firewall, right beside the clutch pushrod ( engine side.)

Doug

[William F.]

Re: Reproduction TI Amp Issues

Certainly could be problem with corrosion at connection at solenoid. Has this problem with low cranking voltage at coil and it was solenoid problem. check this first.

[Scott H.]

Re: Reproduction TI Amp Issues

TI wiring - Firewall Conxx.pdf

Hi Doug,

I also cleaned and inspected the connection circled in red. Please let me know if I am addressing the wrong one.

[Doug M.]

Re: Reproduction TI Amp Issues

bulk head .jpg
Scott,

Takes a bit of wiggling to not break the tabs , but well worth checking this out

Doug

[Richard M.]

Re: Reproduction TI Amp Issues

Doug,

TI has it's own harness. Nothing in the bulkhead connector should affect it. The only wire going through the bulkhead is the Purple Crank wire to activate the starter solenoid, which hasn't failed him. It cranks ok, just won't start. And the Heavy gauge Red wire to power the whole car, particularly feed to the Purple off the Ign switch.

The IGN TI power source lead has it's own wire directly from the Ignition switch, which comes out through a grommet next to the wiper motor, the heavy gauge Pink wire which connects to the white resistor wire in the TI harness. All of the remaining circuits are in the engine bay.

I agree it's a good idea to check bulkhead connections and clean any corrosion, just unsure that anything in there is presently related to Scott's problem.

Rich

[Scott H.]

Re: Reproduction TI Amp Issues

I verified the bulkhead connection was solid. It's a Lectric Limited harness that I put on about 3 years ago. No reason to think the connections are dirty. I changed out the solenoid. It appears to have added a volt to the coil during cranking. With the new solenoid I get:

- 12.6V at battery terminal, not cranking
- 3.5V at +coil ON
- 4.3V at +coil cranking

I tried the jumper to the pink/white connector too. Still doesn't start. I didn't pull a spark plug but did get a signal from an inductive timing light. I'll keep doing that since the start/no start appears to be so random. I'll verify the resistance across the distributor, looking for 500-700 ohms.

[Richard M.]

Re: Reproduction TI Amp Issues

I verified the bulkhead connection was solid. It's a Lectric Limited harness that I put on about 3 years ago. No reason to think the connections are dirty. I changed out the solenoid. It appears to have added a volt to the coil during cranking. With the new solenoid I get:

- 12.6V at battery terminal, not cranking
- 3.5V at +coil ON
- 4.3V at +coil cranking

I tried the jumper to the pink/white connector too. Still doesn't start. I didn't pull a spark plug but did get a signal from an inductive timing light. I'll keep doing that since the start/no start appears to be so random. I'll verify the resistance across the distributor, looking for 500-700 ohms.

Scott, I'm thinking it's time to get back to basics.... Fuel? or Ignition? I'm not convinced which is at fault now.

Have you re-verified adequate fuel flow at the carb since your first reported issue? If so, then back to Ignition diagnosis.

Since it appears to show activity of a spark condition with the timing light, it would be wise to actually check spark at a sparkplug, to see how healthy the spark is. When you checked it with the timing light, was it at a sparkplug or the coil wire? If at the coil wire, there's still a path through the distributor rotor to get to the plugs. May be time to check things inside the distributor at this point as well.

As a reminder, with a TI system, do NOT remove the coil wire and check spark there at the distributor cap. Always only at 1 spark plug.

Rich

[Doug M.]

[John P.]

Re: Reproduction TI Amp Issues

Hello Scott, several years ago I had similar starting problems with my 1966 427/425 with TI ignition. It had a replacement solid state board installed in the amplifier. I found out that some of the solid-state boards will not pick up a signal from the original pick-up coils in the distributor. I checked all connections and voltage readings and found no issues. I spoke with Dave Fiedler and he recommended replacing the amplifier with a stock unit and confirmed that he has also seen issues with the solid-state boards not processing the signal. I installed an original unit, the engine immediately started and has been running flawlessly for years. I run the stock amplifiers in both my 1966's and 1967 with no problems. John

[William F.]

Re: Reproduction TI Amp Issues

Unless transitor systems are different, thought you were supposed to get full 12 V at coil with key to start. ??

[William F.]

Re: Reproduction TI Amp Issues

Glad I don't have a TI system. Slightly different subject. I bought a 1967 Olds 442 with the "high energy" transitor ignition. Was that the same as the Corvette TI system? I never had a problem with the 442 ignition.

[Duke W.]

Re: Reproduction TI Amp Issues

That might have been the capacitor discharge system, which used the same mag pulse distributor as the TI system. The CD system had a red dist. cap and was an Oldsmobile option beginning in 1967 or thereabouts.

It was short lived, and I think the reason is that CD systems are not a good choice for road engines because even though they have high energy, spark duration is short, but road engines that run "lean" (around stoichiometric) mixtures need long spark duration to ensure reliable ignition so inductive systems are the way to go. Short spark duration is good for engines that usually run rich mixtures, like racing engines. The single point ignition spark duration is 120 microseconds, TI is 180, and the CD system was 35.

MSD makes a big deal out of "multiple sparks", which the system can only develop at low to mid revs, but if the first spark doesn't light the fire, subsequent sparks will be severely retarded.

Duke

[Richard M.]

Re: Reproduction TI Amp Issues

Unless transitor systems are different, thought you were supposed to get full 12 V at coil with key to start. ??

William, Yes very different than a points ignition which applies full battery voltage to the ignition coil during Crank.

TI Ignition voltage only powers the AMP and Distributor Pickup coil. Therefore during Crank the full battery voltage is applied only to the AMP and PU coil. The ignition coil is isolated from this path, because the AMP output drives it separately.

Think of the Distributor Pickup coil as a pulse generator. At each pulse of eight during distributor rotation, it sends a signal to the AMP input, which then converts that input pulse signal to a AMP output high current pulse to the Ignition coil.

Think of the AMP as a switch, pulsing the distributor coil+ directly, as opposed to a Points Ignition, which keeps power on Coil+, and switches Coil- via the points.

During Crank, the TI system applies full battery voltage ONLY to the AMP and PU Coil, via Solenoid "R" terminal path, to keep the voltage higher due to high crank current draw, dropping the battery voltage.

Glad I don't have a TI system. Slightly different subject. I bought a 1967 Olds 442 with the "high energy" transitor ignition. Was that the same as the Corvette TI system? I never had a problem with the 442 ignition.

It may have been the "Contact Controlled Transistor Ignition.(Ref HERE) It was a subset of what later became TI. Instead of using a special distributor with a Pickup Coil and 8-point rotating pole stator, a standard Points distributor was used. The AMP was switched by the distributor points.

After a bit of searching I also found this "CD Ignition system". It mentions used for 1967 Olds and Pontiac. This was based on a Capacitive Discharge principle. It could be triggered by a points or a distributor magnetic pickup.

EDIT - In the text of the above article....
"Oldsmobile also added the same CD ignition to its option list for the 1967 model year, calling it the “Ultra-High Voltage” or UHV ignition. It cost about $100 and was offered in 1967-68 under option code K-66 on Oldsmobile 400, 425, 455 engines."

If ordered as a option, it would include the Mag Pulse Distributor. In the aftermarket, it could be used with the existing points distributor.

Rich

[Scott H.]