TI

[Clem Z.]

Re: TI

And, as Mike is aware, GM used this system (and recommended it in the Chevy Power books) in the mid 80's for all their NASCAR teams-which I'm sure had a lot of compression.

the GM TI system was very reliable for racing as long as you never shut down the engine. i never heard of one quiting while the engine was running. all my experience were that the car would not restart after being shut off.

[Duke W.]

Re: TI

Production engines run "lean" A/F ratio at cruise - stoichiometric on modern engines, and a little richer on vintage carbureted engines due to uneven fuel distribution, but the Rochester FI system can run leaner than stoich. because it offers very even fuel distribution.

The above is why production cars always have inductive ignitions. Lean mixtures require a long duration spark for consistent ignition with minimum misfires.

CD ignitions have intense short duration sparks, which are best for consistent igntion of rich mixtures with very high compression ratios. Even though the MSD system offers multiple sparks at low revs, the second or third are signiticantly retarded from optimum timing

The CD ignition is another example of a "race car part" that is not very well suited to road engines.

Duke

[Dick W.]

Re: TI

We put a MSD unit and coil on our '72 fat motor almost 15 years ago and have nothing but praise for it. Fouled plugs are a thing of the past. The idle speed increased about 400 rpms when it was installed. We respectfully have to disagree with you Duke on this. May be a fluke on this car, but it works for us.

[Ken A.]

Re: TI

The original amp boards were very weak in amplifying the signal at low cranking speed & thus were hard to start. The new amp board fixes this problem & will fire off like you've got HEI.

[Duke W.]

Re: TI

We put a MSD unit and coil on our '72 fat motor almost 15 years ago and have nothing but praise for it. Fouled plugs are a thing of the past. The idle speed increased about 400 rpms when it was installed. We respectfully have to disagree with you Duke on this. May be a fluke on this car, but it works for us.

It depends on how the engine is setup and what you started with.

The single point distributors were assembled indifferently by GM and were poor performers from the get go. My 340 HP SWC rarely made it to the redline without breaking up in its first few years, but it probably saved me a broken connecting rod.

Once I figured out how to "blueprint it", it provided a reliable spark to the redline and beyond, so the single point can provide adequate spark for any OE SHP/FI engine that has a proper A/F ratio at the various operating conditions.

My experience with the TI is that is works perfectly or doesn't work at all, and failures occur without warning.

Duke

[Clem Z.]

Re: TI

It depends on how the engine is setup and what you started with.

The single point distributors were assembled indifferently by GM and were poor performers from the get go. My 340 HP SWC rarely made it to the redline without breaking up in its first few years, but it probably saved me a broken connecting rod.

Once I figured out how to "blueprint it", it provided a reliable spark to the redline and beyond, so the single point can provide adequate spark for any OE SHP/FI engine that has a proper A/F ratio at the various operating conditions.

My experience with the TI is that is works perfectly or doesn't work at all, and failures occur without warning.

Duke

the big advantage to the MSD is i never had one or heard of one dieing like the TI boxes. i rebuilt TI boxes back in the day and always carried a couple of spares with me and i never needed one but i sold a few on the road with my corvette club on trips to MB S.C..

[Mike Z.]

Re: TI

the GM TI system was very reliable for racing as long as you never shut down the engine. i never heard of one quiting while the engine was running. all my experience were that the car would not restart after being shut off.

Clem-I understand the NASCAR boys used a redundant system of using 2 OEM amps back in the day, that they could switch from one to the other if necessary-was that your experience?
I can see the failure of the amp at shut down/re-start, due to the germanium transistors used and available at the time were prone to failure due to heat and vibration. We have had great success replacing those old transistors with silicon equivalent value transistors. Performance is as good or better and durability is excellent, as silicon units are impervious to the heat and vibrations experienced in an auto.
Mike Zamora
#12455

[Mike Z.]

Re: TI

We put a MSD unit and coil on our '72 fat motor almost 15 years ago and have nothing but praise for it. Fouled plugs are a thing of the past. The idle speed increased about 400 rpms when it was installed. We respectfully have to disagree with you Duke on this. May be a fluke on this car, but it works for us.

Hey Dick-you seem to have great success with the MSD. It was my earlier recommendation to use like amp and coil-that is the recommendation of my race customers. Are you using the OEM type coil or the MSD coil recommended for their amp model you are using?
Thanks, Mike Zamora
#12455

[Mike Z.]

Re: TI

The original amp boards were very weak in amplifying the signal at low cranking speed & thus were hard to start. The new amp board fixes this problem & will fire off like you've got HEI.

Ken-as a point of interest, we have tested both the OEM amps that we have changed out the germanium transistors with equivalent value silicon transistors and see no difference in pulse output vs. the aftermarket modules. As a matter of fact on the M&H: it does not use the 12v. feed from the starter for starting, so is trying to start with about 7v.DC-the up-graded OEM actually unit has better starting abilities, because of the 12v at start. The Module from K&B tests well against the OEM on our Sun Tester, and uses the 12v lead from the starter.
We have found a more critical component that causes hard starting, is the strength of the magnet. Consistently, tests on our Sun Tester-OEM magnets will not excite the strobe. A change to the K&B coil P/U or just the magnet (w/OEM bobbin) and the strobe fires at very low RPM. It is our theory, since by definition the coil P/U is an electro-magnetic generator the pulse to the amp must be strong enough to excite the transistors. The Sun requires, by our readings, a minimum of 5.0v. AC to the pulse amp. The typical OEM unit reads about 4.4vAC at 500RPM distributor baseline test speed vs. a little over 8.0v.AC from the reproduction.
Based on these tests and some from one of our race customers, we have been changing out the coil P/U in favor of the reproduction with it's stronger magnet, when performance is the goal. We recommend the OEM bobbin for judging purposes.
If the change to an aftermarket module helped your situation-great, but I bet there was a problem with your OEM board that could have been fixed to perform as good or better than the best aftermarket unit.

Mike Zamora
#12455

[Clem Z.]

Re: TI

Clem-I understand the NASCAR boys used a redundant system of using 2 OEM amps back in the day, that they could switch from one to the other if necessary-was that your experience?
I can see the failure of the amp at shut down/re-start, due to the germanium transistors used and available at the time were prone to failure due to heat and vibration. We have had great success replacing those old transistors with silicon equivalent value transistors. Performance is as good or better and durability is excellent, as silicon units are impervious to the heat and vibrations experienced in an auto.
Mike Zamora
#12455

we alway mounted the amps side by side so the plug could be changed if the car would not start

[Clem Z.]

Re: TI

Ken-as a point of interest, we have tested both the OEM amps that we have changed out the germanium transistors with equivalent value silicon transistors and see no difference in pulse output vs. the aftermarket modules. As a matter of fact on the M&H: it does not use the 12v. feed from the starter for starting, so is trying to start with about 7v.DC-the up-graded OEM actually unit has better starting abilities, because of the 12v at start. The Module from K&B tests well against the OEM on our Sun Tester, and uses the 12v lead from the starter.
We have found a more critical component that causes hard starting, is the strength of the magnet. Consistently, tests on our Sun Tester-OEM magnets will not excite the strobe. A change to the K&B coil P/U or just the magnet (w/OEM bobbin) and the strobe fires at very low RPM. It is our theory, since by definition the coil P/U is an electro-magnetic generator the pulse to the amp must be strong enough to excite the transistors. The Sun requires, by our readings, a minimum of 5.0v. AC to the pulse amp. The typical OEM unit reads about 4.4vAC at 500RPM distributor baseline test speed vs. a little over 8.0v.AC from the reproduction.
Based on these tests and some from one of our race customers, we have been changing out the coil P/U in favor of the reproduction with it's stronger magnet, when performance is the goal. We recommend the OEM bobbin for judging purposes.
If the change to an aftermarket module helped your situation-great, but I bet there was a problem with your OEM board that could have been fixed to perform as good or better than the best aftermarket unit.

Mike Zamora
#12455

here is the stuff i was using back in the day but they were germanium.

[Dick W.]

Re: TI

Hey Dick-you seem to have great success with the MSD. It was my earlier recommendation to use like amp and coil-that is the recommendation of my race customers. Are you using the OEM type coil or the MSD coil recommended for their amp model you are using?
Thanks, Mike Zamora
#12455

MSD Blaster II coil.

The GM amps the NASCAR teams used were subjected to exteme vibrations, adding to the unreliability of these units. Like Clem, I used to rebuild these units for Corvette owners. I would get boxes of TI amps that were non-functioning (at one time there were 4 teams based here). That worked well for a while, until they started bedding the boards with GE Silicone Bedding Compound. Every try to dig electronic components outta that stuff??

[Clem Z.]

Re: TI

Clem-I understand the NASCAR boys used a redundant system of using 2 OEM amps back in the day, that they could switch from one to the other if necessary-was that your experience?
I can see the failure of the amp at shut down/re-start, due to the germanium transistors used and available at the time were prone to failure due to heat and vibration. We have had great success replacing those old transistors with silicon equivalent value transistors. Performance is as good or better and durability is excellent, as silicon units are impervious to the heat and vibrations experienced in an auto.
Mike Zamora
#12455

did you use a curve tracer to get the profile of the germanium and then cross reference to silicon ??

[James G.]

Re: TI

i will try and post it here. the wires from the dist to the MSD MUST be TWISTED together to shield it from the EMF that comes from the ignition system.

I hid the MSD Box behind the glove box door area on my 64 fuel injection race car. Worked great, in fact I found 2 seconds a lap with that one change alone over ignition points. Now that was 1988-94 time frame, but same should hold today.