67 L71 TI Problem

[Rano W.]

I have 67 L71, years ago, late 80s or early 90s I had the TI module upgraded by Fiedler (?), is he out of business? The car is restored and I do not drive it but maybe once a year for 20 miles with racing fuel. Then I drain the gas and it sits until next year. Since I finished it it has been a hard starter and dies now and then at stop signs. Yesterday I had a hard time starting it at first, would not pop with ether. I suspect I have an ignition problem that may have been there from the beginning and has gotten worse. The car was a little flat on the low end but did well above 3K. At two stop signs later it died and had to trailer it home. I read in the forums about some of the upgraded TI modules not using the 12v start circuit, does anyone know if this is true of the Fielder (?) TI modules? Not sure if I can use the GM troubleshooting guide solve my problem. Currently not a happy camper!

[William L.]

Re: 67 L71 TI Problem

Rano: Give the guy's at K&B a call, they advertise in the Driveline. I had all kinds of TI problems on my 67 then I switched to their TI board and it eliminated all of my ingnition problems. It's been in my car for about 3 years now.
Give them a call. 770-777-1031
Bill

[Mark K.]

Re: 67 L71 TI Problem

Rano,

Dave Fiedler is still out there at:

http://tispecialty.com/

I also have an L71 and have experienced problems like yours and do not think your problem is related to the TI system. I would start first with the voltage regulator and then to your fuel system/carburetors. Unfortunately, I also think your lack of usage is causing problems by letting the car sit for such extended lengths of time. I think you need to drive your car at least 200 miles per year to avoid some of the driveability issues you are experiencing. L71s that are restored may have all the right parts and may look right but are rarely sorted out in a way that makes them good driving cars which is why so many people are disappointed after driving one.

[Rano W.]

Re: 67 L71 TI Problem

Checked coil, fine. Checked pickup coil and reading was 620 Ohms (cold), ok. Had to take hard lines off of carbs, not fun, need to order some new parts. Filters all clean. All carbs full of gas when I turned them upside down. Fuel pressure ok. Talked with Dave at TI Specialty, he said the most common part to fail intermittently is the pickup coil in the distributer which works and does not work related to heat. A new one is $389, need to make sure that is the problem first. I have a points distributer I can put in there to see if all the problems go away as a last resort before replacing the pickup coil. Any thoughts are welcome.

Does anyone make wrench for holding the carb inlet fittings on a 3x2 while tightening the 3/8" fuel lines, all you can get on there is an open end and not very well?

[Timothy B.]

Re: 67 L71 TI Problem

Rano,

After reading your post I would look at the carburetor for problems. If you drain the gasoline, the carburetor is still holding gas in the float and main/idle wells. Lots of little circuits here that need to be used more than 20 miles per year..

A example of this is a Holley 4160 with a secondary idle circuit that's there for the purpose of keeping fuel in the secondary bowl fresh because there are people not like us that will never exercise secondary operation..

I will also suggest replacing gaskets on both sides of the metering block and making sure air bleeds are open. Probably just a little carburetor maintainance and not related to the TI.

I think the ignition will either work or not at all in your case.

[Michael G.]

Re: 67 L71 TI Problem

Rano,

Others may be right regarding your issue(s).....however should you need a pick up coil Keen Corvette parts offer one from M & H Electric electric for $225.00. Have used products from M & H for years and are good as you'll find. Believe you discover on a TI system either they work or don't.

[Mike Z.]

Re: 67 L71 TI Problem

Rano,
After reading your post I would look at the carburetor for problems. If you drain the gasoline, the carburetor is still holding gas in the float and main/idle wells. Lots of little circuits here that need to be used more than 20 miles per year..

A example of this is a Holley 4160 with a secondary idle circuit that's there for the purpose of keeping fuel in the secondary bowl fresh because there are people not like us that will never exercise secondary operation..

I will also suggest replacing gaskets on both sides of the metering block and making sure air bleeds are open. Probably just a little carburetor maintainance and not related to the TI.

I think the ignition will either work or not at all in your case.

Rano-
I tend to agree with Tim-I believe your problem is carb related. Long hibernations are brutal on any automobile. The fuel left in the carb due to evaporation, turns to part dust, part gunk; gaskets shrink, o-rings and neoprene seals/gaskets deteriorate. Use a fuel stabilizer, even when running (so fuel left in bowl is enriched)-will help, but not a cure all-run it once a month for 10+ minutes really helps.

Having restored TI systems for years, I can add a few comments on the ignition. The modules of more than a couple years ago were primarily supplied by M&H and did not use the 12v. wire lead during starts. Hard starts and fouled plugs is my experience (mine and customers), along with other issues.

The current module supplied by K & B Special Products Dealers (check E-Bay) uses the 12v start and we have had excellent durability experience. Also, check E-Bay for rebuilders/restorers that change out the problematic germanium transistors for equivalent value silicon transistors, which are impervious to heat and vibration-the death of germaniums. It would be my recommendation to switch to the current module or convert to silicon, weather the amp is currently your problem or not-it could/probably will be in the future.

Your reading on the coil "bobbin" is within acceptable range, but really move the wire around and pull on it-they tend to break internally where it comes out of the housing and will cause intermittent problems. Weak magnets can cause poor performance and poor starting. 40+ yr old coils should be changed out, due to electrolysis build up and oil boil out. The current reproduction Coil P/U and Coil from K & B are spot on, and best of all they work. Lastly, check out the newest product from K & B: the Cap & Rotor, which use the originally engineered design spec close "air gap"-they just hit the market, and have had excellent response back from customers.

Hope some of these comments help you find the problem, then once you find it-drive the thing, it will put a smile on your face.

Mike Zamora
#12455

[Domenic T.]

Re: 67 L71 TI Problem

To the carb guys that responded, I agree with what you all say because I went thru it all till I put the cars away with 100 octain aircraft fuel mixed 50/50 with premium. Aircraft fuel does not varnish like auto fuel and makes my high compression engines sing. My shop is on the airport and it's not hard for me to get but no one will pump it in the car. I get it from my airplanes or have them put it in a 5 gal can.
I also put it in all my engines I don't run very much to keep the carb's in shape for the next start. CAN'T use it with unleaded cars with converters on the exhaust because the 100 has lead and will clog the converter.
It is not that hard to get if you know someone at an airport. It does not run as well if you use it 100%. Some say that is because it is formulated for the 2500RPM engines.
IT'S LIKE DRIVING THE CAR BACK IN THE 60's. Also you don't need hard seats in the heads if you use it 100% for about 200 miles after a fresh valve grind. The lead impregnates in the cast iron and gives the seats protection. I have done this for years and never had a valve problem.

DOM

[Rano W.]

Re: 67 L71 TI Problem

To answer some of the questions. The coil is new from the mid 90s, Paragon. The distributer is made up of new GM parts from the mid 90s with an original housing. The TI was converted TI Specialty from the mid 90s, I am told it does use the 12 volt start circuit. The carbs are new service replacements from the early to mid 90s. I had carbs but they were 68s and went with the service replacements right or wrong at the time. I get nicked a little but the car still gets top flight. What is driving me to an ignition problem is it would not even fire on ether and the main carb would squirt gas.

[Timothy B.]

Re: 67 L71 TI Problem

Rano,

If the carburetors have been leaking internally the spark plugs may be so wet and sooty they will not fire. The spark energy is taking the soot path to groung instead of jumping the gap..

One thing you can do is take a new spark plug and when the car refuses to start remove a plug wire and install the new spark plug and touch it to ground to see if there is spark.. You may want someone else to crank the engine while you check this.

Do not just ground the plug wire to check spark, use a spark plug.. This will tell you which area to focus on.

[Larry T.]

Re: 67 L71 TI Problem

I had similar problems with my L-72. I was so frustrated that I sent my entire system (harness, distributor, coil, amp) to Dave to check out. He had already restored the distributor. It ended up being the TI harness.

[Rano W.]

Re: 67 L71 TI Problem

I am back working on the problem. Put in a new battery. Took the carbs off, filters clean and nothing in carbs. It is a nice 60 degree day. Car fired right up and idled well. Drove it around for a while with no problems, then the engine temp got up to 200 degrees and it started missing a little here and there. The more I drove it the more it started to miss more and a few backfires and then it quit. Was able to get it restarted and make it home. Would not restart. Took a spare spark plug and took off a wire and had someone crank it. There was a spark but looked to me like it was miss some times, hard to tell. Have gas in carbs. Took ohm readings on everything, all came back good. Played with all the TI wires, nothing. Still will not start, car is hot. Going to let it cool down and pull the plugs.

[Timothy B.]

Re: 67 L71 TI Problem

Rano,

Do you have a spare coil that can be installed to eliminate that. With the symptoms you describe that may be the best place to start..

[Steven C.]

Re: 67 L71 TI Problem

Rano, I am having the same problems. TI Specialty rebuilt distributor, new p/up coil, new TI harness, correct ohms on TI coil, very hard starting and then runs poorly, shut it down and then no spark. Will not start when hot. The hotter it gets the worse it runs (percolation?). Running 105 octane. Tried K&B TI module and it does not make a difference. Carbs rebuilt.

[Clem Z.]

Re: 67 L71 TI Problem

Rano, I am having the same problems. TI Specialty rebuilt distributor, new p/up coil, new TI harness, correct ohms on TI coil, very hard starting and then runs poorly, shut it down and then no spark. Will not start when hot. The hotter it gets the worse it runs (percolation?). Running 105 octane. Tried K&B TI module and it does not make a difference. Carbs rebuilt.

make sure the ground wire to the amp is connected to a unpainted area of the amp. i always used a nut on the bolt on the back side of the amp to make sure the ground never came loose like it can if the only nut you use is to hold the amp to the fiberglass.