71T, cranks but often wont start

[jameshurst71t]

Hi guys, I have a 71T with 2019 rebuilt motor that’s now 2.2S Ps and Cs and solex cams topped with PMO 40, new Bosch CDI, old Bosch dizzy, new wires and older Pertronix.

For the last few months since I leaned out the carbs, (low 9-10 AFR on WOT hence moved to 130 jets, 190 airs, F16 etubes) I have had intermittent starting issues. Car cranks fine (newish starter) but it won’t catch like it used to nor start smoothly. I smell a little gas so it seems to be pumping. I can see gas in the PMO port holes. I pulled the plugs and they are gray(too lean), the dizzy cap copper connectors are greenish. CDI box is freshly rebuilt, Beru wires are new. S rotor and Cap are from 2019. I reset PMo to 125 jets, 170 air and F11 tubes to enrich it. Still the car cranks but not a great start and sometimes crank and no start.

Do leaned out and gray spark plugs need replacing? How do you know if your dizzy is failing? that part is old for sure. How do you know if your old Pertronix is failing?

My gut is replace plugs, cap, then go to 123 Ignition for 2.2S and see what happens.

Does 123 Ignition replace pertronix igniter as well?

Worst case thinking tells me I leaned out the motor too much and I’ve ruined the cylinder walls, or such so I would feel better to do a leak down and compression test to feel better.

What do you think is causing the car to not start?

[PeteKz]

Review the basics: Compression, fuel, spark.

I'll assume for the moment that since it eventually fires and runs, you have spark at start too. However, if the cap has corrosion in the plug towers or internal poles, or the rotor has the same, either scrape them clean or replace the cap and rotor. For testing I would just scrape them clean.

First test, becuase it's fastest and easiest: spray starting fluid into the intake. Does it fire? If so, then you are lacking fuel at start up. If not, then probably too rich or flooded. Also try starting from cold WITHOUT pumping the pedal first. Then try just one pump.

After that, test compression. No need for leak down test at this point, just a quick cranking compression check for all cylinders within 10%, and within the range of acceptable values. Since you will remove the plugs, do this after you try starting from cold, but without the engine firing, to see if the spark plugs are wet (indicates flooding). While you have them out, check for spark, to verify the assumption above.

My strong advice: get the engine starting and running correctly BEFORE changing the ignition. Don't complicate your troubleshooting by introducing more changes and variables. "One thing at a time."

If you decide to go to the 123 distributor, it eliminates the Pertronix. It can run directly to the coil, and thus eliminate the CDI box too.

[jameshurst71t]

Thanks Pete. It died and was towed the shop.

[jameshurst71t]

Update. Great call Pete on first things first. 123 Ignition can wait.

Starter fluid did not work but did shoot out in a white plume of smoke when finally started.

Swapping the leaned out and gray Bosch platinum plugs to Bosch WR5DC+ spark plugs helped quite a bit but still the starting and catching problem persisted. It would Crank for a while but no start, then usually poor start for like10 seconds. Reeked of gas. Plenty of spark. Swapped in new cap. No change.

Paul Abbott suggested checking my .55 idle jets. I then did and found debris in one and my old eyes may have seen small obstructions in the rest. Blew them all out and the engine fired right up.

Side note: This symptom was different than last time I had debris in an idle jet. Last time the car started fine but only ran on 5 cylinders with bucking. This time, the engine had trouble starting but ran kind of fine eventually. Weird.

Now on to fix a dragging caliper.

[gamin]

Stupid question. Are you using the hand throttle for starting? Open it a bit and prime with the foot throttle. Couple of tries and it starts. Warmed up close hand throttle. My '70 w/ 3.0 has PMO's solex cams so similar to yours. And mine won't start or run if the timing is not set correctly.

[icarp]

the first set of jets is much closer to correct
130 jets, 190 airs, F16 etubes), try 125-185- f16 what size chokes are you using 30-32?
The f11 is for a larger engine and higher HP
Get the 123 + tune you wont regret it
clean Idle jets and pathways are a must.
you need to crack the throttle 12mm when starting on carbs
cold engine, 3 slow full pumps then start

Ian

[jameshurst71t]

To start, I usually shift to neutral, 2 pumps and twist. 2nd start has typically worked unless the car was warm, then only one start needed. I typically always have to use the throttle lever.

Since this past winter, it’s been a slog. I’m hoping clearing the idle jets has solved my problem. I have a 6 hour drive each way in the autobahn next month.