TR4/4A 63 TR4 Help needed Missing / Backfiring

[steve_sims]

Howdy all, Finally got to drive my 63 Tr4 yesterday for the first time. What a blast!!! untill it started missing and even backfiring on acceleration. Car had been parked since 1994 in a nice dry garage and went to my friends garage where we cleaned gas tank, replaced rubber fuel lines, installed electric fuel pump, rebuilt carbs, installed new points, condensor and cap, redid brakes etc. I have plug wires ordered, but they don't look too bad. Car starts easily, runs smooth and revs fine when sitting still but take it out on the road and she starts missing and even occasionaly backfiring. Any ideas where to start? Thanks Steve

 

[Geo Hahn]

Don't be insulted but... when I hear 'misfire' the first thing I wonder is whether you have verified the firing order is correct. 1-3-4-2 of course but it will still run surprisingly well with other arrangements until under load.

Assuming that is okay... you mention all the ignition components except the coil. A failing coil or even the wrong coil could be a problem.

BTW -- I make my own plug wires using a generic set of copper-core wires sold for V-8s. One box is enough to do about 4 sets for a TR.

 

[Adrio]

I had exactly the same thing with my TR4. First, in my case, and your situations sounds the exact same, it was because the mixture was too lean at the time of hard acceleration. Again in my case the reason was the thermostat was not working and in effect always fully open so the engine never got warm.

Here are some things to check/try.
-When you accelerate try pulling the choke to see it the backfire stops.
-check that the temperature gauge shows a fully warmed up engine
-check that the dashpots have oil in them (the oil is what gives you the more rich mixture just at the time of acceleration (from what I know)
-if you are not getting a warm engine check that there is a thermostat in the car
-check you timing and mixture

In my case I just had to replace the thermostat and it all worked well.

 

[steve_sims]

Hi Geo, No insult taken. I ask questions because of my ignorance. Sometimes the simplest things are the hardest to see. The firing order is right { just checked} The negative side of the coil goes to the distributor. Is this right? I recently bought a 69 Benelli scrambler that the coil was wired backwards and when changed back , it ran great. Thanks Again Steve

 

[Geo Hahn]

...The negative side of the coil goes to the distributor. Is this right?

Only if you have converted to negative ground.

If it has been connected in reverse order just switch it back & clean and reset the points.

 

[TRopic6]

Steve,

TR-4s came Positive ground from the factory, but many cars have been swapped over to negative ground. Better check, and if you're positive ground, I think the + side of the coil should go to the distrib.

Jeff

 

[steve_sims]

Thanks guys, The car is possitive ground. I will change it and see how it goes. Thanks Steve

 

[steve_sims]

Howdy All, I put in a new coil today and away she went with no missing or backfiring. I am amazed at how strong running this little 4 is. Thanks Again to all. steve