TR2/3/3A 1961 TR-3 Misses/Backfires

[vinceclortho]

My Dad has a 1961 Triumph TR3. It has been run very little in the past few years and has a terrible miss under load. We started it today and got it to rev fine while it is sitting. Once we started driving, it misses under acceleration and won't make any power.

He spent $2,000 with a supposedly expert mechanic and now has it converted to negative ground and an electronic ignition. It ran fine for a while, but now has this problem under acceleration. When we drove, the red indicator stayed on, I believe this means no charge to the battery. We messed around with the voltage regulator and it stuck on. The fuel pump kept running with the key out. We tapped the regulator and the pump went off and the red light out. It restarted fine, but still misses.

I'm thinking it has to be an electrical problem, although I know zero about SU carbs. I told him to get a new voltage regulator. Where should we go from here? There are a couple rather unreliable mechanics in our area, otherwise we will have to trailer it somewhere. It is a simple old 4 cylinder motor. What are some easy things to try on it?

 

[sp53]

Well I guess I would start by converting it back to the manual distributor. I know that sounds old school, but it might be the only way to isolate the problem. Some things to check before you do that are the oil in the carbs make sure the dampers have the proper amount of oil (just use what you are using in the engine). Again do the basic stuff like spark plugs and wires. Another thing you might check before you go to far is the rocker adjustment. Set them cold at .10 the problem could be that one or more of valves is not closing and becoming a problem under load at higher rpms. Good luck and keep the forum posted there are some real good back yard and professional mechanics on the form.
Sp53

 

[jsneddon]

[ QUOTE ]
What are some easy things to try on it?

[/ QUOTE ]

OK. If I ask you if you are absolutely sure that your spark plugs are connected to the right cylinders you are going to say "of course they are".

That's just human nature.

Now that you've said yes... go out there and make absolutely positively sure that they are hooked up 1-3-4-2 going in the direction of the little arrow on the rotor (counter-clockwise I believe).

#1 is when the rotor is pointing at the #1 spark plug.

I had exactly the same symptoms and after almost THREE MONTHS someone finally beat it in my head to just double check the dang firing order.... I had #3 and #4 swapped. It would idle OK but ran like a complete pig over 2000 rpm.

Backfiring is a sign that you are getting spark at the wrong time. Please check the firing order /ubbthreads/images/graemlins/smile.gif

Then we can talk about ignition timing.

It's the really stupid stuff that will bite your butt every time /ubbthreads/images/graemlins/smile.gif

Oh... and welcome to the Forum!

 

[TNTriumph]

I have a 59 tr3 and I had the same problem. The way I fixed it was a new set of spark plugs and a new coil and there was a world of difference. I would also listen to jsneddon about the firing order

 

[DougF]

How old is the gas? Today's new blends start losing their zip pretty quick(as soon the additives are added) and it goes down hill from there. If what you have is a couple years old, I would start there.
Little use allows connections to corrode. My opinion is that 99% of Lucas' bad rap is due to corroded connections and grounds. This may not have anything to do with your current problem, but cleaning and a follow up with an anti-corrosive/protectant will prevent problems down the road.
Pull you distributor cap and rotor. put a couple drops of oil on top of the shaft. The advance may be hanging up a little; if you are comfortable pulling the distributor, a good cleaning and lube might perform wonders.
Assuming that the car was running well when it came back from the mechanic, I wouldn't mess with the carb mixtures. In fact, I wouldn't mess with timing or any of those other adjustments since none of those things have changed from sitting.
Good luck!

 

[Geo Hahn]

[ QUOTE ]
I had exactly the same symptoms and after almost THREE MONTHS someone finally beat it in my head to just double check the dang firing order...

[/ QUOTE ]

/ubbthreads/images/graemlins/hammer.gif I guess I was the hammer that time.
/ubbthreads/images/graemlins/tongue.gif

Good advice, both the firing order check and returning to points and suspecting the coil & plug wires. Ignition systems are pretty simple but a failure anywhere along the line will present instantly noticeable symptoms.

BTW -- sounds like your fuel pump is electric (the original would have been mechanical) and this too could cause poor high rpm performance... but first and foremost I would suspect the ignition system.

 

[jsneddon]

[ QUOTE ]


/ubbthreads/images/graemlins/hammer.gif I guess I was the hammer that time.
/ubbthreads/images/graemlins/tongue.gif



[/ QUOTE ]

/ubbthreads/images/graemlins/lol.gif

actually Geo it wasn't so much of a hammer-beating as it was someone with a clear head to take it back to basics and start with the painfully obvious.

and I thank you again /ubbthreads/images/graemlins/cheers.gif

 

[Mac]

In addition to firing order, be sure you have dash pot oil and that the pistons are moving freely. I wouldn't use what you put in the crankcase but something a little lighter like 20 weight. Also, make sure the carbs are tuned properly (rich, lean, etc). Might also check the ignition timing and advance. mac

 

[MDCanaday]

I would be MUCH more concerned with the sticking regulator. You will have a serious fire quite soon if you ignore this little problem.My spin on the miss-fire is,did the coil get its polarity reversed with the rest of the system???If it has not been,it MUST be thrown away now and a new one installed.Once its been run backwards it too is a major fire hazard(dont ask me ,see the dark lord himself)....
MD(mad dog)

 

[zblu]

I use sewing machine oil in the carb pots

 

[Camping57]

I just had the same problem with my TR 3 and I fixed it, so it is not hard to do. If it was my car I would put the original dist. back in until it is running right and then put in the electronics.
I agree 100% with MDC that you need to replace the regulator. It will either cause a battery failure or leave you stranded. They are readily available and pretty cheap too.
First off, go out and check the firing order. Now go get a new set of plugs, once they foul it is hard to get them to run clean without quite a few miles of high RPM driving.
Now begins the fun part, and the real key to getting the car to run correctly. Pull out your repair manuals and put every one of the settings on the ignition and carbs back to the default settings as listed in the book. Start out with the point gap and then set the static timing. Next move onto the dashpots and then the adjusting nuts on the carbs. Then onto the choke pull off and butterflys.
At this point you should be able to get it to start and idle, but it will need more tuning. Now set the carb balance for the first time and then tweak the mixture using the adjusting nuts (you should be within about 1 - 2 flats from the initial setting) and then set the timing to run best at idle. Then back to the carb balance again and so forth until it is just right.
In my case I had done like you and tried all sorts of different adjustments until I had everything all messed up. It turned out that I had too much spark advance and I had one carb full lean and the other full rich to try to balance it out.
If you still have a miss after this it will be ignition so you should look at at the dist. cap and plug wires.

 

[vinceclortho]

Thanks for all the suggestions. We will check the firing order first. The car did run right after the initial change to negative ground and the electronic distrubutor. My dad went back later for a water pump and this is when the trouble started. Hopefully, the mechanic mixed up the wires. I'm sure the gas is old also. If we get it going, I'll refill it with new gas.