Now running really rough-help?!?!

[77MidgetMkIV]

Hey all,

Well, I let work yesterday in the midget, everything running fine. I hopped on the highway, since I had to make a quick stop before heading home, and figured that it would be good to blow the car out a little. Ran it down about 8 miles on the HW at around60-65 MPH, and it ran great. I got off, and drove about a mile to my destination and parked. When I came out about 1 1/2 hours later, the car would barely keep running. at first, it wouldn't even start! I could only keep it running with heavy choke or high rev. After determining that I had oil pressure and good temp regardless, I limped the 5 miles home, stalling a couple times. When I got home, it was d-e-a-d. nothing. But it was acting like it does when it is getting no spark, so I am thinking it might be electrical. It just started this morning, but with the same rough run that needs a lot of choke to keep running. if left at idle, it runs so rough that it ends up stalling. I am thinking that possibly 1 or more cylinder is not firing? there is no way that the timing could get that screwed up on one ride, is there?

any advice?

thx
markfitz

 

[lesingepsycho]

Check the points. If you don't have the proper ballast resistor installed, it will over-heat the points in short order and it can even get so hot as to melt the small plastic bit that rides against the distributor shaft.

JACK

 

[77MidgetMkIV]

I will check that out right now. I have honestly never worked on distributors, other than new caps and rotors, so I am a little new to this. Where on these cars do I find the ballast resistor?

 

[77MidgetMkIV]

OK, so I went and looked at the distributor. Took off the cap and the rotor, and expected to find another cap plate that would come off exposing the points. Nope. I had a circular plate with 3 screws and 4 triangular points on the inner edge of the circle that surrounded an object that looked like a 4 pointed star, that was evidently attached to the distributor shaft. One of the screws had a wire attached to it. under and around the inner star shaped object was another semi loose collar that the wires were attached to. I have no idea how to get this off to check it. also, when I took off the circular ring with the 3 screws, I noticed that it had what appeared to be a magnetic gasket of some sort, and it had a crack in it near one of the screws. It was semi flexible. I know that when you break magnets, their poles reorientate themselves, so I am not sure if that has something to do with this. I have attached a crude drawing of what I saw.

 

[Thor]

You might take a look at the carb needle to make sure it hasn't worked loose. Mine did a similar thing this early Spring along with what appeared to be a malfunction electronic ignition. Two things happened at the same time. Image that.

Even after replacing the electronic ignition the car just won't start or if it did with full choke it ran poorly. I checked the carb and the needle had come loose.

Good luck

 

[lesingepsycho]

I would say it sounds very much like an ignition problem to me. I'm not as familiar with the later model ignitions and it sounds like yours may have been upgraded from original to some sort of breakerless trigger system. If you noticed visibly broken parts I would say there's your answer staring you in the face. Good luck!

JACK

 

[77MidgetMkIV]

Well, that is what I am thinking too. If it is the carb needle, then I will find that as well as the whole carb assembly is getting a "going over" next weekend. I will keep poking around. I also have a spare dizzy that I am going to check today for reference, though I think it might be the original, and not the same type as the one in there.

 

[77MidgetMkIV]

Well, the roughness is to rhythmic to be anything other than ignition. I examined the dizzy that I had that came in a box with the car, and it is an Opus type that perfectly matches my shop manual, so I think that was the original. The one in there is completely different. it appears to be electronic ignition type, and has the ignition module mounted right on the dizzy case. Anyone know what types of dizzys were bolt on swaps for the OE stuff that came with the Midgets? If I can get the type, I might be able to find some troubleshooting and part number information.

 

[jim79]

I dont know if this helps you any but I have a 25d (from 1974ish midget i think) distributor system on my 1979 midget 1500. It doesnt have any electronic components (just breaker points/coil) and it seems to be happy at the moment.

 

[77MidgetMkIV]

I have the Lucas Opus dizzy that was in it from the factory too; it came with the box of parts when I bought the car. For educational purposes, I would really like to fix the hitachi electronic one that is in there now. I have found some resources now, but am looking for a good schematic. If I can't get it fixed this week, though, the Lucas is going in.

 

[ThomP]

Diagnosis has to start somewhere. Make yourself comfortable that the ignition is OK. If it is still troublesome after that, ask your self why pulling on the choke helped with the ignition problem? This sounds more like a blocked fuel line to me. The loose needle is also a possibility, but fuel blockage is far more common. Just my 2 cents.

Hope you fid the culprit soon...

 

[77MidgetMkIV]

I completely agree.Checked the fuel line first. It is flowing fine. I am planning on checking the needle as well. The broken magnetic gasket "thing" that I found in the dizzy is curious, though. I am not dead set on the current dizzy being the problem, but it seems likely, given the way that it fires. Pulling the choke does not help the problem, per se, but rather it gets the RPM up enough so that the skip, misfire, or whatever it is, is not able to stall the engine.
Also, the skip, misfire, or whatever, is perfectly regular in cadence, once you listen to it for a minute. I picked up on that this morning.

 

[sparkydave]

Sounds like an unusual kind of distributor that's in there now. The Opus was okay until they usually died without any warning. If you still have the Z-S carb, make sure the diaphragm hasn't torn in addition to make sure the needle is still attached.

-Dave

 

[77MidgetMkIV]

Yeah. It is a hitachi electronic ignition dizzy from, as near as I can tell, a 1979 Datsun 510 (I have attached a pic from NAPAonline). It is an interesting design. The reluctor is a 4 point wheel that attaches to the end of the cam. Around that is the magnetic pickups, which is also 4 pointed. From what I can tell, when the 4 points align, the coil is directed to issue the charge to the plug, like a regular magnetic electronic dizzy. However, there is a layer between the outer pickup ring and the lower metal pickup plate, like a gasket, but it appears also to be magnetic.
On the plus side, I am learning a lot about ignition systems! This week, I am attacking the carb as well. I was working on that last week, however, and it was in tip top shape. And yes, it is a ZS.

 

[77_MG_Midget]

A distributor from a Datsun 510 will fit into the Triumph 1500 motor? This is interesting as my vacuum unit is shot and they are near impossible to find a replacement for.

 

[77MidgetMkIV]

It appears so, and up until Friday, it was running great! I will get the model number for you, but it appears to be from a 1979- prior to that, they used other types. You can get a reman'ed one for about 100-140 bucks, but the kicker is the ignition module that you need-that also runs up there, sometimes more even than the dizzy itself. I have not removed it from the car yet, though, so I cannot get a good idea of the modifications that needed to be done. If I pull it this week, I will get some pics for you.