58 replies to this topic

[Da11yn]

Sounds like weak spark as you say it only splutters once starter disengages and the voltage increases. On a cold engine weak spark can make a massive difference to how quick an engine will fire. Check you have a good positive feed to the coil. Correct coil fitted for the wiring of the car. If possible swap the coil for a known working one to rule out the coil itself. I have wasted hours trying to get an engine to run playing with timing, fueling, did everything but change the coil, as it had only done 2 miles from new. Fired straight up when I swapped it for one I carry as a spare.

[crackfoo]

Sounds like weak spark as you say it only splutters once starter disengages and the voltage increases. On a cold engine weak spark can make a massive difference to how quick an engine will fire. Check you have a good positive feed to the coil. Correct coil fitted for the wiring of the car. If possible swap the coil for a known working one to rule out the coil itself. I have wasted hours trying to get an engine to run playing with timing, fueling, did everything but change the coil, as it had only done 2 miles from new. Fired straight up when I swapped it for one I carry as a spare.

I'm inclined to think it's something with the coil as well. I'm not too confident on its current wiring especially with the couple wires no going to anything. Though I think the wires were like that from the time I got it but perhaps it's been bad for the coil and was destin to fail. I think I need to get a new coil anyway if I'm going to put in an electric ingnition...

[crackfoo]

Anyone have any thoughts on my coil and wiring I described in this post

[crackfoo]

The weather warmed up to 0C so I thought I'd give'r a go again. Took out each plug, cleaned it with brake cleaner, dried them, touched up with a wire brush and double checked the gaps 0.30. All but one were pretty much right on, the odd one was 0.40. Took each connector on the coil off and made sure it was decent and good connection. This time I gave my air filters a blast of quick start and low and behold he fired up on the first crank.

 

He's running pretty rough compared to what he was before this problem occured, but it was also fairly mild out and now it's pretty cold and I had fiddled with timing/idle to try and get him going.

 

Pushing the throttle down gives him the shakes and doesn't seem to have the power from before. I'm guessing I'll need to recheck the mixture and air flow on each of my carbs. First gear seemed decent but each gear up got progressively less power. Exhaust is clean, no signs of smoke of any colour.

 

Not much time left to fiddle today so next warmish day I'll check the rest out.

 

I am getting an electronic ign so perhaps he'd enjoy new wires and plugs too...

[dklawson]

You said you are "getting" an electronic ignition which suggests you presently have points.  The values you listed for the spark plug gaps do not make sense for points regardless of inches or millimeters.  With points you should set the spark plug gap for a nominal value close to 0.025" [0.64mm].  With different plugs of different heat ranges you can open this up a bit to as much as 0.032" [.8mm]... but start at 0.025".  You cannot open the spark plug gap up effectively more than this until you switch to the electronic ignition.  This has to do with the charge/discharge times that are possible with electronic ignition vs mechanical points. 

 

When cleaning plugs, try not to wire brush them.  Wire brushes can leave metal traces behind on the ceramic insulators that are conductive paths.  The old school way was to sandblast them but there were issues with that as well.  Your safest bet is to spray the plug tips down with carb cleaner, clean with a toothbrush, blow dry, then heat the conductive tips of the plugs red hot with a torch to burn off the carbon deposits.  Allow to cool and reinstall.

 

After reading the above, my gut feeling is that you need to work through a complete tune up.  Start by adjusting the valve clearances with the engine cold.  Then fit new, gapped plugs.  Inspect each plug wire and replace the set if you find the wires are craze cracked or carbon tracked.  Likewise, inspect the cap and rotor.  Replace them if they are carbon tracked or cracked.  Fit a new set of points and a new condenser.  Set the points gap appropriately.  Make sure you oil the wick on the points and/or apply a thin film of grease to the 4-lobe cam under the rotor.  When you have done all these things you should feel confident that any remaining problem is with the fuel or air delivery.  Always save mixture adjustments for last after everything else has been made right.

[KernowCooper]

I'm with Doug run through a complete engine tune would be my steps if you brought it to me

[cal844]

I'm with Doug run through a complete engine tune would be my steps if you brought it to me

+1 and always start with the cheapest/free parts first!

[midridge2]

Try putting a new set of plugs in.

[crackfoo]

You said you are "getting" an electronic ignition which suggests you presently have points.  The values you listed for the spark plug gaps do not make sense for points regardless of inches or millimeters.  With points you should set the spark plug gap for a nominal value close to 0.025" [0.64mm].  With different plugs of different heat ranges you can open this up a bit to as much as 0.032" [.8mm]... but start at 0.025".  You cannot open the spark plug gap up effectively more than this until you switch to the electronic ignition.  This has to do with the charge/discharge times that are possible with electronic ignition vs mechanical points. 

 

When cleaning plugs, try not to wire brush them.  Wire brushes can leave metal traces behind on the ceramic insulators that are conductive paths.  The old school way was to sandblast them but there were issues with that as well.  Your safest bet is to spray the plug tips down with carb cleaner, clean with a toothbrush, blow dry, then heat the conductive tips of the plugs red hot with a torch to burn off the carbon deposits.  Allow to cool and reinstall.

 

After reading the above, my gut feeling is that you need to work through a complete tune up.  Start by adjusting the valve clearances with the engine cold.  Then fit new, gapped plugs.  Inspect each plug wire and replace the set if you find the wires are craze cracked or carbon tracked.  Likewise, inspect the cap and rotor.  Replace them if they are carbon tracked or cracked.  Fit a new set of points and a new condenser.  Set the points gap appropriately.  Make sure you oil the wick on the points and/or apply a thin film of grease to the 4-lobe cam under the rotor.  When you have done all these things you should feel confident that any remaining problem is with the fuel or air delivery.  Always save mixture adjustments for last after everything else has been made right.

 

I won't argue that it is likely in need of a good tune up. I'm getting on as best as I know how being my first carb'd car and appreciate the advise from you guys. It's tough being over seas with so few people to meet with and collaborate with. Very few of these cars around here and I don't know any of them.

 

I was using the dial gap setter and you're right those numbers were wrong, but I was setting them to 0.030. I'll pull them in a bit to the 0.025 mark and go from there. I am using the plugs that were in the car when I got it (NGK BPR6ES) , and no doubt are probably 10-14 yrs old. I think perhaps those are not actually the correct ones I should be using as with points I think I need the non R version?

 

Ok, I used a wire brush on the advice of the local shop that does brit cars. Didn't go to hard on them, but won't use it again. Just used some carb/brake cleaner and wiped them up good and dried them off. I didn't torch them, not something I have ATM.

 

I'll look into the valve clearances, are these also called the tappets? I've looked through some thread and with my 276 cam it seems appropriate gaps would be 0.015 ex & 0.012 in? The dizzy did get new points and condenser so will looks to find the appropriate gapping and make sure it's set to that. Visually I didn't see any carbon tracks on the inside of the cap, but the wires are pretty dirty and might have some carbon tracks. Something I'll have to look more closely next time I have a go at him.

 

Thanks!

Edited by crackfoo, 03 January 2015 - 03:00 AM.

[crackfoo]

Well today was really cold (-12C) but figured I'd at least get the plugs gapped properly. So I when out and that was the first thing I did. Perhaps I should have tried starting it first, but regardless, I set the gaps to 0.025 and then tried to start him up and got no love. Just turing over and over. Thought after giving him a little run yesterday that it wouldn't be such a problem. So pulled the plugs out, dried them off as they had fuel on them. They are running rich as they are black with carbon even after yesterday's run after they were cleaned. Something I'll look into once starting is sorted. While I had each one out, I checked for spark but today, there wasn't any. Well, not consistently.  I would only see a spark every few seconds at best... Found this odd as yesterday they were sparking fine. Checked my earths and they are fine etc... The lead coming out of my coil is in rough shape and rusty I noticed. I tried cleaning it up as best I could but didn't seem to make a difference...

[dklawson]

For tomorrow's test, disconnect and plug the fuel line coming from the pump and going to the carbs.  Try to start the engine.  If it fires, runs for a few minutes. then dies, you have an over fueling issue to deal with.  If there is no fire at all, tip a thimble of fuel down the carb throats.  Again try to start the engine.  If it fires to life and quickly dies, you have a low fuel delivery problem to deal with.  If neither condition causes the engine to run briefly, look for ignition and timing issues.

[crackfoo]

For tomorrow's test, disconnect and plug the fuel line coming from the pump and going to the carbs.  Try to start the engine.  If it fires, runs for a few minutes. then dies, you have an over fueling issue to deal with.  If there is no fire at all, tip a thimble of fuel down the carb throats.  Again try to start the engine.  If it fires to life and quickly dies, you have a low fuel delivery problem to deal with.  If neither condition causes the engine to run briefly, look for ignition and timing issues.

 

Ok, will be a few days before I can get at it again. While tomorrow is due to warm up to 0C, we're getting a snow storm of around 15-20cm of snow. Then back to work on Monday. Tuesday will try and check that. I won't be surprised if it turns out to be overfueling. He's been running rich since I got him. Would the lower temperatures exacerbate an over fueling/richness issue? Would running different plugs in the winter help at all?

 

While I don't think the timing is perfect, I think it's pretty decent. He was working really good... and I haven't changed anything that would have thrown that off, AFAIK. The dizzy was marked at a position when I got it and had pretty bad run on, I advanced it a degree perhaps two and the run on stopped and the power picked up significantly so have left it at that.

[dklawson]

Take everything one step at a time.  

 

The resistor plugs you have will be OK.  However, you don't want to use them with resistor plug wires (carbon fiber core plug wires).  Resistor plugs are much more common now but you may still find the "non-resistor" NGK's at some of the parts stores.  If not, ask for Champion N9Y (again... without the "R") I forget what the Bosch and Denso equivalents are.  Many people don't like Champions but they were the plug to have back in the day.

 

You can always set the static timing regardless of how the timing was set and marked before.  If you are unfamiliar with the procedure, let us know.

 

When cars sit it is very easy for their carb float valves to get "messed up", sticking closed or open.  It is easy enough to address either condition once you know it is present.

[crackfoo]

yeah I'll do the fuel test next before anything else.

 

I don't mind replacing as much as I can as I know everything on the car is old and I'd feel better knowing what is what and when it was put on. Plugs and wires seem to be simple items to replace and shouldn't add to the poor state of everything else.

 

I don't have a timing light so I'm limited as to the timing I can actually do, but static timing seems like it would be a good idea and would give a decent baseline. I should be able to find a thread here that talks about it, as I'm not sure how to do it right now.

 

We're building a new house that will have a garage but unfortunately not done for a couple more months so for now I have to deal with the weather exposure which I think is a factor that is adding to the difficulties. 

 

From today's storm

 

 B6gX9TtIUAAUhyr.jpg   25.55K   4 downloads

[dklawson]

I don't have a timing light so I'm limited as to the timing I can actually do, but static timing seems like it would be a good idea and would give a decent baseline. I should be able to find a thread here that talks about it, as I'm not sure how to do it right now.

 

 

Working outside in the weather is awful.  Hang in there and do the best you can.

 

Try the link below for my PDF on static timing.  Hopefully the link works and the file will be helpful.

https://sites.google...icTiming[1].pdf