Hot engine won't start

Choke on this carbie is an "enrichment device" - opens up an extra jet. From memory it has only two stages -i.e. it is not progressive. The inability to adjust the idling suggests the mixture is too rich beyond the range of adjustment to compensate. This may be because of internal leaks in the carburetter or because the petrol level is too high (worn needle and seat of leaky float) or possibly excessive fuel pressure . Sounds as if it could do with an overhaul. But the ignition problems you have indicated could be enough to cause your problems.

John

You're correct about the choke John, it has a three position detent (albeit not a very positive one) - 'rich', 'warm up' and 'normal'. i.e. two choke positions, as you said.

You need to be able to get a 10mm+ SHARP BLUE spark, not a 5mm FURRY YELLOW spark from the plug end of all of the leads. If not, trace the line back to the coil, and replace the falty part. Mine was the carbon brush in the centre of the distributor cap. I replaced the carbon brush only, for about $1.

Aaron.

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Originally Posted by Aaron IIA

I replaced the carbon brush only, for about $1.

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Can you tell me where you got it from?

Well done Dave on your investigative servicing so far!

It is also a good idea to run the engine in the dark and look closely for any blue light from the high-tension leads, or emanating from the distributor cap. This is a much less painful way than feeling for the electric shock ;) If you see any blueness, replace the leads etc. with new ones.

The carburettor sounds like it needs a complete strip down and re-build, remember to check the throttle bushes for wear. I am at the same stage with my 80",

Cheers Charlie

The older type black PVC ignition leads with a copper conductor, are becoming nigh on impossible to find these days.... believe it or not REPCO still stock the stuff and sell it per metre ( about 2$ a metre ) .... You have to cut it to length and fit accordingly . I haven't bought any for a while ... so ask at your local store . I think it is slightly thinner than the original stuff.. but beggars can't be choosers .

The condenser I used is a Bosch unit I think.. on the shelf at Super C Auto .. It's physically same dimension as the original ..I cannot find the package it came in . Don't know if its he same uf, I mean the same capacity .. you'd need a capacity meter to check that out ..I think the average automotive cap. is around .025 uf . .. they reckon too much or too little burns the points .

Mike

Well I'm completely lost now... :(
After setting the spark plug gaps back to .030", fitting an electric water temp gauge (as the 'original' mechanical one was stuffed), and trying to get the oil pressure switch to work (almost got it!) I try to start her up so I can see if the temp gauge works. Can I start it? NO.:mad:
Freshly charged battery, good spark from the HT leads, crank... crank... crank... etc.
Remembered fiddling with the volume screw on the carbi so I set that back to where I estimate it was. crank... crank... crank... etc.
Finally give up on the cold start procedure push the choke in, put the foot to the floor, crank... crank... crank... and it fires up!
Idles okay for long enough for the temp gauge to register something - because of the size of the thread I had to use a sensor I found kicking around in my parts box and I didn't know if it worked at all, let alone with my nice new Centigrade gauge. It seems to work, yay! :D
For some reason I decide to rev the engine for a bit. Engine revs up for maybe a minute and then dies.
Now I can't start the engine hot or cold.:(

I know, I know... carbi overhaul.

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Originally Posted by series1buff

The older type black PVC ignition leads with a copper conductor, are becoming nigh on impossible to find these days....

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Mike, I got some from the 'Vintage Wiring Harness' stand at Eastern Creek earlier this year. Fits in the dizzy very well and looks identical to the stuff that's currently there. Search for vinwire if you're interested. ;)

Narva still market a copper core ignition wire. I buy it by the meter at the local shop. Anybody who stocks Narva produts can order it in. Another local shop sells cotton covered copper core ignition wire in black and brown multi-colour. This is more expensive than the Narva product.

The carbon brush, I bought from the local car parts shop (independant). It was a Bosch product. It was a generic distributor cap brush. You need to have a decent amount of brush springing out from the cap to ensure that it contacts the rotor button.

I still think your problem may be weak spark. Have you checked how long a spark you can get? You need at least 10mm at the plug, preferably more.

Aaron.

I agree with Aaron; it seems that the carburettor is delivering petrol otherwise it would not have run at all.

Presumably the compression pressures are adequate, which is another reason for hard-starting, so I would be most suspicious of the coil.

I once had tremendous trouble with the coil in my P6, which would behave erratically, but substituting an ancient old coil off my saw bench proved it to be the culprit. The visual difference in spark was barely noticeable as well, to further confuse the issue. Try substituting one off any of your cars, you will only need it for ten minutes and can then return it. New coils are only about $35 so it is not a disaster to buy one and then find it was not needed,

Cheers Charlie