Running getting worse

[Robbie693]

No it isn't!

I made a discovery - the connector that connects the condensor to the points had a poor connection on the black wire - barely a few strands were in contact, so I've been up to Aldon to get a new condensor and points. I got them to check the advance whilst there and they reckon it's fine (so did I but I wanted a second opinion). I put a few drops of oil down the shaft and a small amount of grease on the cam.

Now if I can just remember how to static time the ignition I can see if anything has improved!

Fingers crossed

Cheers

Robbie

[oldelanman]

Let's hope that's it.

If it's not too late already - don't forget to set the points gap before you put the distributor back in, it's a lot easier !

Good luck.

[Robbie693]

Hello - I'm back.

So, after some road testing it seemed initially that things had improved. With the water up to temp but before the engine got really hot I managed to pull max revs, there was a slight 'fluffing' as it passed 5500rpm but it pushed through this to the red line. Hurrah I thought!

Tried again a bit later in the drive home and it was back to as before, almost, choking up at 5500-6000rpm.

So I took it out again this morning it was a similar thing - ok before it got hot and reluctant to go much further when hot, although it did pull max revs eventually.

Then I tried Franks suggestion and put a spare distributor cap and leads on I had. Now it was worse - not much beyond 5000. Hmm maybe it is the leads then I thought. Went back to the garage and put the new leads/cap back on but it was still the same. I'm surmising that it's the hotter the engine gets that less it's inclined to rev.

Now I'm really stumped..

I'm having to do some armchair diagnoses as I've now got some work (self employed) so messing with cars will have to wait.

I'm wondering if the float settings I used are having an effect. I used the 16.5mm suggested in the manual for when there are signs of flooding:

"where there are signs of persistent flooding adjust the float level to 16.5mm and fit viton tipped needle valves"

Would this cause the symptoms I'm getting? Would the standard 15mm setting affect this? Anything else I can check or adjust?

Cheers

Robbie

[Frank Howard]

Robbie,

When you changed the cap and the leads and it ran worse, you were changing two things at the same time so you really don't know if it was the cap that made it run worse or if it was the leads. You've got to be more scientific about it. I know it's more work, but you should be experimenting with one variable at a time. Try changing the leads only. If that doesn't improve things, try changing the cap only. Best of luck.

[Robbie693]

Hi Frank,

You're right of course, it was just a quick test to satisfy my curiosity while I had a few minutes to spare. I also need to try the various combinations starting with a cold engine too. The thing that I don't get is why it didn't go back to as it was before when I put the newer bits back on, hence my heat theory.

Something I forgot to mention: I am also getting a surging effect when cruising along at around 60mph and spitting back when on a constant throttle opening at around 3000rpm. If that throws any light on the subject?

Cheers

Robbie

[bcmc33]

Robbie,

It may seem a bit extreme, but I have the distributer and Dellortos from my old engine before I went EFI. It will take an hour to fit them to see if it resolves you problems.

[neilsjuke]

replace the wire from the coil to the dist then hot wire from the solenoid to the coil to check you don't have a low tension intermittent fault in the wiring or ignition switch.
Neil
The other thing that comes to mind is a stretched worn timing chain and sprockets more so if it is a split chain there were some bad chains around .

[Robbie693]

Brian, Sounds like a great idea - thankyou very much. As I mentioned, I'm a bit tied up at the moment but I'll get in touch when I can see some spannering time coming up.


Neil, thanks. the coil to distributor wire I understand but when you say hot wire, do you mean connecting straight from solenoid to the coil? (Sorry, my sparks knowledge is minimal).

The chain is a split link type yes, I know it's adjusted properly but do you mean it may be stretching when under load?

I've not actually tried revving the engine that high without actually driving. Is it a no no to pull max revs while stationary?

Thanks again both

Robbie

[Higs]

Robbie

A misfire when hot is a classic symptom of a failing coil. They tend to short out when hot internally.

Have you tried an alternative one?

Richard

[Robbie693]

Hi Richard,

Yes, I replaced the coil but still no difference I'm afraid

Thanks

Robbie

[neilsjuke]

Answer yes to both and hot wire via cold-start resistor if fitted with a 10v coil .
and disconnect all the wires to the coil also if the car has a coil suppressor (radio ?) disconnect that as well .
Neil

[Robbie693]

Ok Thanks again Neil

[alaric]

Hi. While you're fiddling around with the electrics it would be agood idea to check the engine earth straps and the connections to the battery in the boot including where the negative connects to the chassis. I presume the engine turns over briskly on the starter, so wouldn't be surprised if this were not the problem, but it shouldn't do any harm and won't cost you anything.

Regards.

Sean.

[Robbie693]

Hi Sean,

Thanks - yes I'll check the earth straps. I already did the main earth for the battery as I read on here that it cured multiple problems for someone. No effect for me except cutting the radio interference down. Which was welcome all the same!

Cheers

Robbie

[Spyder fan]

Robbie,
I've read and re-read this whole thread and come to the following conclusion. If you are getting a misfire and no go over 4000rpm but your spark plugs are clean on inspection then you should definitely be looking at a fuelling problem. If the carbs and fuel pump were working properly and you got a misfire as described the plugs would be fouled by all the unburnt fuel.

Check: Fuel line not blocked by debris from rusty tank, this happened to me with my +2 but I got a big clue as I have a high pressure pump to supply the Jenvey throttle bodies and it started squealing in protest at running dry. I managed to crawl home at small throttle openings and way under 4000 revs as just about enough fuel was able to get through, trying to go faster caused a misfire. Spitting and crackling from Webers or Dellorto's is caused by weak fuel mixture which is why they do it on the over run, spitting and crackling at part throttle openings is due to fuel starvation.

Check: Mechanical fuel pump, remove it and inspect the diaphragm or better still get a pressure gauge on it.

Once you have checked and discounted the above take up the kind offer from Brian Clarke and fit his carbs. Your carbs were rebuilt, but to what standard is unclear? It's unlikely given my reasoning on the fuelling and the clues in your posts that the distributor is at fault, but maybe fit that as well because Brian knows that the 2 worked together in the past.

I'm not up to scratch on Dellorto's, but on Webers a major cause for carburettor malfunction is the failure of the rebuilder to replace the pump jet washers when reassembling.

Good luck, hope I'm right and that your nightmare will soon be over.