Fruitcake Type 4 engine rebuild - Finally started

This is a characteristic of the progressive, fortunately its adjustable.

Under the choke capsule there is an adjustment screw. This rides on a stepped cam attached to the choke mechanism. This sets.the cold idle speed.
When you stamp on the pedal once before starting this sets the idle RPM. The screw needs to be loosened until the idle is below 1000 RPM.
Because the idle is too bigh, the distributor winds in timing advance.
So you back off the fast idpe screw, rpm drops and the timing advance drops off fast and then you check the timing and its too retarded and the engine stops.
So you gently tweak the screw 5 degrees at a time and check and reset the timing advance on the distributor each time. Dont try too hard for 850RPM my engine will idle about 1500RPM if its warm and on the cold idle cam. Eventually the choke warms up and it drops the screw off the cam when you blip the throttle.
Now you can adjust the screw on the main throttle shaft. The wire linakage from the choke should be slack.
Again, its tiny changes on the throttle endtop screw and timing checks. Eventually it should idle at 850 rpm.. probably not for long as the manifold cools down....


If you can get it to TE I have a box of carburettor jets to try...

 

Seems to make sense Mike, I thought that the timing was set to 38 degrees BTDC at 3500 rpm? At the moment it's well north of 40 and even holding the revs high on the throttle it still dies if I retard it.
As soon as the service kit arrives I can put the carb back together and try your method.

As I've said previously it's never ran perfectly and has always had a flat spot but now it's undriveable, being an auto I need it to idle at a sensible level with drive engaged.

If the worst comes to the worst I'll try and trailer it to TE

 

I’m pretty sure I had a similar problem setting up my singleWeber after a rebuild. Timing was crazy high. I think my distributor drive gear was index incorrectly or I was using a rebuilt distributor with the notch in the wrong place because different guts were thrown in to the distributor body so the notch meant nothing. I was possibly reading timing off the wrong plug wire.

My worry with running the progressive long term was how puke rich it needed to be and how that would affect cylinder wall wear.

 

Not sure if I'm making progress with the bloody thing or not to be honest. I've fitted the cleaned and rebuilt carb, the choke mechanism clearly has never worked or done anything - it runs rich enough to start on most occasions.

I fired it up and wound up the idle until the engine was warm, I then backed off the timing whilst increasing the idle speed (as it naturally fell) and it now sits at 38 degrees at high revs. I've backed off the idle speed and it will idle, albeit too high.

The latest problem though is that cylinder No3 is eating plugs, they just die after a few minutes of running. I can hook up my strobe to No 3 and watch the plug just stop working!! When I remove the plug it looks fine but is permanently dead, it won't fire in one of the other cylinders.

So the engine runs fine for a few minutes, plug No3 dies, replace the plug and it runs for a few more minutes and so on. It's eaten my 4 spare plugs now

 

Very strange all round, damn shame you're so far away, I'd love to get my hands on it.

 

Post a picture of a dead plug, Paul, perhaps it might help jog someone's memory.

Too hot, too lean, timing wrong, what else would kill a plug?

 

28 dude - 28 when it will advance no more. 30 if you must, but type-4's generally prefer 28. 38 will kill it, it's fighting itself. Probably why it won't idle IMO, the combustion is trying to send the piston back the way it came!

 

I've got a set of 4 new plugs arriving today, I'll fit one and run it until it dies and post up the picture.

 

FFS you're right, I misread the post and mistook 28-30 for 38-40.

The irony is that I actually went to Specsavers last week and sitting here in my new glasses it's as clear as a bell

 

My honest opinion - put points in the distributor if you haven't already. Static time it to about 8-10 degs then leave it alone because it isn't the problem.
Only then do stuff to the carb.

I have no idea why it's eating plugs - dodgy HT lead would be my guess but I couldn't explain why - something to do with increased resistance needing more V to still be enough to jump the gap.

 

I swapped HT leads over after the second plug was eaten so I know the lead's ok, I have another distributor set up with points somewhere, I'll dig it out and fit it.

 

Cracked cap? You can't always see the crack.

 

Wouldn't the pre-ignition caused by the timing advance kill the plug? Or have I got this the wrong way around?

 

New plug fitted in No.3 and the timing set to 28 degrees BTDC. The spare distributor I have is fairly worn with old points and no condenser, currently the bus is fitted with an electronic ignition module, I have no idea what one it is as it came with the bus.

The plug is still hanging on after 10 mins so maybe the over advance was the issue as @F_Pantos suggested. It still struggles to idle though and I'm leaning towards an air leak as the revs also hang for a while before falling when blipping the throttle, there's nothing obvious but I've run out of brake cleaner to squirt around which should cause an increase in revs if it finds a leak. I'll pop into town over the weekend and get some as well as a set of points and a condenser.

 

Better news


Doesn't WD-40 do the same thing? With care, as ever!

 

Yes but it doesn't evaporate leaving no trace.

 

Right, I give up. As I'm getting nowhere fast I've towed up to its winter barn and it can stay there, the weather's too nice and I've got too many things to do without yellow snowing about trying to get the thing to run properly. I'll drag it out later in the year when I've got a clear head and a longer fuse

 

Can you get the lump back out and on the bank of a pickup, or trailer to TE?

 

I don't know if just bringing the engine would help, all we could do would be to take it to bits and put it back together again and maybe find an issue. The problem is runs like a bag of marmite. I could possibly get a trailer from a pal locally and bring it down but the weight bothers me a bit, my car weighs 1820KG, I think a Westy weighs 1500Kg and trailer is 600Kg which is about 300Kg overweight.