19 replies to this topic

[fenghuang]

I'm trying to get it running well enough to get an MOT at the moment. A rolling road is on the To Do list when it's road legal.

[tiger99]

Specifically, if the distributor is worn, at least two different things can happen, which are identifiable.

 

Firstly, if the shaft bearings are worn, which can happen very suddenly, there will be side play on the cam, which can be felt by just giving it a wiggle. It will be difficult to maintain the correct points gap, if you still have points, and the timing will jitter about all over the place.

 

Secondly, if the advance-retard mechanism is worn, the advance curve may be wrong, and the timing may be jittery. Check that it is not sticking by twisting the rotor arm and ensuring that it springs back.

 

I would first put a good old fashioned timing light (strobe) on it, and hold the revs at say 1000 rpm. Is the mark in the same position with every flash of the strobe, or does it seem to jitter between multiple positions? Repeat at say 2000 rpm, 3000 rpm etc. That will identify wear in any part of the distributor drive train including its internals, skew gears, camshaft end float, timing chain and gears.

 

Temporarily block off the vacuum advance pipe. Use the strobe to check the amount of advance at various points in the rev range and compare with whatever is specified for your exact engine. If it is out by say 5 degrees all the way from idle to max, then just adjust the static timing, job done. But if it diverges badly from spec then a rebuilt distributor is probably required. Don't use a Mini specialist for that, the Distributor Doctor is best.

 

http://www.distributordoctor.com/

 

But my preference is to make all this 100 year old stuff a thing of the past and fit a modern fully mappable electronic system.

[Spider]

 

 

A Yellow flame [...] generally shows a rich mixture [...] Ignition timing will have little effect on this.

 

A few things here. At idle with Carbs, the mixture tends to be on the rich side and that's normal. If this is occurring even at around 1500 RPMs or higher, then I'd be looking at the float bowl level and / or the fuel pump pressure, on that the suspicion being that one or the other (or both) are too high.

 

Also, check the needle and the the jet are not worn. [...]

 

[...] you maybe running with needle(s) for 0.090" Jets, but have a 0.100" jet in there, [...] a simple check all the same.

The float bowl and float have been replaced, and I'm pretty sure I adjusted the float correctly. But I can check. If the float is working ok, my guess is that that should rule out the possibility of excessive pressure from the fuel pump. Yes/no?

(As above) the needle and jet are both new.

How would I tell what size the jets and needle are?

 

 

 

Carb - HS4 (FZX1146 ... assuming it's the right tag on the carb)

Manifold - Minispares Stage 1

Fuel pump - standard (old) mechanical (but more than that I don't know)

 

Best way to check the Float level is to run the car then switch off, just a minute will do.

 

Remove the Bell from the top of the Carb and look down the Jet. The fuel level, while not easy to determine exactly, it should be 10 - 15 mm below the top of the Jet.

 

If it's higher than that, then it will cause the engine to flood. It could be that it's set too high in the float bowl (and you need impossible to get aluminum or copper washers to adjust) or the fuel pressure is too high.

 

Test the Fuel Pump Pressure with a gauge, needs to be 2.5 - 3.5 PSI for an SU.

 

I've had a number of mechanical pumps in recent times with high pressure.

[fenghuang]

Correct me if I'm wrong, but this sounds like how to do it on a HIF?

The engine is now running ok, so I think I'll assume the pump is ok. But I'll bear it in mind for future adventures into the dark and greasy world of Behind The Block <cue screams>

Edited by fenghuang, 26 July 2016 - 07:04 AM.

[Spider]

Correct me if I'm wrong, but this sounds like how to do it on a HIF?

The engine is now running ok, so I think I'll assume the pump is ok. But I'll bear it in mind for future adventures into the dark and greasy world of Behind The Block <cue screams>

 

Works just as well on a HS too.

 

And I hear your screams - all the way from here!

 

<EDIT: In regards to over-pressurisation from a Mechanical Pump, I've had two in recent times do just this. I do check the pressure of them when I fit them as a matter of course, but the one that was on the Missus Moke, after 3 - 4 years was flooding something chronic. When I rechecked the pressure, it was around 7 PSI, but when first fitted was just under 3 PSI. A mate had a similar experience (and I think the same type of pump).

 

I haven't had time to pull them down to work out why and how the pressure can go up, but it happens. Yes, I'd expect it to drop off with time as the pressure is determined by the spring within them. >

Edited by Moke Spider, 26 July 2016 - 08:20 AM.