Rough Running - Any Advice

[John P]

I built my Ulsteroid from all sorts of bits many of which were completely worn or very corroded but I did rebuild the early coil engine with new bearings, a re-bore. Reground crank with new white metal big ends etc so I’m fairly sure it’s mechanically OK.

I fitted a 1 ¼” SU Carb from a Morris Minor (I think!) and more recently fed this with a 6-volt SU fuel pump. The SU has a new jet and the recommended needle. (Not totally sure which one but I think it may be an AN).

Anyway, the issue I have is that the engine has always run quite roughly and at tickover the exhaust not isn’t at all even, it actually seems to change in a repetitive cyclic way every few seconds.

I’m not sure if this is to be expected as the engine has oversized inlet valves, flattened cam followers and a late Ruby style head or whether there is something I should do about it.

The only questionable item is the distributor which is a DK4A type and does have some small amount of radial play in the shaft and also a very worn drive gear. I also have no idea how worn the auto-advance mechanism might be.

Any comments / recommendations,

John.

["Slack Alice" Simon]

I think you have answered your own question.

Borrow another distributor.

I prefer the manual ones, one less thing that might be wrong.

Play about with the timing.

[Dave Wortley]

Forget about the auto advance bit by loctiting the cam to the main shaft and use manual advance /retard on the steering column. Something to tinker with when you are driving! I have read somewhere in an A7 book that one variety of DK 4 cam is a superior shape. You can rebush the shaft as they are (were?) available from at least one of the cherished suppliers.

[Bob Culver]

Is the engine simply hunting due rich idle mixture? The SU is not intended for high pump pressure, often an unknown.

[John P]

Thanks for the comments.

I've had a more thorough look at the distributor and the radial play is probably enough to affect the points opening and hence the timing.

I don't really have the money to get it refurbished so was considering re-bushing it myself but, although I'm a retired engineer, I don't have much in the way of equipment apart from a light drilling machine and normal hand tools.

Has anyone on here done this themselves and if so how tricky was it?   I believe The Distributor Doctor may be able to supply bushes but presumably these would have to be reamed out after fitting.

Any advice would be much appreciated.

John.

[Roger]

John,
I fitted a pair of Distributor Doctor bushes (about £8.0) I believe.
The shaft was slightly worn so a reamer would have removed too much metal, I used fine wet ‘n dry on a wooden dowel by hand. To remove the old ones I made a washer the correct size with flats on to slide down so that I could pull each bush out in turn.
Fitting them needs care as they are thin in section, best to warm the distributor and freeze the bushes.
Make sure they enter squarely to start with and gently squeeze in place with a vice.
A vast improvement once it was all done well worth the time and effort.

Roger