Rebuilt engine firing on 2 cylinders

[Oxford Jack]

I bought an engine reputed to have been rebuilt about 15 years ago, dry stored and turned frequently on the handle. The rebuild was done for a client by someone I have not heard of before the surname being Orange or possibly the company, in the Midlands?
It arrived in seemingly excellent condition, complete with rebuilt dynamo, starter, dizzy, 1 1/8"th SU carb, new HT leads, new fastenings every where, painted, filled with oil and said to contain a Phoenix crank etc, it had a blanking plate over the fuel pump location. It had compression on turning by hand, so I decided not to take it apart but hope that it was going to run as well as it looked, I fitted a pump.
I installed it into my RP and connected everything. Turned the engine by hand to start the oil around the galleries, spun it on the starter without ignition until I had oil pressure. Switched on and it started, a small adjustment to the finger tight dizzy and it ran quite nicely for 30 seconds. Then there was a scuffing noise in time with the rotation, which lasted about 1 minute, did not sound serious but as if components were getting used to one another, which then stopped and the engine ran for about 2 minutes before beginning to slow and then stop. Following which it now runs on only 2 and 4. I have drained and refilled the tank to remove old fuel. I have swapped plugs, leads, caps and tried 2 different dizzies known to work ok, I have sparks at all 4 plugs. I can remove plugs 1 & 3 and it runs quite happily on 2 cylinders. I checked compression 115psi on 1 and 0psi on 3? So now I am thinking stuck valves perhaps on 3 or the cotter dropped out of the valve stem, but that does not explain 1 not firing?
I have had to pack it in for the day and am out tomorrow, so instead of ripping into it I thought I would ask if there is something you think I might have missed in diagnosing the problem. I am thinking that my next move will be to remove the manifold and valve chest cover to see what is happening in the valve department. However you may have better ideas, if so I would be grateful for the assembled wisdom please.
Thank you in anticipation
Jack

[Hugh Barnes]

If it was built by the late (and much missed) Dave Orange of the Essex Club, then it should come with some credibility as to the standard of the rebuild... Though that in itself, doesn't help with your problem I'm afraid...

[John Cornforth]

Hi

I'd wager valves stuck open.  Possibly the stems have some dried out oil deposit on them. A look in the valve chest and a check of clearances will reveal all.

[Ivor Hawkins]

Jack, I had a similar problem with the motor in my RP, I had a full photographic record of the rebuild and the old boy appeared to do a good job, a little penetrating fluid and some jiggling of the stuck valves and the motor runs like a Swiss watch.
So I’m in full agreement with John, ten bob it’s the valves!

[Ian McGowan]

Jack, I had a similar problem with the motor in my RP, I had a full photographic record of the rebuild and the old boy appeared to do a good job, a little penetrating fluid and some jiggling of the stuck valves and the motor runs like a Swiss watch.
So I’m in full agreement with John, ten bob it’s the valves!

+1

[JonE]

and you can probably check the crank by removing the oil filler pipe and putting a phone camera near the hole - the different forms/colour should show up with a bit of judicious turning.

[Robert Leigh]

When a friend had similar problems after a lay up period I went and removed only the valve cover and saw that two valves were not closing properly. I asked him to start it and keep it running while I leant on a large screwdriver inserted in turn into the springs of the two affected valves. If that is your problem the technique will save a lot of dismantling; if it is not you will not have wasted a lot of time trying. Good luck.

[Andy Bennett]

I learnt a lot from Dave Orange. Generous with his knowledge and a very skilled engineer and Austin 7 man. If you have one of his engines then you have a good buy.
He had a special he was building for the last 15 years of his life but never finished. The engineering was exceptional. Every time he built an engine someone wanted it so he sold it. I think the last one was measured at c.30bhp from a relatively standard set up and went to Japan.

Interestingly last year we had a workshop day where one of our members had a spare engine built by Dave about 15 years ago and unused since. It also had sticking valves from the lack of use that needed freeing. The rest of the engine was as clean and well protected as the day he rebuilt it.

Andy

[Oxford Jack]

Thank you all for the rapid response, warm words for Dave Orange and reassurance about the probable cause which restores confidence in the man, the engine and my hesitant diagnosis.
I will get back to it I hope on Friday and of course let you know the outcome. I shall sleep better tonight Zzzzzzzz

[Bob Culver]

If/when you take the valve cover off check that none of the guides have been displaced upward. Comfort yourself that it not one of those new fangled ohc jobs where stuck valves cause havoc.