Rebuilt engine firing on 2 cylinders

[Ivor Hawkins]

Excellent news, have a great trip to the dales Jack!

[Oxford Jack]

An update:
I had covered nearly 500 miles of running in, gradually refining various aspects, retightened the head, adjusted the tappets, etc. I found the engine to by rather harsh on pick-up and accelerating, at around 35 mph however it seemed to gain power and smooth out, running quite nicely at 40 (true speed by sat nav)
On Wednesday I called on Ivor while adding some more miles, his observation of the engine while the car was stationery, was the same "a bit hard". We discussed possible causes and while relating the history and what I had done, we came to the conclusion that it might have a slightly lumpy cam and that my fitting an HC head in place of the LC fitted might have not suited the purpose of Dave Orange.
I thought about it overnight and on Thursday bit the bullet and refitted the LC head. The engine was immediately softer in sound and a test drive of 20 miles or so revealed that the harshness had been much reduced and there was no appreciable loss of performance, indeed it still seems to pick up its heels and is happy at 40+ (I am keeping the reins in a bit until the 500 mile oil change tomorrow.
My conclusion is that the tappet profile might be a bit fierce, it may have a modified cam, it was built with larger inlet valves and intended to run well on an LC head. 
On Sunday we set off for the Dales (200 miles) intend to cover about 80 miles a day for 4 days and then 200 miles home. I shall be happy if it continues to run as it did after the head  change.
Thanks Ivor for the suggestion and providing the nudge to actually do it!

[JonE]

OJ - what IS the tappet profile here? - is it flattened but still radiused at both edges? Or something more severe?

[Oxford Jack]

Hi JonE,
I regret I did not take much notice of the profile, I did notice that it is a constant radius I think, rather than shoulders and a flat top, but I cannot say what dimension. At the time I was more involved with unsticking the valve stems and ensuring the cam followers were not cracked, tidying up the tappet screws and lock nuts.
It will have to do for the moment, we leave for Parts Northern tomorrow.

[Ivor Hawkins]

Have a great trip Jack and nice to see you and the car in fine form!

[Oxford Jack]

I am not entirely happy with the results so far. The engine is really noisy under load, it does however pull well at higher revs, it has an uneven exhaust note and poor low down torque.
I can sometimes see vapour blowing out of the SU carb when blipping the throttle, and the I think the main rear bearing is in need of attention. When accelerating the engine sounds like stones being swirled around in a bucket of water, grumbling, rumbling, but not evenly. As soon as the throttle is eased that satisfying purr is heard even at speeds over 40. It is sluggish when pulling away or if dropping a gear is left too long. I have been working on the timing and can find a point at which there is power, in advance of which the rumble becomes unbearable and no increase in power. 
I think its going to have to be engine out and a strip to examine the noisy bits, timing gears, front and rear mains, cam, followers, flywheel, balance etc

[Ivor Hawkins]

The performance issue sounds a lot like cam timing to me and the noise is classic mains...that is disappointing as in theory that should have been a cracking motor.

[flywheel1935]

Hi Oxford, if you go to page 5 and see my thread on "Why is my sump filling with oil" I had exactly as you described, got to set timing at 20 degrees BTC, Champion D16 plugs, and dropped valve in carb to lower float level, now runs a drives OK, But loose oil slinger made horrible noise at speed, so f/wheel is now off to resolve.
forgot to mention, this is also on a new 'fully rebuilt' engine, with a few other tweeks.