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MG MGB Technical - Engine rebuild - starting time!!

After nearly 6 months of rebuild, I've just started the engine for the first time. Replacement crankshaft, new shells, 60 thou rebore, new pistons, HR270 cam with Peter Burgess Fast Road head. I'd set the valve clearances and static timed the ignition. The carbs were as I took them off in December. Freshly charged battery. I got oil pressure after 20 or 30 seconds cranking having filled up everything I could get at with oil previously. That was last night. Tonight engine started with 10 seconds and an oil pressure of just under 70 psi. I left the engine running at 2500 rpm for 17 minutes before switching off and finding out why the engine sounded like a bag full of spanners and firing on 3 cylinders (ok maybe not that bad). I was loath to switch off before as everyone says it could compromise the bedding in period of the camshaft otherwise. I eventually found a valve clearance which was way out. Obviously something wasn't seated properly before. I rechecked all the other clearances although the engine was warm. They all appeared ok. Started up again and running better so ran at 2500 rpm for a further 10 minutes just to be sure.
The engine still sounds very 'tappety'. I'll recheck clearances tomorrow when the engine is cold. I'm presuming a clearance of 15 thou as per book. Then its dynamic ignition timing and carb setup. Maybe I'll have time for some Jubilee celebrations after all.
Steve Church

Hi Steve

Glad engine is 'alive'. Inlet setting 16thou cold and ex 18 thou cold. take off three thou if warm.

Peter Burgess Tuning

Will use those tomorrow Peter. I think some sound deadening to line the bonnet with to mask the clatter. What do they say, "a noisey tappet is a happy tappet" !
Steve Church

BMC A and B series engines always were tappetty in my experience. I started my 1275 Midget last Monday for the first time in about 15 years and went through the same set of emotions as you - "What a racket" was the first thought. But it settled down and is running well now. Got it's MOT yesterday and a nice new (free) tax disc, so its ready to go.
Mike Howlett

Hi Steve,
V pleased you've made it work again after all the trials and tribulations ;0).
Refitting the carbs as removed will get you going but with the level of "tune" the engine has now it's likely a different set of needles will be required. Are you planning a trip to Peter's for the full RR set-up? It will be petrol well used...

M McAndrew

I believe the needles are already one step up. No 6 instead of 5 (?). I don't have a set of K&Ns yet but intend to soon. I have already discarded the air filter cans and used a one piece aluminium plate bolted over the stock air filters. I shall replace these with the K&N equivalents.

I took the car out for a short drive this morning. Nothing fell off or blew up! I have to run the engine in for a few hundred miles before I can tell just how effective the mods have been. I'm contemplating a long weekend in Derbyshire to incorporate a trip to Peters RR but need to make sure that the ignition system is up to scratch beforehand. I noted an anomoly yesterday when I had the timing light on it. I have yet to investigate. Lots of things (non MGB) going on this weekend so no opportunity yet to spend quality time with my 'B. Hopefully Monday.

Steve Church

Hope you have more success than me. I re-built an engine, almost identical to yours. I balanced everything to within an inch of it's life, gas flowed the heads, Peter B did the inserts etc., Piper HR 270. It vibrates like hell!!! Can't work out why, it delivers good power and torque. Will check cam timing and change front damper/pulley. Am on verge of pulling it, or putting in a V8!!!!!
Allan Reeling

This thread was discussed between 01/06/2012 and 02/06/2012

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