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MG MGB Technical - Engine Work Necessary?

My 73 CB Roadster is a hobby I have been tinkering with for 3/4 years now. Having refurbished the suspension last winter, I now am planning next winters project - a full strip and refurbishment of the engine bay (it needs it!).

In pulling the engine it makes sense to have it checked and given the amount of fun we have driving it, I am looking to extract a little more power from it by having the cylinder head reworked, probably to Peter Burgess' Fast Road standard. Nothing silly mind you!

The engine is an Ivor Searle remanufactured leadfree engine fitted in 2003 and has done 30,000 miles since. There are no obvious signs of engine fault, loss of oil, high temps, etc.

Should I be prioritising other issues, such as camshafts, reboring, or other areas to be checked first before potentially wasting money on a new cylinder head? At 30k surely the engine does not need refurbishing again?

Grateful for suggestions, or pointers, experiences or other advice!
A Riddett

If you've had no issues with it, I'd leave it alone.

I'm planning on fitting one of Peter's Econotune heads when I finally get mine back together.
Dave O'Neill2

The only thing you should probably do is change the shells, the WSM does advise changing these at 30-50k 'for maximum service life', presumably of the crankshaft. I don't know about a 4-cylinder but I checked the shells on my V8 for the first time in about 100k a year or so ago, and found them all at or just inside the tolerance for *new* shells with no copper showing. They were also standards, which meant the crank had done 200k, and the journals were all highly polished with barely a mark. Pretty good, but then the MGB V8 is under-stressed.
PaulH Solihull

The most bang for your bucks comes from the head. Peter will point you in the right direction. But pointless having a "good" head without a "good" exhaust, good inlet, and carbs and dizzy in good nick. You see how one thing leads to another!!!!
Allan Reeling

as long as the oil has be changed regularly there should be very little to do.... shells would be done as a matter of course and as Allan says the head gets the most bang. One of Peter's will be a good choice.
But wait a minute,Ivor Searle's have a good rep... Do you know anything about the spec. of the head fitted before you splash the cash?
I would plan to take a peek and assess what you have before deciding what to do. Take the carbs off and check to see if the inlet ports have been worked on. Take the rocker cover off and check the valve lift for none standard lift. You might find it's been done if you are lucky. Check the needles fitted to the carbs are standard as rich ones would indicate a none standard engine.
But if money's no object go for it...

MGmike
M McAndrew

30,000 could be quite a lot on a repro camshaft, that is why we use billet cams only for B and A series engines. If the engine is being stripped new bearings and probably new piston rings would be good.

With regard to head specs we have always understood 'shades of grey' and are happy to look over a head and suggest cost effective ways forward based on what we find when we look.

I agree with Allan about good dizzy, the carbs need to be in good condition. As far as ex systems go I reckon the standard system has always worked well although the Maniflow ones do liberate some bhp mid range and upwards.

Peter
Peter Burgess Tuning

Thanks all!

The bearing shells sounds like a complete engine strip and rebuild job - if it's necessary then I will investigate but would prefer not to as money is not, alas, abundant. The exhaust and carbs are standard, the latter serviced recently and in good working order with standard needles. The head does then sound like the right way forwards, and I have already considered adding an electronic distributor; several ideas beckon.

I will get on to Ivor Searle and see what was done, particularly the standard of camshaft. The head was converted to leadfree.

Peter, great to see your comment, I will endeavour to get TJ through it's MOT and head up your way sometime in the near future! The Avon address is a blog spoof, it's actually Portsmouth so a bit of a drive.
A Riddett

I was stuck in Avon until I managed to change my details after being goaded by Nigel Atkins , I cannot remember how to do it now :)
Peter Burgess Tuning

Wow, and I thought California Smog II was a hike. Yikes, MOT be gone damn spot. Of course Peter would advise trimetal shells I'd bet. FWIW, if you can't go the extra for Peco, we've seen seat of pants improvement with a clay extruded stock MGB exhaust manifold, and ceramic coating. Besides tight carb shafts and a Petronix ignition, the very best return for a pound spent is Peter's head work. I put his BVFR head with a P270 camshaft on the Eaton supercharger 6 years ago and produced 123 BHP and 133# torgue on the SAE dyno run with the K&N filter off. Cheers Vic
vem myers

Why not start with a compression test.
R Walker

"The bearing shells sounds like a complete engine strip and rebuild job"

Nope, the big ends can be done without removing anything else, maybe even in-situ (like on the V8). With the engine out the only additional thing to do the mains is remove the timing gear so you can lift the crank out. This is a lot easier and cheaper than the other things you are talking about. If you are planning to uprate the performance then not replacing the shells while the engine is out and partially stripped (seeing as how the timing gear will be off to change the cam anyway) is a false economy.
PaulH Solihull

Actually, FWIW, you can change all the shells with the engine in situ - removing the main bearing caps will allow the crank to drop enough for the top half of the shells to be tapped round the shaft and removed.
Chris at Octarine Services

Wait and see what you find when you take the head off ... I had an Ivor Searle engine on Primerose, and had made all these plans on what I was going to do to the engine - took the head off - to discover it already had +40 pistons on anyway!!!!!!! I checked through the past receipts that came with her - and, sure enough - just one for "Ivor Searle replacement engine"!!!!
rachmacb

Thanks all, some good advice there. So bearings it is, but definitely going to get the head done at some point. Time to get studying the books then!!
A Riddett

This thread was discussed between 11/04/2012 and 28/04/2012

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