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MG MGB Technical - Valve Cover (dressing up the engine)

Good evening,

I have a 1979 MGB with a Weber carb / Cannon header and Peco exhaust. Looks much nicer than the original set-up (Zenith single carb and etc.) RUNS better too!

In Penna, I do not have to meet any emmissions requirements as it has Antique Plates.

My question is I read someplace that if the valve cover is changed, not only will it improve the appearance of the engine bay, but would make the valves a little less noisy.

Is there any truth to this?

And if my current set-up doesn't use the emmission equipment (it's all removed) then is it ok to purchase the valve cover without the vent pipe?

Looking forward to your replies.

Don 1979 mgb roadster
Donald Wheeler

I believe the valve cover without a vent pipe has a vented oil fill cap - at least mine does. I didn't notice much of a change in valve noise.
There have been many posts in the past about having the proper spacer (or something like that) on the factory rocker cover, or it will transmit noise. Its been so many years since I installed the old cover I can't remember the details. Its in the archives though.
Jeff Schlemmer

I prefer the honest pressed steel engineered down to last ha'penny factory fit. But it's your car.
Stan Best

"but would make the valves a little less noisy". ?

yes - but only a little less.

No truth in that at all. Aluminium never suppressed noise in its life in fact quite the opposite.
Iain MacKintosh

In most cases noisy valves are a sign for worn out rocker assy's. Having covered 60.000 miles or so, it is a good idea to spend the money for an exchange there than to try it with an light alloy rockercover.
By the way, Lindsey Porter was the first who wrote about this nonsense.
Go and ask someone at your local speed shop, they are selling such items for the V8's and never argue this way although it looks great.


i have an alloy cover - looks good, sounds much the same as it did with a steel cover. i have got my clearances correct, and so i am now presuming that top end noise is a feature of these engines. doesnt worry me too much, can hardly hear it in the car. always worse until the engine is warmed, then its no worse than any other old engine (my mechanic friend just usually smiles, chucks his fag on the floor and says something about old pushrod engines not being designed to purr, or at least thats what i think he is saying, its all beginning with F usually).
i should add that years of loud music has done little for my hearing at the best of times.
m rae

I can imagine a cast cover transmitting less noise than a pressed cover, but would never fit one for that reason or for appearance.

I've not heard of rocker cover spacers limiting noise (although they may well do), the rubber washers (under the cup washers) are there to give the correct compression of the cork gasket and hence a good seal. Although that is dependant on the correct thickness of both washer and gasket, and I don't think current supply of one or both is what it should be, I had to add shims before I could get a decent seal.

How much of your emissions stuff has been removed? The canister and pipework? If so the vent on the rocker cover should have been sealed and a vented oil filler cap fitted at the time, or it can draw dirt and moisture into the engine, even though it is restricted. Sealing the vent, or replacing the rocker cover with a non-vented type, without fitting a vented oil filler cap will result in no through ventilation of the crankcase and the likely developing of condensation and corrosion.

Removing the air pump, gulp valve etc. is one thing but there is no good reason to remove the canister (except for one of space) and anti-run on valve which have only benefits.
Paul Hunt 2

Thanks all for the replies!

I think I will just put a new gasket on the old cover after I adjust the valves... maybe sand the cover down and give it a new coat of paint. (it already has a vented cap).

After all, with the top down, driving at normal speed who hears the valves anyway.

Safety fast,
Don 1979 MGB

Donald Wheeler

As far as valve adjustment there is an old saying, " It's better to hear them than smell them."
John H

John, I thought that comment was about the passenger...
Jeff Schlemmer

This thread was discussed between 20/02/2006 and 21/02/2006

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This thread is from the archive. The Live MG MGB Technical BBS is active now.