MGB Register Forum

Quiet here at the moment!
As far as I know, my engine is a standard 1978 one.
The valve gear has always been a bit ticky, well a lot tickier than my Cortina and MM.
The car is in daily use, and runs well. I've been tempted reduce the clearance, but wisely, I think, refrained.
How do others find?

The top end of the B series is nearly impossible to get quiet (well not as much as you would like). I've renewed everything in my valvetrain - camshaft, followers, pushrods and rockershaft) and it still ticks. It's a bit quieter when it is stonking hot. I do the exhaust clearances fairly tight on the 15 thou feeler and the inlets to 13 thou which I think is safe as they don't get as hot and later cars were set to 13 thou in any case. I don't think the standard 252 deg cam changed over the years. (if only we could get hold of the profile drawing or at least the number). I use the rule of 9 to set which should work providing there is little base circle run out. My camshaft is Indian made but no worse than the original factory one in this respect. I believe the shafts are ground on centres which can lead to run out. I know some people faff around trying to find the point where the clearance is greatest, but I don't.

I have a Piper cam in my BGT which requires 15 thou clearances, so is usually quite ticky. I have had one valve which was louder than the others, I identified it by inserting a thin feeler gauge along the line of rockers with the engine running. Easy to identify the culprit and a little tightening made it much better.
This can be messy as oil gets splashed about, so you need covers either side of the engine to catch most of it.
I have to confess to never replacing the rockers or the pushrods. I have lashed out (pun intended!) and replaced the rocker shaft once, as the wear was quite noticeable.
Runs very well, and I would be more concerned about a quiet engine!

Ian F

Nice to know that it is normal for the valve gear to be ticky!

Like Ian, I seem to have one that is noisier than the others, despite clearance rechecks. Probably due to the business end of a rocker being indented?

I once tried Ian's way of checking clearances on a running engine many years ago. What a mess, and it didn't find the ticker either!

BMC A and B Series engines are known for noisy valve clearance even if everything is replaced and the correct gap set. It's something you'll have to live with. It's part of the charm of these engines.

Hi folks,
It is reassuring that others also have noisy tappets as I have been plagued ( and embarrassed ) by this for many years. I`ve checked the clearances on many occassions (all at 0.015") and tried using a feeler gauge whilst engine was running technique only to destroy the feeler and learnt nothing.
The engine always ran very well, on several occassions pushing on for very long distances at high cruising speeds (70-80mph) the noisy tappets nerver got any worse. As already mentioned, if it is quiet the gap maybe too tight it`s just the way they are. I think we are inclined to compare moden engines with highdraulic valves with those developed in the dark ages. If the engine is in good order don`t worry.

I remember reading about the Mercedes Grand Prix cars of the 1930's. If the engines began running quietly, Alfred Neubauer, the genius running the team, knew that failure was imminent. In this case I think it was flexing of the crank.
A ticking valve indicates it is closing - always a good thing!
Incidentally, I never try to set the clearances with the engine running, but inserting a thin feeler gauge with the engine running allows identification of the single irritating ticking of a valve which may be set just a little too wide.

Ian F

Loose valves won't cost you money__TIGHT ONES WILL!

That was drilled into my head when I bought my first (of 17-18 total) MGB back in 1973.

By whom? Bill Maciolek, a BMC dealer trained mechanic & MGB E-Production racer.

If you reduce the clearance to make the valves quieter, you'll almost certainly burn the edges of the exhaust valves (the ONLY time an exhaust valve can dissipate the combustion gas heat, is the time it spends in contact with the seat, and tighter clearance reduces that amount of time).

If the valve noise bothers you, install a better head-unit/amplifier__lots easier/cheaper than replacing the cylinder head and/or doing a valve job.
++

Sometimes if the hammer end of the rocker is worn the real clearance will be greater than that measured by the feeler gauge. You can get around this by using a dial gauge baring on the top of the rocker above the valve stem.

Only one rocker shaft pedestal has a grub screw to lock the shaft. The others rely on shims under the middle 2 to create a bending load. It is possible to drill the 3 plain pedestals and add grub screw to them. This will eliminate movement at those pedestals that could be a source of noise.

All modifications are at your own risk.

David Witham wrote: ↑Tue Dec 13, 2022 10:06 am Sometimes if the hammer end of the rocker is worn the real clearance will be greater than that measured by the feeler gauge. You can get around this by using a dial gauge baring on the top of the rocker above the valve stem.

Only one rocker shaft pedestal has a grub screw to lock the shaft. The others rely on shims under the middle 2 to create a bending load. It is possible to drill the 3 plain pedestals and add grub screw to them. This will eliminate movement at those pedestals that could be a source of noise.

All modifications are at your own risk.

Thanks David. I'm happy with the responses that these engines are top end noisy.
So I'll carry on putting up with it as I have done for the last 5 years!