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MG MGB Technical - tapping/ticking noise on acceleration

I just noticed today on the way back home form work that under a load when accelerating I here a ticking noise. It seems to happen at all RPMs when hard accelerating. I have never noticed this before

The facts
Engine is a rebuilt form Glen Towery and has about 5K on it
I do not here the noise when sitting in neutral and revving the engine
I had an empty tank and filled up with a low grade fuel
The distributor is a mechanical advanced dual point distributor that was converted to a module
Besides for the ticking the engine runs great
No lack of performance
The carb is a Weber down draft
The engine temp was about half way on the gage
The outside temp was in the 90s
The noise does not sound rhythmic

Could it be the low grade fuel?
Any other ideas

Thanks
Bob
RSF Bob Fowler

My first impression is that you may have an exhaust leak - could be a leak in the intake/exhaust gasket, or in the "donuts" between the exhaust manifold and the 2-to-1 pipe. I had the exact same symptom a few months ago, which progressed to a larger loud leak. In my case it was the donuts, which were very difficult to get out. I ended up strapping the whole system to the roof of my other car and taking it to a muffler shop. Twenty minutes later (and quite a bit of acetylene) he had them out.
The studs/nuts in the manifold are often hard to get apart without breaking them. I had to have a couple replaced. Now it purrs like a kitten.

HTH,

Erick
Erick Vesterback

I would try retarding your timing a bit to see of that helps. Your filling with low grade fuel comment is why I say this. Pinging, pinking, preignition, whatever you call it can be kind of like a ticking sound. Some even call it knocking (some cars have a knock sensor that retards timing automatically when it hears a knock), but that may be a more severe case than yours.

Anyway, either retard timing or drive with less throttle until you use up the low octane gas. Then put in a higher grade and see if it's better. Then you can decide if you need to continue using more expensive gas (and still maybe retard a bit), or retard more and use the cheaper stuff.

Tell us what happens.

Tom

Thanks for the advise.

BTW this is a 79 MGB (forgot to mention that)

Bob

RSF Bob Fowler

Aren't there octane booster additives that can be used? If so, try adding that and seeing if it helps.

BH
BH Davis

I misread the part about the noise not being rhythmic, so my previous post may not be valid! Does the sound seem like pinking, or does it sound more like a valve is out of adjustment, but only when on the throttle?
Pinking is a timing/compression ratio issue, which is worsened by low octane fuel, as the others have said.

Erick
Erick Vesterback

well I used about half the tank and then put in a higher octane fuel in.
The Pinking has stopped.

Thanks for the advise

Bob
RSF Bob Fowler

This thread was discussed between 07/09/2007 and 08/09/2007

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