MGB & GT Forum

Is this normal? looks different than the others, looks as though it's binding or something? And is wearing into the shaft. I opened the valve cover to investigate a rattle/spinning kind of noise that happens at all RPM's. Did a forum search and didn't see anything else like this. Thoughts?

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Jay D
"Bee Sting"
'77 MGB Mk. IV 1800CC
Weber 32/36 DGV Carb
Ported Intake
Pertronix Distributor
Early 70's exhaust manifold
Magnaflow muffler
Driven daily and loved daily
by a poor college student

And yes, the clock works.

Hard to see any wear without removing the rocker assembly. Compress the spring and run a fingernail across the surface...if it catches there's wear.

Very easy to pull the rocker assembly. Good chance to disassemble and completely clean all of the passages as well.

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"One test is worth a thousand expert opinions"--Alvin "Tex" Johnston...Boeing test pilot.

"Who do you think you are? I am."...Pete Weber

73 MGB. Tires: Round, black, hold air. Oil: Sometimes old, sometimes new...always slippery. Oil filter: Yellow, usually full of oil. Carbs: 2 SU HIF. Distributor: Yes. Headlights: Not that bright but bright enough. A bunch of other stuff most cars have but not really important enough to itemize. Oh, wait...it has a cool sounding exhaust with stickers on the chrome tips. Really slays the ladies...



Edited 1 time(s). Last edit at 2016-04-30 12:00 PM by HiPowerShooter.

That spring does not look right. It is bent. Whether that is causing it to bind or a bind caused it to happen I don't know.

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Eric Russell ~ Mebane, NC
1961 MGA #61, 1981 Alfa Romeo GTV6, 1984 Alfa Romeo Spider, 1991 Honda ST1100

I can see where it is worn, there's two silver lines where the spring is touching. If the noise I've been hearing was caused by this, it's only been a few miles so the wear isn't severe. No earthly idea how the spring got bent like that.

If I took apart the rocker assembly and replaced this spring, how easy is it to put the assembly back together? My dad says it'll be hard because of the spring tension but I don't think these springs are that tight.

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Jay D
"Bee Sting"
'77 MGB Mk. IV 1800CC
Weber 32/36 DGV Carb
Ported Intake
Pertronix Distributor
Early 70's exhaust manifold
Magnaflow muffler
Driven daily and loved daily
by a poor college student

And yes, the clock works.

There is no tension really. They're VERY easy to R&R. Just lay it on the bench, pull the cotter, disassemble and lay it all out in the order it was removed. If the shaft is excessively worn, it can be rotated 180deg as a temporary fix or to troubleshoot. If it's the rockers banging away, the noise will disappear.

If you need new parts; PM me...I have spares.

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"One test is worth a thousand expert opinions"--Alvin "Tex" Johnston...Boeing test pilot.

"Who do you think you are? I am."...Pete Weber

73 MGB. Tires: Round, black, hold air. Oil: Sometimes old, sometimes new...always slippery. Oil filter: Yellow, usually full of oil. Carbs: 2 SU HIF. Distributor: Yes. Headlights: Not that bright but bright enough. A bunch of other stuff most cars have but not really important enough to itemize. Oh, wait...it has a cool sounding exhaust with stickers on the chrome tips. Really slays the ladies...

With the rocker shaft off the engine that spring is easily replaced and there is practically no tension at all on it, so no worries there. You can easily compress that spring by hand. Frankly I'm not sure it's worth the trouble to change it...

That being said, I think it's highly unlikely that the spring touching the rocker shaft is causing any kind of an audible noise. I would look more deeply into the noise. Can you describe it in more detail? High pitched tap? Low pitched knock? Whirr? Grinding? Spinning rotational sound? Present with fan belt off? Present at all engine speeds? Only when engine is speeding up? Only when engine is slowing down? Only at steady state? Try pulling one spark plug wire at a time off while engine is running. Does this change the sound?

Dick

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Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

The noise is not related to RPM, it happens at idle, at speed, clutch in or out. Don't think it's anything fan belt related, I tightened all the pulleys and still have the noise.

It's like a rattle or spinning noise, that's about the best way I can describe it.

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Jay D
"Bee Sting"
'77 MGB Mk. IV 1800CC
Weber 32/36 DGV Carb
Ported Intake
Pertronix Distributor
Early 70's exhaust manifold
Magnaflow muffler
Driven daily and loved daily
by a poor college student

And yes, the clock works.

That spring is bent/twisted and needs to be replaced. Maybe it got caught on either the pedestal or the rocker arm, examine them for burrs. The springs are symmetrical and evenly wound. Follow the instructions in the service manual for removing and replacing the rocker assembly.

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Be safe out there.
Kenny

If you choose the above 'fix' you will need to drill a hole for the locating screw. Advice is to don't do this, unless you are very, very poor. A replacement shaft is only minor expense.



B

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Life's most persistent and urgent question is, "What are you doing for others?"

Actually the hole is drilled all the way through and for the purposes of trouble shooting it doesn't even need modification as there's plenty of purchase on the smaller hole for the grub screw. Add to that, the slight bend in the shaft due to the shims and you can easily flip the shaft for a short while. Most of the rocker wear occurs on the bottom side so when you "flip" it, the rockers are again nice and tight. If it cures the issue...buy a new shaft. If it doesn't, flip it back.

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"One test is worth a thousand expert opinions"--Alvin "Tex" Johnston...Boeing test pilot.

"Who do you think you are? I am."...Pete Weber

73 MGB. Tires: Round, black, hold air. Oil: Sometimes old, sometimes new...always slippery. Oil filter: Yellow, usually full of oil. Carbs: 2 SU HIF. Distributor: Yes. Headlights: Not that bright but bright enough. A bunch of other stuff most cars have but not really important enough to itemize. Oh, wait...it has a cool sounding exhaust with stickers on the chrome tips. Really slays the ladies...

I think that your father was referring to the valve springs being difficult to compress, when replacing the rocker shaft assembly, not the rocker arm spacers themselves. Your noise just might be a failing throwout bearing. It has all of the symptoms. RAY

It's not the throw out bearing. I just replaced that last summer. Also, the noise happens regardless of clutch action.

I think I discovered the problem. I have a sizable crack in my exhaust header. Pretty certain that's what the noise is, as I've had an '86 Raider with a cracked header that made a similar noise.

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Jay D
"Bee Sting"
'77 MGB Mk. IV 1800CC
Weber 32/36 DGV Carb
Ported Intake
Pertronix Distributor
Early 70's exhaust manifold
Magnaflow muffler
Driven daily and loved daily
by a poor college student

And yes, the clock works.

In that case, I would replace your header with a pre '75 stock cast iron exhaust manifold. Few headers can surpass the performance and lifespan of these units. RAY

Way ahead of you Ray.

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Jay D
"Bee Sting"
'77 MGB Mk. IV 1800CC
Weber 32/36 DGV Carb
Ported Intake
Pertronix Distributor
Early 70's exhaust manifold
Magnaflow muffler
Driven daily and loved daily
by a poor college student

And yes, the clock works.

Glad to hear it. RAY