MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - bucket of bolts rocker assy

Hello Petrol heads
The midget 1275 engine in my Frog has been totally rebuilt. Runs fine but sounds like a bucket of bolts. (Tappet racket)
Its a cooking engine and I want it to stay that way, I just want it quieter!
Ive been told that roller rocker assembly is the way to go - BUT - I just want something that I can bolt into place without any other mods or hassle.
Sooooo, can any of you petrol heads avise me of a reasonably priced source of such acutrement? and indeed if you believe that this will acieve my aim? Minimal change, plug and play if possible.

By the way, I recently fitted an Alan Anstead roller thrust bearing to the car, and it works a treat..... just thought id throw that in for anyone interested. I have to say though, that I became near suicidal bleeding the bleeding clutch hydraulics - high bleed nipple and vac bleed finally cracked it.
Oh the joy of a friendly clutch!!!
Bob
R C Skerritt

There should be no need for roller rockers on a standard engine. There must still be some wear, somewhere.
Dave O'Neill 2

What is your valve clearance like? That is often the cause of a noisy engine. My 1500 was rebuilt and uses stock factory components and is very quiet. Mind you it isn't a 1275 but no reason apart from clearances not being correct that I can think of that will result in a noisy engine. Well, if all the bearings are within specification that is.

Clare
Clare Ravenwood

Bob,
quick thoughts -

. how recently rebuilt
. many miles on it
. what does the engine builder suggest
. what oil is in the engine
. as Clare, valve clearances
. is your rocker box cover the old metal type of bling modern
. any under bonnet insulation and/or body insulation
. have you got sensitive hearing
. are you sure it's the tappets, if so see all of above :)
Nigel Atkins

As Clare and Nigel on clearances, but you need to check for rocker shaft wear as well, which happily is easy. Choose a rocker that is slack with its valve open. Back off the adjuster and slide the rocker along the shaft against the spring. Now run your thumbnail along the underside of the shaft where the rocker was and feel for a wear ridge. If there is wear on the shaft no amount of tappet adjustment will make it quiet.

While you have the rocker away from the valve check for movement between the shaft and the rocker bush. It's less likely as the 1275s rockers are better designed than the 1500s and quite robust, but it's worth a feel.

Nigels point about the rockerbox cover is good. It's amazing how often you'll find a rocker politely tapping on the cover. It's one of those things that sounds worse than it is.

All of which assumes the noise is at the top of the engine and not something more ominous downstairs. But you did say tappet racket.
Greybeard

Hello folks
Thanks for your swift replies.
Definately sounds like tappets.
The engine was completely rebuilt with a new rocker shaft, new followers, 0 road miles ago. All new bearings and regrind, rebore new pistons new oil pump, seals etc care taken to make sure push rods went back in same holes.
Ive used classic grade 20/50 oil.
The rocker cover is Alloy, blingy! (I'll check to see if the rockers are trying to get out)
No under bonnet insulation its a Frog.
Wife recons i'm deaf as a post, but that may be selective hearing!
Ive adjusted the tappets at least five times, perhaps more.
Engine builder reccomended roller tappets, but i want to be as sure as possible.
I posted pictures of my rockers as I was assemblig the beast because I was concerned about rocker alignment but was advised that some minor missalignment was normal.
thanks peeps
Bob
R C Skerritt

Look for scuff marks inside the rocker cover but be aware they can be just slight, and very hard to see.

Have you checked for binding coils on the valve springs at full lift?
GuyW

Bob

Thank you for mentioning my roller clutch release. I should have suggested that you fit a remote bleed.

I have high lift rockers on my Sebring Rep. The hardened roller tops make it sound like a sewing machine.

I recently fitted a new rocker assembly to an engine for someone. The oil feed hole from the head to the rocker shaft pedestal did not line up at all and
had I fitted the assembly no oil would have got through to the rockers.
I countersunk the oil feed hole at the base of the rocker shaft pedestal with a large drill so that oil could again flow.

Only one of the four pedestals has an oil feed hole.

Alternatively it may be that whomsoever rebuilt your rockers has assembled the pedestals in the wrong sequence and that you are not getting any oil to the shaft.

Alan
Alan Anstead

Rod,
I wish I was clever enough to think of a rocker tapping the cover, I was thinking of the more general alloy covers cutting down on the amount of tappet noise heard compared to the original metal covers.
Nigel Atkins

A dry rocker will always squeak not rattle. You said you had a 'cooking' engine so I assume you mean it has been modified. Which cam and what clearances are you using? Roller rockers tend to be the noisiest and most clattery of all, followed by the forged/cast ones, with the sintered 'A' Plus rocker the quietest of the lot.I have these on my 1330 with a 544 and they are to all intents and purposes inaudible.
f pollock

Hmm, I thought 'cooking' was standard?
Dave O'Neill 2

I'm an old, old fart. In my day "cooking" meant standard unmodified. Sorry for confusion caused.
I will certainly check out the oil feed to the rocker shaft and rockers via the pedestals.
It seems that the advice I received about quietening it via roller rockers was incorrect, i've now heard that its likely more noisey with them fitted from a number of sources.
thanks
Bob
R C Skerritt

So, what does a sintered rocker look like? Are we talking about pressed steel?
R C Skerritt

We three must be old, I thought cooking was standard or perhaps a make-do as in cooking sherry/wine for drinking.
Nigel Atkins

This is a sintered rocker - picture from Minisport

Dave O'Neill 2

Sintered rocker http://www.minisport.com/cam289-standard-sintered-rocker-arm.html , IIRC from Vizard they were OK for standard applications but not good for upgrades, The pressed steel being good and easily strengthened with appropriate welds and if it failed it bent and didn't result in much damage.
David Billington

Make that 4! Cooking, when referring to engines, means standard, unmodified.
GuyW

Yes, what he meant was " really cookin' "
Nick and Cherry Scoop

Cherry's got sintered rockers. Reading about the manufacturing process, I don't really fancy them much. Metal powder, heated and pressed into shape, and no bush required because they are porous?

I must confess that they have worked fine for 10 years. But the other thing I don't like is the ratio. Keith Calver says:-
"1275 pressed steel (1.27:1)
forged original S (1.22:1)
latest sintered type (1.21:1)"

I don't really see how that can be, with the shaft in the same place, the pushrod in the same place, and the valve stem in the same place. It can only be the shape of the rocker tip, presumably, angling off to give less lift at maximum.

Nick and Cherry Scoop

1275 pressed steel rockers are actually 1.25:1 - at least they should be, according to the original drawing.

The amount of lift can be altered (slightly) by moving the centreline of the rocker pad radius in relation to the shaft.
Dave O'Neill 2

This thread was discussed between 13/07/2017 and 15/07/2017

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.