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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 - HG Failure - postscript

I'm pleased to say that after all the trauma of my HG failure and broken rocker (see earlier threads), I'm up and running again!!

I took the opportunity to refurb the cylinder head with C-AEA526 valve springs and fitted my (spare) 1.5 ratio rockers. The latter are forged steel and have stronger adjustment screws. I no longer trust pressed steel rockers (not at high revs anyway). I would have fitted forged 1.3 ratio rockers but when Abingdon MG (David Manners) supplied me with some they came on old/early aluminium rocker pillars (which are c**p and would not fit anyway) and so I returned those and used my spare hi-lift ones. The engine seems even more revvy that ever although the roads round here are so heavily caked in salt that I've not road tested it yet.

Talking of hi-lift rockers, I checked in the archives and the consensus seems to be that valve clearances should be set at anywhere between 16-20 thou. I set mine to 16 though but they seem incredibly rattly so I don't know what they would be like at 20 thou. Is this other peoples experience?

Finally, many thanks to all on this BB who offered suggestions and especially to Dave O'Neil for visiting and having a go at diagnosing my troubles. Wishing you all a great Christmas and happy midgeting in 2012.

Chris
Chris H (1970 Midget 1275)

That's good progress Chris.

<<they seem incredibly rattly>> May be worth checking that they are not just kissing the inside of the rocker cover, especially if you are using an alloy one.
Guy

Guy
I never thought of that - but how can that be checked let alone recrified?
Chris H (1970 Midget 1275)

Look for telltale marks inside the cover?

Alternatively you can press some plasticine or some such (maybe even daubs of grease) on the highest point of the rocker assembly, replace the cover, and then turn the engine over for a few revs... remove the cover and look for grease on the inside or flattened plasticine.

Ah, the off season... when you have the time to catch up on your to-do list, but the weather and streets are too miserable to enjoy your handiwork!

Cheers,

-:G:-
Gryf Ketcherside

Chris,
I am no expert, but speak from my own experience. I fitted some 1.5 roller rockers and they clattered like hell. Without someone experienced to advise me otherwise, I just thought "yep, they are right roller rockers are noisy!"

But later, after close inspection I found that #1 was just skimming the inside of the alloy rocker cover - Difficult to tell, but there was a slight scuff mark showing where there hadn't been one before. 10 minutes with a Dremel was all it took to provide an extra 1/32" clearance at that end of the cover. Although admittedly still more noisy than standard, the drop in noise level was a revelation!
Guy

Mine are not roller rockers but Minispares forged rockers. I think they require less clearance than rollers but I will check along the line suggested by Gryf

Gryf - nice point about catching up with jobs but the weather being bad. There is heavy snow forecast for hereabouts (West Midlands)tonight, so no road test this weekend!!.
Chris H (1970 Midget 1275)

Chris,
Ship it over here to Florida. My Midget will be laid up for a while (see "Wrecked" thread) but the weather is 75 deg. Perfect for driving and I'd be happy to get your valve train sorted.

I'll get my hat. . .

Phil
Phil Burke

Phil

Sorry to read about your damaged Midget. I hope it gets sorted soon. In the meantime enjoy the sunshire (I'm jealous).
Chris H (1970 Midget 1275)

Chris,

I use the same rockers but I believe the camshaft spec dictates the final clearance.
With a Swiftune 05 I was advised to use 19 thou, which I have to recheck when the weather gets warmer. That'll next year then!
Derek Stewart

My camshaft is described as 270plus but not sure of the manufacturer. It was supplied and fitted by Peter May who recommended 12 though with standard rockers. There is a thread in the archives that suggests 12 thou becomes 16 thou so I went with that (not sure how that calculation goes but it sounds about right).
Chris H (1970 Midget 1275)

Chris

If you divide 0.012 by standard rocker ratio (1.25) and multiply by high lift ratio (1.5) you get 0.0144

Try setting your clearance to 14.5 thou
Dave O'Neill2

Hi Chris
I fitted 1.5 roller rockers to my a35, they just caught the inside of the cover, simpliest way of discovering if yours are catching is to simply start engine and then undo the two rocker cover nuts and then move the cover about, not just up but side to side and end to end, if this resolves the noise take a grinder stone to where the inside of the rocker is marked.
I agree with Dave and adjust to 14 thou, as its only the roller tip that need greater clearance.
Good luck
Rob
Rob Newt

Dave/Rob
Sound advice - as always.
Chris H (1970 Midget 1275)

Chris, you could try a second gasket eg two at once. This will give you an extra .1 or so clearance..

Just use some instant gasket if you intend to leave it in there for a while ;0)

MGmike
M McAndrew

This thread was discussed between 15/12/2011 and 16/12/2011

MG Midget and Sprite Technical index

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