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MG MGB Technical - Tappet clatter

I'm getting more tappet noise than I think is normal so was wondering if swapping out the rockers/shaft with a reconditioned unit would be beneficial. Is this the most likely source or can there be problems with the cam/follower. It certainly seems to be coming from the head. I've also heard that fitting an alloy rocker cover helps dampen the noise. I know that the engine is supposed to be a bit 'tappety' but I'd like to reduce the under bonnet clatter a bit.
Steve Church

Steve,

Certainly you can do it, but instead of shot-gunning the problem, why don't you take some mechanic's blue and check the fit/alignment between your push rods, rockers and valves?

Wipe everything dry and add the bluing and look at contact points. Sometimes just swapping the rockers around will improve things. If you get new rockers, they may need the bushings pressed in and then the oil hole drilled through. The bushing is reamed after this to fit the shaft.

I know you know that valve setting impacts noise. I like to slip in a .014 and if it fits, the .016. If the larger doesn't I know I'm about .015.

An alloy valve cover looks nice and will dampen out the noise some, as will the proper bonnet lid blankets.

warmly,
dave
Dave Braun

If I do remove the rocker assembly to swap them around (or even to swap out the assembly) will removing the bolts compromise the head torque. Will I have to release/retorque all the head bolts when reassembling?
Steve Church

Check the rocker shaft for wear. I would drain the water, release all the bolts slightly and remove the ass'y. Then retorque later.
Art Pearse

Hi Steve, If you are using the "rule of 9" to ajust your tappets, then try the other method of ajustment by setting them "on the rock" ie both valves closed on the same cylinder at the same time I did this to my '73bgt having had a tapping from a couple of valves, two of the valves were 20thou.+, reset to 15thou.tapping completely disappeared Regards Bill
wm griffiths

Similar to previous poster, how are you checking clearance? Worn rocker pads can give oversize clearances even with the correct feeler gauge, and the maximum gap may not be at the strict 'rule of nine' point on all valves. For whatever reason my back three have the greatest gap noticeably to one side or other of the RON point, so that's where I adjust them, and it has made a difference. Like Dave I use .014 as a go and .016 as a no go, much easier than trying to judge if .015 is gripping/slipping the right amount. I did wonder if this was going to cause valve seat recession but not so far after quite a few years and tens of k. Finally as you say B-series engines are known to be tappety, and after-market alloy rocker covers are supposed to quieten them a bit, maybe you are just expecting too much i.e. comparing it with a modern engine.
PaulH Solihull

I set the clearances using 'rule of 9'. I'm aware of how loose these period engines can sound having had a 1971 midget for a few years.

So presumably I have to measure at all points around the cam profile to determine where the maximum gap is? Or is this 'both valves closed' point a better bet. It will certainly be quicker! I'll try this over the weekend.
Steve Church

Steve,
If you want alloy for appearance then go ahead, but i doubt whether you would notice much reduction in tappet noise. Also if the rocker shaft and rocker contact faces are worn feeler gauge adjustment won't help much, rule of nine or not! On my dad's Opel, the clearances were set with the engine running, using a feeler gauge. When the pads were undercut, the gauge used to get nicely crimped!! Have a go see what you get.
Allan Reeling

I remember once having a set of feeler gauges that I had ground down to be the width of a valve stem. This meant that I could sit them into the 'groove' in the contact face. I may try the same thing again.
Steve Church

Why not remove the rocker shaft and reface the pads under the rockers to remove the indentations. To remove the shaft slacken each bolt in turn and retorque it to 20LBS/FT. When you have the assembly off the car check for slackness between the bushes and the shaft and if this turns out to be the case replace the assembly. Then refit the rockers and torque the whole assembly in steps to 50lbs/ft. As Alan suggests I would then adjust the rockers with the engine idling slowly that way you can hear when a noise stops and take the necessary action. Now on the subject of alloy rocker covers I was always taught that alloys did not dampen noise very well so frankly I would steer clear of these things.
Iain MacKintosh

Expensive, but has anyone dared to go for these 'roller rocker' assemblies. They have an altered ratio to give more lift all across thr rev range. I wolud not entertain them since they are so expensive. and I cannot see the point of needle roller as the pad end does not complete a full revolution. I suppose their lightness may help reducing mass of those components? Mike
J.M. Doust

How about using a DTI?
R Fowler

It is probably regarded as sacrilage, but I was told that by nipping the rocker on to the valve and then undoing the screw 1/4 turn this produced a gap of .014. The pitch of the adjusting screw is such. However there is still the problem of cam position. I guess it is a variation of Clik-Adjust, which I have used but frankly found it required more hands that I possess.
Michael Beswick

This thread was discussed between 21/07/2011 and 22/07/2011

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