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MG TD TF 1500 - Valve adjust dial indicator

Was looking for the jig to carry the dial indicator sled (lost iny shop). But took a look at the dial indicator and magnetic base I have. The magnetic base works rather well on the intake manifold. The mag base came with some arms that can position the indicator where ever needed.
McMaster Carr P/N 20715A44. Indicator and base only $32.67 for the kit.
http://www.mcmaster.com/#20715a69/=d5d75p
Catalog page 2264.

Peter Dahlquist

Second attempt Pic 2. No need to remove bonnet.

Peter 54TF

Peter Dahlquist

Thank you Peter
Mort TD 1851

Peter
I have a similar setup, but have never used it on the "T"...How did you get the "0" point?
Edward
E.B. Wesson

Ed I'll set the indicator on the rocker and note the 1st reading (R1). Does not have to be any specific number.
Then raise the rocker to get a second reading (R2).
R2 - R1 = 0.012 gap.
A bit of adjusting will dial in to the desired Gap.



Peter 54TF
Peter Dahlquist

Peter, I agree, this is a better way to determine valve clearence (as opposed to feeler gauges), as it eliminates out-of-flatness wear from the equation. The only thing that concerns me is that if you measure with the axis of the dial gauge out of line approx. 30 degrees with the axis of the valve, you might measure a couple of thousanths less then the actual gap.
Steven Tobias

The clearance is measured in line with the valve stem, Having the indicator at an angle causes the reading to be other than the true clearance, and different angles give different readings for the same real clearance. Side loading an indicator mounted on a long springy arm makes the readings totally unreliable. Reading off an irregular surface also screws up the measurement as the angle of contact of the indicator end changes.

This approach is a PITA, which gives a totally unjustified impression of accuracy, to a degree that is totally unnecessary. I have done a lot of precision measuring with the 2 dozen or so indicators I own, but it is a waste of time on valves. +/- .001 is sufficient, even .002 will not hurt anything.

I would suggest forgetting the whole affair: learn how to use a feeler gauge. If you are concerned about wear notches in the rocker face, resurface them or grind the feeler to be less than the width of the valve stem, and insert perpendicular to the rocker shaft. It does help to use a stepped adjustment feeler. These have an end section rough ground to .001 under, and a step up to .001 over, the rough part slides in easily and the step will stop it from going in any more if the adjustment is correct. Put the stepped side down against the valve stem.

You could also calculate the degrees of screw turn from the thread pitch and rocker arm ratio, and set them that way, or measure degree adjustment on a carefully adjusted clearance. I do this on engine rebuilds, only final measuring after the head has been final retorqued. On MGB, two flats or 120 degrees is just about the requisite .015.

FRM
FR Millmore

For someone that wants to assure themselves, there are tools available to accurately adjust the valves by rotational clicks, which represent a given amount in thousandths per click. These do adjust for the interface of the rocker arm striking face and the top of the valve stem.
One brand is "Clikadjust".

fwiw

Dallas Congleton


I'm a self employed product designer. Meaning I can't work with others and hold a job.
Always looking for something different.
This is what happens between contracts.

Peter 54TF
Peter Dahlquist

Peter
I do appreciate your method, and I'm glad you posted it. I have done this, when checking valve lift, on 18V engines, and it was very helpful, in pointing out wear on the lifters and cam lobes, without taking it all apart....
I can't see any harm in trying it out, and it might even be a time saver, since the wear on the pushrod, or rocker, is not a consideration with your method.
Thanks
Edward
E.B. Wesson

This thread was discussed between 12/07/2011 and 13/07/2011

MG TD TF 1500 index

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