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MG MGA - Vernier Timing Gear Instructions

Anyone have a set of instructions for the Vernier Timing Gear that they could share? I picked up just the adjustable camshaft gear from British Parts Northwest, alas no instructions were included. I could probably figure out the installation, but instructions will save a lot of fiddling.

thanks, John
John Backman

You need a cam degree wheel and dial gauge to setup. Summit Racing supplied the unit I own (reasonable price). You also need your Cam Card that will give you the set up spec. Vernier is a misnamer as it doesn't have a vernier scale attached - it just means that they are finely adjustable compared to std setup that is very coarse (tooth pitch) or stepped keys that are available in 1 degree increments. The adjustable timing gear means you can easily adjust just by tapping the outer section with the clamping bolts loose unti you get you reading/setting then tighten clamp bolts. I can post detailed instructions and links if above is not clear.
Mike
Mike Ellsmore

Mike,

Thanks, I have a cam degree wheel and dial gauge. What I don't have is any info on the cam itself. In that regard I am planning to use the dial gauge to get an idea of the lift and duration. I suspect the cam profile is other than standard since I was not able to get a stock timing gear set to line up as described in the workshop manual.

I have printed out the Crane Cams spec sheet to give me a baseline for comparison. Any thoughts or guidance would be appreciated.

John


John Backman

If your cam was out of the engine all you need to do is take it to a good cam grinder and they will put in a device know as a cam doctor - cam is rotated with a sensor on the lobe connect to a software program that plots the cam profile and determines all the timing settings.
Normally all this stuff is on the cam card that comes with the cam when you buy new or have ground. See image of typical cam card. On this cam card you will see the valve opening at TDC - you set the dial gauge up on the push rod cup ledge till you get the lift specified, just nudge the cam around till you get this reading and then tighten the adjustable gear clamping bolts.
In you case where you know nothing about the cam all I can think to do is set the adjustable gear so it mirrors a standard cam gear and set it up as per the workshop manual for a standard gear (you may have to add a pop mark on your gear if you don't have one).
Barney maybe able to help further?
Mike

Mike Ellsmore

Sorry for the photo being upside down - it is not because I am down under, just held the iPad the wrong way!
Mike
Mike Ellsmore

MOST aftermarket cams have their I,D, stamped on the end of them
gary
William Revit

John,
I just rebuilt an early 3-main 1800 engine and used a new D9 camshaft that I bought from Basil Adams in California. Here are some instructions for this cam that he posted on MG Experience. I'm sure he wouldn't mind me passing them on to you.
"All, The D9 is a great cam (and yes, I sell them) but timing is important. An offset key or a vernier gear helps dial it in. The #1 intake valve should be open .050" at 8.3° BTDC. That means that you want the valve end of the rocker to have moved .063" - .064" to take up the lash and open he valve .050" The stock MGB rockers are a 1.4375:1 ratio so if you put your dial indicator on a perfectly upright pushrod and turn the crank to 8.3° BTDC, you should be able to turn your cam so that the push rod is up .044". You know that .044" x 1.4375 rocker ratio will move the valve end of the rocker .06325". Then put the chain on. When you do, the timing may change a little so rotate the engine a couple of turns and get your degree wheel back to 8.3° BTDC and check the lift again. With a vernier gear (yes, I sell those too) you can immediately adjust the cam position to where you need to be. With offset key (yes, I make those) it may take a few tries to get really close by removing the cam sprocket, installing an offset woodruff key, and trying again until you're close. It's not hard and there is no need to do all the lobe center stuff because you can measure directly and use some simple math to dial it in exactly. Let me know if I can help any of you. Thanks. Basil"

Jim
JL Cheatham

This thread was discussed between 31/03/2015 and 02/04/2015

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