valve clearances

johnhcrighton · Post by **johnhcrighton** » Mon Feb 27, 2012 9:45 am

Hi. New to the world of E Types - I have a '66 Series 1 FHC (4.2). Having nil experience in setting OHC clearances I thought I should at least start off on a good (tuning) foot and get them checked by a professional. More out of curiosity than anything else I checked the result while I had the cam covers off to be polished. Surprise!

Inlet: 3, 4, 3, 4, 6, 6 thou
Exhaust: 6, 7, 5, 3, 5, 5 thou

Manual says 4 thou on inlet side, and 6 thou on exhaust.

I imagine that it is possible to get minor variances simply by the process of reassembly, but are these variations (and values) acceptable?

cheers

John Crighton (Currumbin Australia)

Post by **1954Etype** » Mon Feb 27, 2012 12:35 pm

John you will probably find that it is ok but I would personally set them correctly. As the cam covers are off, it is a pretty easy task.

Angus

Post by **mgcjag** » Mon Feb 27, 2012 1:34 pm

Hi John have a look at the attachedit came via jag lovers...it gives info on cam identification & the associated clearences.......You never konw with an old car if the cams have been replaced at some time....Also when i did mine I found that i had the scoloped shaped cam sprocket centers which several articals ive read recommend to change out for the solid centre that have better fitting seration teeth.......Regards Steve http://www.georgiajag.com/Documents/Camshafts.html

johnhcrighton · Post by **johnhcrighton** » Mon Feb 27, 2012 8:14 pm

Steve - thanks for that article. I will check carefully but I think my cams are standard.

Angus - I am encouraged that you think adjusting the clearances is a 'pretty easy task'! But I am up for the challenge and will have a go. I like things to be as correct as I can make them, so if I left the clearances as they are it would prey at the back of my mind forever

thanks guys

Post by **1954Etype** » Mon Feb 27, 2012 8:29 pm

Just make sure the cams are set using the tool and don't turn the engine. Loosen the top timing chain. Remove the cams (1 at a time) and measure the thickness of the shim. You then fit a bigger or smaller shim as required.

Refit the cam, again, using the setting tool. Repeat for the other cam, torque it all down and retighten the timing chain.

johnhcrighton · Post by **johnhcrighton** » Mon Feb 27, 2012 9:06 pm

Angus

Thank you. I presume the 'tool' is to make sure the cam is at exactly 90 degrees. I will ask where such a tool can be purchased, but I imagine also it is possible to make one up in sheet metal (provided the dimensions are accurately determined).

One question - when checking the clearances initially I rotated the engine using the crank. When the cams are refitted one by one (sprockets disconnected) I presume you still need to rotate the cam to check that the adjusted clearances are OK. Is it a problem rotating the cam by itself?

You guys are VERY helpful!

cheers

john c

Post by **1954Etype** » Mon Feb 27, 2012 11:05 pm

John you can't rotate the cams independently with both the cams installed as the inlet and exhaust valves will be out of synch and collide. You have to rotate the cams with one removed. Don't forget to use the setting tool when you refit. Read the manual carefully and you will be ok.

christopher storey · Post by **christopher storey** » Tue Feb 28, 2012 7:42 am

Angus and John : DON'T ROTATE ANYTHING WHEN THE HEAD IS ON THE ENGINE !! Even with the opposite camshaft removed , the valves will hit pistons with the usual consequences if the camshaft is rotated independently of the crankshaft

johnhcrighton · Post by **johnhcrighton** » Tue Feb 28, 2012 8:48 am

Well I am glad that you made that point!! I was aware of the interference issue, but I (it now seems incorrectly) assumed that you could 'test' the adjustment, one side at a time, by rotating that particular camshaft, then removing it before testing the other.

Is it correct to say the correct procedure is to check current clearances, remove both cams, fit whatever shims are required for the appropriate adjustment, then refit both cams, and only then rotate the engine to check that the adjustments made are correct? If changes are still not satisfactory, start again.

I note the manual warns against rotating either the engine or the cams with the sprockets disconnected, but then goes on to suggest that it is OK to do this if one cam is either removed, or the relevant bearing caps are slackened to their fullest extent to allow for the valves to be released. It was on this basis that I was thinking it might be ok to fit the new shims, and then while to ther cam was still of the head, rotate the cam sufficiently to recheck the clearances. Obvously when both cams are in place, it would be essential to ensure that the engine was at TDC and both cam keyways at 90 degrees to the camshaft cover face

Thanks again guys for your perserverence with newcomers!

cheers

john c

christopher storey · Post by **christopher storey** » Tue Feb 28, 2012 3:13 pm

John : certainly you can do it one side at a time by the method you suggest i.e. measure clearances, remove shaft , measure each shim, calculate new shims required and fit new shims . You can then replace cam, connect up sprocket and chain on both cams and check the clearances before moving on to the other side . However, it often happens that if you measure shims on both sides together , you will find that some rejected on one side, or indeed one valve even, can then be used on other valves, thus minimising the number of shims you need to order .

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