Valve Clearance other CAMS

[rgh0]

A clearance change will also change where the cam hits the follower and if there is an existing wear pattern this may cause noise until it wears in again. It may also cause rocking of the follower in its sleeve to change if its worn which could also cause noise.

cheers
Rohan

[miked]

Thanks Rohan,

I will go back to inlet spec' then as the cam followers are a good fit with it only being 8k odd miles since the head work by the PO. Will report back. Bit harder to do now with the car on the deck.


Mike

[promotor]

Hi Mike,

Inlet valves (and consequently clearances) aren't subject to the same heat as exhaust valves are so in theory the clearances close up less under running conditions on an inlet valve than an exhaust. Inlet valves are exposed to less heat - exhaust valves suffer with the incredible temperatures of the hot gas rushing past them while being "off-the-seat" which means there is nowhere for the valve-head heat to be dissipated to except for up the stem. Inlets can radiate their heat better during the hot phase of the stroke as they are either on the seat loosing heat or being cooled by cold inlet charge.

If you intend to close you clearances down it would be safer to only adjust the inlets. If absolutely necessary by only 1 thou on the exhausts.

Did you use all the same followers in the same positions as previously installed? Just wondering if you have inadvertently caused one to be looser by it being in a different position? The road to worry never stops when you hear a noise!! Certainly not for me anyway!

** Edit ** just noticed you addressed the issue of loose followers in your post that I didn't read!

[miked]

Hi Al,

Thanks for the advice. Yep all followers back in their own positions. Always sit them back on after taking out the shim. I only intend to touch the inlets clearances as the exhaust ones are within the spec' of standard setting. It is clear from standing near the engine that the inlet are causing the noise. I am very careful about exhaust ones. I don't know as much about the theory but know they get significantly hot in the gas stream and close up a fair degree with temperature.

Yep I agree about noise. I drive the wife crackers when out listening for stuff. Major worry if a stone flicks up around the wheel arches. Stop, get out, check all wheel spinners etc

Mike

[miked]

Took lid off and reset clearances back to 6 thou Inlets (Ex left at 10). Run up to temp and sound good as it did before I started. So much for CPL 2 settings.
I just found my old book from when I got the car when it had less than 900 miles since it's head work. First clearance check of the setting (by me) back then was 5/6 inlet and 8 Exhaust. The head had been into Paul Exon for further guide work. He has a great reputation and must have done lots of builds and dyno runs in his life. so I am comfortable with these.

Thanks guys.

Mike

[elanman999]

Mike,
That's interesting, I suppose I could try that.
Cheers
John

[miked]

John, I would go for it as I was very aware of the noise driving down the road at 30/40 mph which I had never been before. It was there unless you overcame with some throttle. Not right.

The last time I went in the cam cover I did not ever lift the inlet sprocket right out. I managed to separate the sprocket from the cam shaft and lay a fat felt pen/marker through the sprocket so the whole lot stayed in place without disturbing the chain. Other may have done this, I have wired the chain up in the past but always removed the sprocket. Or just let the chain drop and lose the ignition timing.
If you have offset dowels they can turn from PCD and be pain so I was quite pleased with the maker pen idea and minimal disturbance. The trick seemd to be lifting the cam of with the left hand and laying in the middle whilst holding the chain and sprocket with the right hand and slipping the pen in. Only a small point but made my day easier. Also, for the first time, I have gone to grease on the head side of the cam cover gasket allowing re entry.

Mike

[elj221c]

While I realise you are using Kent Cams spec are the cams actually from Kent as I have an old Burtons spec sheet listing the CPL2 cams with the lower settings.

Not forgetting that the profile is actually a Cosworth one. They quoted in era 6 and 8 as in Brian's Burton brochure. L1 and L2 at 7 and 8.

The current Burton spec is not the same as an original CPL2. http://www.burtonpower.com/road-sprint- ... -cpl2.html One assumes that the current profile is an improvement based on more modern principles?

It's the old, old story. Who knows what is right. My manual, 36T327, states standard opening as 22/62 and SE as 26/66 wheras Wilkins' book says the CPL1 was SE spec but with 22/62 and vaguely says the CPL2 was a higher lift cam at 26/66.........

For me, if they are genuine Cosworth items or old Burton ones I would use the old settings.

BTW, I'm not sure why you would want to grind a shim. If you are taking off a thou you know what size you want. They are hardly expensive and the one that is left over may well come in useful at a later time.

[miked]

Hi Roy,

Thanks for the reply. I failed to find out what CPL2 spec? they are except that they were meant to have been reprofiled about 4-5 years ago.

Re: shim grinding, it was a bit of a frustrated suggestion of mine as I have done two of my mate?s engines last year and the two of my own and no matter how many shims you tend to gather you are always short and end up with multiples of the same ones. It is that delay when you need them that is frustrating. As you say they are not expensive, I just need to wait and be more patient.

I suppose it helps to keep good data sheet records of what has gone in so that when the same engine is ready for checking you can at least prepare with shims around those thickness sizes.

Mike

[john.p.clegg]

Mike
What sizes are you after,I'll check the shed...

John

[elanman999]

mike

I suppose it helps to keep good data sheet records of what has gone in so that when the same engine is ready for checking you can at least prepare with shims around those thickness sizes.
Mike

Yes if you know what's in the engine it's easy to check the tappets to see what you need and order them before you get around to changing them.
Being able to grind or make new ones is useful so that when things don't go to plan you can grind one to suit with out having to wait. Particularly useful on a Bank Holiday weekend.
Cheers
John

[miked]

Mike
What sizes are you after,I'll check the shed. John

Thanks very much for the offer John I am ok now. I am done for the time being.

Mike