Head rebuilt but noisy

[Matt7c]

I have finished my top-end rebuild, but the noise from the timing case is now very loud. Before the rebuild, I could hear the timing noises if I tried to but only when stood over the engine with the bonnet up, but not at all with the bonnet down and never once while driving. Now I can hear the timing noise at all times - even when sat in the seat driving down the road - and it is a lot louder with the bonnet up.

Question: is this the natural consequence of new parts in the head, or is something amis?

Finally, does anyone know a source for the blue cam cover paint?

[type26owner]

Matt,
Try adjusting the slack on the timing chain while the engine is not running. You can do this without removing the camcover. Just run the adjustment screw in until it goes solid and back it off exactly 3/4 of one turn. Lock it down there. That gives you exactly the 1/2" of slack in the chain measured between the cam gears.

Here's a heads up. The instructions in the manual are flat out wrong on how to adjust the tension. Trust me, it does not work like that. Either a spacer must be placed underneath the spring or a different tension spring must be used. The stock spring only loads the chain with 10 pounds of force. I had to up that to 25 pounds to get rid of the noise mine was making.

[jkolb]

Keith,
What spring or spacer do you recommend. My engine is about to go back together and I would like to make sure that everything is as it should be in this area.

Jerry

[type26owner]

Jerry,
Start with a new 10 pound spring first and see if that works. I had to buy some more heavy duty springs from Barnes Spring I think. The spacer is simply a ball bearing which goes between the spring and the plunger. The ball is used because there is a small bleed hole in the plunger to allow any oil forced into there to bleed back out quickly and not cause a hydraulic lock. The ball won't plug off the existing oil bleed hole. There is a tremendous amount of oil which gets swept up by the chain when it's at full song. Imagine a puddle of it as a standing wave gets piled up there against the camcover cause that's exactly what happens. That's why you must pay attention that the oil bleed hole in the plunger is not blocked off or it will self-destruct in nothing flat.

That is the slack side of the chain the tensioner is loading. The load or drag from the oil pump will influence the amount of tension needed also. I installed a high pressure, high capactiy oil pump in my Elan. The reason I did is so I could run 10-30W engine oil and still have the necessary oil pressure to run the at WOT on extremely hot trackdays but not have the oil over-pressure bypass valve open all the time. Hence I needed to up the spring tension. Our BRM with dual stage dry-sump oil pump also requires similiar spring tension on the chain tensioner.

[type26owner]

The section E.6 TIMING CHAIN TENSION in the manual is misnamed. It should read TIMING CHAIN SLACK instead. The adjustment does nothing in the way of the tensioning the timing chain.

An important point I did not cover is the spring and spacer must NOT become completely coilbound before the pusher adjustment screw flange can contact the plunger. The adjustment screw must only control the amount of free slack and not the tensioning. It helps a bunch to have a Rimac Valve Spring Tester to do this setup.

[sk178ta]

When my engine was rebuilt there was a chainy noise which I thought acceptable but the builder, High Peak Classic Autos, didn`t. Taking the head back off revealed that a piston was just, only just, kissing the very edge of a valve.
He dropped the pistons out through the sump and machined off a tiny smidgen from the edge of each piston and solved the problem.
Jim

[steveww]

If there is a lot of tappet noise may be you need to check the tappet to cam gap. This will need doing again after 500 miles or so as everything beds in. I rebuilt the head on my S4 last winter and after a summer of use the tappets need shimming again.

I adjust the timing chain with the engine running. If it is too tight you hear a noise a bit light a straight cut gear box whine, too loose and you hear the chain rattling. I tightened it until I got the whine then back off until the whine disappeared.

[type26owner]

Oh yeah, because I'm winding my engine up to 6500 rpms frequently and it's still got the cast iron crankshaft I added a harmonic balancer to dampen the pounding in torsional twist the crank experiences to keep it from cracking. That has increased the inertial forces the chain tensioner has to deal with too.

[Matt7c]

After a little more listening through a screwdriver, I agree that the noise is eminating from the tappets. I set the chain as Keith suggested, but it made no difference. So the tappets will get reset once the winter maintenance schedule starts, although as I am moving house in a few weeks, that will probably have to wait a few months. Thanks as always for the tips.
Matt