Rebuild or replace...

[rasouth]

I have a '78 spider that I have had a frustrating time trying to find the source of a knocking noise. At first the noise only happened AFTER the engine warmed up and was coming from the no. 1 exhaust valve area. I replaced valve shims, (no difference), changed to heavier oil, (still no difference), removed head and examined valves. Other than the exhaust valves being a little pitted the springs look good, (nothing broken or out of place), valves move easy in guides and oil is pumped to all valves. Head is not warped.
My question is how hard is it to replace valves and guides or should I spend $500 for a new head with everyting installed?

[So Cal Mark]

a competent machine shop could rebuild your head for much less than $500. Why do you think the noise is from the valve train? Did you replace the shims because the clearance was wrong?

[rasouth]

Yeah, I replaced shims becuase the clearance was wrong. I have been playing around with timing and camshaft alignment and the car is running fairly smooth except now there's a tapping/clacking noise coming from the intake valves. I used a stethescope and the ol' screwdriver method to isolate the noise. With the screwdriver I can feel the tapping on the intake side. Could too heavy of an oil have an affect?

[So Cal Mark]

oil isn't the problem. Is it just one valve or several? I'd go back and check the clearances and make sure a shim didn't come out

[rasouth]

It's the entire intake side making noise. All clearances are within specs except for one. It measured .50mm when specs call for .48mm max. I just checked cam position and moved forward and back but made no difference in intake clatter. I replaced timing belt a while back during a tune-up so belt is good. Cams seem to be lining up with marks on pulley when number 1 and 4 pistons are at TDC

[So Cal Mark]

have you removed the cover to inspect? Is the pulley bolt tight? Is the pulley plastic?

[rasouth]

I have removed cover several times, checked for tightness, clearance and even removed the cam housing to look at springs to be sure they were in place. Nothing seems to be out of place, seems to be timed right. I believe the pulleys are plastic.
Could it be the cups that the shims sit in? I removed those when I pulled the cam housing off but did not check for out-of-roundness. I did put them in the order I removed them along with the corresponding shim.

[ventura ace]

You didn't mention the aux shaft pulley, so I have to ask -- do you have it timed correctly? The noise moved from #1 exhaust valve to the entire intake side. Maybe it's not in the head, but rather the aux shaft knocking against #2 connecting rod.

Alvon

[rasouth]

I checked the position of aux shaft before installing and rotated engine by hand after putting belt on. When I removed the head to look at #1 ex I cleaned some carbon off the valve stem, checked for smooth travel, checked for obvious signs off cracks or breaks. Other than the valve being a little pitted it looked fine. Since replacing the head I have not heard the knocking from the exhaust side yet. Now it sounds as if the intake valves are being slapped but all the valves are within specs except for #3 which is over by a hair. Even changing that shim does nothing for the noise.

[ventura ace]

There were about ten 124 spiders on a drive in your area today. I wish you could have met up with them -- then you'd have 10 different opinions for what the noise is!

If it's driveable, maybe you can get over to Mark Allison's shop in Upland, and have them take a listen.

Alvon

[mdrburchette]

I would set the engine back to TDC and make sure that aux shaft is aligned properly. It sure sounds suspect that you're hearing the noise on the intake side where the lobe could be hitting the #2 rod bolt.

[rasouth]

Checked and rechecked all positions for pulleys, shafts , belts, valve clearance, etc. I have decided to pull head off and have it rebuilt. I am at my wits end with this noise. I'm thinking now that the noise is coming from valve itself or valve guide, maybe. I'll check when I get the head off.