The spider ran like a champ for 4 months, it was my daily drive for most of that time. Then on Aug 23, 2000 it died. About a month before it died for good I parked it because it had dropped cylinder #1 (not literally, it was misfiring). I checked the compression and got 0 in that cylinder, the rest were near 160 psi. I have been down this road before and experience told me that it was most likely a badly adjusted or burning valve. Being in the middle of moving to my new house I was in no position to tear into the little motor so I parked it and drove my X1/9 .
When I finally found the time to tear into it I found that the #1 intake valve gap was nonexistent. I adjusted it and checked all the others. A compression check showed that the adjustment had done the trick and I thought I dodged a bullet. I drove the car to work for two days only to find that it was starting to drop cylinder #1 again. So off came the valve cover once more and I found the #1 intake gap had closed again. Dead in the water. The valve was either stretching or the valve seat was being recessed into the head. Off came the head.
Below are the pictures of what I
found. In summary, the valve seat was toast, it was not only recessing
into the head but it was totally loose! You could spin it with your finger.
Imagine the damage if it had worked itself completely loose and rammed by the
valve to the point of falling into the cylinder. I'd be replacing pistons
as well as valves if that would have occurred. To make matters worse,
I also found that the head was cracked right between the #1 intake and exhaust
valves. This might explain why the valve seat came loose.
| The offending valve is the intake valve on the right. It's easier to notice how it's recessed further into the head than the #2 intake valve in the lower photo. I apologize for the inability of my $120 digital camera to capture close up shots. If you look closely at the upper picture you can make out the crack in the head between the #1 intake and exhaust valves. |
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Those
who are familiar with 850 heads will notice that the valve seat is clearly
just sitting loosely in the head. I'm not kidding that it spins
freely in there.
One last little surprise that I found was that the #3 spark plug threads were stripped out. There was this funky insert in there that didn't seem to work very well since there was evidence of leakage. |
Yup, you read that right. I've come across a 40DCOE Weber carb complete with manifold and seriously ported head for an 850. I get the feeling that this Spider, not to be outdone by the dual Dellortos on my Coupe, puked up it's valve seat on purpose the same weekend I brought that carb and head home. Follow the links to read on...
40DCOE Conversion
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