<VV> Pete's Engine
ellispj at cogeco.ca
Wed Jul 12 09:37:04 EDT 2006
I have been following along with Pete on his engine woes and have sent him a post with some suggestions. Thought that I would post them here to see what you guys think.
I am still concerned that there is more to his engine problems than meets the eye. Recall that he has now removed the driver's side head and discovered that number 4 valves are burnt through near the seat (compression was 40 Ib.). Based upon his previous symptoms when it was running (severe pinging when hot and under load, apparent change in timing after many attempts at resetting etc.), I suspect that the timing is changing via some as yet unknown mechanism which in turn has led to the pinging and then to valve destruction. Maybe I'm all washed up but there are a few possible reasons that I can think of for this to occur:
1. The symptoms are very indicative of a failing harmonic balancer (i.e. the outer ring is moving relative to the inner ring). However, every time I have looked the alignment marks seem to be where they should be. Should have another very close look to verify this once again. Look all around the circumference of the inner and outer rings just in case there are some alternative marks which I haven't seen. Is it possible that the rubber has softened so that the outer ring moves relative to the inner ring when under load but goes back to the original position when not? There are signs of deterioration of the rubber.
2. Look in the Corvair Technical Guide under the section "ENGINE - MECHANICAL" on page 38. This section is about finding the camshaft timing mark. If you carefully read the info. in the second column it will tell you what to do. Also, read the "Technical Editor notes" at the bottom of this same column. The possibility here is that a key has sheared in either the camshaft gear or the crankshaft gear, thus allowing one of the gears to turn. Or, the gears weren't installed correctly by a previous owner.
3. Another possibility, although somewhat more remote, is that the distributor drive gear located on the back end of the crankshaft is turning. Removal/replacement of the distributor drive gear is described in the shop manual Engine Mechanical - page 6-21 of my '65 manual (probably a different page in your '68 manual). There is a picture of it on page 6-52 of my manual. I wouldn't get into this just yet.
My opinion is that Pete shouldn't proceed with spending significant money on this engine until he figures out what the root cause of the valve failure. If he just gets the head repaired and puts it back together he may just end up with the same problem all over again in a few miles.
Any thoughts on this?
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