2011 at the Hammond Barn

[Phil Waterman]

Hi Bob

Interesting diagnostics, the pair test I’ve never done but will definitely have to try, I’m getting ready to do a test on the engine out of the HUP so I will have to try it. Though I may have to ask for more explanation of which pairs should be the running pairs, I think I understand.

Concerning disconnecting vs grounding particularly with your high voltage coil be careful of burning holes through the insulation on the new wire or carbon tracking the distributor cap or blowing the coil. I’ve played with this on test stand, (think I have video of the test). If you ground out a lead there is no problem but if a lead or more than one lead is off the spark potential goes way up. With a standard 6 volt coil it will jump ½ to 3/4 inch but at some point the spark potential doesn’t jump the gap and goes looking for an easier jump like down the insulation on the coil or through the wire insulation. My understanding is that once it starts jumping where it shouldn’t it doesn’t take long to create a permanent path for the spark. When I was running my bench test I had use a 1 inch thick block of oak to hold the adjustable spark gap at the point where the spark stopped jumping the gap it started flowing through the oak to the metal bench underneath which I was leaning against at the time. Then I put it on some ½ thick plastic.

Not sure I follow the logic of which cylinders are the strong ones and which are the weak or problems, it would seem to me that if you can run the engine on three pairs of two then all the cylinders are relatively the same. Conversely if it will not run on any of the pairs then all the cylinders are relatively weak (or there is a different issue). But if any one pair or two pair causes the engine to stall then that one or two pairs are the strong cylinders which are carrying the others.

“Did the same with 5 and 2 and the engine stalled out.” To me that the engine stopped when you had grounded out all but 5 and 2 would seem to say that they are the strong cylinders

One thing I think your test is showing is that there is something different between the cylinders. Now the 64 dollar thousand question what? Mouse sleeping under and intake valve.

If all of the cylinders are showing compression at cranking speed of 135 or better sort of says it is not a compression issue.

That your vacuum gauge indicates good vacuum I assume without any flicking of the needle, would seem to rule out a stuck intake valve or badly burned exhaust valve. Out of curiosity did have the vacuum gauge attached during the pairs test?

I’ve got a though about another possibility but want to try to figure out a test that doesn’t require taking the engine apart. Let me do some playing with the 216 on the test stand and see what I come up with.


Cheers Phil