Brodhead Pietenpol Association

Original Posted By: "David B. Schober"
Doug,Thanks for the article. I have read that article at least 20 times trying tounderstand what Jim is talking about. Maybe I'm dense.My vacuum was locked out as Bernie and Jim said. My initial timing was 14Deg. + 12 deg. of centrifical advance (I thought), but this was with theoriginal centrifial springs. Then I changed the springs to weeker ones. andreset the advance to 23 deg. + 12 centrifical = 35 deg. This was the Max.one should set the advance accordig to Jim's Bpan article. And Bang.. ithappened anyway. I was using 100 LL. avgas. Of course I don't really knowwhere the advance ended up at full throttle setting since my timing light(red neon) wasn't bright enough to check. This is when it happened. I couldnever get back up to 2600 RPM after that. Ran rough, with smoke (Steve...Ididn't need any oil injected into my exhaust). I tested the compression andfound I had a problem. Courious thing though my overflow vent which waspreviously giving me a positive pressure in the crank is now like a vacuumcleaner sucking air into the crankcase. Cyl. 2, 4 are now contaminated withoil and have been firing intermitent. Checked the wires and plugs they'reO.K. must just be the oil fouling them. Will pull the head this week. Thequestion is ... is there a hole in the pison or are the valves damaged orboth? Stay tuned for the answer?Domenic________________________________________________________________________________

Original Posted By: BELLISSIMO, DOMENIC
Doug, I forgot to add I do not have a cooling problem. I'm probably runningtoo cold at 165 deg.F. ----------________________________________________________________________________________

Original Posted By: dannymac
Sounds like a hole in both #2 and #4 -- the pistons, not the valves. Arethese both on the same side? If so, one of them could be holed and therecould be some kind of transfer of gases during the intake pulses. If it's ahole in a piston, you were running it too advanced and experienceddetonation. This also explains why the engine won't make the RPM you want --not enough ponies, with a blown piston.It would be a good idea to have a speed shop dial in your distributor on adistributor machine for the maximum advance that you require. Springs aresometimes not what they are supposed to be, even right out of the box.Setting it up on a distributor machine is the only inexpensive way to findout. It is also possible that the distributor has worn parts that make thetiming at RPM something other than what you think it is. This could bethings like worn bushings and breaker plate, flaky springs or worn weightpivots. To make a distributor behave correctly, everything that rotates orsupports rotating parts needs to be checked and replaced if it is out oftolerance.Personally, I think a good electronic ignition would solve all of theseproblems and also (with a knock sensor) adjust for the maximum useableadvance at any RPM.Regards,Mike________________________________________________________________________________

Original Posted By: Earl Myers
Doug,Thanks for the article. I have read that article at least 20 times trying tounderstand what Jim is talking about. Maybe I'm dense.My vacuum was locked out as Bernie and Jim said. My initial timing was 14Deg. + 12 deg. of centrifical advance (I thought), but this was with theoriginal centrifial springs. Then I changed the springs to weeker ones. andreset the advance to 23 deg. + 12 centrifical = 35 deg. This was the Max.one should set the advance accordig to Jim's Bpan article. And Bang.. ithappened anyway. I was using 100 LL. avgas. Of course I don't really knowwhere the advance ended up at full throttle setting since my timing light(red neon) wasn't bright enough to check. This is when it happened. I couldnever get back up to 2600 RPM after that. Ran rough, with smoke (Steve...Ididn't need any oil injected into my exhaust). I tested the compression andfound I had a problem. Courious thing though my overflow vent which waspreviously giving me a positive pressure in the crank is now like a vacuumcleaner sucking air into the crankcase. Cyl. 2, 4 are now contaminated withoil and have been firing intermitent. Checked the wires and plugs they'reO.K. must just be the oil fouling them. Will pull the head this week. Thequestion is ... is there a hole in the pison or are the valves damaged orboth? Stay tuned for the answer?Domenic________________________________________________________________________________