DISTRIBUTORS (Problems and Fixes)
Daniel McNeil, #301
I don't know about all years but the A-4 in my boat, hull #301, has the old style "prestolite" distributor. I had been having problems with loss of power for several years with frequent changes of the points necessary. I purchased an electronic ignition kit from Indigo Electronics (www.atomic4.com) and installed it last year. It uses the original distributor which necessitates reworking. I learned that the old distributor uses a mechanical advance system utilizing weights and springs that swing out when the engine accelerates causing the spark to advance. Much to my surprise I learned, upon removing the breaker plate and exposing the lower part of the distributor, the whole mechanical advance mechanism was one rusted, frozen mass. Obviously my advance system had not worked for years and this was part of the cause for loss of power at higher rpm's. The electronic ignition upgrade went very easily and the old cast iron genny hasn't run this good in years! So, look to your advance system, and check out the electronic ignition. It may help with your problems. Good luck!
Jeff Maher, #30
Your advance mechanism may be stuck--the cam assembly rusted to the drive-shaft spindle. You may be able to unstick them with some PB blaster or other penetrant. Or your springs are broken or corroded, which would have the same effect because your weights would always be thrown outward--in a state of permanent advance. If either of the spring-posts on the drive-shaft plate are broken, your probably going to have to replace the distributor in its entirety if it's Prestolite (an old, used one in good condition) or get new parts if it's Delco. Prestolite drive shafts and cams are no longer available from either the manufacturer or several of the jobbers who bought-out their old stock--been there, done that. Springs, weights, bearings, breaker-plates,cap-clips, and terminal kits ARE available for Prestolite (Autolite--same diff) If you need any of those, let me know and I can hook you up.
You can get all those parts by calling Neal, dba Obsolete Parts and Equipment, at 513-731-4134. Addy is 2187 Bluegrass Lane, Cincinnati,OH 45237-3525. I just got all those and a bearing kit from Neal.
If you have been setting your timing by rotating the cap for highest rpm, more than likely you've advanced the timing to as much as 20 degrees before TDC. At this setting, you would get OK running at idle, but the added 17 degrees of advance at speeds above 1200rpm would cause rough running as the rising pistons push against prematurely exploding vapors. Of course, this happens only with a properly working advance mechanism. The original A4 manuals tell you to set timing for highest RELIABLE rpm. The Moyer manual says to adjust SLIGHTLY from static setting--not necessarily to highest rpm, just the best. (smoothest running?) Bottom line is that I was confused by all the hair splitting references about setting timing this way, and I went for highest rpm which resulted in over-advance. I finally figured it out when I used the timing light. Apparently it's a common problem, and some very good mechanics say that you should ALWAYS set with a timing light because prolonged running with over advance can overheat the engine, burn the valves, and wear out the rod bearings.
Maybe you could try a timing light? Hope this helps...
Daniel McNeil #301
I just saw this note about the advance system on the A-4. I don't know about all years but the A-4 in my boat, hull #301, has the old style "prestolite" distributor. I had been having problems with loss of power for several years with frequent changes of the points necessary. I purchased an electronic ignition kit from Indigo Electronics (www.atomic4.com) and installed it last year. It uses the original distributor which necessitates reworking. I learned that the old distributor uses a mechanical advance system utilizing weights and springs that swing out when the engine accelerates causing the spark to advance. Much to my surprise I learned, upon removing the breaker plate and exposing the lower part of the distributor, the whole mechanical advance mechanism was one rusted, frozen mass. Obviously my advance system had not worked for years and this was part of the cause for loss of power at higher rpm's. The electronic ignition upgrade went very easily and the old cast iron genny hasn't run this good in years! So, look to your advance system, and check out the electronic ignition. It may help with your problems. Good luck! Daniel
Lee Umphres, Lastochka, #273
Sorry for the late reply, but Don Moyer has some of the old Prestolite distributors that he may be willing to sell. I recently traded a Delco for a Prestolite. The Delco will not work on an early A4 with a stock water jacket cover plate. The cover plate is too large at the back to allow the distributor to seat. In talking to Don, I believe that if a Delco is fitted you also need to drill a hole for the adjustment clamp.
This is from Don a couple of weeks ago... I had inquired about trading a spare Delco that I had for a Prestolite...
"You might consider keeping the Delco for a spare. In the unlikely event that your Prestolite ever self destructs for some reason, the Delco will slip right in, and all you have to do is drill and tap a 5/16" (course threaded) hole behind the distributor housing to accommodate the hold down bracket of the Delco. Many people would consider that modification to be an improvement.
I guess I just answered my own question regarding your side plate. If memory serves, the Delco hits the cast iron side plate of your early engine. If so, go ahead and send us your Delco, and we'll send you a Prestolite in comparable condition. Don "
Morgan Auto Parts in Pasadena, Texas says that they are able to supply a NEW Prestolite distributor for an A4 for around 250 dollars. If you are interested, talk to Gene at 713 473 1744.