66 - Missing at highway speeds!!!

[Gary S.]

The joys of driving old cars! I was coming back from a nice little 40 mile highway cruise and all of the sudden the engine on my 66 327/350 lost power for just a split second then gave a very slight backfire. I thought maybe it got a bad shot of gas or something. Then about 1-2 minutes later it did it again, this time with a loud backfire. I figured out that if it stumbles and I catch it immediately by pushing in the clutch, it won't backfire. It did this for the next 10 miles home, occuring about every 2-3 minutes. I am thinking that maybe the coil is going? Can it be intermittanly failing either due to internal failure or heat? I am assuming that the backfire is because the engine is still sucking gas down the carb but it has no ignition for just a microsecond or two and when it lights off again it has too much gas in the engine and tailpipe. Ergo the backfire. This is about the only thing that I can come up with. A couple of weeks ago, I posted a question about a wandering idle of up to plus or minus 25 rpm. In addition, if you are just cruising lazily at around 25-30 mph it sounds like a very slight miss but not all the time. Any suggestions on the major problem I first described? Fuel? Spark? Plug wires? The car has a brand new set of points, condensor, and the plugs were gapped and cleaned. That is in addition to a distributor rebuild and newly adjusted timing, dwell, and idle. Other than the static tests described in the GM Chassis Service manual for resistance across the poles of the coil are there any bench tests I can do? Thanks Gary

[Dave M.]

Re: 66 - Missing at highway speeds!!!

I had a similar problem. I finally determined that the distributer shaft bushings were worn. I contacted T.I. Specialty (http://www.tispecialty.com/contact.htm), discussed the problem, and subsequently had the repairs made by them. My '66 has never run better through its entire RPM range. Suggest you contact Dave Fiedler (owner) at T.I.....I highly recommend T.I., based upon Dave's attentiveness, willingness to discuss all options, and for ultimately providing me what ended up being the correct solution. Turn around time was great. Visit their Web Site to either contact them by email, or pick up the phone and talk directly with Dave.

[Dave - NCRS#24235]

Re: 66 - Missing at highway speeds!!!

It happened to me between Helena Montana and Jackson Hole Wyoming four years ago during a 4k mile trip. My new Delco fuel pump had cracked internally and had pressure but no flow. I believe the flow test is half a gallon per minute. You need to shoot fuel into the carb to do it. - Dave