misfire that won't quit

[Ron Dame]

Dammit, new Autolite plugs...that didn't work either.

[allstateguy]

have you checked the valve adjustment for tight intake valves? and with backfires that intense, you may have blown a vacuum hose or weak intake gasket out someplace too?

[KGlowacky]

I am no expert but the other day I was driving my Stude and stopped at a local shop. They had a 69 Firebird in there missing and backfiring when they put on the gas. They found one of the lifters had collapsed. Replaced it and everything was fine. No idea if this will help but wanted to tell you just in case. I wish you well.

[jclary]

So I go to my Automotive Encyclopedia, copyright 1954 with added updates, mine being 1960. If I understand your problem, the engine idles fine and the problem is that it backfires on acceleration. If it is idling with no skips or missing, that should tell you that the valves are seating properly and at least at idling speed, the timing is OK. I don't know if your advance in your distributor moves the distributor or the breaker plate. However, I still believe that you are having a problem with the ignition timing curve as it relates to engine speed. That is related to your vacuum advance or centrifugal advance or both. In other words, your engine is firing at the wrong time while a valve that is supposed to be closed is still open. The mystery here is just what component is failing? Some where there is what I call a BKS reason (Butt Kicki'n Simple). I think that if it were a cross cylinder gasket problem, it would probably happen under idle conditions as well as higher speeds and more than likely be a skip and not a backfire through the intake. That is the reason I wanted you to test the advance diaphragm and make sure you got movement. Under vacuum, either the distributor itself or the breaker plate should rotate slightly. The only other problem I can think of is an intake valve that is binding or dragging in the guide causing a delay in closing. If that is the case, you would need to determine just which cylinder that is happening. That would probably require connecting it to some kind of diagnostic equipment. I'm afraid that my OBDII code reader is not "Backward Compatible" to these Studebaker engines...Probably need one of the old SUN diagnostic machines for that.

[Ron Dame]

Know any one who has a Sun or just and oscilliscope and knows how to use it does around here? I think you are in Greer or thereabouts, that would be OK too.

So I go to my Automotive Encyclopedia, copyright 1954 with added updates, mine being 1960. If I understand your problem, the engine idles fine and the problem is that it backfires on acceleration. If it is idling with no skips or missing, that should tell you that the valves are seating properly and at least at idling speed, the timing is OK. I don't know if your advance in your distributor moves the distributor or the breaker plate. However, I still believe that you are having a problem with the ignition timing curve as it relates to engine speed. That is related to your vacuum advance or centrifugal advance or both. In other words, your engine is firing at the wrong time while a valve that is supposed to be closed is still open. The mystery here is just what component is failing? Some where there is what I call a BKS reason (Butt Kicki'n Simple). I think that if it were a cross cylinder gasket problem, it would probably happen under idle conditions as well as higher speeds and more that likely be a skip and not a backfire through the intake. That is the reason I wanted you to test the advance diaphragm and make sure you got movement. Under vacuum, either the distributor itself or the breaker plate should rotate slightly. The only other problem I can think of is an intake valve that is binding or dragging in the guide causing a delay in closing. If that is the case, you would need to determine just which cylinder that is happening. That would probably require connecting it to some kind of diagnostic equipment. I'm afraid that my OBDII code reader is not "Backward Compatible" to these Studebaker engines...Probably need one of the old SUN diagnostic machines for that.

[rockinhawk]

Ron, I had a Dodge do something like this and it was the spark plugs. They were fairly new and I did everything short of yanking the engine until my son decided to change the plugs just because it was the only thing we didn't do. Again, they weren't old, tired plugs but only in there while I was getting the car roadworthy. Happened a second time on a Corvette I was putting together and I went right to the plugs and solved the problem without going through all the gyrations I went through with the Dodge. Both times they were Champion plugs...don't use them for anything anymore.

ErnieR

I recently had a similar problem with a ohv6. It had a fairly new set of Autolites in it. I pulled them and replaced them with a used set of Champions out of an old engine I had laying around. Problem solved. So I use nothing but Champions if I can get them.

[Ron Dame]

The used Champions were replaced with the new Autolites...HAH! and it still runs like cr@p. It's gotta be carb related...that's where it all started. I'm gonna pull a really crusty, nasty RBS out of my stash and see what happens...why not? I'll even get some of the old heating oil out of our abandoned oil tank and try it. Maybe try flint rock ignition. Mebbe Ted Harbit has a fuel injection system all sorted out for a 170 OHV.

Sorry for getting so sarcastic, but between this and the DD which today has proven to be NEFR (Not Economically Feasible to Repair), I am in a really bad mood.

I recently had a similar problem with a ohv6. It had a fairly new set of Autolites in it. I pulled them and replaced them with a used set of Champions out of an old engine I had laying around. Problem solved. So I use nothing but Champions if I can get them.

[rockinhawk]

Just a thought... Have you checked the lobes on the distributar shaft? I have seen those wear down and allow the points to "float". Although i'v never seen it on a Studebaker.

[PlainBrownR2]

.....Maybe try flint rock ignition. Mebbe Ted Harbit has a fuel injection system all sorted out for a 170 OHV....

That's seems to have been a touch and go idea with a few of the other members very early on my own thread, so you might be on your own with that six cylinder fuel injection idear at the moment.......

[Son O Lark]

Any updates on what the problem is (was)?

[Ron Dame]

Any updates on what the problem is (was)?

Not yet, mebbe this weekend, though it's busy too. Here's the current plan: the AS carb has been gone through AGAIN, paying attention to the power circuits, but I found nothing obvious. I'll next take the intake off and see what shape the gasket is in, even though it idles fine at 1 turn of the idle screw (Is this unnecessary? please tell me before I ruin a good gasket)..

Last night, Wolfie and wife brought me an old WE that was good a couple of years ago, so I'll clean it and try it next.

If all else fails, I have two leads on people who may have an old Sunscope that works, and I'll attempt to drive it to them, because I am out of ideas.

Ron

[ROADRACELARK]

Ron,

I just helped a friend with a similar problem on a mid-sixties Dodge Dart with a slant 6. He chased the problem from the gas tank to the carb throwing parts at it and just knew it had to be the fuel system. He told me it had an electronic conversion unit in the distributor, new cap, wires and rotor, when he bought it. He said it had the original coil on it. His theory was, it runs, so the coil must be ok. If the coil was bad, it wouldn't run at all. WRONG I told him to go buy a new coil, he did and installed it.....purrs like new. I know you said in an earlier post you had a used coil and it made no difference. Considering everything else you've done....you might try a new coil. Hope this helps.

Dan Miller
Auburn, GA

[Orestudeguy]

Ron,
I haven't messed with one of those engines in many years. Seeing that you have changed just about everything and still have the problem, I'm thinking it's got to be something that's been overlooked.
What about the carb mounting gasket? Could it be blocking something on the base of the carb?

[jallen]

Since you don't have the Sun equipment in your garage how about pulling one spark plug wire out of the DISTRIBUTOR at a time, and see if that stops the back fire. Good Luck, you will find the problem.

[Son O Lark]

The advance weights in the distributer may be sticking.