Where should I start first????

sean m · sean m's Garage

First my background is never worked on a car in my life, got Wayne's book and the Bentley's and have done some "minor things" like....fuel filter, fuel pump, valve cover gaskets, added 11 blade fan etc.... in Wayne's book I'm 2 mechanic guy.

Did a little tune up on my '77 S a couple months ago......oil change, filter, new plugs (not sure when the last time they were changed).

Everything was fine. The last couple times I've taken it out though, it seems to take a couple miles before the "stumbling" quits. It never did that before. I start it up, let the idle hunt a little (2 or 3 min), start driving slowly until oil temp gets up. First 3 or 4 miles is rough and then, all of a sudden, it runs like a champ.

What'd I screw up? Where do I start?

My thoughts were a plug, or a wire were not on right. If that's it, wouldn't run rough all the time?

Second, I know all the wires were correct because I did them one at a time.

Any help is appreciated.

Hugh R · 08-27-2008, 03:31 PM

Try some Chevron gas treatment. It's cheap and won't hurt.

sean m · sean m's Garage

Thanks Huge, I've done that.....no change.

Besides, I was thinking if there was a fuel issue it'd be there all the time. It runs great after 3 or 4 miles.

Could a plug be bad? Even with a bad plug I would think it'd stumble all the time.

Zeke · 04:05 PM

My 77 was cold blooded as many are. One thing you have to do is drive these things hard. You can't putt around the neighborhood and expect the motor to stay clean. Did you use the same type plugs? Another brand could be slightly colder and load up more easily.

Also, while you're sorting this out, make darn sure you have a pop off valve installed. I didn't way back when in the early 80's and blew the box off the intake one morning just starting the car. That's when they do it.

sean m · sean m's Garage

Thanks Milt.....it's got the pop off valve. The plugs I put in were different. I put in
NGK spark plugs.

Maybe I've just got to "blow it out" a little.

ossiblue · 08-27-2008, 04:44 PM

A couple of things also may account for your problem.

First, you mentioned you let the "idle hunt for 2 or three minutes." If you mean the idle races and drops and races and drops, that is not a normal condition. Usually it indicates an overly rich mixture. Also, the unstable idle--whatever you mean by your description--seems to be overly long in it's duration, but again, it may just seem like it's 2 or 3 minutes when in fact it is shorter.

Second, since you changed the plugs, it is possible that one or more of the connectors has worked loose or isn't seated properly on the plug--that happens quite often. If you have stock plugs with Beru connectors, be sure you feel the definite "snap" when the connector seats. A weak or misfiring plug will often smooth out when the engine warms and the revs are high, hiding the fact that the connection is bad.

Hope this helps, and keep us posted.

sean m · sean m's Garage

L.J.
I say 2 or 3 minutes....it's done it from day 1, it's probably a minute. Goes up and down from 2000 to 800 a few times and then idles at 900.

I've wondered about the ignition wires. I've searched and seen that people say when the wires go bad you see a light show if it's dark....no light show as yet.

I'll check to insure all wires are seated correctly. Can the wires be bad and not have a light show?

Just wondering.

ossiblue · 08-27-2008, 05:32 PM

Quote:

Originally Posted by sean m

L.J.
I say 2 or 3 minutes....it's done it from day 1, it's probably a minute. Goes up and down from 2000 to 800 a few times and then idles at 900.

I've wondered about the ignition wires. I've searched and seen that people say when the wires go bad you see a light show if it's dark....no light show as yet.

I'll check to insure all wires are seated correctly. Can the wires be bad and not have a light show?
Just wondering.

Absolutely! You can check the resistance on each wire but I have had problems where the connector measures correctly until you tap or vibrate it and the connector shorts out. Wires themselves can get "tired" and become less effective without giving off sparks.

I suspected your idle description was not as extreme as I has interpreted, and is probably not related to the stumbling you describe. Believe me, it's very easy to misconnect the plug connector (color me guilty) and not know it. Eliminate the easy/free solutions first.

Paulporsche · 08-28-2008, 05:11 AM

If your idle hunts in a sort of rhythmic fashion, then usually your mixture is too rich. You can try leaning it in small increments (say 1/16 turn) and see if it improves. You can also take it to a shop and have the mix set @ 3 to 3.5%. If altering the mix doesn't do it, then you should check the operation of your WUR (warmup regulator) which controls the mixture throughout the entire temp range, and your AAR (auxiliary air regulator) which keeps the revs up for a few minutes from a cold start.

CharlesJones · 08-28-2008, 06:19 AM

That "stumbling" for a couple of miles - have you changed your dizzy cap and rotor arm recently? If not it might be worth a try - it would only cost you a few quid, and I think they're as critical as the plugs and ignition wires.

sean m · sean m's Garage

Thanks Charles.......never changed the cap or the arm on the dizzy. I'm sure it's time to.

I did a search and there's some great articles on cleaning the dizzy as well.

I'll give it a shot.

Thanks again