318 Sputtering at Low RPM

[akesel13]

Hello All,

I have a 67 D100 with a 318 and it's been running well up until a week or so ago. Now it sputters pretty severely at low RPMs. Once I get to higher RPMs it runs great. Idling has never been its strong suit, but once I get it warmed up it idles well.

This same thing happened to me almost exactly a year ago. I thought it was the carb, but I took it to a trusted mechanic versed in older motors and he determined it was the distributor. He replaced it, the cap and got the plug wires put in the right spots. It ran great after that, but now I'm back where it started. Could it be the distributor again? If so, something has to be wearing the bearings out in it. I'm going to take a good look this weekend, but thought I would see if anyone had any ideas.

Thanks in advance for the help.

Andrew

[PwrWgnDrvr]

Nylon bump pad on points wears and they have to be re-set, condensers go bad, cap can go bad, timing changes. Several things to always be checking. U didn't say how many miles on it since last tune up.
How did the wires get in the wrong spot? That doesn't happen by itself. Did it get messed with again?

[akesel13]

I'll definitely start there. My mechanic tuned it up for me when he replaced the distributor. So about a year ago and maybe 2K miles.

The wires weren't in the wrong spot, but the cap was installed 180 from where it should have been. He said it was weird, that all the wires were in the right spot for the cap being installed the wrong way. Not sure how that happened as I bought it a couple years ago and that's the way it was when I bought it.

Thanks for the advice and I'll remember to check these things on a regular schedule.

[nutz]

might want to grab the dist shaft and check for side to side play .
just to make sure bearings aren't worn out again .
then grab the rotor an twist it to make sure you mechanical advance is returning back to idle
and of coarse what others posted
hopefully the guy replaced the dist with a good part

[akesel13]

For as much as I know things look good. Distributor is making noise when it's idling, but I don't know if it sounds like the bearing is bad.

Is there an easy way to post photos and videos on here? It's saying my flies are too big. I guess I could add a Dropbox link?

If I pull the choke about halfway out it idles well, but it still sputters when driving. If I push the choke back in while idling it shakes and almost dies then revs back up again. It will do this for a couple minutes and then die. I'm a bit out of my depth at this point.

[nutz]

could be a vacuum leak can spray around carb/intake with gum cutter or brake clean and see if idle changes
but be careful if you have a bad wire ignite it

[PwrWgnDrvr]

could be a vacuum leak can spray around carb/intake with gum cutter or brake clean and see if idle changes
but be careful if you have a bad wire ignite it

Nutz, please put periods at the ends of your sentences. Posts written without can be tedious to decipher and many times there can be more than one meaning. Its disrespectful to others to expect them to take the time and effort to figure out your grammar for u.
btw - this has been an issue here for the 15 yrs since the forum began and all have realized the problem and respectfullly don't do it.
That said, your suggestion on the vacuum leak is a good point.

[akesel13]

This is next on my to do list! Thanks for all of the suggestions.

[nutz]

sorry 44 years as a mechanic has left the spelling /grammar hard to read.
will try to be more coherent.

[martincom]

How many miles on the engine?

Correct me if I'm wrong, but it idles well now? If so, I wouldn't think it would be a vacuum leak. If not, yes. A few other things to check:

Pinch off the hose to the PCV valve (in the top of the valve cover) with a pair of needle nose. If the idle improves you have a defective PCV valve. With a good PCV valve and a correctly functioning engine, the idle speed will drop approximately 50 RPM when the PCV hose is pinched off.

If you have power brakes, pinch off the vacuum hose to the vacuum booster with a needle nose in the same manner. There should be no change in idle speed or how well the engine is idling. If it does, you may have a leaky vacuum booster. These are getting old enough where that is starting to become a common problem.

[akesel13]

Hey martincom,

Thanks for the notes. 94K on the engine. Unfortunately it will barely idle now.

I've traced the vacuum lines and everything checks out. I definitely think it's a timing issue. I'm going to double check this weekend if I have time.

I know a few people have installed the PerTronix Ignitor II. Seems like some hate it and some love it. Think it's worth a shot? I also see that some have gone with electronic distributors. I could also go that route. I've looked at the Proform 66990 which says it's for small block chrysler's. Anyone have experience with these?

Thanks for the help!

[PwrWgnDrvr]

I had a nightmare on a poly that I drove daily from the 80's to 2000. It was the factory exh valve seats melting away from unleaded gas and valves sinking into the head. Valve job fixed that.

[akesel13]

UPDATE

So I gave in and bought the Pertronix Ignitor II, Flamethrower II Coil and new plug wires. It's only been a week since I installed it, but it's running like a top. Fingers crossed it keeps it up. I kept the points for a back up.