1968 Plymouth fury won't run right!! Help!!

[68plymouth383]

1968 Plymouth fury 440

Hey guys, I've been chasing down some crazy drivabilty symptoms for the last few months. This summer I changed all the plugs, installed a new fuel pump, and fuel pump pushrod, that solved all the fuel starvation, and poor running issues. a few months ago I was driving my car, and it started running terrible... No power, missing just rough all together. I swapped the fuel filter, and that helped some. I did a test, and found out my distributor vacuum advance was blown. long story short I swapped that out, and the car ran perfect. I go to drive it the next day and it's back to running erratic. idle is terrible, has ok power, but it's just lazy. I changed all the plug wires, and it seemed ok. but I go to take it out this morning, and it won't run right at all. There has to be something crazy simple that I'm missing here. when the car is in neutral it runs ok, but you can here the miss. when you put it in gear it surges, and the ampmeter dips way down.

 

[The Horvaths]

Basics: have you checked your base timing and made sure you put the plug wires back in the correct order? If you changed the rotor or pulled the dizzy, did you put it back in the same spot? Do you have EI?

 

[68plymouth383]

Yes, base timing was set, and car was tuned. I made sure the plug wires are all in correct order. I'm running a pertronix ignitor 2. distributor was marked for location, and cap, and rotor were both changed.

Basics: have you checked your base timing and made sure you put the plug wires back in the correct order? If you changed the rotor or pulled the dizzy, did you put it back in the same spot? Do you have EI?

 

[The Horvaths]

You may want to check your timing with a vacuum gauge incase something slipped. Have you checked for a vacuum leak or bad coil? Have you checked fuel pressure with a gauge?

 

[70bigblockdodge]

Fuel filter

 

[goldfish65]

I'm not a tech at all but if you have power brakes the booster may be starting to go and it's giving you a vacuum leak. Let us know what you finally figure out.

 

[GregG48203]

You may want to check the quality of your replacement parts (i.e.: vacuum advance). Some people have had good luck with Pertronix; I have not. -Unless you consider five years from an Ignitor 3 to be "good". For me, that's no better than points.

 

[3C's & a D?]

I seem to recall reading on this site years ago that the pertronix 2 and 3 don't work right on our cars. I've put many miles on a few different engines 360's, 383 and 440s with pertronix 1 with zero problems. One time the 383 started running rough, swapped in a new coil, ran great until I killed it.

 

[mdh157]

well, you could swap back to points/condenser if you still have them sitting around to rule out the pertronix.........but my $$ says the answer is in this sentence:

"I did a test, and found out my distributor vacuum advance was blown. long story short I swapped that out, and the car ran perfect. I go to drive it the next day and it's back to running erratic."

Did you swap the advance out with a used or new part?

 

[68plymouth383]

Ok, I bought my pertonix ignitor 2 in 2007 when I bought my car. it worked perfectly on my 383, and when I switched to the 440 it was moved to that distributor. The 440 distributor was a a1 cardone reman unit... I've had lots of issues with those. that one had the blown vacuum advance. I searched for 3 weeks to find a replacement because there not being made anymore. all the replacements wouldn't hold a vacuum when tested. I purchases a new Chrysler electronic ignition distributor, and bought the pertronix ignitor 2 for that one. I'm having the exact same symptoms with the new one, as I did on the other distributor. I know the pertronix is a good system, and 2 different distributors cannot have the same issues happening. or maybe I'm wrong? today I swapped coils for a know good used one, I also changed the fuel filter with no change in the running condition

 

[68plymouth383]

I also sprayed the carb base, all vacuum lines, and intake with carb cleaner to check for vacuum leaks. none were found

 

[1966newport]

timing chain

 

[3C's & a D?]

Are you saying you are using an electronic distributor 72+ with pertronix 2? Is that even possible? If so, I would think that would be at least part of, if not the complete problem.

 

[68plymouth383]

Further investigation lead me to believe the intake manifold had an air leak. I pulled it, and the engine builder only used the valley pan to seal the cast iron heads to my aluminum intake. I completely cleaned it, and used a new Valley pan, and 1 gasket against the intake. No change. My dad took a listen, and said possibly a blown head gasket. The car has never overheated, and the engine has under 10k since a complete rebuild. I'm really starting to question the build quality. I paid a ton... what do you guys recommend for head gaskets. I'm running a built set of 906 heads. Next step is a compression test

 

[70bigblockdodge]

I have never had a head gasket, steel shim, composite, fel-pro or jimbobs brand. Age and rust are the only reason a head gasket fails on a BB Mopar. Compression test will tell you more.

 

[68plymouth383]

Ok, thanks Dave I was hoping you'd chime in

 

[70bigblockdodge]

If it is sputtering and sluggish I still point to fuel. Also how many volts to + coil with car running/idle. Does it act up with the choke on or does it run better when cold and being choked. If no choke well disregard that.
You know I'm not a fan of petronix but they do work and what about your fusible link didn't Scott have a problem with petronix and fusible link. Make sure it is has not become a voltage drop resistor instead of a protection device.
I know I'm kind of guessing here but all I mentioned cost nothing to check. Hit a few points where you know you should have full battery voltage with the car running like ballast resistor, cigarette lighter, terminals in fuse box, just to make sure your electric system is good.

 

[1966newport]

follow up?

 

[saforwardlook]

I didn't see this thread in the beginning. But if your carburetor is the original Holley 4 bbl used on the 440s in 1968, you should always start there when you have any driveability issues. Those carburetors simply did not run well after a couple years and they can not be rebuilt successfully either after many years of operation because the metering blocks and fuel bowls and every other major part of those assemblies warp and cause nothing but problems just like you are experiencing. And they are erratic in nature. I agree with Dave that you should start with the fuel system, and whenever I see one of those original Holleys, I just take them off in the first place. They were just junk when they were a couple years old and had gone through repeated heating and cooling cycles. Either get an original AFB of that era and put it on your car or get an Edelbrock or even a new Holley (which are good carburetors). Then if you have a problem, then proceed with other possibilities.

And like Dave, I am not a fan of Petronix. Most people that switch over to them from points usually have more problems with them than the points systems they replaced.

 

[70bigblockdodge]

I didn't see this thread in the beginning. But if your carburetor is the original Holley 4 bbl used on the 440s in 1968, you should always start there when you have any driveability issues

I'm pretty sure Jason's is not original 440 and I think he has a newer Eddy on it.