Slant six ignition(?) issues

[SputnikOne]

Hey all, continuing to sort through the seemingly never ending list of slightly inconveniencing issues for my 1973 Dart.

Recently, I've noticed that it takes longer to fire up while cranking than usual, during cold starts it's usually pretty fine, but sometimes it'll stall and die, and then when I go to start it again it cranks for a long while and sometimes won't fire.

The cranking issue seems to present itself more often after turning the car off after driving it for abit, it'll crank healthily, but just won't fire, once it backfired through the intake the moment I let off the ignition key.

I'm not too sure what could cause this, the fuel filter has a good amount of gas in it so I don't think it's the fuel pump, I'm lead to think maybe timing, but I don't have a light to check it just yet. Could it maybe be a fuel mixture issue?

When it's experiencing the issue it cranks nice and fast, it sounds like it wants to start, but it just doesn't, but when it's left for a bit it'll cold start fine again, unless it stalls out like it does sometimes.

 

[MadScientistMat]

You could try using a shot of starting fluid to see if this is a fuel or electrical problem.

 

[SputnikOne]

Suppose I could try, but it'd be hard to tell if that's what caused it to start or if it just decided to fire like it usually does after it cranks for awhile

 

[RustyRatRod]

Suppose I could try, but it'd be hard to tell if that's what caused it to start or if it just decided to fire like it usually does after it cranks for awhile

Then just don't do anything at all. Just don't try.

 

[slantsixdan]

Make sure your choke is working correctly. Refer to this article, but note that the not-very-good '73 factory choke thermostat is not adjustable like the '72-down ones. Make sure the choke pushrod hasn't been bent/brutalized; it should be in a neat, straightened-out-letter-Z shape. If your choke thermostat and its associated parts (the electrical control widget at the other end of its wire, for example) are in less-than-perfect condition, save yourself a lot of aggravation and install a № 1231 Electric choke kit, which is better and adjustable.

Beyond that: Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download. Find tune-up parts-and-techniques suggestions in this post.

 

[SputnikOne]

I'll check the choke yeah, don't really see how it could fail in a way that prevents the engine from starting unless it's somehow full leaning, could be the fuel mixture is just set too lean aswell, I'll check it out tomorrow morning.

I currently have the choke so it's just about fully closed when cold and just under fully open when warm, but yeah, the choke spring and rod are all pretty rusted, though even rich it still should start while warm, yeah?

 

[SputnikOne]

Here's some pictures I took this morning of the choke while cold and after warming up and driving home.

 

[slantsixdan]

Yup, your choke pushrod and choke thermostat have been brutalized, and your choke thermostat is sitting all cattywompus. Probably happened when someone put on that '71 (+70 California) Carter BBS carburetor in place of the original Holley 1920. Good swap, but neatness counts, and that choke sloppiness is going to interfere with ease and consistency of cold starts. Go get that № 1231 electric choke kit, install it and adjust it, and your starts will likely get easier and more consistent.

Can't see from these pics how whoever did the carb swap handled the different fuel inlet location (front on the BBS, side on the 1920). If their fuel line work matches their choke work…clean that up, too; do the fuel line mod, which will help with ease and consistency of hot starting.

 

[RustyRatRod]

Yup, your choke pushrod and choke thermostat have been brutalized, and your choke thermostat is sitting all cattywompus. Probably happened when someone put on that '71 (+70 California) Carter BBS carburetor in place of the original Holley 1920. Good swap, but neatness counts, and that choke sloppiness is going to interfere with ease and consistency of cold starts. Go get that № 1231 electric choke kit, install it and adjust it, and your starts will likely get easier and more consistent.

Can't see from these pics how whoever did the carb swap handled the different fuel inlet location (front on the BBS, side on the 1920). If their fuel line work matches their choke work…clean that up, too; do the fuel line mod, which will help with ease and consistency of hot starting.

Good eye, Dan! It's also hard to see, but I wonder if the bolt that holds the choke thermostat down is broken off in the manifold? The choke rod is in the way in those pictures and you cannot tell.

 

[SputnikOne]

I can get some better pictures of the choke when I get home, the fuel line is currently fuel hose (diabolical! I know), I'll add the choke kit to my to-buy list, though I suspect it wouldn't be causing the motor to simply not start, unless it controls more than just the air valve on the top and I'm confused.

The previous owner said he installed the BBS from recommendations from this forum, but unfortunately means it's another thing that I don't know the state of since I didn't do it myself.

 

[TF360]

Yea, good eye Dan. There's no bolt in there, so the rod will rub against the housing and may not move in and out properly. Looks like an easy fix. Also, check your Battery. My Slanty wasn't starting properly, but my worn out AGM Battery was Turing the motor over like normal. Car wouldn't start every so often-Battery was bad

 

[melcardona]

I'll check the choke yeah, don't really see how it could fail in a way that prevents the engine from starting unless it's somehow full leaning, could be the fuel mixture is just set too lean aswell, I'll check it out tomorrow morning.

I currently have the choke so it's just about fully closed when cold and just under fully open when warm, but yeah, the choke spring and rod are all pretty rusted, though even rich it still should start while warm, yeah?

just my 1.5 cents......ive had to replace more timing chains and gears on mopar engines then any other make....ck to see if your cam is chaseing your crank...the poping is a tell tail sign at turn off.......remove dist cap..turn crank one way then the other...note how far the crank moves before the rotor moves........

 

[SputnikOne]

Planning on picking up a timing light finally to see what the timing is set too, so I'll probably have some questions on getting that to work, but I thought of something and figured I'd see here.

Can the curb idle being too low cause this? It would explain to me why it doesn't want to start when warm, and maybe why it stalls sometimes after starting?

 

[SputnikOne]

recorded this mornings cold start, don't know if it's helpful at all.

 

[SputnikOne]

And here's the dreadful warm Start after turning the car off for like a minute or too and trying to restart it after it was warmed up, coughed at me and everything.

 

[SputnikOne]

Well I have it some more idle speed and returned the idle mixture (it wants alot of quarter turns to the rich side, not sure how many is considered not normal, but I started at the 1 1/2 and it ran terribly so I kept giving it more and it just kept getting happier so it's at about 3 turns out right now and it starts and runs way better, so I'll have to see how the cold start is now once it cools down again.

 

[RustyRatRod]

Well I have it some more idle speed and returned the idle mixture (it wants alot of quarter turns to the rich side, not sure how many is considered not normal, but I started at the 1 1/2 and it ran terribly so I kept giving it more and it just kept getting happier so it's at about 3 turns out right now and it starts and runs way better, so I'll have to see how the cold start is now once it cools down again.

3 turns is in the "about right" range.

 

[SputnikOne]

So should I keep going? I stopped at three cause I don't know how many turns I can do or if it would just unscrew the screw, but it seemed like it wanted more turns to me.

 

[slantsixdan]

Planning on picking up a timing light finally to see what the timing is set too, so I'll probably have some questions on getting that to work, but I thought of something and figured I'd see here.

Can the curb idle being too low cause this? It would explain to me why it doesn't want to start when warm, and maybe why it stalls sometimes after starting?

Yup, go spend some time on those "tune-up parts" and "Carb manuals" links I posted. Time to do some maintenance.

Also, given those starter sounds, I'd put a compression test on the to-do list.

 

[TF360]

Along with the tune up, put a new fuel filter on it too.

 

[RustyRatRod]

Yup, go spend some time on those "tune-up parts" and "Carb manuals" links I posted. Time to do some maintenance.

Also, given those starter sounds, I'd put a compression test on the to-do list.

Compression test is always the first thing I do when I get one. No sense in spending tuneup money on one if it needs engine work. That's the first thing I did when I got Vixen. Still had the original 170. It was skipping where it sat since 1980 when the guy dumped gas down the carburetor and hit the key. I figured burned valve. But I got it home and it had 160 PSI on all six! I hollered "HOT DAMN IT'LL RUN!" Kitty thought I had lost my mind. I adjusted the valves and did a major tuneup and she ran like a swiss watch. lol

 

[SputnikOne]

Yeah, it's has a sputter at idle ever since I had it, I assume at least one of the cylinders is not having the greatest time. How do I compression test? With a vacuum gauge? Or does that involve taking it apart? I've seen people test vacuum from a line but how would I check individual cylinders?

 

[RustyRatRod]

Just get a compression tester and pull the plugs.

 

[slantsixdan]

[YouTube vid]

Blue smoke on rev like that seconds the request for a compression test.

How do I compression test?

Get a compression tester.

Make sure the battery's charged up.

Remove all six spark plugs.

Remove the multiwire connector from the ignition control module over on the driver's-side inner fender.

Remove the throttle return spring and make sure the choke and throttle are both open.

Install the compression tester in the frontmost cylinder and crank the engine through five "chugs". It's best if you can arrange to do this so you can watch the compression tester gauge during cranking – get a helper inside the car operating the key, or operate the starter from underhood by carefully connecting the two largest terminals on the starter relay, or even more carefully by using a screwdriver to connect the large and small terminals on the starter itself. You'll be writing down the gauge indication after the fifth "chug", but what you're watching for is how quickly it builds up to that final reading. Does it get most of the way there on the first chug, then the other four just nudge it up a bit more? Or does it have a feeble first-chug reading, a little higher on the second, a little higher on the third, etc?

Write down the final reading, then move the compression tester to the next cylinder and do it again.

Post your results and observations here.