Tune-up

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70DartSedan

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Betty (as suggested by goldfish) in another thread runs a little rough during idling, I'm trying to track down the problem(s). Well The car was idling really nasty and I checked for vacuum leaks. I found the carb was not even bolted down (hand tight, barely) from the time it went to a shop. That made it a little better. So then I check the heat sensor and it is bad. I gotta get on that. So Finally I flip through the owners manual for some info and I read the spark plug section. It said that bad plugs will cuase a rough idle. So I pulled out the plugs and they were brown and some were rusty, the gaps were different on each plug.

Info:

225 CID L6
54,360 miles
lash is good
fresh oil & filter
new fuel pump
Original coil, dist, and wires
550 RPM in Drive
Ign Timing 5 degrees BTDC
new fuel pump

Also what is the torque specs for a plug on the 225? Not in the FSM, at least that I can find...
 
Hey Buddy,
Sounds like you have everything under control. What did you gap the plugs at? Like 35 on a feeler guage?? I have never used a torque wrench on the plugs. Most likely not correct but I snug them and give the ratchet one extra little nudge. One thing though. If you put new plugs on the car did you leave the little washers on them? This sometimes will create a little leakage by the drool tubes. I cut mine off. The plug seals better that way. On the carb. Have you adjusted the fuel mixture screw? I know you had a carb issue and work was done but if that is not adjusted right the idle will be rough. I do mine by ear and turn the screw all the way in until it seats, (no forcing here) and then back it out 2 1/2 turns and just tweak it a 1/4 turn a so either way to get a smooth idle. Another trick is to lightly spray some starting fluid or carb cleaner around the base of the carb and by vaccum lines etc. If there is any leaks the idle will drop or rise depending which you have sprayed. Another trick is to get a fantastic bottle and fill it with water. At night spray the plug wires a little while the car idles and look ar arcs in the plug wires. Have you replaced the intake/exhaust gasket? Another possible issue. There is still other things but this should keep you busy for awhile. By the way, looking at two Fridays from now getting out to Mickey Ds on 132. Like to meet u with you there!!
chas.
 
ChazRam said:
Hey Buddy,
Sounds like you have everything under control. What did you gap the plugs at? Like 35 on a feeler guage?? I have never used a torque wrench on the plugs. Most likely not correct but I snug them and give the ratchet one extra little nudge. One thing though. If you put new plugs on the car did you leave the little washers on them? This sometimes will create a little leakage by the drool tubes. I cut mine off. The plug seals better that way. On the carb. Have you adjusted the fuel mixture screw? I know you had a carb issue and work was done but if that is not adjusted right the idle will be rough. I do mine by ear and turn the screw all the way in until it seats, (no forcing here) and then back it out 2 1/2 turns and just tweak it a 1/4 turn a so either way to get a smooth idle. Another trick is to lightly spray some starting fluid or carb cleaner around the base of the carb and by vaccum lines etc. If there is any leaks the idle will drop or rise depending which you have sprayed. Another trick is to get a fantastic bottle and fill it with water. At night spray the plug wires a little while the car idles and look ar arcs in the plug wires. Have you replaced the intake/exhaust gasket? Another possible issue. There is still other things but this should keep you busy for awhile. By the way, looking at two Fridays from now getting out to Mickey Ds on 132. Like to meet u with you there!!
chas.
Click to expand...

Thanks for the advice Chaz. I'll look into the spark plug washers. I've got the car just about where I want it. I'm going to follow up with the shop that did the initial tuning and I will check in with them. I know I need a new heat sensor I'll also look into the plug wires.

I'll be there at the Mickey D's. I also will be at the Mopars in the Park in Fox Lake on Sunday the 24th.
 
Good to go on Mopars in the park!! Thats like the 24th of this month right. I am planning on attending as well!! Wouldnt want you to take all them slant trophies, HA HA!! Anyhow, I would like to meet you and see that car in person. Better not let me be alone with that car without some supervision, have some hidden tools and my car needs alot of little things, just kidding!! Anyhow try the carb cleaner. Spray it around the base of the carb while the engine is running, a little shot by the flange on the end of the manifold by the motor, near vaccum lines and listen for any kind of surge in the idle, and what do you mean by a heat sensor?? Do you mean the little bolt sticking up at the front of the head that brownish colored wire hooks up to, that ones a snap!! I did not cover this one but if you pull the pcv out of the grommet and shake it does it rattle inside. If this gets clogged it can make your car run like crap too. Are you still running points and if so where did you get them? Cheapo kits lend crummy results IMO. Anyhow, lots of little things you can check. Thats what makes slants so much fun!!
Chas.
 
ChazRam said:
Good to go on Mopars in the park!! Thats like the 24th of this month right. I am planning on attending as well!! Wouldnt want you to take all them slant trophies, HA HA!! Anyhow, I would like to meet you and see that car in person. Better not let me be alone with that car without some supervision, have some hidden tools and my car needs alot of little things, just kidding!! Anyhow try the carb cleaner. Spray it around the base of the carb while the engine is running, a little shot by the flange on the end of the manifold by the motor, near vaccum lines and listen for any kind of surge in the idle, and what do you mean by a heat sensor?? Do you mean the little bolt sticking up at the front of the head that brownish colored wire hooks up to, that ones a snap!! I did not cover this one but if you pull the pcv out of the grommet and shake it does it rattle inside. If this gets clogged it can make your car run like crap too. Are you still running points and if so where did you get them? Cheapo kits lend crummy results IMO. Anyhow, lots of little things you can check. Thats what makes slants so much fun!!
Chas.
Click to expand...

Yep the 24th this month. I'll check out the carb cleaner trick. The heat sensor is the one that is inside the air cleaner, has a hose from the carb and a hose from the vacuum canister on the snorkel. It lets the engine suck in hot air from the exhaust manifold to help warm it up. The PCV was changed a week ago and it needed it. It runs a lot quiet without the damn thing rattling around inside there. As far as I know the car is running on the original factory points.
 
Ah, I dont have one of those (see picture) so it all 'Greek' to me. I would get them points changed out. Most likely they have corrosion on the contacts. THAT will make that car run 'not so good', hope you have small arms and hands. My forearm is 17 inches around and I have some big mitts so when I gotta get near that distributor I get my son to do the nasty and I direct him!!
Chas.
 

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You can find info about "don't use gasket on slants w/ spark plug tubes" and much other tuneup info in many FABO posts. Search SlantSixDan's posts since he has some archival info. I read that leaving off the gasket puts the spark plug gap in a better position in the cylinder.

When you consider upgrades, conversion to electronic ignition is a big bang for not much money, if you go the HEI junkyard route. That will keep your hands out of that tight nasty crevice where the distributor sits. You can get new spark plug tube seals cheap to make it less nasty. I took off the factory coil and mechanical fuel pump, so my slanted side is much cleaner.
 
I'll have to keep the points for now. Maybe an electronic upgrade in the future.
Say Chaz you wouldn't know anyone around here that does points adjustments do you?
 
1 - Ignition points sound like the likely culprit here. Either worn out or not adjusted properly.

As the points wear down the gap gets much smaller, creating more dwell time(time that the points are closed). More dwell time means that the coil does not have enough time to build back up to maximum energy, which results in a weak spark. It's also got the effect of retarding the timing. The later the points open, the later the spark is to the cylinder. Same with spark plug gap. Both could be causing the rough idle.

2 - Rule out an air leak at the intake gasket and at the base of the carburetor. Carburetor cleaner works well here. spray around the base and the bottom of the carb, see if the engine idle raises. same with all the intake ports.


3 - Carburetor adjustment. Idle mixture screw could need an adjustment. Chaz explained this well. I prefer to set by ear. When you adjust from that 2 1/4- 2 1/2 turn out, slowly move the screw out at first. The engine will either pick up ever so slightly or lay down. If it picks up, keep going until it begins to level out or start slowing. When it does that, go 1/4 turn in the other direction and your golden. Just readjust the idle if needed.
Be sure to rule out #1 and #2 first.

Oh yea, and +1 on the Home made HEI. If there is one thing that the General did right, it was electronic ignition. VERY VERY well designed system with a low failure rate, provided you buy a decent non china made HEI module. Electronic distributor is pretty cheap for these engines. HEI module and coil can be had from a junkyard. I grabbed a coil from a 98 Silverado. Napa HEI mod.
 
Check valve lash adjustment. This is a normal maintance procedure to be conducted every 12 months or 12,000 miles as part of a tune-up.

Quoting FSM: " Should engine continue to be noisy and idle rough after tune-up, adjust valve lash to specifications."
 
wjajr said:
Check valve lash adjustment. This is a normal maintance procedure to be conducted every 12 months or 12,000 miles as part of a tune-up.

Quoting FSM: " Should engine continue to be noisy and idle rough after tune-up, adjust valve lash to specifications."
Click to expand...

this was just done three weeks ago.
 
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