Slant Six Forum
https://slantsix.org/forum/

Rough Idle
https://slantsix.org/forum/viewtopic.php?t=32885		 Page 1 of 1
Author:  GENT [ Thu Dec 18, 2008 6:29 pm ]
Post subject:  Rough Idle
Ok on my 67 Dart-

The muffler is blown out,and im not sure if that has anything to do with this. Ok BEFORE I adjusted the Valves today,the car would idle pretty well(besides the clacky valves) and every once and a while it would miss.Im not sure what the miss was,or if it is a miss.But it would idle smooth and then the engine would shake and I would get a little pop from the exhaust(not a big backfire pop but just a little pop) then idle smooth.Today I adjusted the valves got rid of the clacking,and the engine seemed to run pretty smooth.Then I shut it off,put a new valve cover gasket on,got the valve cover on nice and snug.Hooked the PCV and Vac advance back up and fire up the car.The valves still sound good,but the engine what shaking and doing that miss thing a lot more often.I rechecked all of my connections,all good,adjusted the idle,and still the same thing! I took her for a drive and here is what happened:

As soon as I put her in gear the idle went very smooth,and the miss was not happening as much,in fact a lot less.Then when I drive her she feels GREAT.Feels more powerful and more alive than before.Nice pull with light and heavy throttle,no miss no hesitation.Then come to a stop in gear and she is smoothe with a little hiccup here and there,and soon as I put her in neutral same story as before...Man I am lost.Could a bad muffler be doing this? The spark plugs are new,NGK .035 gap.But the wires are old,could it be the wires? No idea how long ago the points were changed or checked... :?

Just want to know what you guys think? Did I mess up my valve adjustment? I want some opinions before I start replacing parts,because I really dont have any spare cash!
Author:  Aggressive Ted [ Thu Dec 18, 2008 7:07 pm ]
Post subject: 
Sounds like it's running a little rich. You can lean out the idle mixture a little. The muffler would create more back pressure and keep it from sucking the fuel out. Replace the muffler and it will help.
Example:
Since my muffler is new and very free flowing design, a Thrush copy of the FlowMaster 40, I run a little more seat time on the valves, .012 and .022. It idles much better with the valves closed a little longer. It also provides a little more low end torque.
Author:  Eric W [ Thu Dec 18, 2008 7:36 pm ]
Post subject: 
Still have points? Change them and see what happens. I used to set my exhaust at .022" like Ted, but left the intake at .010". The best tool for setting the mixture screw is a vacuum guage....shoot for the highest reading possible.
Author:  GENT [ Thu Dec 18, 2008 8:27 pm ]
Post subject: 
Thanks Ted and Eric! Can you reccomend a good vacuum guage,and where to get it? Also whats the best source for a good vacuum reading?
Author:  Eric W [ Thu Dec 18, 2008 8:50 pm ]
Post subject: 
You can pick up a guage at Kragens (soon to be O Rileys) for around 20 bucks or so. I use the choke pull off nipple on the carb, so make sure the engine is warmed up first. A steady reading in the range of 16-20 Hg is good. Lower than 16 or so indicates a vacuum leak.
Author:  THOR [ Thu Dec 18, 2008 9:04 pm ]
Post subject: 
Quote:
You can pick up a guage at Kragens (soon to be O Rileys) for around 20 bucks or so. I use the choke pull off nipple on the carb, so make sure the engine is warmed up first. A steady reading in the range of 16-20 Hg is good. Lower than 16 or so indicates a vacuum leak.
Or a stretched timing chain!! Hehe...

~THOR~
Author:  Eric W [ Thu Dec 18, 2008 9:20 pm ]
Post subject: 
A streached chain will cause the reading to be unsteady.
Author:  THOR [ Fri Dec 19, 2008 1:27 am ]
Post subject: 
Quote:
A streached chain will cause the reading to be unsteady.
So will a leaky intake valve. I had a low vacc. reading on my '71 before I changed the chain, fixed it right up, but it still had a slight twitch on the needle at idle.


~THOR~
Author:  rock [ Fri Dec 19, 2008 5:25 am ]
Post subject:  Gent, as per a vac. gauge, I will make you a deal
Gent,

First, ya gotta know I love tools and spare parts. Since I finally put a gauge under the hood as well as in the cab, I reluctantly decided I don't need the gauge I used on startup after rebuilding. This is a gauge about 5 inches in diameter that I selected because I wanted to be able to hang it up and see it clearly from anywhere if my head was under the hood, which of necessity yours will be if you are doing idle setting. I also set it in the floorboard when cruising because I wanted to clearly see what was happening from the driver seat, before I put in a typical 2 5/8 inch diam gauge.

It was a $60 gage, but if you want it, I would let you enjoy it for $15 plus probably about $5 shipping. (I don't know if you know the term CRC for cyclic redundancy check, but it is comforting to me to have it on the wall and match its readings to those inside cab and under hood.)

rock
'64d100
Author:  GENT [ Fri Dec 19, 2008 9:47 am ]
Post subject: 
rock- You have a PM :D
Page 1 of 1 All times are UTC-08:00
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/