|
|
|
Your donations help keep this valuable resource free and growing. Thank you.
|
Idle varies when hot |
Post Reply 
|
| Author | |
dodgemahal 
AMC Apprentice 
Joined: Dec/11/2015 Location: Illinois Status: Offline Points: 48 |
 Post Options
 Thanks(0)
 Quote Reply
 Topic: Idle varies when hotPosted: Oct/03/2017 at 9:35am |
|
When I got my 76 Pacer I replaced all ignition items. Replaced all of the filter items. Rebuilt the carb and dialed it in. It ran near perfect and seemed razor sharp. However, the other day when the ambient temp was 95 degrees and the engine was idling while hot, I noticed the idle RPM was fluctuating slightly, maybe(and just guessing here) 25-40 rpm up and down. Most folks wouldn't notice but I have an ear for such things. Any ideas as what could cause this.
Keep in mind I'm still going through this awesome ride, just have a lot of demands on my time right now. BTW, for those that recognize I have an egr thread out there now, note that the egr is closed so that shouldn't be the culprit.
|
|
 |
|
|
Lyle
AMC Addicted 
Joined: Jul/17/2014 Location: None Status: Offline Points: 772 |
Post Options
Thanks(0)
Quote Reply
Posted: Oct/03/2017 at 10:45am |
|
I'll take a stab at it being fuel flow.
At idle your float is opening and closing allowing slightly cooler fuel to the carburetor. This slight variation in temperature would change the combustion ever so slightly until equilibrium of fuel temperature. This in turn would vary RPM ever so slightly. If you take a real good digital timing tachometer to a car with a carburetor it will never be completely steady at idle or at lease I've never seen it.
|
|
|
|
|
mixed up
AMC Addicted
Joined: Jun/16/2015 Location: Monroe mich Status: Offline Points: 2177 |
Post Options
Thanks(0)
Quote Reply
Posted: Oct/03/2017 at 12:21pm |
|
look down the carb see if you can see fuel dripping if so you might have a bad needle and seat or flout level to high or sunken flout
|
|
|
69 amx 290 auto
65 220 290 4spd 80 ford fairmont |
|
|
|
|
FSJunkie
AMC Addicted
Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4742 |
Post Options
Thanks(0)
Quote Reply
Posted: Oct/04/2017 at 8:55pm |
|
Ambient temperature will affect the idle speed and mixture. You just have to keep retuning it as the weather changes.
|
|
|
1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
|
|
|
|
dodgemahal
AMC Apprentice
Joined: Dec/11/2015 Location: Illinois Status: Offline Points: 48 |
Post Options
Thanks(0)
Quote Reply
Posted: Oct/06/2017 at 11:14am |
|
Those are great comments/ideas guys. I know carburetors have inherent inefficiencies and it's difficult if not impossible to get them 'just right'. I was curious about the physics of this or if the problem could lay elsewhere, such as timing, vacuum, distributor. As I continue to work through this Pacer I will likely find other things to fix. It's all fun and a great toy to play with. I may be forced to sell it someday due to finances here at home. PM me if you are interested. 30K miles and is original and really good condition.
|
|
|
|
|
CamJam
Moderator Group 
Joined: Jan/04/2014 Location: Arizona Status: Online Points: 6547 |
Post Options
Thanks(0)
Quote Reply
Posted: Oct/07/2017 at 11:24am |
|
My 304 does the same thing in hot weather. I've always just assumed it was the nature of the beast with carbs.
|
|
|
'73 Javelin 360 (current project)
'72 Baja Bronze Javelin SST '69 Big Bad Orange AMX (2018 Teague Heritage Award) SOLD  |
|
|
|
|
amcfool1
AMC Addicted
Joined: Jun/18/2011 Location: roanoke va Status: Offline Points: 1075 |
Post Options
Thanks(0)
Quote Reply
Posted: Oct/07/2017 at 7:25pm |
|
hey, if your biggest problem is idle fluctuation of 30!, thirty!? rpms, well, my friend you are doing better than most of us! Hey, enjoy the car, if really worried, take some time to read up on old school carb/choke/timing issues, if real concerned, put in a modern A/F meter, and tune from there.
Sheesh, I wish I had problems like this, oh wait, I did...:) good luck, gz
|
|
|
george z
|
|
|
|
|
dodgemahal
AMC Apprentice
Joined: Dec/11/2015 Location: Illinois Status: Offline Points: 48 |
Post Options
Thanks(0)
Quote Reply
Posted: Oct/08/2017 at 9:42am |
Haha! It's a curse to be a perfectionist sometimes. I do enjoy the car.....it's a blast! I get so many smiles and thumbs up from others. My Uncle had been itching for me to buy it from him. I resisted for years because I have a million or so cars already(I'm a Mopar freak/geek). As I mentioned I was curious to why this is happening and I have had many good responses here that have been very informative. This is a great forum. |
|
|
|
|
amcfool1
AMC Addicted
Joined: Jun/18/2011 Location: roanoke va Status: Offline Points: 1075 |
Post Options
Thanks(0)
Quote Reply
Posted: Oct/08/2017 at 11:54am |
|
hey, yeah, I know, for years we had a 76 Pacer, (also 258 1bbl),white over teal, we could not leave the driveway, the driveway!, without someone smiling/thumbs up/cool car, etc etc. Pacers Rule! good luck, gz Just the Happiest car ever made! Secure with its funky look and body image, when you see a Pacer coming, you just gotta SMILE!
|
|
|
george z
|
|
|
|
|
Post Reply
|
|
Tweet
|
| Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |
Click for TheAMCForum Rules
Topic Options
amcfool1 wrote: