45 Guests, 0 Users

Author Topic: carb tuning  (Read 2185 times)

0 Members and 1 Guest are viewing this topic.

Offline cobra

  • Pinto Member
  • **
  • Posts: 14
  • FeedBack: +2/-0
  • Gender: Male
  • Another Pinto Driver

  • Total Badges: 2
    Badges: (View All)
    Topic Starter Fifth year Anniversary
carb tuning
« on: October 09, 2011, 03:47:03 PM »
I can really use some help. My crab tries to rev up without touching anything. I installed an electric temp on the crab and not running the exhaust into it either. It seems as though I have a vacuum leak but cannot fine it. The only vacuum line I have connected is to the distributor, others are plugged for the time being. Timming and dwell are correct. Anyone have any ideas they sure would be appreciated.

RSM

  • Guest
Re: carb tuning
« Reply #1 on: October 09, 2011, 09:00:52 PM »
Never seen a crab rev up before...might be kinda interesting LOL....just kidding. A little more info would help. Did this problem just occur or did you do something to the carb then it happened?....need info.

Offline cobra

  • Pinto Member
  • **
  • Posts: 14
  • FeedBack: +2/-0
  • Gender: Male
  • Another Pinto Driver

  • Total Badges: 2
    Badges: (View All)
    Topic Starter Fifth year Anniversary
Re: carb tuning
« Reply #2 on: October 10, 2011, 04:38:35 PM »
It's a 1974 pinto. I rebuilt the engine, honed out the cylinders and valve job, and have compression of 135 on 3 cylinders and 1 with 130. I put on 3 rebuilt carbs but couldn't get it to run right. I got a new one and can't get it adjusted right. When it's timed correctly vacuum is low. When I advance the timing I get good vacuum reading but it won't idle down. It wants to stall out like it's not getting enough gas. I had an auto mechanic get it running fair with the timing correct but it idled at 1100rpm but only for a few seconds. Then it started to rev up. Now I have messed with it and must call the mechanic back too get it close again. I am building a kit car (29 Mercedes) and once I put the body on there is not much room to work on the carb.
I have even gone as far as to think about moving the timing belt 1 notch to see if that makes a difference.
Any suggestion would be appreciated.
Thank you

RSM

  • Guest
Re: carb tuning
« Reply #3 on: October 10, 2011, 09:53:12 PM »
A good place to start is to double check your timing marks and make sure everything is timed correctly. If your off 1 tooth on the cam it will really throw things off. Your ok with the one cylinder down 5psi, within spec. Check that and let us know if it's correct.

Offline cobra

  • Pinto Member
  • **
  • Posts: 14
  • FeedBack: +2/-0
  • Gender: Male
  • Another Pinto Driver

  • Total Badges: 2
    Badges: (View All)
    Topic Starter Fifth year Anniversary
Re: carb tuning
« Reply #4 on: October 11, 2011, 11:02:45 AM »
The timimg mark on the crank should be tdc. and not set at 3 degrees.  Is that correct?  The cam mark is about 1/16 inch off. I think that is due to the play in the mounting bolts of the cover. I don't know how many degrees it will change if I move it. I am getting out of options.
Bob

RSM

  • Guest
Re: carb tuning
« Reply #5 on: October 11, 2011, 11:06:52 AM »
Everything should be at 0 when installing the belt.Is the belt new??

Offline cobra

  • Pinto Member
  • **
  • Posts: 14
  • FeedBack: +2/-0
  • Gender: Male
  • Another Pinto Driver

  • Total Badges: 2
    Badges: (View All)
    Topic Starter Fifth year Anniversary
Re: carb tuning
« Reply #6 on: October 11, 2011, 05:00:29 PM »
Yes it is. What does the lock mean next to my inquire?

Offline Pinto5.0

  • Pinto Master
  • *****
  • Posts: 1974
  • FeedBack: +77/-0
  • Gender: Male
  • 80 hatch, 76 Wagon, 72 & 73 Sedans, 71 half hatch

  • Total Badges: 7
    Badges: (View All)
    Topic Starter Signature Poll Voter Mobile User Fifth year Anniversary Windows User 1000 Posts
Re: carb tuning
« Reply #7 on: October 11, 2011, 08:52:57 PM »
Yes it is. What does the lock mean next to my inquire?

That lets you lock the topic so no further comments can be added.
 
I'm thinking you either have the timing belt off a tooth, have a leak at the carb gasket or possibly the intake manifold to block gasket. The gaskets can be checked with the engine running by spraying starting fluid around the gaskets. If the engine revs you have a gasket leaking. You may also have an open vacuum port you missed.
'73 Sedan (I'll get to it)
'76 Wagon driver
'80 hatch(Restoring to be my son's 1st car)~Callisto
'71 half hatch (bucket list Pinto)~Ghost
'72 sedan 5.0/T5~Lemon Squeeze

Offline cobra

  • Pinto Member
  • **
  • Posts: 14
  • FeedBack: +2/-0
  • Gender: Male
  • Another Pinto Driver

  • Total Badges: 2
    Badges: (View All)
    Topic Starter Fifth year Anniversary
Re: carb tuning
« Reply #8 on: October 14, 2011, 08:12:15 AM »
I have done those things be to no avail. I rechecked the timing and it is right on. I will recheck the vacuum lines that are plugged to be sure the caps don't have any cracks in them.