Classic Mustangs (Tech) Technical discussions about the Mustangs of yester-year.

Valve lash question

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Old Apr 1, 2007 | 03:42 PM
  #1  
paddy187's Avatar
paddy187
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From: Eke, Belgium
Default Valve lash question

Ok a while ago I adjusted my valvc lash on my car as per the FAQ and then didn't have a chance to run it, broke spark plug wires, went on hoilday got ill andthe battery went flat. This weekendI finally got it going but it wouldn't idle it just keep cutting out. I know that I have a carb fuel leak, carb is being rebuilt this week (is my number onesuspect) butI remember somethingI read saying that if the valve lash was over tightened it would effect the idle. Is this true or did i remember wrongly? I also remember reading that u can't overtighten the valve lash, is that true?It is just my first carb rebuild so my confidenece in it will not be 100% and I want to make sure i didn't screw up the valve lash first. Also if anybody has any tips a getting thick undercoating of the battery tray bolts let me know!!

Cheers for you help

Paddy
Old Apr 1, 2007 | 04:19 PM
  #2  
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my77stang
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From: Citrus County, FL
Default RE: Valve lash question

do you have adjustable rocker arms? if so then you want zero lash plus 1/4 to 1/2 a turn when yoru absolutely sure the cam is down.

that should get ya right where you need to be.
Old Apr 1, 2007 | 04:35 PM
  #3  
paddy187's Avatar
paddy187
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Default RE: Valve lash question

I did 1/2-3/4 of a turn as the http://raceabilene.com/kelly/hotrod/valveadj.htmlsuggested. I beleive they are the postive stop ones but could you tell me how i would tell the difference so i can check next weekend mystang77? cheers

Paddy
Old Apr 1, 2007 | 04:47 PM
  #4  
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rmodel65
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From: deep in the heart of dixie GEORGIA
Default RE: Valve lash question

if they have a shoulder on the stud then they are positive stop if no shoulder then they are adjustable
Old Apr 1, 2007 | 04:49 PM
  #5  
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my77stang
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From: Citrus County, FL
Default RE: Valve lash question

yup, and if your using late model stuff with stamped steel rocker arms then have bolts that bolt down to 15-18 lbs. instead of nuts.
Old Apr 1, 2007 | 04:51 PM
  #6  
paddy187's Avatar
paddy187
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From: Eke, Belgium
Default RE: Valve lash question

Cheers, would over tightening cause problems in the idle?
Old Apr 1, 2007 | 05:42 PM
  #7  
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67t5ponycoupe
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Default RE: Valve lash question

Yes
Old Apr 1, 2007 | 05:49 PM
  #8  
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Default RE: Valve lash question

Absolutely. Another way to adjust them is to loosen then until they rattle while the engine is running then tighten them slowly until the rattle stops. It's a messy job, so have the car out where you don't mind oil getting on the ground. Get that carb going first before you suspicion the valves being too tight. You do not have solid lifters, you have hydraulic valves.
Old Apr 1, 2007 | 06:02 PM
  #9  
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paddy187
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From: Eke, Belgium
Default RE: Valve lash question

Yeah, glen that isthis weeks fun task clean and rebuild my 2100 and if the idle problems are still a problem after that recheck the valve lash. Just going to take the rebuild quite slow so I can make it good.
Old Apr 1, 2007 | 06:07 PM
  #10  
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From: NJ
Default RE: Valve lash question

In case you are confused by the replies let me explain. These engines have two different valve adjustment proceedures on for the earlier and another for the later models.

If your 65 has the original engine it has the early set up.

There are two different but equally proper proceedures to adjust.

One with the engine running one with it not running.

The simplier but messier way is with the engine running. This call for backing off the adjustment nut until it clatters. Tighten till it quiets. Then tighten an additional 1/2 to 2 full turns (depending on who is telling you) Personally I use the 3/4 turn.

As you tighten the the engine should go rough then smooth out.

If it does not smooth out then you most likely have a stuck lifter problem.

That of course opens another whole can of worms.



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