Valve adjustment,running issues?

[72 four door]

I adjusted my valves on my 82 sc and everything seemed to go well. A couple of times when iv'e had her out and shut her down shes a pain to start. Today I drove to the post office and she wouldn't start after i went in. Could I have made the valves to tight? before I did the valves she always started right up. When shes cold she starts but blurbes then slowly comes to idle. Anyone got any ideas Thanks

[kodioneill]

Most likely a fuel issue and a coincidence. You should check your fuel pressure while warm and system off and see if it holds residual pressure.

[Drisump]

I can't see that your valves could be so out of whack as to contribute to starting problems, as kodi says, you probably have a problem unrelated to the actual adjustment.

[72 four door]

I did check the valves [adjustment] 3 times so i think there good. i went down and tried to start it,and shefired and died then ran but with a low idle. I limped home but she didnt seem right. I have been messin with the big screw on the cis maybe i have it adjusted incorrectly. In to increase out to lower idle right? Does anyone know how many turns from the all the way in point will at least get me in the ballpark of having it idle? thanks again.

[Scott R]

You need a gauge on it, you're likely losing residual pressure from somewhere. Maybe the FD, maybe the accumulator or the check valve.

[mytoy]

Originally Posted by 72 four door

I did check the valves [adjustment] 3 times so i think there good. i went down and tried to start it,and shefired and died then ran but with a low idle. I limped home but she didnt seem right. I have been messin with the big screw on the cis maybe i have it adjusted incorrectly. In to increase out to lower idle right? Does anyone know how many turns from the all the way in point will at least get me in the ballpark of having it idle? thanks again.

I may be wrong but I believe that you have this reversed. If you are looking straight at the big screw when adjusting it turning clockwise will lower the RPM as well as make the mixture richer and if you turn it counterclockwise you will raise the RPM and make the mixture leaner. The large screw is and air bleed idle adjustment the same as on a carb. The more you turn it out the more air you allow and the leaner the mix. Now I may be totally out to lunch and I am sure the experts will jump in to correct me if I am off base. Have been before.

[kevstens]

Do you get the same results by turning the idle screw on a DME engine? Does it change the mixture?

[mytoy]

Short answer Yes.

Think about it if you introduce more air into the throttle body below the butterfly valve then you must be increasing the amount of air in your mixture therefore leaning out the mixture. Same as a vacuum leak. If you reduce the amount of air then you are then enriching the mixture.

Now don't get me wrong here. This adjustment is a fine tune adjustment dictated by an orifice and needle valve and the range of lean to rich is very limited unless you completely shut off the valve or completely remove the valve. It won't take a mixture of 14.1 to 13.1 or 15.1 but rather may take 14.1 to 14.05 and 14.15. So you can see that it is not a large step in rich or lean but a very small step in order to fine tune the idle speed.

[TibetanT]

Hello There:

I am no expert, but after setting the valves did you set the timing? If not, that is part of your problem.

On my 911SC, the valves are set, then the timing is set. During the process the idle screw on the CIS intake housing is turned to adjust idle speed up and down when the hose is removed from the distributor advance. In other words, when you remove the hose from the distributor housing the idle speed goes up, so you have to bring it back down to approximately 950RPM...then check the timing with a timing light moving the distributor appropriately. Then, re-attach the hose to the distributor and the idle speed once again will need to be adjusted to 950RPM.

The warm-start issue could be the fuel accumulator going bad. If the fuel accumulator is the original unit, now over 25 years old, it needs to be replaced. I had the same issues with my car not starting after being hot, or rather warmed-up after driving.

Worse case, start by setting the timing and following the procedures in the Bentley manual now that you are assuring us all that the valves are set correctly.

Hope this helps and good luck.

[72 four door]

Ok well heres what I found I checked the fuse for the fuel pump and the end was really corroded and burnt looking. I unscrewed the wire cut the end to a nice section of wire. screwed it back in and it started right up. Now of course i have to fine tune my air mixture as i was playing with it. I guess i need to set the timing before i do that according to ed.