Tuning Questions Part 2
Thread Starter
Pro
Joined: Apr 2001
Posts: 545
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From: Waukesha WI
Tuning Questions Part 2
Ok I spent some time tuning today. I followed Lars procedures, and order. Set dwell, set timing, adjusted idle screws and stop screw. Got it all running perfect. Would start, high idle, slow down, idle smooth, no stumble. Let it run for a good 15-20 minutes at idle/blip throtle, wait, idle, blip etc. No prob. Shut her down and went for a cruise a few hours later, had to give gas to keep running until warm, then idle was way to high 1500-2000 rpm. Idle was right at 1k earlier. However at one stop light it was back to normal, then the next back up too high. Whats going on?
Earlier problems were an idle that would surge, and slow down over and over. I was able to fix this by adjusting mixture screws. I think what was happening was that it was losing vacuum and the choke pull off was letting go, would rev up, then die due to on off choke. (Does this sound right) Seemed to smooth out after idle screw adjustment. Now idle is steady but to high.
NOT SURE WHERE TO LOOK NOW? :confused:
Earlier problems were an idle that would surge, and slow down over and over. I was able to fix this by adjusting mixture screws. I think what was happening was that it was losing vacuum and the choke pull off was letting go, would rev up, then die due to on off choke. (Does this sound right) Seemed to smooth out after idle screw adjustment. Now idle is steady but to high.
NOT SURE WHERE TO LOOK NOW? :confused:
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Re: Tuning Questions Part 2 (DollaGreen)
Check to make sure your throttle cabel is not binding somehow. I had a problem with it. Try to to get the car to stick at that high idle then pull your air cleaner and see if you can pull the throttle back to where it is idleing normal. I had to trim some of my cable but I think it is the stock q-jet cable and I am using a Holley carb. I also put some grease on the bare cable right by where it goes into the case and kept pulling it in and out while apply grease every so often. This seemed to help it slide smoother. This is a quick and easy check before starting to tear into the carb.
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Racer
Joined: Aug 2001
Posts: 473
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From: Raleigh NC
Re: Tuning Questions Part 2 (DollaGreen)
For what it is worth, I am having similar problems with a fluctuating idle. My car is in the shop now getting a lot of stuff done, and I think we have figured out what is happening with the idle.
At idle, you can get it to settle down nicely at 700-800 RPM. Blip throttle etc. and it stays at same RPM. Take it for a cruise and drive a bit, and the idle inches back up to 1100-1200 or so. Turns out the choke coil spring is old and lost some of its strength. It operates fine sitting there and watching it. It will open and hold the choke fully open. However, under driving conditions, it does not seem to be able to hold the choke open all the way and hence the higher RPM.
Good luck.
At idle, you can get it to settle down nicely at 700-800 RPM. Blip throttle etc. and it stays at same RPM. Take it for a cruise and drive a bit, and the idle inches back up to 1100-1200 or so. Turns out the choke coil spring is old and lost some of its strength. It operates fine sitting there and watching it. It will open and hold the choke fully open. However, under driving conditions, it does not seem to be able to hold the choke open all the way and hence the higher RPM.
Good luck.