olecow Posted February 7, 2015 Report Share Posted February 7, 2015 Hey all, Looking for the brass plug/cap on my 82 720s carb so i can drill it out. I need to adjust the mixture screw that is hiding behind it! Sorry if this has already been answered! My patience for searching for it is running thin :) Quote Link to comment
datzenmike Posted February 7, 2015 Report Share Posted February 7, 2015 It's aluminum actually. It's on the base of the carb on the passenger fender side. It will be milled off smooth with the casting and hard to see... Drill a 1/8" hole in the aluminum plug about 1/8-1/4" deep. (don't hit the adjusting screw). Drive a wood screw into the hole and the plug will back out when the screw bottoms out, or just pry it out with vice grips on the screw. 1 Quote Link to comment
olecow Posted February 7, 2015 Author Report Share Posted February 7, 2015 PERFECT! Thanks! 1 Quote Link to comment
olecow Posted February 7, 2015 Author Report Share Posted February 7, 2015 Adjusting the screws. Adjust idle until it is at speck rpm, 800. Screw mixture in until its about to die and out until its about to die, then find the smoothest and fastest happy medium. Idle screw again to 800... repeat. HOWEVER,the idle screw is all the way backed out, so i can only get it to around 950, however, the idle speed passed at 963, so that'll be ok as far as smog goes. is there anything else I can adjust to bring it a bit lower? Thanks! Quote Link to comment
Doctor510 Posted February 7, 2015 Report Share Posted February 7, 2015 Check the linkage especially the cable type, get some slack in it. Quote Link to comment
datzenmike Posted February 7, 2015 Report Share Posted February 7, 2015 Some causes of a fast idle Throttle cable too tight Choke on, or linkage stuck. Fast idle cam stuck on last step. Primary throttle plate worn, rubbing/stuck against bore. Secondary throttle plate not fully closed. Timing set too advanced. (be sure to disconnect the vacuum advance when adjusting) BCDD not shutting off, set too sensitive. High idle speed could possibly be fast enough for the mechanical advance to be adding some timing advance. It could also add some ported vacuum advance. Pull the vacuum advance hose off and see if it drops. Quote Link to comment
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