Guest Anonymous Posted July 6, 2001 Share Posted July 6, 2001 I believe that my car may be running too rich. I have a 750 DP w/ factory jet setting with 4 corner idle adjust. Motor is a 350 with Vic Jr., 292 angle plug heads, flat tops 10.25 CR Comp Cams 292 Mag Cam. 1 3/4 headers, MSD etc. To set best idle I have adjusted the idle mixture screws aproximately 1/2 to 3/4 turn out from stop on all four barrells. This has produced an idle vac of 10 inch and the best I can get. I have also adjusted the throttle shaft on the back two barrells so that idle the primary throttle is in the lowest position ie. the idle set screw is not in contact with the shaft. Idle is 1200 rpms Idle is fine as is off idle response. My reason for believing that the carb is too rich is because of what I have read, the idle mixture screws should be set 1 and 1/2 turns out from stop. Also the car does not pull hard in 3rd gear or at higher RPMS ie over 6000. I feel that a leaner seting may make more power and have a complete set of holley jets. Just wanted a 2nd opinion before messing up somthing that is currently adequate, but may not be optimal. Quote Link to comment Share on other sites More sharing options...
pparaska Posted July 6, 2001 Share Posted July 6, 2001 I'm definitely no expert, but my experience and reading says you are on the right track and the jets are too rich. Maybe some holes in the secondary plates are called for, to get more air at idle? Quote Link to comment Share on other sites More sharing options...
Kevin Shasteen Posted July 7, 2001 Share Posted July 7, 2001 I agree w/Pete-you're running way too rich; especially if you cant idle any lower than 1200rpms. A magnum street cam should get you in the 850 to 900rpm w/properly tuned carb. You're on the right track & currently in the investigative stage-obtain as much info on jetting/tuning your carb: check out a decently stocked book store for the appropriate carb book w/instructions on your set up & then follow them to the letter....1st step 1st, 2nd step 2nd, 3rd step 3rd/dont skip any steps. I had a "66" Olds Cutlass w/Police Interceptor 330/V8 once that had an idle problem; drove me crazy-did all the tweaking/tuning of the Q-Jet; tune up engine ect,ect then I finally got frustrated & removed the carb only to find part of the base gasket had eroded & separated-it slipped/moved into blocking the incoming air (thus creating a rich running symptom); replaced the gasket & the car idled at 650rpm's. I also had a 70 Cutlass w/320hp 350/V8 that also had an idle problem. The tach indicated the idle would fluctuate from 1200-1500 & I couldnt get it below 1200...incredibly frustrating!!! I consider myself pretty good at turning a wrench & was beginning to doubt my abilities. I even took it to two different turn up shops only to be told, "They couldnt figure it out-they've never had this problem to this extent before (carb was already rebuilt). The cutlass was bone stock-linkages, carb, lines ect...after many hair pulling (stare down sessions-BTW/the car usually won) I finally decided to remove the Cruise Control [Rod]...that's right-this car had the factory Cruise Control Rod-not a the usual little metal ball connecting the carb linkage to the Cruise Control Servo. Turns out this rod linkage was pinching the Q-jet's throttle & causing the throttle to stick. As soon as I removed the rod & retuned my Carb-the car idled/purred like a kitten at 700rpms. Just forwarded all the above info as a reminder-sometimes the ovbious isnt always so obvious; but dont give up/these are mechanical animals & any problem that surfaces does so because of "something". Keep asking questions & make one change at a time-sooner/later you will figure out the problem! And then you can come back here & tell us what the solution was! Kevin, (Yea,Still an Inliner) [ July 06, 2001: Message edited by: Kevin Shasteen ] Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 8, 2001 Share Posted July 8, 2001 Changed jets today. Reset idle. Will drive tomorrow. Stock jets were 71s front and 80s rear. switched to 68 / 77. I will continue with trial and success. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 8, 2001 Share Posted July 8, 2001 Make sure also that it doesn't have a vacuum leak. A vacuum leak can make it idle high and you'd never be able to get it to idle down (at least this was my experience with my own car). Lightly cup your hands over the top of the carb, if it wants to die, great its fine, if it smooths out and picks up rpms, start looking for the source of the leak. Just a thought. Regards, Lone Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 9, 2001 Share Posted July 9, 2001 I believe one reason for the high idle is that the timing advance in locked out. ie. fixed at 36 degrees. I will however check for a vac leak. That is good advice. The throttle response is excellent 1000 to 6000 befor you can lift your foot. I will try it out on top end later this week. Too much traffic on my test road. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 9, 2001 Share Posted July 9, 2001 I know what you mean, they do tend to cover alot of ground in a big hurry. Regards, Lone Quote Link to comment Share on other sites More sharing options...
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