Dennis, Your changes at WOT are due to the "power valve" opening, part of Holley's better idea to richen the mixture as you need more power, as it see's the vacuum in the manifold drop it opens. the numbers are supposed to correspond to the inches of vacuum that it will open at. Such as a 65 will open when the vacuum drops below 6.5 inches. John Althaus 64 Savoy Hemi 4 spd 214-673-7540 cell In a message dated 4/20/2009 9:27:56 P.M. Central Daylight Time, big-d@xxxxxxxxxxxx writes: You are doing it right. Establish what ratio the car likes and you like then work towards it. Gnorally speaking most carbs want two jet sizes from the old or out f the box settings. but I wuldnt make it a hard fast rule. Anymore than 4 jets sizes you are probably off track a bit. never be afraid to retrace yousteps either. Don ----- Original Message ----- From: "Dennis C." <dennis.2914@xxxxxxxxx> To: <1962to1965mopars@xxxxxxxxxx> Sent: Monday, April 20, 2009 4:50 PM Subject: Air-Fuel Ratio Tuning Questions Hello, I am using an Innovate LC-1 Air-Fuel Ratio meter to jet my carburetor. I would appreciate comments from anyone who has used an instrument like this or has had experience jetting by Air-Fuel Ratio. I have not found good information on what Air-Fuel Ratio (AFR) I should be shooting for. I have seen information ranging from people who are shooting for the ideal AFR of 14.7:1 to those who feel that a "Safe" range is between 12.8:1 to around 13.4:1. I have a Holley Street Avenger 670 on my 383. I now know that it was probably not the best choice for a carburetor however when I got it I was looking for just street performance on a driver. I am now a follower of Don Dulmage.s messages and learning more with each new message he posts about tuning and carburetors. The carburetor was running very lean out of the box with 65 Primary jets and 68 Secondary jets. At 68 Primary jets I am running 14.0:1 at idle and 13.8:1 to 14.0:1 cruising level ground 65 to 75 mph. At 70 Primary jets I am running 13:0:1 at idle and 13.0:1 to 13.5:1 cruising level ground 65 to 75 mph. To me it looks like #69 jets may be what I need. I have some data on WOT with 70 Primary and 74 Secondary jets however I want to get the Primary circuit set first. It is interesting that on a 4th gear pull on the road from 2000 to 3500 rpm it first drops to around 12.0:1 then around 3000 rpm it drops again to under 11.0:1 and was still dropping when I let up on the gas. Again if anyone has experience in this areas comments would be appreciated. Dennis C. 1996 Dodge Ram 3500 Van Conversion 1964 Plymouth Belvedere 318 Auto 1963 Plymouth Sport Fury 383 4-speed 1949 Dodge Pickup 289/C4 soon to be changed 1998 Honda Valkyrie Standard ---- Please address private mail -- mail of interest to only one person -- directly to that person. I.e., send parts/car transactions and negotiations as well as other personal messages only to the intended recipient, not to the Clubhouse public address. This practice will protect your privacy, reduce the total volume of mail and fine tune the content signal to Mopar topic. Thanks! '62 to '65 Mopar Clubhouse Discussion Guidelines: http://www.1962to1965mopar.ornocar.org/mletiq.html. ---- Please address private mail -- mail of interest to only one person -- directly to that person. I.e., send parts/car transactions and negotiations as well as other personal messages only to the intended recipient, not to the Clubhouse public address. This practice will protect your privacy, reduce the total volume of mail and fine tune the content signal to Mopar topic. Thanks! '62 to '65 Mopar Clubhouse Discussion Guidelines: http://www.1962to1965mopar.ornocar.org/mletiq.html. **************A Good Credit Score is 700 or Above. See yours in just 2 easy steps! (http://pr.atwola.com/promoclk/100126575x1220572844x1201387506/aol?redir=http://www.freecreditreport.com/pm/default.aspx?sc=668072&hmpgID=62&bcd= Aprilfooter420NO62) [Non-text portions of this message have been removed] ---- Please address private mail -- mail of interest to only one person -- directly to that person. I.e., send parts/car transactions and negotiations as well as other personal messages only to the intended recipient, not to the Clubhouse public address. This practice will protect your privacy, reduce the total volume of mail and fine tune the content signal to Mopar topic. Thanks! '62 to '65 Mopar Clubhouse Discussion Guidelines: http://www.1962to1965mopar.ornocar.org/mletiq.html.