My set up. SFT cam. 259/266. Timing all in by 1500. Stick car. Here’s the issue that I have been fighting for several years. My car is a street/strip car. When cruising just off idle, between 1300-2000rpm, I’m getting a “buck”, not a miss, a buck. If I give it a bit more gas, It’s as smooth as you can ask for. Full throttle is also perfect. It’ s Just the frickin’ buck that has me stumped. IFR’s. .035”. HSAB’s. .033”. LSAB’s .073”. PV is a 4.5. Idle is 950 rpm. Oh, Victor intake with RPM heads. Suggestions??
What first and axle gear ratios do you have? Why is the timing “all in” by 1500??? That’s not a good way to do it IMO.
Two other questions. What ignition are you using and how did you come up with a 4.5 power valve?
. Timing is all out for throttle response. Gear ratio is 4:56. Power valve was determined by idle best vacuum (8hg) then divide by two. 4.5 got me close so I used it. Ignition is Digital MSD.
Base your PV off your cruise vacuum. Example 11in at cruise use 5.5 PV.
. Roger that. What I’ve done so far,,,,,,, IFR’s up to .039”. Power valve to 6.5. IAB’s down to .070”. The car runs allot better but with a very, very slight buck. Hardly noticeable for a passenger, but for me as the main driver, I can still feel it. I’m going to live with it for a bit. Thanks everyone for your input. Really appreciate it.
