QFT Jetting?
If pinged at part throttle, then the vacuum advance and/or advance rate can be adjusted to prevent that.
If it pinged at or near wide open throttle, then the advance rate needs to be slowed.
You wanted to do some modifications? This may be your opportunity.
Timing works hand in glove with fuel mixture and combution.
The goal is to change the spark lead so the burn always results in maximum pressure to take advantage of maximum leverage on the crank.
The faster the engine spins, the more lead time is needed - until some rpm where the combustion starts burning faster and additional lead doesn't ahve toi keep being added.
The less dense the air fuel mixture, the slower the burn. Vacuum advance provides additional spark lead with lean mixtures
Nice illustration here: Ignition System Analysis (Session 259) from the Master Technician's Service Conference
What was the initial timing that you were using, and at what rpm?
What distributor are you using?
Back to carbs.
Chrysler has some decent overviews of how carburetors work. Although they are more oriented to the Carter designs, the concepts are pretty much universal.
Here's one from 1970 Carburetion Fundamentals & Facts (Session 273), Master Technician's Service Conference
and the filmstrip that went with it. 1970 Carburetion Fundamentals and Facts Filmstrip with Mr Tech
Although I like the 1966 version better since emissions aren't a concern for what you are doing.
1966 Carburetor Fundamentals from The Master Technician Service Conference Series (Session 222)
Not based on the information so far. One step at a time when doing this type of tuning.
Its OK. The IFRs are probably between .028 and .035" and the e-holes are probably .028, but maybe just maybe they are .023 or smaller. Standard drill sets don't go that small. QF might tell you - they would have before the Holley takeover. If you do find a build sheet, thats good, just don't bet the farm on it being 100% correct. You could try searching over at Racing Fuel Systems forum. All sorts of stuff people discuss there. Unfortunately the interface is terrible since tapatalk took over the board and that includes the search function. :(
Great! It may need slight adjustment when the idle speed screw is reset.
Makes sense. Just that with your hot rodded engine, it will have to be addressed a little differently.
If pinged at part throttle, then the vacuum advance and/or advance rate can be adjusted to prevent that.
If it pinged at or near wide open throttle, then the advance rate needs to be slowed.
You wanted to do some modifications? This may be your opportunity.
Timing works hand in glove with fuel mixture and combution.
The goal is to change the spark lead so the burn always results in maximum pressure to take advantage of maximum leverage on the crank.
The faster the engine spins, the more lead time is needed - until some rpm where the combustion starts burning faster and additional lead doesn't ahve toi keep being added.
The less dense the air fuel mixture, the slower the burn. Vacuum advance provides additional spark lead with lean mixtures
Nice illustration here: Ignition System Analysis (Session 259) from the Master Technician's Service Conference
What was the initial timing that you were using, and at what rpm?
What distributor are you using?
Back to carbs.
Chrysler has some decent overviews of how carburetors work. Although they are more oriented to the Carter designs, the concepts are pretty much universal.
Here's one from 1970 Carburetion Fundamentals & Facts (Session 273), Master Technician's Service Conference
and the filmstrip that went with it. 1970 Carburetion Fundamentals and Facts Filmstrip with Mr Tech
Although I like the 1966 version better since emissions aren't a concern for what you are doing.
1966 Carburetor Fundamentals from The Master Technician Service Conference Series (Session 222)
