TUNE TO WIN-A/F vs TIMING

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So did I hear right he changed the timing and that changed the AFR?

Timing changed the fuel metering coming out the carb..........:lol:
 
So did I hear right he changed the timing and that changed the AFR?

Timing changed the fuel metering coming out the carb..........:lol:
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Captain obvious with that vid.

Probably did the Video cause of nit picking comments, obviously if your way off your power is gonna be way down and not run right, but if your in the ballpark a few degrees or jets are not gonna make or break your setup.
That’s the point I got from it.
 
Probably did the Video cause of nit picking comments, obviously if your way off your power is gonna be way down and not run right, but if your in the ballpark a few degrees or jets are not gonna make or break your setup.
That’s the point I got from it.
Well. I can tell you this much:
a. Two jet sizes can make a difference in the quarter mile.
b. Two jet sizes can produce a noticible difference on a dyno, or, make a very small difference depending...and when its that close, go toward the richer pair.
c. Two jet sizes on the primary side can make a HUGE difference crusing at interstate speeds. Like the difference between drivable and not drivable.
-- You probably can take a pretty good guess at how I learned these things.
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Well. I can tell you this much:
a. Two jet sizes can make a difference in the quarter mile.
b. Two jet sizes can produce a noticible difference on a dyno, or, make a very small difference depending...and when its that close, go toward the richer pair.
c. Two jet sizes on the primary side can make a HUGE difference crusing at interstate speeds. Like the difference between drivable and not drivable.
-- You probably can take a pretty good guess at how I learned these things.
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No-one said it don't make a difference, it's just the 80/20 rule, it takes 20% of effort to get you within 80% optimal, and 80% effort to get the finale 20%.
 
No-one said it don't make a difference, it's just the 80/20 rule, it takes 20% of effort to get you within 80% optimal, and 80% effort to get the finale 20%.
That's the difference in what I'm saying. Its not that much harder to get it much closer. For wide open throttle power, the effect of changing fuel restrictions is relatively easy to observe until we get to within a jet size or two. The high effort is only to obtain the last 2%. For timing at WOT, I'll grant there is more effort for the last 2 to 5%, in part because its more dependent on engine conditions (how heat soaked the engine is).

In fact in my experience, the most time is spent early on when getting into the ballpark for both. Because they have work together, a big change in one sometimes means some adjustment in the other. So that can be a lot of back and forth. Once they are close, especially the timing, then stepping toward the best mph in the 1/4, or area under the curve on the dyno, becomes pretty straightforward.

OK. Why did I say 2% ? Because 5 hp gain on 250 hp is about 5% and that's roughly what I've seen for changing a pair of jets two sizes jets.

For highway driving I don't have a way to measure the gains in part throttle fuel consumption, but when its just a jet or two over the edge on the lean side the engine will rev up and die when the boosters take over. That's uh, I don't know, I guess 100% off!
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That's the difference in what I'm saying. Its not that much harder to get it much closer. For wide open throttle power, the effect of changing fuel restrictions is relatively easy to observe until we get to within a jet size or two. The high effort is only to obtain the last 2%. For timing at WOT, I'll grant there is more effort for the last 2 to 5%, in part because its more dependent on engine conditions (how heat soaked the engine is).

In fact in my experience, the most time is spent early on when getting into the ballpark for both. Because they have work together, a big change in one sometimes means some adjustment in the other. So that can be a lot of back and forth. Once they are close, especially the timing, then stepping toward the best mph in the 1/4, or area under the curve on the dyno, becomes pretty straightforward.

OK. Why did I say 2% ? Because 5 hp gain on 250 hp is about 5% and that's roughly what I've seen for changing a pair of jets two sizes jets.

For highway driving I don't have a way to measure the gains in part throttle fuel consumption, but when its just a jet or two over the edge on the lean side the engine will rev up and die when the boosters take over. That's uh, I don't know, I guess 100% off! View attachment 1715559213

All I mean is that 80% of people would be happy even if their timing and carb is set slightly less than optimal.
For the last 20% tune for every last drop of performance.

What I got out of the video is for the average guy if your in the ballpark your fine.

Looks like you race your car, most just putt around on a Sunday and peel out once and a while.
 
All I mean is that 80% of people would be happy even if their timing and carb is set slightly less than optimal.
For the last 20% tune for every last drop of performance.

What I got out of the video is for the average guy if your in the ballpark your fine.

Looks like you race your car, most just putt around on a Sunday and peel out once and a while.
That's different! Yes. We have so many people that ask about changing carburetion or timing that I tend to think that 'most' hobbiest are looking for some sort of improvement. But that's probably not a true generalization at all. What makes people happy is whatever makes them happy.

I'm not a drag racer but I occassionally take it to the track and also autocross it.
Probably more to your point I like trying to get what is reasonably possible out of the machinery.
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That's different! Yes. We have so many people that ask about changing carburetion or timing that I tend to think that 'most' hobbiest are looking for some sort of improvement. But that's probably not a true generalization at all. What makes people happy is whatever makes them happy.

I'm not a drag racer but I occassionally take it to the track and also autocross it.
Probably more to your point I like trying to get what is reasonably possible out of the machinery.
View attachment 1715559229

But on the other hand there's probably quite a few who are way out of tune and blame over camming, carb etc..
 
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