WOT too Lean

[lippy]

I think Brent is spot on. I use an 850 on a 487 FE. The adjustments you made are radical, which led me to think earlier something wasn't right.

[fastd]

But isn't carb CFm a trade off? Too big gives weaker response at low end and more hp on the top end? So if I am satisfied with how it drives at 0-2500 rpm then I should be ok with a "bigger" carb? And since this 461 has plenty of low end Torque then it mitigates the low end somewhat...?

My problems with this carb were in the 3-4k range initially. It's smooth there now. Didn't have any complaints on the low end although I feel like a 750 would give me a bit more "Pop" at launch.

[blykins]

IMO, you spent a lot of time trying to make something work that was totally not right for the engine.

If CFM was a trade-off, and bigger carbs always made more horsepower, then most of my customers would be putting 1450 Dominators on everything.

Carb CFM follows a rule of diminishing returns. A bigger carb doesn't always make more horsepower. I think you could slap a smaller carb on there, not notice any WOT power difference, and gain lots of happy street manners down low.

[fastd]

ok. thanks

[fastd]

After all this tuning I to get the car dynoed; same place, same dyno, same tech...

Before I did all the carb work, I had the engine dynoed on 12/21/2015 in Raleigh, NC; 66 degrees; 35% humidity.
Max HP and torque results at the rear wheels were 358 hp @ 4400, 431 torque @ 3300-4200 (very flat); a/f ratio was pretty lean throughout the dyno pull; low 14s.

After carb turning: 95 degrees with the same 35% humdity. a/f was very consisent in the very high 12s, very low 13s.

Hp was down to 281 hp...! How can this be?

[Gaz64]

Hi Phil,

What camshaft and compression ratio in this engine?

You have made many changes to the carburetor with little or no response.

Another carburetor gives the similar results?

I'd be looking at the exhaust system.

Has the dyno operator verified ignition timing has not mysteriously retarded at higher rpm?

I would expect 400 rwhp out of that engine.

Gary