Great performance at high rpm, low rpms not so good

[asifallasleep]

74 2002, 32/36 Weber (recently calibrated), new Pertronix ignition, new plugs, new 8mm wires, new coil, new fuel filter, new air filter plugs gapped at 24.

If I go to 3rd gear before car gets to 3000 rpms, car seems to misfire/hesitate as if gear is to high for low speed. Even at idle there's the occasional hesitation. If i drive aggressively, as in not going into 3rd gear until i'm at 3000 rpms car runs fine. Highway speeds car is great.

Perplexed. Almost as if it's tuned for higher speeds. I know spark plug gap can effect this. But for what Im describing wouldn't it point to a large gap? Any ideas?

[jrhone]

How is the timing? Too much advance?

[c.d.iesel]

at what stage of all yer parts swapping DID THIS BEGIN TO HAPPEN ?

retrace yer steps to happier- smooth running

try to pinpoint at what throttle opening does it

act worse?

at o - 1/4 throttle opening ?

at 1/4 to 1/2 throttle opening ?

at 3/4 to WIDEOPEN throttle ?

((it's assumed your compression readings, valve adjustment,

and ignition timing are "correct"))

[nbristow01]

74 2002, 32/36 Weber (recently calibrated), new Pertronix ignition, new plugs, new 8mm wires, new coil, new fuel filter, new air filter plugs gapped at 24.

If I go to 3rd gear before car gets to 3000 rpms, car seems to misfire/hesitate as if gear is to high for low speed. Even at idle there's the occasional hesitation. If i drive aggressively, as in not going into 3rd gear until i'm at 3000 rpms car runs fine. Highway speeds car is great.

Perplexed. Almost as if it's tuned for higher speeds. I know spark plug gap can effect this. But for what Im describing wouldn't it point to a large gap? Any ideas?

Mannn I just went thru this same scenario. So mechanic runs compression test. real low on all 4. in fact I had 70-90-110-80 or something like that. Yank valve cover. ALL valves too tight. I guess as the seats wear in the valves come up higher. Has the car been harder to start? Almost wanting to flood at times? Run a compression test. Its easy and cheap. i learned my lesson. Once he adjusted the valves back to normal car hauls ass

[asifallasleep]

74 2002, 32/36 Weber (recently calibrated), new Pertronix ignition, new plugs, new 8mm wires, new coil, new fuel filter, new air filter plugs gapped at 24.

If I go to 3rd gear before car gets to 3000 rpms, car seems to misfire/hesitate as if gear is to high for low speed. Even at idle there's the occasional hesitation. If i drive aggressively, as in not going into 3rd gear until i'm at 3000 rpms car runs fine. Highway speeds car is great.

Perplexed. Almost as if it's tuned for higher speeds. I know spark plug gap can effect this. But for what Im describing wouldn't it point to a large gap? Any ideas?

Mannn I just went thru this same scenario. So mechanic runs compression test. real low on all 4. in fact I had 70-90-110-80 or something like that. Yank valve cover. ALL valves too tight. I guess as the seats wear in the valves come up higher. Has the car been harder to start? Almost wanting to flood at times? Run a compression test. Its easy and cheap. i learned my lesson. Once he adjusted the valves back to normal car hauls ass

Compression test was done when pertronix was installed and was fine.

[nbristow01]

Only other thing I can think of is you are running too retarded at the lower rpms.

[jrhone]

You dont say that the timing was checked or set. If so what settings? How much advance and at what rpm?

[TobyB]

...might also look at what the primary barrel of the carb's jetted to.

t

[asifallasleep]

going to increase idle speed a hair and make carb 1/2 turn richer. may also gap plugs to 30. currently at 24 with pertronix installed. i keep thinking engine is not getting enough fuel at low speeds with higher gear. if gas pedal is halfway pressed or more, no hesitation at all.

i've always had 5 speeds or 6 speeds. perhaps i'm shifting too soon? i'm already in 3rd pre 3K rpms. if i leave in 2nd until 3K rpms and beyond, car rolls like a rocket. real spirited driving. but don't want to drive like that all the time.

[asifallasleep]

going to increase idle speed a hair and make carb 1/2 turn richer. may also gap plugs to 30. currently at 24 with pertronix installed. i keep thinking engine is not getting enough fuel at low speeds with higher gear. if gas pedal is halfway pressed or more, no hesitation at all.

i've always had 5 speeds or 6 speeds. perhaps i'm shifting too soon? i'm already in 3rd pre 3K rpms. if i leave in 2nd until 3K rpms and beyond, car rolls like a rocket. real spirited driving. but don't want to drive like that all the time.

big improvement. upped the plug gap to 28 and 1/4 turn richer on weber and she hums now. hopefully the missing won't come back.

thanks everyone