My car gets terrible mileage (but actually doesnt stumble and generally seems to run ok) and I am trying to improve it so I can drive it more.
I have this carb Holley 0-80508S 750 CFM Classic Holley Carburetor - Holley Performance Products
Engine is the original 70 351c 4v rebuilt to 9.7:1 CR, small comp cam, blue thunder intake, stock fmx with stock converter, and 3.00 rear (not a rocket ship).
I hooked up my wideband (I have a bung welded on the left exhaust about 12 inches down from the manifold). The idle was pretty rich, the cruise is very rich.
Through trial and error I got the idle to 14.5-15.2ish. It is hard to adjust though because I have to have both screws in all the way then about a 1/2 turn out. The carb is very sensitive to any movement.
I do not think my factory tach is very accurate since it only settles down to 200rpm but this is at about 1200 rpm in park, and 900 in gear (so probably 700 in reality). With this air fuel ratio and 12 degrees initial timing with the vacuum disconnected it pulls 14" of vacuum.
While driving the second I get into any pedal it all it riches up to 10:1 AFR, sometimes even richer, even at only 1500 rpm at cruise. At fuel throttle it is about 10.5:1.
Where do I start here? Is it possible the fuel pressure is too high and that's why the screws need to be in so far? I set the float levels in the past. I am using the old Holley mechanical pump for the 351c.
Any help is much appreciated. I am thinking if I could get cruise AFR up to 13 or so it would yield an increase in mileage.
I have this carb Holley 0-80508S 750 CFM Classic Holley Carburetor - Holley Performance Products
Engine is the original 70 351c 4v rebuilt to 9.7:1 CR, small comp cam, blue thunder intake, stock fmx with stock converter, and 3.00 rear (not a rocket ship).
I hooked up my wideband (I have a bung welded on the left exhaust about 12 inches down from the manifold). The idle was pretty rich, the cruise is very rich.
Through trial and error I got the idle to 14.5-15.2ish. It is hard to adjust though because I have to have both screws in all the way then about a 1/2 turn out. The carb is very sensitive to any movement.
I do not think my factory tach is very accurate since it only settles down to 200rpm but this is at about 1200 rpm in park, and 900 in gear (so probably 700 in reality). With this air fuel ratio and 12 degrees initial timing with the vacuum disconnected it pulls 14" of vacuum.
While driving the second I get into any pedal it all it riches up to 10:1 AFR, sometimes even richer, even at only 1500 rpm at cruise. At fuel throttle it is about 10.5:1.
Where do I start here? Is it possible the fuel pressure is too high and that's why the screws need to be in so far? I set the float levels in the past. I am using the old Holley mechanical pump for the 351c.
Any help is much appreciated. I am thinking if I could get cruise AFR up to 13 or so it would yield an increase in mileage.
