well about a month ago i got a 2 bolt rebuilt 350 installed 010 casting it came from a engine rebuilding place and is Stock. i used to have a 4bolt 350 same 010 casting. i used to get much better gas milage even know it wasnt good i was getting around 10-12. now i find myself puttin in 8 gallons and driving around 60 miles and having to refuel it just sucks it up. on hard turns i can see my rpms drop or stall if hard enough turn indicating i need to ajust my float bowl. ive been messin with the tunning of my carb i have it running good. but no matter how i set it rolling from a stop sign i hit gas slowly and i get a slight hesitation. when i blip the trottle from under the engine bay i can hear the gas squirt into the carb and acually see it like its pouring in.

could a bad ajusted float bowl give a car bad gas milage any other opinions?

350 block
hooker headers high flow cat 3 inch exhuast
holly contender intake
600cfm edelbroc carb has gone a defident 3 years without rebuild.

 

That's the accelerator pump working. You'd have problems if it wasn't.

 

Aside from the carb there are a few other critical things in a motor that affect mileage:

1. Ignition timing. Is yours set properly? This can also cause a stumble and/or general lack of power if it's off far enough.

2. Cam. Bigger duration cams and/or cams with tighter lobe separation angles will get worse mileage than smaller cams with wider LSAs.

3. Compression. Up to the point of detonation problems a higher compression motor will get better mileage than a low compression motor, all else being equal. You've probably heard that a pont of compression is worth about 4% more power. Well it's worth significantly more than that in mileage- about 10%.

 

well ive had my car twice to the guy who put the engine in and he checked the timing its at like 12 degree's idle and 36 i believe total he said its not that high and he wouldnt put it any furture cause the risk of detonation (what probally happen to my old engine blew a piston) the compression on my old engine was higher cause the 305 heads. this is totally stock he said i dont know what the stock cam is but id guess its whatever cheap one they can find for a 350. i know about the compression since i said cant you bump it up alittle for gas milage and he said what i said above.

the only thing that has me stumped is the hesitation at around 1250 rpm's when slowing down and not a complete stop and re applying the gas it rises quick to 1250 then stops drops maybe a 100 and then fly's up and hits 1500 shifts. never does it at a dead stop though.

 

That sounds more like your transmission downshifting.

 

thanks for the quick reply i thought that too also so i decided to drop it down the gears as i slowed down and did the same thing in 1