carb -fuel issues

did some testing last night and it did not go well, car has been doing 1.60 in the 60ft and 11.00-.11.12 range, at the hit of throttle it falls on its face then picks up..bog..picks..it does this till about 100 ft out about the same time the front end settles down, only changes i made from last week was the rear fuel bowl and i cut a hole in the hood cause the carb was all way against hood, and re ran valves ,i raised the fuel in bowl to the marks on sight glass and it keep getting better , (750 race demon) i raised it till fuel was almost coming out of vent tube, which was in same place as last week , i know this is not correct, i am thinking that the car is now leaving hard enough that it may be uncovering the jets, and raising the fuel in bowl helps this..any opinions

Put jet extenders on the rear jets so it stops uncovering the main well.

kim wrote:Put jet extenders on the rear jets so it stops uncovering the main well.

Yes, and a vent line connecting the front and rear bowls w/slit in the top of tube.And lower the float settings back down. You are gonna flood the engine BADD.

bbf-falcon wrote:

kim wrote:Put jet extenders on the rear jets so it stops uncovering the main well.

Yes, and a vent line connecting the front and rear bowls w/slit in the top of tube.And lower the float settings back down. You are gonna flood the engine BADD.

Yessir. With float levels that high, a warm engine will heat soak that carb and flood it.

Did it do this before you cut the hole in the hood?

supervel45 wrote:Did it do this before you cut the hole in the hood?

no, it only does it the first 60-80 ft and its comes on like donkey kong, i just put jet extensions in and put a a rubber hose over the vents and i just seen fuel pressure was only 6 lbs ,so i sit it at 8, and i reran rocker's,

I was thinking the hood might have restricted air flow like a choke does, and the hole changed the tune making it run leaner, as it seems to have started after this. If that is the case, and from what you describe, I would play with shooters and pump cams first.

I don't think fuel pressure is your problem, and 8 is a little high. I would not go over 7lbs, and there is also the guage accuracy to consider. Don't make to many changes at once either.

supervel45 wrote:I don't think fuel pressure is your problem, and 8 is a little high. I would not go over 7lbs, and there is also the guage accuracy to consider. Don't make to many changes at once either.

6, 7, 8... no difference, your adjusting the pressure from the regulator to the needle and seat.   Above 10 psi you can push the needle off the seat.  To try and compensate for not enough pump when doing a alcohol carb dyno test, we dead headed the 400gph electric at no bypass, the before carb regulator was left at 11 psi...  needle and seat functioned, no fuel overflow.

How high are you carrying the wheels off the ground? Did you check to make sure the float is clearing the jet extensions and is the proper float? Just checking to rule out posabilities .

supervel45 wrote:How high are you carrying the wheels off the ground? Did you check to make sure the float is clearing the jet extensions and is the proper float? Just checking to rule out posabilities .

4-6 inches now, it was just about 1-2 inches, i put in 4.10 gears (was 3.73) and took off the front sway bar,i just put in the jet extension and changed the squriters today, have not been to track yet

Extensions with a notched float?

is it a BBF because the 750 Demon may not be enough...what is the setup?

maverick wrote:Extensions with a notched float?

just put them in, have not been to track yet

FalconEh wrote:is it a BBF because the 750 Demon may not be enough...what is the setup?

393w, i know the carb is on the small side

My bad I forgot about the new SBF Ford section(dumb question on my part), the 750 should be fine, I think you have solved the greater problem with the jet extentions, now fine tune the carb and timing for the newly found air and it should pickup more.

made few changes and it went well, first pass 10.98@121 then a 10.96 and a 10.94 60ft was 1.53 and 1/8 mile was 6.95 and 6.91

johndickjr wrote:made few changes and it went well, first pass 10.98@121 then a 10.96 and a 10.94 60ft was 1.53 and 1/8 mile was 6.95 and 6.91

So what exactly did you do?

supervel45 wrote:

johndickjr wrote:made few changes and it went well, first pass 10.98@121 then a 10.96 and a 10.94 60ft was 1.53 and 1/8 mile was 6.95 and 6.91

                                                                                                                                                                                             So what exactly did you do?

37 squriter up front..35 in rear..jets extensions..tighten up lash by 5thousand

Nice.

johndickjr wrote:made few changes and it went well, first pass 10.98@121 then a 10.96 and a 10.94 60ft was 1.53 and 1/8 mile was 6.95 and 6.91

It has got some 10.60s in it ! Very good tuning and driving skill !

yep it will go 60-70, but it will have to have either some suspension or more tire, and it still a 750 carb , the first 200 feet is a total hand full, bet i drive 1400ft in the 1/4

10.92 last week, think i found my other issues with suspension, one its worked out i would like to see a 10.70-80

update..ran 11-01-2015 at mokan dragway, #2 qualifier in shootout , went to the final and got runner up, brung home $290

10.88---122mph --1/4 mile
6.89@99 --1/8 mile
1.48--60ft