Intermittant starting line bog

-
7

70net440

Well-Known Member
Joined
Nov 13, 2004
Messages
256
Reaction score
16
Location
yreka, ca
Had my car(74 Dart 440/727/3.91 w/spool gutted interior sub-frame connectors 8 pt. roll cage) out twice at two differant tracks with the new motor.(Specs below) First pass off the trailer I've run 12.98 and 13.0 at 105 mph both runs. The car pulls hard through the lights at about 5600 rpm. After the first pass it will bog off the line and sometimes die completely. I am launching at about 1200 rpm because my 235/60R15 drag radials don't hook real well. I'm running 12* initial and 32* total all in at 2800rpm. I was planning on bumping the initial up once I got the new motor broke and everything else sorted out. When we went to load the car up it fired up and died and backfired through the carb. You guessed it, fire in the hole. Got the fire out. Pulled the carb at home expecting to find carnage, but it looked clean inside. Wondering if I should rebuild this old Holley or saving up for a new carb. I have a 3310-2 on my street car I was thinking about putting on and resetting the timing. Elevation at Medford is about 1,400 and I think Redding is a bit lower. The car has always seemed rich at idle. Can't get much adjustment out of the two mixture screws. Thanks for any replies.

'73 440 .030 over 9.5-1 pistons
Stock 213 heads with hardened seats and Comp springs to match cam
XE274 Comp cam
Intake .488 lift 230 duration @.050
Exhaust .491 lift 236 duration @ .050
Holley blue pump regulator set at 7lbs.
Weiand single plane intake
Stock electronic dist.
MSD 6A box
Accel coil
About 3,000 stall w/ reverse manual vb
Carb: Holley 4779 dp
Primaries 76 jets white acc. pump cam can't find number on power valve
Secondaries 78 jets pink acc. pump no power valve not even threads to put one in
#32 pump squiters on both sides. I believe it has the large acc. pumps.
 
Get the timing adjust before the carb...not enough timing for a BB...need a better advance curve then a stock electronic

4779 Holley starts with a 70 primary jet with a PV and a 80 secondary jet with no PV...
 
Put the 3310 on and set the initial at 18*. Got a best idle vacum of 13" with the mixture screws at 1 turn out, which is what that carb liked on my street car's 440. Throttle response seemed a bit crisper but, it still smells rich at idle. Not sure if I can get to the track this weekend have to work, maybe next weekend.
 
At 18* initial I would think it is still set too low.
I would advance it to say 24*. Let it warm up if it still starts without dragging down on the starter, leave it there. If it don't like to start back it off 2*. Reset your Dizzy on the mechanical so it is 34* all in @ 2200 RPM. That should wake that puppy up real good make it crisp and clean and no more stinkyyyy!

Remember...

Timing first then the Carb. Doing it in a different order will have you chasing your tail.
 
Just a tip, with a carb fire, crank the motor without touching the gas it will suck the fire in the motor and put it out.
 
We did crank the motor and smothered the carb with a large rag. Everytime we pulled the rag off it flared back up. Had flames coming out of the vent tubes and the throttle body. It only took a very small shot from the extinguisher to put it out. Didn't even get any residue inside the carb.
 
Well? So I dicided to take the car to the track with the 3310 in it. Set the initial timing at 18* gave me 38* total. I know, a bit too high. First pass the car ran well and pulled all the way through the lights. Second and third time trials it felt like it was laying over at about 1,000 ft at about 5,600 rpm. First round of eliminations we got shut down in the water box for track clean up. I kept the water pump and fan on trying to keep things cool. The car felt like it stumbled just a bit off the line and sounded like it was shooting ducks right before the 1-2 upshift. I'm not 100% sure because the car in the next lane left at the same time and had really loud exhaust. When we went to load up the car died just as it hit the ramps again. Popped the hood and saw fuel running out of the secondary throttle shafts. Pulled the lid off of the air cleaner, it had fuel splashed on the lid and in the base. Fuel pressure was at 7psi I have backed it down to 6.5. There doesn't seem to be fuel perculating or flooding out of the boosters while it is idling. I checked the plugs, they are a good medium brown color with a slight amount of color on the porcelin.

1st pass: 60' 2.08 1/8th 8.40 85.24 mph 1/4 13.02 105.74mph

2nd pass: 60' 1.88 1/8th 8.07 86.42 mph 1/4 12.68 104.50mph
(not sure where this one came from, they re-prepped the track shortly before this run)

3rd pass: 60' 2.11 1/8th 8.43 85.31 mph 1/4 13.06 104.9mph

Elims: 60' 1.99 1/8th 8.63 82.34 mph 1/4 13.36 103.77 mph

Sorry this is so long, just trying to get this thing consistent and makes some laps.
 
You've got dirt in the needle and seat assembly or a bad N&S assembly/o-ring. Could also be a sunk float in the carb. 7 psi pressure is not excessive with a holley.

Make sure float level is set properly.

Older 3310's don't have power valve protection in them. You may have popped the PV.

38 total on an open chambered BB isn't crazy.
 
I think I'm going to rebuild both carbs with new power valves and needles and seats. It seems the 4779 is putting too much fuel in at the hit. Might try downsizing the squirters then play with jetting.
 
Bog and die after the first pass, and the first pass is always good. I would suspect vapor lock. Just one more thing to look for.
 
If you got one of those little chrome fuel pressure gauges that are so popular,check it against a quality gauge for accuracy. I had one reading 2 lbs low. PITA.
 
must have gotten it sorted out..his last post was 2 yrs ago...
 
Either that or sold the POS.
 
You must log in or register to reply here.
-

Back
Top