Re: 383’s with AVS not launching well
[Re: MHZ]
#2922719
05/15/21 08:55 AM
05/15/21 08:55 AM
|
Joined: Mar 2011
Posts: 3,076 Michigan
A727Tflite
master
|
master
Joined: Mar 2011
Posts: 3,076
Michigan
|
That’s where I would start.
Tighten up the spring a half turn until the bog disappears. Check the pump shot too. But for it to stall usually is the air door.
Last edited by Transman; 05/15/21 08:56 AM.
|
|
|
Re: 383’s with AVS not launching well
[Re: A727Tflite]
#2922761
05/15/21 10:43 AM
05/15/21 10:43 AM
|
Joined: Jan 2003
Posts: 14,471 renton, Washington
ph23vo
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 14,471
renton, Washington
|
always floor it for a blip... just before staging,... this loads the secondary wells with fuel so you don't open the secondaries with no fuel there for a few seconds..... float levels may be low also.. never hurts to double ck
Last edited by ph23vo; 05/15/21 10:44 AM.
|
|
|
Re: 383’s with AVS not launching well
[Re: MHZ]
#2922990
05/15/21 09:10 PM
05/15/21 09:10 PM
|
Joined: Jan 2004
Posts: 8,255 fredericksburg,va
cudaman1969
master
|
master
Joined: Jan 2004
Posts: 8,255
fredericksburg,va
|
cudaman1969, both cars have headers. Both cars were street driven into the track, raced, and street driven home. We did not uncork. Both cars are running drag radials. Honestly, the only difference that I see is traction. In fact after one of my runs in my automatic car with a huge bog when I got to the return road I stopped and brought it off and it was perfect; literally 20 seconds after the bog on the line.
Well that tells the story, blowing the tires off shows the problems, timing and carb. Ump timing up to full in (37) by 2000, tighten the air door a turn or two.
Last edited by cudaman1969; 05/15/21 09:12 PM.
|
|
|
Re: 383’s with AVS not launching well
[Re: cudaman1969]
#2923049
05/16/21 06:25 AM
05/16/21 06:25 AM
|
Joined: Feb 2005
Posts: 4,313 Prospect, PA
BSB67
master
|
master
Joined: Feb 2005
Posts: 4,313
Prospect, PA
|
cudaman1969, both cars have headers. Both cars were street driven into the track, raced, and street driven home. We did not uncork. Both cars are running drag radials. Honestly, the only difference that I see is traction. In fact after one of my runs in my automatic car with a huge bog when I got to the return road I stopped and brought it off and it was perfect; literally 20 seconds after the bog on the line.
Well that tells the story, blowing the tires off shows the problems, timing and carb. Ump timing up to full in (37) by 2000, tighten the air door a turn or two. This. Age old problem back in the day with the factory AVS. Car's fine on the street. Sticky tire/hot track - bog. Tighten the air valve.
|
|
|
Re: 383’s with AVS not launching well
[Re: ph23vo]
#2923137
05/16/21 12:49 PM
05/16/21 12:49 PM
|
Joined: Jun 2008
Posts: 3,916 usa
lewtot184
master
|
master
Joined: Jun 2008
Posts: 3,916
usa
|
back in the late '60's nhra had a pure stock class (not to be confused with todays pure stock). a lot of us guys would run that class. there were a lot of 383 road runners and super bees and they all suffered from what we thought was vapor lock. truth was that the crummy 2 valve factory pumps rated at 3-5psi were usually around 3-3.5psi. they'd drive ok and street performance didn't really tell the story of how bad they were. when at the track the pumps would get hot in staging and then there wasn't nothing but crummy starting line and total track performance. we were doing everything including the clothes pin trick to solve the problem but the only solution was a better pump.
there was something else i've noticed in the past several years with a rash of 8:1 compression 383's; performance is dismal. i worked on a '70 road runner, basically stock, 8:1 with a 3.91 gear and automatic. even after a good tune-up that turd couldn't spin the tires! 383's aren't good torque engines and need a good ignition tune-up, not be over cammed, and do like a little gear. i've always used 2 1/2 turns from the air valve just seated on the carb top. float level should be looked at and make sure you don't have a fuel filter on the suction side of the pump.
Last edited by lewtot184; 05/16/21 12:51 PM.
|
|
|
Re: 383’s with AVS not launching well
[Re: lewtot184]
#2923255
05/16/21 08:37 PM
05/16/21 08:37 PM
|
Joined: Feb 2003
Posts: 2,810 Sobieski Wi
bee1971
master
|
master
Joined: Feb 2003
Posts: 2,810
Sobieski Wi
|
Was never mentioned
650 AVS 2 OR
800 AVS 2
1971 Dodge Charger Superbee 2011 Ram Sport 1500 Quad Cab Deep Water Blue Loaded Siberian Huskies
|
|
|
Re: 383’s with AVS not launching well
[Re: captaindodge]
#2926220
05/24/21 03:55 PM
05/24/21 03:55 PM
|
Joined: Oct 2004
Posts: 2,820 Connecticut
FurryStump
master
|
master
Joined: Oct 2004
Posts: 2,820
Connecticut
|
I have been running an 800 thunder AVS for 8 years? This is what I have have found. 410 CI 3445 lbs 4:10 gear auto. I found that mine likes the pump linkage in the hole the closest to the pivot, or the biggest shot possible. Next mine really didn’t like the stock jetting. In fact it likes CRAZY jetting. I run .416 jet in the front and .419 jet in the rear. I have actually run no rear jet at all. I found that until recently before some intake work it like to be rich up front and lean in the secondaries. I ran 3 stages rich up front and 3 leaner in the back. So you would think, ok, bring them both back to stock and there you go, no way! I think it likes it because the fuel up front helps to cover the transition to the secondaries. The AFB has a small port that the butterfly swings by to help pull fuel to cover the transition. There is no provision for that in the AVS. Even if there was the door opens so fast it probably wouldn’t help. Some of the NSS with stick cars do remove the door, but they can launch at crazy rpm! I also drilled the shooter nozzle, but they now sell a kit with different nozzles. I needed to install the large needle and seats so it wouldn’t drain the bowls. I run a big mechanical and a holley red pump. First try a bigger pump shot. Then start moving fuel to the primaries. I have tested to determine when and how quickly it opens the air door. On mine it takes .3 of a second and starts to open 2500 rpm. Be careful on tightening the door spring. It is easy to break, I would not go more that 1 turn tighter than stock. Some of this will not translate to your car. I’m pretty far from this carbs comfort zone.
Last edited by FurryStump; 05/24/21 03:57 PM.
|
|
|
|
|