Carter AVS Setup & tuning book/guide?
- Thread starter Sir Dodge alot
- Start date
Sir Dodge alot
Active Member
Oh I found my problem, sorry about the fuss.
Carb was on the fast idle cam.
*facepalms self*
If I had an excuse to make, the carb being a 4 barrel is one. Never have I touched a 4 barrel carb before.
Only 2 barrels.
Aside from showing my incompetence to carburetor tuning, thanks for sparing your time to answer.
Carb was on the fast idle cam.
*facepalms self*
If I had an excuse to make, the carb being a 4 barrel is one. Never have I touched a 4 barrel carb before.
Only 2 barrels.
Aside from showing my incompetence to carburetor tuning, thanks for sparing your time to answer.
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marty koirtyohann
Well-Known Member
ok that makes cense
marty koirtyohann
Well-Known Member
well u have been luckythen after a whike the aluminum and the base wears after yrs i=pf use if there is any playif the base shaft it needs to me bushed . they drill out the base press in a bronze bushing then that stops tye play . now many shops bush all bases when they come in . tpo stop problems in the future i dont know in yur case im not there
marty koirtyohann
Well-Known Member
this guy makes his own kits
he use to make carbd=s for the modle a&t frds ! i was told he was the only one that can too'
Sir Dodge alot
Active Member
I didn't know of that he makes his own kits! Probably better than Mikes carb parts eh?
Sir Dodge alot
Active Member
My older Stromberg WWC-3 had no play in the shaft so I guess I'm running with the gamblers luck!
Sir Dodge alot
Active Member
I reckon the wear and tear from todays ethanol fuels are a contributing factor also to shaft wear!
Throttle plates don't usually warp, being as thick and hard as they tend to be. Same with throttle shafts, BUT the shafts can wear the bores they operate in in the carb's throttle body, which can affect how the throttle plates seat in their bores. BUT that should not cause the idle speed to be as high as it seems to be.
I know of one carb guy in the midwest who does not like the OEM AVS carbs, when compared to the prior AFBs. But that is HIS orientation of things. I see no reason an AVS should be any worse than an AVS, fwiw.
When they were available, back in the middle 1970s, I got an AFB Strip Kit from Carter and the same thing for Carter Thermoquards. The AVS, for tighter emission control, uses a three-step primary metering rod, whereas the AFB uses a two-step rod. But I switched the AVS in my '70 DH43N to the two-step rods and could tell no difference in how the engine ran, with the same power and cruise diameters of the rods. Just as when I was trying to get a bit more economy out of the AVS, I went to some rods with a leaner cruise section, but NO discernable differences in MPG or performance. Which leads me to believe that unless you start to get richer main and secondary jets, per the MP Performance Manusl, then you can do a lot worse than stay with the OEM fuel calibrations.
With the additional "mixture scfrew" on the '68 carb, it might be that it is really an "air" screw, which controls an additional circuit to further lean the basic idle mixture. In that case, rather than "all the way out", that screw should be "all the way in" to minimize the additional air added to the idle circuit.
There were some Rochester 2GC carbs which had an "Adjustable Part Throttle" circuit in the middle 1970s. One fix for that was to remove the lead solcer over the adjustment screw and close the circuit by screwing the screw all the way in. Perhaps that "third screw" on the '68 AVS would be similar? Just my suspicions . . . OF coiurse, these things would only affect the low-speed circuits and NOT the WOT power circuit.
The holes in the carb base gasket/insulators should clear throttle plates 1.75" in diameter, which is larger than the 1.69" sizes on the carbs.
Worst case scenario, send the AVS to Dana at Woodruff Carburetors (he is a member of this site) and let him work his magic to get it all to what it needs to be to work correctly.
Enjoy!
CBODY67
I know of one carb guy in the midwest who does not like the OEM AVS carbs, when compared to the prior AFBs. But that is HIS orientation of things. I see no reason an AVS should be any worse than an AVS, fwiw.
When they were available, back in the middle 1970s, I got an AFB Strip Kit from Carter and the same thing for Carter Thermoquards. The AVS, for tighter emission control, uses a three-step primary metering rod, whereas the AFB uses a two-step rod. But I switched the AVS in my '70 DH43N to the two-step rods and could tell no difference in how the engine ran, with the same power and cruise diameters of the rods. Just as when I was trying to get a bit more economy out of the AVS, I went to some rods with a leaner cruise section, but NO discernable differences in MPG or performance. Which leads me to believe that unless you start to get richer main and secondary jets, per the MP Performance Manusl, then you can do a lot worse than stay with the OEM fuel calibrations.
With the additional "mixture scfrew" on the '68 carb, it might be that it is really an "air" screw, which controls an additional circuit to further lean the basic idle mixture. In that case, rather than "all the way out", that screw should be "all the way in" to minimize the additional air added to the idle circuit.
There were some Rochester 2GC carbs which had an "Adjustable Part Throttle" circuit in the middle 1970s. One fix for that was to remove the lead solcer over the adjustment screw and close the circuit by screwing the screw all the way in. Perhaps that "third screw" on the '68 AVS would be similar? Just my suspicions . . . OF coiurse, these things would only affect the low-speed circuits and NOT the WOT power circuit.
The holes in the carb base gasket/insulators should clear throttle plates 1.75" in diameter, which is larger than the 1.69" sizes on the carbs.
Worst case scenario, send the AVS to Dana at Woodruff Carburetors (he is a member of this site) and let him work his magic to get it all to what it needs to be to work correctly.
Enjoy!
CBODY67
marty koirtyohann
Well-Known Member
marty koirtyohann
Well-Known Member
in my 45 yrs of playing with mopars i ha seen a lot of strange ****
i had most happen to me too'
marty koirtyohann
Well-Known Member
i had a holley thet we couldn't get to run right to save our selvs it was the on that hsd a worn shaft (itws allmost wore into1 MY COUSOIN HIS SHOP FOREMAN HAD NEVER SEN IT BEFORE . A OLD MAN ATVTHE QUAD SHOPN SEEN IT 2 IMES 1 ON A HOLEY THE OTHER ON A AFB
marty koirtyohann
Well-Known Member
marty koirtyohann
Well-Known Member
MY FIRST MOPAR I BUILT THE 400 IT RAN extremely WELL FOR CLOSE TO 20 YRS ON THE TRACK
marty koirtyohann
Well-Known Member
it would allmost pull the wheels on launch
Sir Dodge alot
Active Member
The idle now seems to be in workable levels, I'll try adjusting the mixture screws further tomorrow.
Correct, the Air bleed screw only has air traveling behind it to admit more air to the mixture screws below.
marty koirtyohann
Well-Known Member
do u know how to do that ?
idlemixture screw? my cousen swould never let me doit (he said i would screw itu p & now
I cant bend over the fender due to a screwed up lower back)
Sir Dodge alot
Active Member
Yes, I believe I can, I'll be tuning mostly by ear and smell from the exhaust and with the vacuum gauge, aiming for highest vacuum reading while alternating from each mixture screw, not including the air bleed screw.
Sir Dodge alot
Active Member
Finally got the idle to come down,
The issue will probably make you say "yeah, of course it was you idiot"
Anywho. I wanted the idle to drop down from 850/930 to about 600/700.
What I did was bent the choke pull off rod further back toward the heater box.
Then I lowered the curb idle speed just a tad.
Reset the (fuel) & air mixture screw(s) to bottom of the seat, then gave 3 whole turns out.
Air bleed screw, 1 turn out.
I learned that these pre-smog AVS's need more fuel at idle as the idle jet is about .031
(Hence the 3 turns out of seat)
The jets size that is more optimized everyone uses nowadays is about .035 or .038, you can work with 2 turns out of seat with those bigger jet sizes.
(More typical mixture screw base adjustments)
So to explain as best as I can,
To achieve the low idle I needed to adjust the choke valve opening to be more closed, (richer, less air)
Bent the choke pull off rod to hold the choke valve closed MORE.
The issue will probably make you say "yeah, of course it was you idiot"
Anywho. I wanted the idle to drop down from 850/930 to about 600/700.
What I did was bent the choke pull off rod further back toward the heater box.
Then I lowered the curb idle speed just a tad.
Reset the (fuel) & air mixture screw(s) to bottom of the seat, then gave 3 whole turns out.
Air bleed screw, 1 turn out.
I learned that these pre-smog AVS's need more fuel at idle as the idle jet is about .031
(Hence the 3 turns out of seat)
The jets size that is more optimized everyone uses nowadays is about .035 or .038, you can work with 2 turns out of seat with those bigger jet sizes.
(More typical mixture screw base adjustments)
So to explain as best as I can,
To achieve the low idle I needed to adjust the choke valve opening to be more closed, (richer, less air)
Bent the choke pull off rod to hold the choke valve closed MORE.
Sir Dodge alot
Active Member
All I need now is somthing to work the throttle linkage and potentially a velocity stack air cleaner base with or added spacers.
Edit: no accelerator linkage connected but was able to put the car around in the driveway. PROGRESS!
Edit: no accelerator linkage connected but was able to put the car around in the driveway. PROGRESS!
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