Dave999
Well-Known Member
I have a 265 Cubic inch six
that is 724 CC per cylinder
bigger than yours
I run 40MM chokes in a 45 DCOE.
back in the day, a warranty claim of "my weber equipped mopar don't run right" At Chrysler Australia, was often a retro-fit of 38 MM choke instead.
smaller choke bigger torque at lower RPM
The biggest you can fit in a 45 a 42 mm choke if you can find one, but it would be madness to do that, as the Venturi effect is lost some what, you would be way better with 42 chokes in a 48 MM carb. because to neck a 48 mm bore to 42mm involves a choke that properly "chokes" rather than the thin shim of a thing it would be in the 45. you have problems the other way as well i have some 33mm chokes for a weber 45 but offically 34 is the smallest
too narrow and it messes with the flow through the auxiliary venturii above it and you can't pull fuel out of the bowl from the mains early enough
36 or 38 .....!
Drilled choke and venturi screws are standard those little buggers will come out if not wired.
I think you'd want 36 mm or 38 as you main ventuti/choke
i would suggest you stick with the 4.5 Auxiliary venturi
if you have 3.5 that would be OK but i doubt you need the 5.0
this Aux. Vent. measurement is the area of the end of the spout that sticks into the middle of the bore of the centre ring of the auxiliary venturi.
smaller = less signal transmitted through to emulsify fuel/air in the main well at higher RPM
i.e if i was good at 800 rpm good at 1500 rpm but tending very rich between 2500 and 5000 i might go to a 3.5 but that would mess up all tuning between progression into mains...
leave alone for the time being
anyway
what i have
40mm Main vent/choke 40 is a sensible choke for a 45 mm weber
4.5 Aux vent The middle one of the 3 that works in most cases
145 main jet
195 air corrector
F2 emulsion tube (emulsion tube changes shape of fuel curve worry about this later)
55F9 idle jet F9 has a 2mm bore and a smallish air hole i.e kinda rich but good reserve, it hangs on longer into progression (i have idle jet spreadsheet if you need one)
45 accelerator pump jet.
200 needle valve.
The accelerator pump inlet in the bottom of the bowl is the small ball valve with 0 on it i.e it doesn't have a check ball bypass hole in the side a feature which you can use to tune the pump shot length after you have chosen speed of delivery(spring/jet size) and amount to be delivered (length of rod)
the accelerator pump rod is standard length with standard spring.
leave accelerator pump stuff alone unless until you have to get that involved
My only variation from 1971 settings caters for ethanol fuel and my none standard cam is the float height now 1.5 mm higher.
My carbs were fresh new... jetted at factory for a 4 cylinder. Like all of them were. 4 cylinder engines in general have poor balance and slop the fuel about in the bowls. not a problem on a six so you can raise the float setting by 1-2mm. Nobody tells you this.....
, But in any old weber book with configurations for engines you don't know the 6s and v8s have the float level set higher than the inline 4, 3, and flat engines
You don't need MISAB or rubber mounts or special nuts and spring washers either
its a 6....
and i use the 195 air corrector instead off standard 170.
this stops me going pig rich in the 3000-5500 range
you are 615 CC per cylinder and your rod ratio isn't as square as mine. yours is kinda Long-Rod in comparison.
so my settings potentially won't work but might help comparison wise, with what you have in your carbs.
you now know what to look for, all parts have their number on them
strip one down a bit and check, id expect similar configuration.
I suggest for an easy life would be 36 mm chokes 4.5mm aux vents and work from there
remember all those Weber graphs of choke size vs cylinder vs RPM were drawn for 4 cylinder engines with a 4 cylinder float height spinning as standard, to a redline of 6500, and the webers we being strapped on to expand that rpm range
we have a big six, and we are working on a 1000 to 5500 range. 7000 rpm breaks cranks and rockers.
we have no need for a huge choke if we want all of the boogie to be in the 1000 to 5500 range
Having spent 10+ years messing and i'm still making improvements
with hindsight this is the order i would do things.
Ignition
initial balancing and idle
idle and progression
main jetting
emulsion tube tweaks
Cylinder pressures will rise, you are cramming much more smaller grained better mixed fuel and air, into the cylinder and it all heats up and tries to expand when compressed, as such, your plugs and ignition that worked previously will drop out and not work in certain rpm bands and you will blame the carb.
The internet ifs full of "they never run right those webers"... they do once you have sorted the ignition.
A holley or carter on a branched manifold on a six is throwing lumps of wet coal on the fire
a weber, port on port, its coal dust and ether....
its not the carbs.... its the leads, the plugs, the timing, the coi,l the cap
long reach NGK 6 with the low profile earth strap
45 thou gaps
a proper little welder of a coil
initial timing of 10-15 BTDC.
then mess with the carbs.
if they ran on a slant in the past you are already miles ahead...
to make my linkage and do my install i purchased
these filters. and i bored the base plates for slip in trumpets rather than the bolt down dellorto type they are designed for
3 1/4'' Air Filter Assembly (side draft) DHLA & DCOE
3 of these they can go on facing left or right and they are offset so you can vary where you put em
Linkage Arm - fits L/R side DRLA, IDF & FRD Type-1, 2 & 4
one of these to cater for an over the rocker cover throttle cable run
Linkage Arm - fits L/R side DRLA, IDF & FRD Type-1, 2 & 4
i purchased locally an appropraite length of 1/2 in hex bar
Steel Hex Cross Bar (specify size)
and i drilled and tapped into both ends to allow me to suspend the hex bar between 2 rod ends using 2 long bolts with 2 lock nuts.
I see your inlet manifold has no space for mounting the rod ends at both ends of the casting
i.e one hole is between carb 2 and 3
so you could vary what i got and use carb throttle shaft linkage between 2 carbs and a pull lever off the linkage for the others. 1 pull to drop links and a carb coupler
you can get left hand a right hand throttle shaft levers for webers
and you can get inter carb couplers, but these only work if you have quality manifold that mounts all carbs perfectly in line.
or just use the offset levers to the best configuration you can reach
anyway i have rambled on and on.. apologies
found some pics, if not apparent what i have done comparing links above to the pics below can get some more. my car has aircon heater box hence rear filter gets pushed into a strange place
doubt that would be a problem on the truck
that is 724 CC per cylinder
bigger than yours
I run 40MM chokes in a 45 DCOE.
back in the day, a warranty claim of "my weber equipped mopar don't run right" At Chrysler Australia, was often a retro-fit of 38 MM choke instead.
smaller choke bigger torque at lower RPM
The biggest you can fit in a 45 a 42 mm choke if you can find one, but it would be madness to do that, as the Venturi effect is lost some what, you would be way better with 42 chokes in a 48 MM carb. because to neck a 48 mm bore to 42mm involves a choke that properly "chokes" rather than the thin shim of a thing it would be in the 45. you have problems the other way as well i have some 33mm chokes for a weber 45 but offically 34 is the smallest
too narrow and it messes with the flow through the auxiliary venturii above it and you can't pull fuel out of the bowl from the mains early enough
36 or 38 .....!
Drilled choke and venturi screws are standard those little buggers will come out if not wired.
I think you'd want 36 mm or 38 as you main ventuti/choke
i would suggest you stick with the 4.5 Auxiliary venturi
if you have 3.5 that would be OK but i doubt you need the 5.0
this Aux. Vent. measurement is the area of the end of the spout that sticks into the middle of the bore of the centre ring of the auxiliary venturi.
smaller = less signal transmitted through to emulsify fuel/air in the main well at higher RPM
i.e if i was good at 800 rpm good at 1500 rpm but tending very rich between 2500 and 5000 i might go to a 3.5 but that would mess up all tuning between progression into mains...
leave alone for the time being
anyway
what i have
40mm Main vent/choke 40 is a sensible choke for a 45 mm weber
4.5 Aux vent The middle one of the 3 that works in most cases
145 main jet
195 air corrector
F2 emulsion tube (emulsion tube changes shape of fuel curve worry about this later)
55F9 idle jet F9 has a 2mm bore and a smallish air hole i.e kinda rich but good reserve, it hangs on longer into progression (i have idle jet spreadsheet if you need one)
45 accelerator pump jet.
200 needle valve.
The accelerator pump inlet in the bottom of the bowl is the small ball valve with 0 on it i.e it doesn't have a check ball bypass hole in the side a feature which you can use to tune the pump shot length after you have chosen speed of delivery(spring/jet size) and amount to be delivered (length of rod)
the accelerator pump rod is standard length with standard spring.
leave accelerator pump stuff alone unless until you have to get that involved
My only variation from 1971 settings caters for ethanol fuel and my none standard cam is the float height now 1.5 mm higher.
My carbs were fresh new... jetted at factory for a 4 cylinder. Like all of them were. 4 cylinder engines in general have poor balance and slop the fuel about in the bowls. not a problem on a six so you can raise the float setting by 1-2mm. Nobody tells you this.....
, But in any old weber book with configurations for engines you don't know the 6s and v8s have the float level set higher than the inline 4, 3, and flat enginesYou don't need MISAB or rubber mounts or special nuts and spring washers either
its a 6....
and i use the 195 air corrector instead off standard 170.
this stops me going pig rich in the 3000-5500 range
you are 615 CC per cylinder and your rod ratio isn't as square as mine. yours is kinda Long-Rod in comparison.
so my settings potentially won't work but might help comparison wise, with what you have in your carbs.
you now know what to look for, all parts have their number on them
strip one down a bit and check, id expect similar configuration.
I suggest for an easy life would be 36 mm chokes 4.5mm aux vents and work from there
remember all those Weber graphs of choke size vs cylinder vs RPM were drawn for 4 cylinder engines with a 4 cylinder float height spinning as standard, to a redline of 6500, and the webers we being strapped on to expand that rpm range
we have a big six, and we are working on a 1000 to 5500 range. 7000 rpm breaks cranks and rockers.
we have no need for a huge choke if we want all of the boogie to be in the 1000 to 5500 range
Having spent 10+ years messing and i'm still making improvements
with hindsight this is the order i would do things.
Ignition
initial balancing and idle
idle and progression
main jetting
emulsion tube tweaks
Cylinder pressures will rise, you are cramming much more smaller grained better mixed fuel and air, into the cylinder and it all heats up and tries to expand when compressed, as such, your plugs and ignition that worked previously will drop out and not work in certain rpm bands and you will blame the carb.
The internet ifs full of "they never run right those webers"... they do once you have sorted the ignition.
A holley or carter on a branched manifold on a six is throwing lumps of wet coal on the fire
a weber, port on port, its coal dust and ether....
its not the carbs.... its the leads, the plugs, the timing, the coi,l the cap
long reach NGK 6 with the low profile earth strap
45 thou gaps
a proper little welder of a coil
initial timing of 10-15 BTDC.
then mess with the carbs.
if they ran on a slant in the past you are already miles ahead...
to make my linkage and do my install i purchased
these filters. and i bored the base plates for slip in trumpets rather than the bolt down dellorto type they are designed for
3 1/4'' Air Filter Assembly (side draft) DHLA & DCOE
3 of these they can go on facing left or right and they are offset so you can vary where you put em
Linkage Arm - fits L/R side DRLA, IDF & FRD Type-1, 2 & 4
one of these to cater for an over the rocker cover throttle cable run
Linkage Arm - fits L/R side DRLA, IDF & FRD Type-1, 2 & 4
i purchased locally an appropraite length of 1/2 in hex bar
Steel Hex Cross Bar (specify size)
and i drilled and tapped into both ends to allow me to suspend the hex bar between 2 rod ends using 2 long bolts with 2 lock nuts.
I see your inlet manifold has no space for mounting the rod ends at both ends of the casting
i.e one hole is between carb 2 and 3
so you could vary what i got and use carb throttle shaft linkage between 2 carbs and a pull lever off the linkage for the others. 1 pull to drop links and a carb coupler
you can get left hand a right hand throttle shaft levers for webers
and you can get inter carb couplers, but these only work if you have quality manifold that mounts all carbs perfectly in line.
or just use the offset levers to the best configuration you can reach
anyway i have rambled on and on.. apologies
found some pics, if not apparent what i have done comparing links above to the pics below can get some more. my car has aircon heater box hence rear filter gets pushed into a strange place
doubt that would be a problem on the truck
Last edited:
