Weber 32/36 Swap Guide

[StewyN]

Hey guys, so i know this one has probably been beat to death, but i cant find a complete start to finish on it. So here we go...

 

Working with an 85 720 2wd with the Z24, with the 6 wire carb.

 

Ordered the K646 weber kit from redline, has everything for a "direct" bolt in/up.

 

I'm hoping to gather everything i NEED to know. Vacuum delete seems to be preference (unless emissions restrictions). Ive came across mentions of the O2 senor becoming pointless/not needed after swapping (old carb 6 wires, new carb 1 wire for choke, yea we're losing 5 electric items😏) but i also came across charlie69 saying he has his working with a weber, but doesn't elaborate on how. And as for the other 4 IF possible id like to have them hooked up.

 

Basically I would like to do this as right as possible and keep as much working as possible ( yes i have to pass emissions, but around here, all a truck that old gets is hooked to the smog pump, they've never popped the hood or checked for a cat).

 

Thanks in advance.

[datzenmike]

There's no smog pump on the 720. One of the wires is for the idle cut solenoid that your replacement weber should have. keep this.

 

There is a pipe from the exhaust manifold to the air filter that uses the exhaust pulses and one way valves to draw air into the exhaust so the converter has oxygen to burn the emissions. I would try to cut the bottom of the air filter housing to fit the stock one onto the weber. This will also keep the ATC (air temp control)  in the snorkel functional. This system draws warmed air from the hot exhaust and mixes it with outside air to keep it at a constant 100⁰. Does it get near freezing with fog and or rain in Idaho??? his will prevent carburetor icing problems.

[StewyN]

5 minutes ago, datzenmike said:

There's no smog pump on the 720. One of the wires is for the idle cut solenoid that your replacement weber should have. keep this.

 

 

Guess i was a bit to vague about "smog pump". What i meant by that was, the just hook their tester up on the exhaust and call it good.

 

Good to know on the idle cut. Wouldn't have thought of modding the exhaust pipe in. good point mike.

 

It defiantly gets freeing around here, but usually not coupled with fog, and not many freezing rains. Not to say that it never happens tho.

[captain720]

I have had a weber with no warming method ice up a good bit in the venturis cause it gets around 0°F here in places. Its only happened to a point it caused an issue once and 15 minutes engine off hood closed fixes it, definitely would be worth having the warmed air in there

[Charlie69]

17 hours ago, datzenmike said:

There's no smog pump on the 720. One of the wires is for the idle cut solenoid that your replacement weber should have. keep this.

 

There is a pipe from the exhaust manifold to the air filter that uses the exhaust pulses and one way valves to draw air into the exhaust so the converter has oxygen to burn the emissions. I would try to cut the bottom of the air filter housing to fit the stock one onto the weber. This will also keep the ATC (air temp control)  in the snorkel functional. This system draws warmed air from the hot exhaust and mixes it with outside air to keep it at a constant 100⁰. Does it get near freezing with fog and or rain in Idaho??? his will prevent carburetor icing problems.

Every 1980 L20B 720 I have owned had a smog pump from the factory.

 

 

[datzenmike]

 

I forgot the '80, sorry Charlie.

[StewyN]

So which wire is which, the choke is blue? and the idle cut..?

[datzenmike]

 

L is Blue

Idle cut solenoid is Red. On the 720 it may have it's own Black ground wire.  On the 32/36 it will ground through the carburetor body.

[Sleepybean]

On 8/17/2020 at 3:47 PM, StewyN said:

Ordered the K646 weber kit from redline, has everything for a "direct" bolt in/up.

 

Hi Hello, also first post here... Anyways, I just bought an '85 and it has the same issue as my old Toyota and mighty max had with the 32/36. If you install the redline kit without another modification the fuel pump will overpower the float. It will "run fine" but the idle mixture will have little impact and the engine will diesel after shutdown. These carbs should be installed with a pressure regulator set to 2.5-3PSI (Note 1). It's fixed the issue on my previous installs and got the idle circuit working properly and passing the emission test in the Portland OR metro area (Exhaust Probe & Cat check).

 

Sure this is common knowledge, I just didn't see anything about it in the thread. This causes a lot of folks to give up on their truck after expecting the new carb to fix their issues.

[Charlie69]

If you install the Weber 32/36 DGEV using the stock carb electric fuel pump and the factory steel fuel line that the factory carb used you will not have any high fuel problem.

 

The factory steel line Need to be tweeked a little to get the rubber fuel line to connect to the Weber.  I use a  Phillips screw driver slide into the stock steel line and bend the line a little at a time checking after each bend to see if the rubber line will go on without kinking it.  Be gentle when tweeking the steel line you do not want to kink it.  I do this with the steel line bolt in its place.  I do not remove the steel line to do this.   Some people make a little loop in the rubber fuel line to connect to the Weber.