Tuning Weber 32/36 on a 2F (1 Viewer)

[firefighterjed]

There’s a thread about tuning a 38-38, but I was encouraged to start a separate thread since they are substantially different carbs, so here we go!

This thread should serve to document a thourough set up of a Weber 32/36 carburetor.

I my fj40 was aquired with a Weber 32/36 DGV 5A, DUI-HEI, and headers already in place. It ran poorly when I got it. It idled fine, but any acceleration had to be very slow and steady or else the engine would falter, cough and sputter.

I bought a rebuild kit for the carb and successfully cleaned and calibrated it to the included specs. Performance was marginally improved. Then I replaced the plugs and checked the timing. Timing was off (retarded) quite a bit. Set timing on the BB and performance was much improved. I read in the DUI-HEI lit that they like to be advanced about 12 degrees. I believe the BB at the pointer is 7 degrees, so I advanced the timing until the BB was at the edge of the window. This was too far because the motor almost wouldn’t turn over, due to ignition during the compress stroke I think. So I backed it of a little and bam! Things are running pretty darn good. Not perfect tho.

The current annoyance is a hesitation and sputtering if attempting to accelerate hard. This seems to happen as the secondary kicks in. Once the sputter is overcome, the engine accelerates nicely up to red line.

I understand that rejetting a Weber is a trial and error process. I’m hoping the great folks here will help me thru that process.

Here’s a couple pics, because pics are fun.

 

[firefighterjed]

Questions:
I assume there are kits of jets for the Weber. What jet set should I purchase for the trial and error phase of jet adjustment ?

My altitude is around 3000 feet usually with trips up to 6-7000.

I have an old, basic timing light. Is an adjustable light helpful enough to justify the cost?

Will I need other tools like vacuum gauge or hand vacuum pump?

Also, the rebuild kit didn’t come with an accelerator pump or one other triangular diaphragm item that I encountered. For piece of mind I’ll order those when I order the jet kit.

What else?

 

[thebigredrocker]

Vacuum gauge is a must. Adjustable timing lights are handy. The light I bought will also display dwell and RPM’s. I think @Rock40 got @Jason Reed ’s 32/36 dialed in. Jason, is it running strong?

 

[firefighterjed]

RPMs would be good data to have. I’ll get a full featured timing light coming.

 

[Dizzy]

The primary throttle plate is likely too open at idle on these motors. If you time the motor with the vacuum advance line connected, then you will be running ported vac to the DUI-HEI unit, because the throttle plate is open by more than 1.5 turns on the Ilde Speed Screw. If you time the motor with the vac advance line disconnected, then you will be off at idle when you finally reconnect the line. Because the motor displacement is too big and you are at too high of an elevation, and the throttle plate is open too much to get the needed air for idle, but it still runs 'ported' vacuum.

I got an adjustable timing light from Harbor Freight. There is evidence that the previous owner of my truck was reading advance by placing marks on the harmonic balancer.

So, one option is running only centrifugal advance and static advance-twist on the distributor. The vac line is capped on the Weber, and you bump it up, at the base of the distributor, I forget how many degrees for your situation, but it is like 12* or 14*.

On my Nissan mini truck, my Weber DGV can't handle the elevation where I live. I run the truck up to 10,300' regularly. So I drilled a 1mm hole in the primary throttle plate, opposite the progression holes, and it gets enough air so I can keep the Idle Speed Screw no more than 1.5 turns in. It is dependent on elevation, and engine displacement, so an F or 2F might need two holes, one the primary and one on the secondary.

All of that aside, the only symptom of trouble, that you have is at more throttle. Changing your jets, or making sure that it is properly timed, is going to be important. Have you read your spark plugs for signs of lean or rich conditions?

I wonder if your accelerator pump diaphragm is cracked/ It looks kinda greasy at the four screws just to the bottom left of the fuel inlet line. They recommend changing these like as frequent as once a year, due to ethanol in our gas.

 

[Rock40]

I can tell you that getting a Weber 32/36 tuned was anything but easy. I did re-jet both the primary and secondaries to go a bit leaner. I suspect you’re rich just based on your altitude and the fact that the Weber is a bit on the big side for the Toyota motor.

I was finally able to dial @jason Reed’s engine in when I bought a wide band O2 sensor and gauge for about $150. With the O2 shoved way up the exhaust pipe, I could get real time readings on the mixture both at idle and during acceleration. Without the gauge I got it close, but it wasn’t correct either.

 

[Rock40]

Oh yeah, and like stated above. You absolutely cannot have your idle screw turned in too far as it will effect the rest of the tune. I can’t remember if the spec is MAX 1.5 or 2.5 turns in

 

[Dizzy]

1.5 turns in maximum on the Idle Speed Screw.

I read that a wide-band O2 sensor can be read with a digital multimeter with it set to voltage. Then it would be like $5 at a junkyard, or $20 new. They make clamp-on O2 sensor bungs. All you have to do is drill a hole at a hot spot, and clamp.

 

[Rock40]

1.5 turns in maximum on the Idle Speed Screw.

I read that a wide-band O2 sensor can be read with a digital multimeter with it set to voltage. Then it would be like $5 at a junkyard, or $20 new. They make clamp-on O2 sensor bungs. All you have to do is drill a hole at a hot spot, and clamp.

Probably true but too much guess work for me. I wanted the air/fuel ratio to be VERY steady at 14.7 which is right where I got it. I think that’d be terribly hard to do with simply an O2 sensor and a meter. The new wideband digital gauges are extremely fast to record air/fuel ratio changes. The information is literally real time

 

[firefighterjed]

here’s a pic of my plugs.
Left 6-5-4-3-2-1 Right
They’re about a week old. Ran around the block a few times and then accelerated to where it falters and shut off the engine. Coasted into the garage and pulled plugs. Engine was probably not up to normal operating temp, but choke was off and running smooth.

 

[Dizzy]

Do you still have your old plugs?

Do you have dieseling (engine run-on) after you turn off the ignition, particularly when the engine is hot? Will running enough choke to barely get you at fast-idle reduce the faltering on the upper throttle range?

 

[firefighterjed]

Do you still have your old plugs?

Do you have dieseling (engine run-on) after you turn off the ignition, particularly when the engine is hot? Will running enough choke to barely get you at fast-idle reduce the faltering on the upper throttle range?

I don’t/haven’t had a dieseling problem.

I changed my plugs when I did the carb rebuild and timing. Prior to that it was running so different than it is now that I don’t thjbj seeing those plugs would relevant to the current set up.

 

[firefighterjed]

I adjusted the choke so there’s a cm or more of throttle increase before the choke begins to close for a high-idle function. Leaving the choke in high-idle did not affect the stumble at the early/mid acceleration.

I’m starting to suspect the accelerator pump. I was already planning to replace it, just to rule it out. When I accelerate, as long as I’m mellow with the initial push, it does fine & I can mash the throttle once it’s spun up. If I am cursing at a constant rpm and then mash the throttle it stumbles.

Edited the original post to include that I’m working with a 32/36 DGV

 

[Dizzy]

You can check for a squirt of gas going into the primary barrel with action of the throttle.

 

[firefighterjed]

Back to basics:
I did a bunch of reading and learned that before I start screwing with the carb I need to determine the baseline health of the motor.
I’m a new owner and the motor’s history is unknown. It has been painted and it sounds good so I assume that is has been worked over at some point.

I pulled the rocker cover and found the top end to appear very clean. No accumulation of sludge anywhere and all parts we’re getting good oil at idle.

I checked all the valves, but only had to adjust a few. Had to loosen one exhaust rocker and snug a couple intake ones.

Next I hooked up my new vacuum gauge and found only about 3 inHg at idle. Vacuum increases rapidly with the throttle, but is almost absent at idle.

Squirting ether around, I found leakage in the stack of adapters that were installed to accommodate the Weber.

I will get some gasket material and re-make the stack with fresh gaskets. Is a little RTV or gasket adhesive recommend / discouraged?

 

[thebigredrocker]

Wow only 3hg. What port did you hook the vac gauge up to? I think if you hooked to a ported vac fitting it would be low and climb like that.

 

[firefighterjed]

Wow only 3hg. What port did you hook the vac gauge up to? I think if you hooked to a ported vac fitting it would be low and climb like that.

I put a T in the hose to the distributor. It pulls off the base of the carb. Is that bad form? I swear I’m mechanically inclined... just a newb at proper tuning a carbuated engine.

 

[firefighterjed]

Vacuum tested from a port on the intake manifold. 19inHg

 

[Dizzy]

Lower elevations work for smaller carbs, air is denser the lower you go.

My guess is that you will be able to deliver enough gas, just not enough air. Do you find yourself needing a heavier foot?

 

[firefighterjed]

So good valve adjustment.
Good vacuum, needle doesn’t bounce at all 19 inHg at idle.
Still need to redo carb base gaskets and check bolt length on adapter plates.

Next thing to rule out is the accelerator pump I think. It gives a good squirt when I manipulate the throttle, but maybe it’s a little too late? After the throttle plate has already opened to far? Is the timing of the throttle open and accelerator pump adjustable?