Weber Carb Sizing

[deejay1272]

I found an affordable Weber carburetor with an electrically actuated choke (needs slight rebuild), but it's a 32/32 rather than a 32/36. I gather that these numbers represent the diameter of the two barrels (one for low speed/low vacuum cases and one for high speed/high vacuum cases). I'm wondering if this 32/32 carb will perform on my Tercel. Does anyone have experience with testing out different barrel diameters? If I install this carb, am I asking for trouble down the line when I run the car at higher speeds?

(I previously posted about how I want to stick with my stock carb, but I'm dabbling around to see if I can't reduce some of the vacuum line mess that's under the hood!)

Thanks in advance for any advice...

Ps- this site (http://webernorthamerica.com/pdffiles/W ... sguide.pdf) is a good place to learn about the various Weber models offered out there.

[takza]

Typhrus had his OEM carb set up with reduced spagetti...and got good mileage....not quite sure how he did it...might search or ask?

[Petros]

it should work out okay, it just means you will have a less maximum hp at full throttle. compare it to the stock size, or you can also compare the max CFM rating. If the Weber is greater, it will produce more hp than the stock carb.

You will likely have to rejet the carb, but there is lots of info on the web (and jet kits) available about doing that.

Good luck.

[teranfirbt]

Considering a Weber 32/36 is designed for engines up to 2.4L, a 32/32 should be much better suited to a 3AC... The 32/36 on mine has major issues during the transition to the secondary, most likely with the drop in vacuum causing a timing stumble. At some point I'm going to be looking into necking my 32/36 down to a 32/32 or even 32/30 with a restricter in the secondary.

[SynthDesign]

A 32/32 DGEV will work great for our little T4WDs. 32/36 is just the standard redline kit covering the A and T series Toyota motors(sub 2.0 litres). The 32/36 is excessively oversized for our valve/head design and exhaust system.

I'm going to be running a 32/34 which started out as a 32/32 like what you have. The benefit is a little better gas mileage and you can mash the throttle without stalling it. A problem with the 32/36s if your a leadfoot. I drove a 3a with a 32/32 and it didn't seem like it was lacking any horse power or torque compared to the 32/36 carb. Also with Weber Carbs, the trick is in the fine tuning more than anything.

[gatemaster]

I have a 32/36 and there is no hesitation during transitition from the primary to secondary. It used to but I changed the secondary idle jet from 50 to 60 and that fixed it.

[Snax]

I've got the 32/36 and I agree that on an otherwise stock motor, it's more than necessary. It just gets to a point in the throttle where it sounds like the motor just can't suck in any more air.

[keith]

Back when I put a 32/36 Weber on our 4AC, I found a cfm calculator on a web site. According to it, the 4AC will only draw about 165 cfm at 5500 rpm. A 32/36 can deliver 330 cfm. Based on that, I think a 32/32 or even smaller will work just fine.

[deejay1272]

Hey everyone. I've been doing quite a bit of research into the use of the "Weber 32" carb for my T4WD. After emailing someone at Weber, I've confirmed that the Weber 32 DFT series carburetor is not the best for our application despite the fact that it was designed for smaller engines and may be sized for less flow (i.e. lower CFM rating). It seems that the DFT series carbs have limited tuning options, limited parts availability, and they are meant for fuels that burn leaner than today's fuels (this may be associated with the presence of lead in the fuels back in the day?).

I've pasted the email response I got back from Weber below.


"The older DFT carbs were created before "emissions carburetors" became more common. The DFTs are not necessarily based on small or large engine applications. Previously, DFTs were used on many applications, primarily Ford of England and Europe and then eventually the US applications.

If you have a choice the 32/36, calibrated and installed correctly, will offer best tuning options. It also offers a longer service life and more reliability over the DFT models.

The tuning concepts and circuits will be the same: You'll still have idle jets, a low speed circuit and a high speed circuit . Each carb (the DFT and DGV series) will have its own ratioed fuel volume. While this may sound like other carbs this is a really big difference in how Webers perform over other carbs.

So if you have purchased nothing yet, stick with a DGV family of carb. They will be considerably better than your OEM application and you should see improved fuel economy and you can tune based on your engines demand.

Example: your current carb consumes more fuel now than it did when your car was built because the fuels used today are roughly 25% leaner burning. To make your car run appropriately you're now required to expose the throttle opening to gain a smooth idle. But you do not have the ability to change jets on your OEM carb. A Weber will allow you to trim both fuel and air to maintain a proper ratioed volume. The fact that fuels burn differently today means your current factory carb will consume more fuel to simply idle and run normally.

Weber's advantage is that they have a low speed jet that controls fuel mixture up to 3000 rpm and a main circuit that blends in around 2700 RPM. Depending on your driving habits and gear box you can tune specifically to your needs with a Weber. Typically a 32/36 tuned and driven properly will offer 10 to 15 % better fuel economy than a new OEM carb provided that the timing is set correctly.

With a Weber you'll want to disregard vacuum retard and bump timing to 12 maybe 14 degrees initial (depending on altitude). I believe your current timing is ~5 degrees.

I believe you will find more parts available and more value in the DGV family. If the DFT is just too good a deal to pass you will have to make or modify a DGV adapter to mount and use the DFT. We do have jets available but as tunable carburetors go, its not the most user friendly. The DGV family is easier for most novice Weber tuners to deal with.

Again I hope this helps and I hope I'm not too confusing with my comments"


Does anyone have comments to add to this email?

[SynthDesign]

I have a weber 32/32 DGEV.

Not a DFT!

The 32/32 DGEV's are out there with the proper redline intake manifold adapter, I assure you.

[deejay1272]

I have a weber 32/32 DGEV.

Why can't I find these anywhere? How does yours perform? Did it add HP or improve fuel economy? I'm most interested in learning about how the 32/32 improves fuel economy so if you could share some thoughts, I'd appreciate it.

[Snax]

"With a Weber you'll want to disregard vacuum retard and bump timing to 12 maybe 14 degrees initial (depending on altitude). I believe your current timing is ~5 degrees."

Interesting point probably worth experimenting with.

[SynthDesign]

I have a weber 32/32 DGEV.

Why can't I find these anywhere? How does yours perform? Did it add HP or improve fuel economy? I'm most interested in learning about how the 32/32 improves fuel economy so if you could share some thoughts, I'd appreciate it.

My 32/32 has been resized to a 32/34 to go with my Toda cam. I have the jet #'s but not sure what they mean. I'm hoping to fire up the motor before the end of the month, but the weather is making it hard to work in the garage. Who'd of thought Seattle would be seeing 30 degree weather for almost a week.
As for HP/ fuel economy, I'm hoping to see above 30mpg but the displacement on my motor is 1.67 liters. Pretty much the max a 3ac block can be bored with out having to do sleeves. 25mpg @90hp is reasonable I think. I'm also using a 1 7/8 ID exhaust system which should help the motor breath a bit more too.

[Snax]

[25mpg @90hp is reasonable I think.

Yeah, it's a solid 3 mpg better than I ever got in my STi.

[deejay1272]

My 32/32 has been resized to a 32/34 to go with my Toda cam

Synth, I thought the "32/32" referred to the diameter of the primary and secondary circuits (in millimeters). What was involved in making your carb a 32/34? Was this a jetting modification?