Which carburetors *actually work* for an FJ40?? (1 Viewer)

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Disclaimer, this is a bitchy thread but I just want to start some conversation.

I'll start my question by giving some background. I bought a 1973 FJ40 with the original motor a few years ago and I rebuilt the motor. Mechanically, the engine should be near perfect. Unfortunately, one of the previous owners replaced my carb with a weber 32/36. It was auto choke. All crummy inside and in dire need of replacement.

Because I didn't know better, and because I was told by several people that it was a sufficient carb, I replaced it with a brand new manual-choke version of the same carburetor.

I tuned it, I've had it professionally tuned and jetted, and STILL it doesn't run right. The best way I can describe it... It just doesn't have a 'sweet spot'. It's either too lean for the freeway or it's too rich to idle without dieseling. And I can't trust it to start if it's been sitting more than 48 hours. This part is the scariest to me, because I'm driving a Toyota Land Cruiser gosh dammit. Not a Kia.

So, what's the truth? I've heard webers are great, I've heard they suck; I've heard the Aisin carbs are great, and I've also heard that they suck too. I kinda want some numbers on the CFM these motors require. Or at least to hear from someone who really knows their s***. I know it's an old truck, but it's also a Toyota. Running perfect shouldn't be too much to ask.
 
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Get a properly built Aisin by @65swb45 or @FJ40Jim, or a Holley Sniper kit from @FJ60Cam

Got some mates here who had baffled 350 Holleys built and I think an extended vent tube or something like that, and they seemed to do pretty well but no experience personally.
I actually received a complete carburetor (for the same year truck even) as part of a larger purchase. Held onto it just in case. I just don't like the idea of another old used carb when I'm sure someone out there makes a better one nowawadays and it'll be brand new n clean.
 

3_puppies

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I just don't like the idea of another old used carb when I'm sure someone out there makes a better one nowawadays and it'll be brand new n clean.
most current new carbs are being produced in not the best markets for quality.
a good rebuilt stock carb from Mark or Jim will be far superior to most new carbs out there.
 
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Ok, here's the old timer checking in:
1. There are some here on Mud who have been very happy with a Weber conversion, but they are very few and far between.
2. Back in the 1970's when guys were having trouble with their factory carburetors (during the time I worked at Toyota Motor Sales USA) mechanics wouldn't rebuild a factory carburetor because the rebuilds wouldn't hold, mechanics got real tired of the constant "come backs", so they would only install a new carburetor. Along comes IH8MUD, along comes way too many complaints of bad factory carburetors (still to this day), then along comes 65swb45 and FJ40Jim who have evidently figured out how to properly rebuild the factory carburetors- - -so that may be the route to go.
3. Getting back to those days when factory carburetors were poo poo, no MUD yet, no 65swb45 or FJ40Jim yet, Downey offered Holley 350 conversions, but they soon got a bad reputation because guys would go off roading "without" the Holley being baffled. If you look at the drawings on ebay #254412275238 you'll see what the problem is with an unbaffled Holley in off road terrain. Then look at ebay #264808304851 and you'll see a full baffled Holley- - -just saying.
 

FJ40Jim

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Weber makes some good carburetors.
Weber does not make a good carburetor for a 1937 tractor engine.

The stock 38/38 F carb is a a good fit for an F engine. There are no new ones available.
There are many sources of aftermarket 2F carburetors that claim they fit on the F. The air cleaner won't fit, throttle cable doesn't connect, choke cable doesn't connect, ICS wire doesn't connect and the fuel line doesn't enter in the right place. So other than that it fits, I guess?
 

flee

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Do not fear the Weber. The advantages are that they are fairly simple and very tunable.
I don't think your starting difficulty is because of the brand of carb.
Prior to the rebuild, my engine had no compression in 2 cylinders and started easily with the Weber.
I would take a hard look at the ignition system and fuel delivery to the carb as well as the fuel pressure at the carb.
OEM fuel pumps can put out more pressure than the Weber is designed for - <4 psi.

BTW, my old '70 (the one in my avatar photo) ran great on and off-road with a baffled Holley 350.
 

Goldbug

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My '78 with a rebuilt f.5 came with 4 carbs, none of them from '78. It was 3 Aisins and an aftermarket "one from Japan" that the PO put in. It ran like crap when I brought it home last spring. I sent the best two Aisins to @FJ40Jim and he sent back one rebuilt carb and did a fantastic job. He truly is an artist when it comes to these machines. It made it run better, but redoing the idle solenoid and fixing the timing made it run great. So your problem might be carb related, but often the carb is the easiest suspect, not necessarily the only one.

Perfect world, I might have gone the Holley Sniper route..
 
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Sorry to hear about the carb woes...they can be annoying.
What are your plans for your cruiser - ie off-roading or just around town?

So for myself I run a 1967 F motor with a 32/36 Weber carb and have done so for ~24yrs. My Weber is finicky (anyone I wheel will laugh at that) but I have never changed it in 2 decades. Does awesome until it floods or stalls then it’s a PITA to start. As long as I can keep it going, hasn’t stranded me yet. I currently run it mounted 180 degrees turned (backwards) to alleviate some flooding issues. Tried the float bowl mod and was happy but had some downstream issues and de-modded at the time. For this truck, only thing of note is I did install a fuel regulator to turn down a bit...think mine is around 3-4psi.

My brothers 2F runs a 38/38 Weber and does fine. His is only a daily driver (no wheeling) but starts good, etc... does run rich.

With above said, I am having a more “modern” 2F built for my 40 (out of a 85 FJ60) and will try the fabled Aisan. I rebuilt it myself with a kit so nowhere near the skill of the legends referenced above. Will see how it does.

...and haven’t ruled out a FI kit if the Aisan doesn’t suit, just for fun. As easy as carbs are to tinker on and more “reliable” when off-roading I do long for the day I can simply start my 40. I do know the “oh no...it isn’t going to start feeling”.

Not that my response helps at all, just wanted to put a thumb up for the Webers. :beer:

Nik
 
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I've been running a Weber 32/36 for 15 years with no problems. Getting the jetting right was a pain but once that was figured out it's been flawless. I'm running:
Idle: 90/70
Air: 150/170
Main: 140/175
DUI distributor, header on a F.5 engine bored .40 over. It was jetted lean when I got it and smoked the #5 cylinder.
 
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I've been running a Weber 32/36 for 15 years with no problems. Getting the jetting right was a pain but once that was figured out it's been flawless. I'm running:
Idle: 90/70
Air: 150/170
Main: 140/175
DUI distributor, header on a F.5 engine bored .40 over. It was jetted lean when I got it and smoked the #5 cylinder.
I've got a bored F.5 as well. What do you mean by, "smoked the #5 cylinder"?

Also, what altitude are you at?
 
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I've got a bored F.5 as well. What do you mean by, "smoked the #5 cylinder"?

Also, what altitude are you at?
I'm at 3900' but regularly drive down to SL and up to 6000'. I've had it up to 9000' with no issues. The problem with #5 was a burnt exhaust valve. It read 0 on the old compression gauge. With the jetted Weber and the DUI distributor I have not tuned it up in 15 years. I used to spend a lot of time with points, dwell angle and timing guns. Now I just drive it and change oil.

PS the burned valve was on the F engine I had before the F.5 was rebuilt and installed.
 
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I run a Webber on my 40 and an aisin on my 45 and they run about the same, one has points and the other electronic ignition. I suspect you have something else going on with your engine.
Like what? Valves are tuned to spec, and I it should be timed right...
 

RWBeringer4x4

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I’ve found a lot of carburetors just don’t retain modern ethanol gas well. My FJ40 has a small block 350, running a Rochester Quadrajet. After 2 days, the float bowl is bone dry, and you have to crank the starter for about 15 seconds to get fuel back in the bowl so it will fire. I’ve tried anti-drainback valves, expoxied the plugs notorious for leaking on quadrajets, tried two different carbs and done about everything I can think of, but after 2 days, the fuel is gone.

I’ve heard a lot of folks running Webbers have similar issues. My friendly with a Carter 4-barrel on his Cobra kit car has the same issue.

This is to say - the issue you described isn’t necessarily unique to a Webber. I’ve been meaning to try some non-ethanol gas if I can find any and see if there is an improvement.

No experience tuning a Webber, but I’ve found any carb is tough to find a “sweet spot” on - made even tougher if you’re matching a carb to an engine it wasn’t designed for. Almost any carb will work (within reason) but it takes a lot of trial and error to get it right.
 
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1978 Aisin rebuilt by @FJ40Jim, for ‘78 FJ40, with factory electronic ignition, was night and day to what she was when I bought her.

Eventually, the oem dissy vac advance module developed a huge vacuum leak and I had an issue with the oem fuel pump diaphragm splitting and pumping fuel into the crankcase.

I bought a 2nd 1978 Aisin (from a MUD member) and sent it to @65swb45. Mark has come to Vegas for a wedding and we hiked and cruised together. He told me that he had learned some performance tricks that would make her run like an SBC.

I replaced the oem dissy, coil and igniter with a DUI and redesigned my fuel delivery system, eliminating the oem fuel pump and replacing it with two electric fuel pumps (One for each tank).

Once I installed the Aisin with Mark’s performance enhancements, she literally ran like she should have.

She started easily, easily cruised at 70... I passed at 75... once at 80. Once I found out all was good, I again kept my speed below 65.

I know nothing about other carbs... I do know Jim and Mark know their stuff.

I also know DUI, when installed as DUI recommends (timing @ ~12*BTDC, plugs gapped @ .050”-.055“ (I kept them at .050”), in concert with Mark’s performance enhancements gives more power and speed than a 40 rightfully needs.

Electric fuel pumps offer the security of never having fuel dumped in the crankcase and the inherent risks to engine intervals

Dual electric fuel pump provided me the security of knowing a pump failure would not shut me down... I just made sure I never kept less than 1/2 tank in each tank, minimum. I’ve been known to carry another 20gals on the roof rack.

So, this is my long winded way of saying there are experts on here that can make an Aisin carb hum. But, as @fireflyr inferred, above... you could be trying to fix an ignition issue, vacuum leakfuel delivery issue, etc., by tweaking your carb.

Good luck!!
 

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