highonpottery

iTrader: (1)

On my 75 hilux, it's got a supposedly new Weber carb 32/36...and it does look fairly new. Anyways, there's a hesitation or a flat spot when you stomp the gas. In reading through info i'm thinking it's the power valve like a few suggested to me it might be.

Wondering if anyone can clarify the testing procedure for this part? From diagrams it looks like this valve is deep inside the carb, so I guess I'm going to have to take it apart? Do I need a full carb rebuild kit with new gaskets or can I simply order just the power valve?

83

I don't have advice for replacing the valve, but I will say that going carefully through the Weber tuning instructions, and making sure everything else is tuned up on the truck first, is a very very good idea.

Obviously check the condition of the plugs and wires and cap and rotor, adjust the valves, check the timing. Even compared to your 93, as I'm sure you've noticed, this truck is so damn simple. Everything is just right there in front of your face, just asking you to check it every now and then, it's all so easily accessible.

If those things don't do it, then tear into the carb.

kawazx636

iTrader: (3)

I had the same problem with my 32/36. I tried rejetting everything and every adjustment possible but I was still get getting a stumble when I stomped into the secondary barrel. Turned out that my accelerator pump couldn't keep up with the sudden fuel demand of the secondary barrel. I was able to tune everything else to minimize the stumble but it ended up causing a rich mixture and ultimately trying to minimize the stumble came at a cause of power and fuel economy. I actually just installed a Weber 38 and LOVED the performance gains that I saw during the half mile I drove the truck before my throttle cable snapped on me....

imhousing

classic accelerator pump. they stick pretty easy if they sit for a while due to the amount of surface area between the accelerator pump piston and it's wall. take apart your carb and polish the piston and it's wall.

re: stomping the gas pedal... yea most carbs don't have an accel pump big enough to stomp, one must apply a gradual increase to throttle till it's floored for best accelerations. even our 69 roadrunner w/ a 383 lags if you stomp.

edit: yea having a gasket kit for when you take it apart is a good idea. and take pictures! GOOD pictures!

enigmaT120

See, it was going faster because you were pushing harder on the gas pedal!

You'll let us know your new mpg?

highonpottery

iTrader: (1)

so this accelerator pump - can I access this from the exterior of the carb right? I was looking at the rebuild process here: http://www.mk3supra.org/topic/561-gu...236-dgav-carb/
and it looks like I can pop off the cover and do the cleanup like you mentioned. Should I order up a diaphragm for it or just clean up inside and inspect?

on the subject of jetting - this truck's got a headman header and I think a 2.5" exhaust. I do know there's a leak between header and the rest. Do you think any of this is effecting the problem?

highonpottery

iTrader: (1)

ok, so check this out...
i'm pretty sure this is the accelerator pump location:


but what's up with the opposite side of the carb - is there a part missing here? to me it doesn't look normal and something's missing, but i'm new to looking at these:

83

I'll go take a look at mine, but I'm pretty sure that's just how they look

83

Yep, looks just like mine. Not sure what could possibly bolt onto there, but no 32/36 that I know of has anything there.

I bought mine brand new.

highonpottery

iTrader: (1)

i confirmed that after looking a dozens of pics online. everyone seems to get the angle that doesn't show that side, lol.

gonna try messing with carb stuff this weekend.

highonpottery

iTrader: (1)

Messed with timing today. Had to move distributor over a tooth and grind more adjustment into the slot. Drives and sounds better but still some hesitation in carb I think. Not nearly as bad as it was. Was originally timed at like zero and now is maybe 8-10 degrees (only one timing mark on oil pump)

83

When I first swapped my Aisin for a Weber, I noticed a little lack in initial acceleration. The Aisin seemed to have a little more get up & go from a stop. I did the same stuff...tuned the carb, checked the timing.

Not sure if I just got used to the slightly different handling of the Weber, or if I finally did something to "fix" it...but I have no issues with how my truck runs now.

I'd say you can mess with it as much as you want. It IS a lot of fun, afterall...but if everything checks out as far as being in tune and adjusted correctly, maybe just have fun with it and drive it for a bit and get used to how it drives, compared to your other trucks. Hard to say from the internet how bad the hesitation is, so only you can decide if it's "normal" or "acceptable" or not.

I will say that my 78, even with the camper attached to it, is surprisingly peppy around town. Interstate is a whole different deal...but it can actually move around town pretty well.

highonpottery

iTrader: (1)

Haven't resolved this issue yet but think I know where I'm going to start.

This past weekend I think I may have discovered an air leak at the bottom of the Weber, likely as gasket on one of the 2 adapter plates it's got underneath. I heard whistling after driving it around and investigated. Traced sount to the back of the carburetor, assumed there was a leak there and sprayed some cleaner in the area - the engine picked up, so leak.

I also discovered a hole in the bottom of the air filter adapter plate when I pulled the filter off. Called Redline to inquire about said hole and he said it's a smog related port and since I'm de-smogged, just seal it off.

While I had Redline on the phone, I inquired about the issue with my carb. Immediately he said jetting. I guess it explains why the truck idles ok and will accelerate ok with mild throttle. When trying to accelerate with more throttle it stumbles and then picks up when the secondary kicks in. So I guess I'll order up a jetting kit and swap over the the next size up (primary, right?). Time to read up on Webers. I found some good info already about tuning one properly, so I'll follow that this weekend and confirm that my jet is too small.

83

If you're using the Weber 2-piece adaptor kit, I'd change that. I used something I found on Summit Racing. If you're interested let me know and I'll find exactly what it was. Only thing is that it'll raise the carb up an inch or so, which means you'll need to do some very basic modifications to the throttle bar linkage.

highonpottery

iTrader: (1)

I saw reference to that adapter here on YT. Maybe later I'll get it or the LCE spiral version if it leaks again.

Today I popped my carb cherry and now I think its mostly tuned. Found what was causing a leak in carb. It was one of the tapered screws for the first adapter plate not seating fully - had to file the edge and finally got it to seat properly. Made my own gaskets from 1/32 gasket paper and now no more leak! Did mess with linkage a tad so it wasn't putting pressure during idle.

Oh yeah, surprise coolant coming out when removed lower carb adapter plate. Good thing I was paying attention and had a rag stuffed in the intake or I would have flooded the inside! Drained radiator and all was good, disaster avoided.

Changed primary idle jet to the next size up, 65, and it's running much better. Still a slight hiccup but nowhere near what it was and now I can accelerate pretty good. Think I should try to get it fully tuned up - get a better timing light on it, a tach to set idle, check floats and idle circuit, etc and then adjust again.

Observations: Really need to swap out that flowmaster, it's soo loud, lol. Maybe I should check my gear ratio too, seems to wind up pretty high when cruising in 4th gear around town and I can even get into 5th on street. Maybe I should just get a tachometer.

83

Nice!

LCE Spiral Adaptor is not made for 20R engines. I had to find something elsewhere.