After reading through here and comparing pictures on here and ebay, I am pretty sure I have a Weber 38. The truck runs good, though it didn't like the cold weather a few weeks ago.

Here's my engine:


Here's my carb:




sideways view of back of carb:


My question has to do with the air cleaner assembly. Would the truck run better if I had something like the stock assembly back on to funnel in cool air instead of the engine area air? I just found some stuff on another site about that, but it was from an older article on 22r's so I didn't know if that was still the consensus. The filter is a K&N, and the engine has lots of smog stuff removed. I bought it this way, so I am just seeing what the forum thinks.

Thanks in advance.

 

The factory had a duct that ran from a cover on the exhaust manifold that when the engine was cold, a little door in that duct pulled warm air from the manifold until the engine warmed up then it would close and only get cool air from the intake duct on the factory air cleaner. With your setup, when you are driving, the air in the engine compartment is really quite cool, so it is not like the air entering your air cleaner is hot by no means. The factory cleaner is way more restrictive and not really to your advantage, except for the warm air on cold start feature, which really you don't need as long as your choke is working properly.

 

Thanks for the quick reply. That's exactly what I wanted to know. thumbs up YT!

 

I also am running a weber 38. I used to run the open weber air cleaner, but have since switched back to the stock air cleaner assembly. I have not noticed any reduction in performance and it is much better at keeping mud/water out. In MN the hot air intake feature is helpful in the winter too.

 

I beg to differ. My carburetor, though it may be stock, has a perfectly fine choke, though when my HAI was not there, it would ice up and not run right. IMO you should run something like the stock air intake during the winter, so the HAI will work, but that one you have on there is good for the summer.

 

I bought the truck back from a guy in Minnesota. I think I have read your posts on their local board.( I went there to download some pics of the rig in action up North). Anyway, the PO garaged it for most of the winter, so it probably didn't bother him. However, a few weeks ago, it actually got to freezing here and the truck ran like crap on the highway. There is a stock air assembly on ebay I might have to bid on and do some experimenting.

 

hey 4rocker, you had the stock carb and made the swap out right? if so was the gains worth the dollar? appreciate it man

 

Yes, I am on the MN boards as well by the same name. My truck is also my DD to get me through college and beyond so quick cold starting in the MN winter is important to me. I have definately noticed a difference in the winter between an open air filter and the stock box with the HAI. Now with my header, I dont have the little heat shield piece that the HAI hose connects to, so i just run the hose down between some of the header tubes and I think this does just as good of a job to pull the warm air from around the header.

I have also experienced less than idea performance and fuel economy with my carb only when it is extremely cold. When it warms up to even the 40s again around here I will probably see a 2-4mpg increase. I think it is just the nature of the beast with carbs in cold weather.

yotaman84, I did run a stock carb before I rebuilt my engine. It is hard to really measure the gains because I also installed a TRD midrange cam and some other goodies at the same time. All in all, I think a weber carb would be a great option for replacing the stock carb. If your motor is relatively stock, I would recommend going with either the 32/36 or 34/34 to maintain better fuel economy. The 38 is a great performance carb, but unless you have a good amount of other engine mods to support it, you probably wont be utilizing all of its potential. The 38 is also a bit of a gas hog in my opinion. If i could do it all over again, I would go with either a 32/36 or 34 and a low range torque cam. I think that this would give better crawling ability and improve fuel economy.

That reminds me, it can also take a bit of time to get the 38 well-tuned. Having the TRD cam with that carb usually means I have to up my idle to about 900-1000rpm to get it to idle real smooth in the winter.

Hope this helps!

 

It sounds like your 4runner is set up much like mine. I know when the engine was rebuilt, he put a performance cam in, but I am not sure of what type or specifics, and its running headers and a custom exhaust. When I drove it back, I was amazed at its performance and fuel economy. Granted, I did backroads and cruised at about 60-65 for most of the trip, but I pulled 20mpg for most of the trip and thats with the 35's(regeared to 4.88's).
However, in the city, I will get 16 and when it was cold...damn...14mpg...maybe?

BTW, I was real impressed with the knowledge and support of the local board in MN. My girlfriend and I also enjoyed Minneapolis for the few days that we were there.

 

Wow, 20 mpg would be amazing! Sometimes in the summer on a good tune i can hit 19-20 on the highway. Last weekend I drove down to IL and back and I averaged a painful 13.82mpg for the whole trip (max 15 min 12.2) in very cold weather doing about 70ish on the interstate (with a crazy strong headwind on the way back). I think one of the factors killing my mileage is the fact that I am running 31" tires on stock 4.10 gears. I think having some 4.56s would help some with this because even though the engine would be reving higher, it would not be working as hard. Unfortunately, these trucks are not too common up here and finding good used parts on a college budget can be tough. If I buy new gears, I would bump up to 4.88s because I am pretty sure that my next set of tires will be 33x10.5 after reading some recent threads about those tires fitting stock suspension.

The MN board is great, I have not yet had an opportunity to do any trail runs with them but I hope to change that this year.

 

So how do you guys like the performace of your 38's. I am thinking of getting one for my 84. It's not my daily driver, so I am not really worried about economy. Check my sig for my mods. Just looking for some input, looking to buy in a couple of months, I've got parts on the UPS truck for dual cases right now, so I've got to save some money.

 

I am happy with the performance of my 38. The carb does not seem to be a limiting factor when it comes to power. They can be tricky to tune sometimes. A 38 would probably work just fine with your setup and they are much simpler than the factory carb.

 

4Rocker:
I think part of the reason for the good hwy mileage on the way back was that I kept it under 70 the whole way. On gearing, the PO geared it with 4.88's and its perfect for me. If it had 5.29's the rpm's would be too high on the highway for me. He also put the extra low in the transfer case, so it can still crawl around without problems.

Jmazosa: I am a novice about carbs, but I like the performance. I think, from what I have read, the 38 is overkill if its a stock engine, but if you add other stuff or plan to(headers, cam, exhaust) then its worth it. I bought my truck set up like this and I have no complaints. Most non toyota people flip when I tell them its got a carb'd 4 cyl engine.

 

Sounds like good gearing and slower speeds can really help the mpg! If I can somehow manage to lighten my right foot I will have to do some experimenting.

Austin's comment reminds me of a time in a parking lot when someone asked me if I had swapped a v8 after starting up my truck with the flowmaster 40 on. Their looked awfully confused when I told them it was a 4cyl!

 

Mine sounds like a V8 too. My current plan for engine mods is a Weber (probably a 38, I'm not a daily driver so I'm not really worried about milage, too much), a header, new distributor, and a multi-spark coil.