i think the 2150 is about the best carb to learn on. i wonder if they use them in auto shop class?

this is only the second carb ive had experience with, and the other was a VW.
let me know if your gas milage has gone up or down after the rebuild.(i assume you put the new jets in before you put the carb back in the truck.)

 

it's my first carb to work on.

it's a "new" truck. i've only filled it up once since i got it and i've just now used a quarter of the tank. Needless to say, i don't know the gas milege before i rebuilt the carb. this is my play truck (project), so i was going for power not MPG.

check out my pics

 

best thing you can do for that truck is have the gas tank blown out and resealed. it costs about 100 to 150.
there's no point in running dirty gas through a clean carb.
and replace all the rubber lines from the tank up.

 

i checked out the pics, you did get a beauty! your engine setup looks exactly like mine. except for the drivers side fender wall, do you have p/s?

 

yep.

still havent gotten around to putting #66 jets in... have you changed jets yet, and if so, what number did you put in?

 

im still holding off to find the right value power valve for the #60's i found (in a friend's garage!)
i drive this truck all over town so i need to improve milage along with hp(efficiency is my best friend)

 

i haven't found any power valves for motorcraft, BUT i did hear that holley's would fit in there...

which power valve are you looking for? keep me posted on the benifits -- i might just tear mine back apart and replace it !!!

 

that's the problem! i dont know enough about how this system works to know what value to try first.
even on bubba's wonderful site(i learned a lot) he says its a trial and error thing. the reason i started this thread was to get some others' experiences on doing this, but apparently either no one has tried or no one wants to share their secrets.

or maybe, like it says on bubba's site, it depends too much on altitude and the info from others would have no relevence on my situation. i sure would like to learn more about it though!

 

i'm searching archives now for power valve.
found a guy that is running a '75 couger on 10 h.g valves - 15 mpg. in OK


~~ nothing else though

 

i'll definately let you know if i find out anything.

when i first opened up my carb it had a holley pwr valve that the p/o had put in.
looks like he (dont know who it was) started this process. i threw it away before i knew to look for a value so i dont know what it was.

 

FYI, the three power valves that i have seen (the one originally on the truck, the one in the kit, and the holley p/v that i bought) none of them had any sort of numbers on them.

 

O.k, here goes for the 2nd time..... My memory is rusty, so please forgive.

You really need one of those HP books on how to modify and tune carburetors. Even if you go to the store and thumb through it. You will learn a few things. As for power valves, the best way to size them is to run a vacuum guage to see what the motor needs and what the vacuum runs. If you have a fairly healthy engine under a small 2150 you will see vacuum drop under WOT until around 3500-4500 rpm, where it may go back up because it cannot suck anymore air through that little carb. This is where the 2150 may stumble if you don't have big enough jets in it to support the top end HP. The powervalve is what supports the power until the rpms get high enough to support the vacuum to suck more fuel through the jets. If you have a stumble then you need to go to a higher # ( I think, I could have it backwards, I've been awake way too long today.) valve so it opens sooner. A 6.5 is pretty good for most engines, but you can mess around and change it. Sometimes going to an 8.5 will really wake up a lazy mid-range. The pump shot is easy to tune, just go all the way to the biggest one, and it will probably be the best.

As far as performance with economy, the 2150 is a really good carb up to about 250HP. Anything beyond that, and it will really begin to show that it is too small. I've done almost every mod that you can to one, including chopping off the choke and blending the airhorn ( Didn't work too well, I could never get it tuned right after that.) The bigger ones came on FE's. Look for 3/4 ton and larger trucks, including industrial ones. Jets are a big problem ( that's why I went to Holley's ) but they can be found as you have found out. Again. Junkyards and recycling centers are the best places to find jets. ( I've even gone to the scrap iron places and found piles of these old carbs laying around.) Just stay away from the VV variable venturi ones that came on cars ( they are truly junk ). If you really want to mess with one, then the places to start for more air is around the butterfly's. You want to use a really good dremel tool and thin out the throttle shafts and blend the screws in. Be careful, if you mess up you can kiss the whole thing if not your engine goodbye. Then polish the casting flash off the boosters and the area above the venturi. Whatever you do, don't reshape things or mess with the venturi itself. It has lips and ridges for a reason. Then use a really tall air cleaner. As I said, I didn't have very good luck removing the choke-horn, but that's not really that much of a hindrance since the throttle bores are so small. You can however make your own version of a K&N stub stack out of epoxy or bondo and cover it with fiberglass mesh and coat it will resin. Just remember you want a smooth transition from the inner portion of the air-cleaner base to the venturi's. All of that work will bring the 400 CFM version up close to a 500 Holley carb. The 325 version will barely eek out around 400 when you mess with it.

As for MATT. If you want a bigger carb there is an old white water truck at the junkyard in Glendale ( Arrowhead Towing) with a 331FE that has the big carb on it. It's rusty, but the casting can probably be saved. That's the only one I've seen in all my digging around Vegas. I don't think they crushed it yet, but you never know when it will be done.

Good luck. You are starting with the easiest carb in the world to work on. Just wait till you get to quadrajet's. They are soooo much fun.......NOT!!!!!!!!!!!!

 

Jets: bigger is richer

Power Valves: Smaller number, kicks in later; larger numbers come on sooner.
The # is the vacuum the valve opens at. When the PV opens, that is as close to a 4bbl you will get, then the engine will rev, vac builds, PV cuts out. Sorry

 

thank you so much jfinlen, and rebel ranger, this info has mde my decisions for me, as for the junkyard carb, as interested as i am in it, since i already have two, i'll keep futzing with these ones for now. thanks again for trying.

ive got a dremel and am going to use it. i think i'll start with #60 jets and a 8.5 pwr valve.

 

turns out i had #57's in the truck and the other carb i have had #59's all i did was change them out and the truck has never been faster! dont know about the milage yet though. im going to replace the p/v this weekend.