carb problem? Carb gurus help please... UPDATE 2/24/13- changing carb

[maup]

I have no power half the time, and none of the time when trying to go up hill, it won't idle (may have found the problem here) and when I am off throttle the engine dies.

Its a 302 with the 289 intake and 2bbl stock set up, 3spd column shift.

I took it apart that far (see pic), I have never taken one apart and don't know what to check/take apart next...the float doesn't seem stuck and the its not real dirty...other things I could check - clogged fuel filter and timing maybe?

As far as having no power up hill, would a brake booster/power brake set up or power steering require any vacuum? Could this make me bog down when I give it more throttle?

 

[oleguy74]

looks clean.check float level.check timming,power stearing no vac.power brakes needs vac.

 

[jckkys]

The power valve could be bad. The diaphragm ruptures and all your symptoms could be explained by this. Turn the carb over and you'll see a square cover held on by 4 screws. That's the power valve. I simply suck on the side with the diaphragm. If you have air coming through, the power valve is gone. Replace it with a Holley. They're better quality and easier to find. Try 8.5hg. That's about right for a 302.
Power steering is unrelated. Power brakes could cause bad idle if there's a vacuum leek, but a bad power valve would cause all your problems.

 

[Gray035]

Sounds like a vacuum leak to me. Check the gasket between the carb and spacer and the one under the spacer. I had a leak there on mine and caused all sorts of problems.

 

[oldiron]

Are you using an EGR intake? Or a standard (no exhaust running to carb mounting area) type?
I'd lean heavily toward vacuum leak (most common). If thats eliminated, next would be accelerator pump, easy to check, just operate the throttle and ensure that fuel is coming out of the squirter. Blown power valve will cause similiar symptoms, i.e. no power to accelerate but it will idle and hold steady rpm just fine. (usually only show up under load conditions).
Let us know what you find.

 

[maup]

Thanks for the responses, I didn't get a chance to check yesterday but hopefully will tonight.

oldiron - I am pretty sure its just a standard intake but I'll have to look tonight if I get a chance...

As far as the not idling issue - one more thing I forgot to mention, after removing the carb it looks like the butterfly valves are almost all the way closed at 0 throttle...but maybe it was enough to idle without a vacuum leak? does that make a difference?

 

[broncnaz]

If they are completely closed then you may have a vacuum leak. Does adjusting the idle mixture screws make any differance? usually with a vacuum leak you dont have much if any adjustment and it will die on you. Also a higher than normal idle speed that cant be lowered is also a sign of a vacuum leak.

 

[maup]

When it was idling I thought it was running a little fast...I didn't get a chance to fool with it last night and doubt I will tonight, but between most of the responses on here there's a good chance I have a vacuum leak somewhere...the carb is still off so I plan to take a look what jckkys said to check first...

After I put it back on I'll (try to) start it and mess with the idle screws and check the accelerator pump...

best/easiest way to check for vacuum leaks? or just check all the connections and hoseclamps/hose condition?

 

[SDlivin]

to check for vacuum leaks, get some carb cleaner spray and spray around any mating surfaces; intake, carb, etc... Iwhen you spray an area if the idle goes up that means that is where your leak is. The vacuum leak sucks in the carb spray.
If you have a power booster on your brakes, cap this off at the carb/intake port. That will eliminate that being a leak problem. If it is the booster itself, those sometimes leak when your depress the brake pedal, and at the same time you will notice the engine idle drop because of the introduction of the leaky booster, then when you let off the brake pedal the engine idle will go back up.

One other item to invest in is a vacuum gauge, 20-30 bucks at a local auto parts store. Helps with timing your vehicle as well.

 

[maup]

Update - I got the carb put back on, it wasn't the powervalve....Weather hasn't cooperated with my wrenching time to roll it outside and start it to look for the vacuum leak...the gf works this weekend so I should have some time...

 

[maup]

carb problem = decided to change carb now

So thanks for all the replies a while back - I had put the carb back on and tried to start it so i could check for vacuum leaks and it made a loud pop sound a couple times, and there was a small wet looking spot on the hood right over where the carb is...

I have decided to just swap the carb to a newer 4bbl, I have a chance to get a good deal on an edelbrock here soon so thats probably what I'll use.

My question is - can I use the 4bbl carb with the stock 289 2bbl intake? Or do I need to get an intake manifold as well.

 

[Justafordguy]

you will need a 4bbl manifold. also the edelbrock carb isn't going to work well Offroad.

 

[maup]

This is just something to get me by for a season or two until I can finish collecting parts for for the EFI swap.

What have you had luck with? I'll be on pavement for a while until I shakedown all the new/untested parts (brake system, power steering, suspension...) Then some mild off-road stuff...

Whatever the solution, it either needs high resale value or be cheap and reliable...I am open for suggestions..

 

[Justafordguy]

2100 motorcraft is the easiest and most reliable 2bbl you can have. if you can't figure your old one out just go buy a rebuilt one from any auto parts store. it will work and have a warranty for a little over $100.

 

[broncnaz]

X2 your best option is the stock carb. You may have to much igintion advance and got a couple of back fires through the carb. As was said 2100's are easy theres not much that goes wrong with them. I'd get the engine started again and go from there.