I have a 1977 F-150 351m c-6 tranny auto.I have done everything you can do to get more hp and it just bogs down. Everthing under the hood is new. I even checked all vaccums and no leeks. When you hold in the brake and give it gas, it almost stalls. My ? is can this be a brake booster leek or this something else? Any other IDEAS will be greatly appriciated!!!!!

 

what do you mean by everything??
carb replaced with a non-holley(not my choice for carb) 4 barrel or a better 2 barrel?
checked the fit of the intake for a bad seal to the heads and while you in the area the carb base

now for a crazy (problem i had (one of them lol)) shot in the dark
any shutter b'ween the gears?? possible tourque converter failure iment DONT drive it i did an 3 days later POW tranny time cause its now full of metal
check the rest of the tranny for adjustment linkage/bands
just guessing plz give details

pick up a mityvac vac tester and giv the egr/ booster the vac

 

The carb is a 2150 reman. Everything else from the horn relay to the pick up coil inside the dist. is new.I am going to take it to get the torque converter checked.

 

I just got the tranny checked. It is a ok.He said he thinks it is loading up with gas. Any ideas on what to look for here?

 

Even though your carb is rebuilt something may be wrong with it. What did you change to get more HP out of the motor? If your timing is good and you have a hot spark then you should look at the carb for issues. It may need some tweaking with the the jets. It may have been on a completley different setup and from a different part of the country and needs to be adjusted for your vehicle.
Good luck,
Brian

 

how do you go about adjusting the jets? never done that before.I looked down into the carb, and you can see it spray gas.

 

any buddies with a exaust sniffer?
but try the accelerator pump (availbe in the help section of the parts store)
pull the air cleaner and give a look the rot out or git a pin hole and gas the truck
in case you not fimiliar its the inch and a half square cover on the front of the carb with a lever off it that gives a shot of gas
or it could be a leaking bowl gasket
if its been rebuild they used the calibration tag off it and odds are they didn't even look at the jets or was it one of the home rebuilds
bubba (i think it was his sight) recomended a 2150 from a 82 mustang gt and un hook the egr the send more gas

too much gas is unusual prob.. do you have the egr hooked up? unhooking it leans it out i beleave

 

I just put on a new egr. It ran good for a while(a week) and than it went back to being a turd.I then played with the timing agian. I got it almost perfect by ear.But it would not start.So I backed it off agian.Now it starts good.I am getting 8mpg and can not even throw gravel when I floor it. I can not figure out this motor(LOL)

 

Never buy a reman carb. Get new or rebuild it yourself. They sit around for years in parts warehouses and all the seals dry out. Your problem sounds like a bad power valve.

 

thanks scroob,But what the heck is a power valve?

 

Recently changed ign. system on truck and set at the manufactures spec's and could not blow match out from exhaust. Used a vac. guage to set timing and found that am now running several degress advance over spec's. Runs much better. Just suggestion.

good luck,
dave

 

I did advance it but had to back off because it was hard to start. If I get a vac gauge,where do I stick it to use it?

 

I wouldn't think that adjusting your timing to vacuum readings is good practice unless maybe you kept it at a base rpm.
I've only used vacuum for adjusting air/fuel mixture and engine diagnosis.

 

Thank you, But what is a power valve? I never heard of this part before.

 

The power valve is part of the carb. On the Autolite, it's located under a small square housing on the bottom. The housing comes off with 4 screws, and the power valve screws into the carb body.

Holley's are notorious for blowing these out when the carb backfires. Autolites don't have this problem, but if the carb sat for a long time the rubber diaphragm in the power valve could have dry rotted.

Your strange, intermittent symptoms sure sound like carb to me. The power valve is vacuum operated and gives a squirt of fuel when needed. It's something like the accelerator pump, except that the accelerator pump is operated by the throttle. Your accelerator pump could also be bad. That's the square housing on the front of the carb that has four screws and a rod that connects to the throttle mechanism.

I always rebuilt my own carbs. A person who can read and turn a screwdriver can rebuild an Autolite 2150. After watching friends buy and return rebuilt carbs over and over and over again, I saw that they are not worth buying. For one, who knows who rebuilt it and what they did to it? Second, how long has this thing sat on the shelf somewhere? Third, how good is the quality of the parts that were used?

Your problem COULD be a vacuum leak. I would double check to make sure that the carb base gasket is installed and in good shape. Ditto for the gasket under the carb spacer or EGR valve. Is the PCV port hooked up properly? Stuff like that. If you squirt some oil around the carb base while the engine is running, you can spot vacuum leaks very quickly. The leak will suck the oil up and you'll see a puff of smoke from the exhaust.

If it's not a vacuum leak, then my money is on a bad carb.

One thing that hasn't been mentioned, and that should definitely be checked, is that your timing chain may have jumped a link.