Rochester Monojet carburetor???

I have a 1969 Chevy van with a 250 6 cly engine in t
It. The Rochester carb on the engine is overloading. It has a flat screw on the top of the carb that I don't know if it is for adjusting something or what but it is loose and won't tighten up. The van had been sitting in storage since 2004 & had not been run. I got it running but when I crank it up it pours gas out of the top where the big flat screw is. My question is that is the screw on it supposed to tighten. I took the top off of the carb & the screw looks like it is maybe has something to do with the float but I am not sure.

donavan you make vanning a lot easier with all of your knowledge....keep up the good work.

Thanks for the info donivan65 I ordered a rebuild kit for it this morning. I am going it rebuild it I have never had any experience with these carburertors so I just wanted to ask about the screw to make sure it was not supposed to tighten up.... Once again thanks for all of the advice & help that you always give all of us....

I have the same carb on my chev 250 straight 6 motor.

I recently rebuilt the carb, cleaned out everything and it seems to work fine. My only problem is that when she stands for a few days it really battes to start up, even with a functioning automatic choke.

any ideas would be much appreciated.

thanks in advance

There are 2 possible things that it could be. One is the diaphragm in the fuel pump is bad causing it to leak back down & lose its prime & the other one is that the rubber hoses are dry rotted and are causing the fuel pump to lose its prime. There could also be a very slim chance that the metal gas line could have rusted pin holes in it but if it did you would probaly see or smell gas in that case. I had the same problem with my 69 Chevy van & it turned out to be the rubber gas hoses on it. The rubber gas hoses are kinda a pain to replace cause one is in front of the gas tank & you have to drop the tank to replace it & the other one is up front moumted on the body close to the fuel pump.

Thanks for the reply.
All my fuel pipes are metal and no they are not pitted and no holes as i'm not smelling any fuel. Where there are rubber fuel hoses, these are all new.

Interesting comment about the fuel pump. I never would have thought about that.

After a few days standing I opened the top of the carb to see if there was fuel in teh float chamber and it was very low, like it evaporated of drained out...to teh fuel pump and back to the tank

I would check all of the lines & hoses & make sure they are tight cause if they are just barely loose you can have that problem. Now there are actually 3 rubber gas hoses as I think of it now or atleast there is on my 69 Chevy van. There is one coming from the tank that none ts to a fuel filter that I forgot to mention. If your van has a fuel filter in the back coming from the tank & it has not been replaced it might be your problem. I also remember someone saying that there is a gasket or something in the carb that can cause the carb to lose its prime. I think that it might of been Donivan65 but I am not for sure. Maybe someone will give more advise on what it might be.

I recently had teh truck restored so everything was out. The hoses at the tank are fine and no there is no filter there.

I actually installed an in line filter just before the fuel pump.

The problem is very frustrating. Really dont' want to stuff up my starter trying to get it to take after standing for a week.

Everyday start is no problem. But I do not start it everyday. Its my classic drive reserved for the Sunday morning cruze.

I under stand your frustration I had the same frustration before I finnaly figured out my problem. If I didn't crank up my van every day I would have to prime the carb with gas to finnaly get it cranked. Good luck on solving your problem.

OK BOYS!! Heres the fix for the gas leaking out of any=any!! Rochester card for ya.@ or 4bbl even the quadrajets- In the manfacturing process -they machined / drilled all the passeges & sealed the bottoms of those with a lead. pull them bach apart & look - you will see these areas. You need to find a product called "Gasoila" comes in a small metal can with a brush. with carb apart- loghtly=LIGHTLY smear some of that over those areas of lead-let dry & put back together. Just make sure that before you do that you have claebed that same area with some carb cleaner or brake cleen/ start fluid. Then put the stuff on .If you have trouble finding that stuff - id try NAPA 1st. then an OMC marine dealer. Mercury marine used it also =all under their usual names - yet was always labeled as above-gasoila. The lead areas of seals - over time & vibration will leak fuel out & thence -a no fuel to start condition. Be sure if you get a can= close it very tightly as it will evaporate on you badly over time . a can of that stuff will last you a lifetime too.Happy vannin http://www.gasoila.com/ Its the Hard Set sealant u need

Yes the choke is working correctly. Its the coil spring type that bolts on the manifold. No I do not have points or condensor. i have the original distributor but the electronic kit for it. By the way, even with the points in it did the same thing.

I shall have a look for this seal in the carb. Damn, will have to pull it apart in order to find it, but rather get it sorted once and for all. I wonder if that product is available in South Africa.
So would I be able to notice that the gas has leaked out or would it leak internally into the motor. There are no signs of leaks on the float bowl.

With air cleaner on or off same story.

Once she fires up all is fine.

The problem is that standing for a week and she struggles to fire up. I would love to get that fixed as I really don't want to ruin my starter motor cranking to get her to start up.

Like i mentioned before, if I start up daily it fires up after following this start up procedure, pump the pedal 3 times, hold pedal half way down and crank motor and she starts up first time.

Leave it standing for a week and the pedal is pumped many more times and motor cranked 4 times. Each crank for about 10 seconds each...

Ok will give it a bash and let you know. Will only try it in a few days though as the van was driven yesterday and will start up with no issues today.

Ok had a look at the choke operation and all seems fine. It closes completely during the startup.

Why would the fuel be evapourating or leaking?.

Maybe you should tear it apart & check the gaskets & make sure the bottom bowl gasket is on right. I took mine back apart and as don had said I did Infact have it on backwards. I am still having problems with my carb not idling & don has suggested that it is probaly sucking air & I think that he is right on that to. I hope to figure out my problem soon & hope that you do to. Just keep plugging at it & eventually you will figure it out as I am sure I will to.

Might re-read my post on page 1?

If there was a lot of scraping done T.P. could be right. The gaskets on my carb popped right off & I had to do very little scraping on mine hardly none.

My gasket was upside down or backwards just as you said don. I did put it back in the right way when I found out that it was on wrong. I have been sick with bronchitis for a couple of weeks so I haven't got to check the carb to see if it is sucking air as you said that it probaly is. The studs in the intake are short and don't give hardly no space left to really torque it down at all so I think that you are exactly right about it . I hope to get to check it when I get feeling better. I am going to take the studs out of the intake and install some new longer ones & torque the nuts down good then check it out. As for kevesh's problem I think that the diaphragm could be bad in the fuel pump causing it to lose its prime when it sets a few days. I have had the same problem with a few vehicles & one of them my 1969 GMC Van so just sayin there could be a chance that that is the problem.