Inliners International Forums General Discussion Engines carburator on a 250 motor

Okay guys, some of you have answered me a lot of my questions in the past and it has helped. My 50 Chevy is finally done. My problem right now is that my carburator isn't running right.
There's a few open lines that I don't know where they go.
I'm hoping someone has a picture of a 250 with the 1bbl or a website that will show me a diagram so I can figure out where all these lines go. Thanks again. Here's a pic of my motor.
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first off you need vacum to the dist.which from this photo it will come from That Blue plug at the base of your carb. The other vacum should come off the Intake and go to your PVC valve.
also off the intake a vacum line will go to your tranny.
Could you give us a better pic of the base of the carb and The intake between carb & valve cover?

Sure, I will post a picture sometime today. Thanks a lot, this is going to help me a lot.

By the way a friend of mine told me that because I have a 3 spd. tranny I don't need a vacum line going to the tranny.
I do have a PVC valve but I have it going from the side of the valve cover to the bottom of the air cleaner.

On that stock intake center runner there should be a Port for it,
That is where the pvc goes. Ok on the tranny I did not know you had a stick.

Okay, here's some more pictures. I hope these help.
Thanks again.

That yellow hose is my vacum line that goes to my dist.
And like I said, from the side of my valve cover where that black grommet is, it goes to the bottom of my air cleaner with the PVC valve.

The one that has the red & black cover is where you PVC should go.

Okay so if I put the PVC valve on the black one for example, where does the other end goes to? If it goes to the side of my valve cover then where do I put the hose from underneath the air cleaner?

The PCV valve needs a vacuum source.
The original setup had a large tube connect from the air cleaner to the hole in the front side of the valve cover. The valve cover hole at the rear held the PCV. A hose from there went to a vacuum source at the manifold or carb base, depending on the year and carb used.
The idea is to have fresh air that is filtred by the carb air filter, enter the front of the valve cover. That fresh air enters the engine as the the crankcase fumes are drawn through the PCV valve to the intake manifold and burned with the air/fuel.


I modified the air cleaner to fit a 4bbl, but the hose to the front of the valve cover, is the original. This is a '67 with oil bath air cleaner. Yours probably had a dry filter directly above the carb.

The down slopping port you have the black plug/cap on, is for a vacuum cannister. That replaced an idle vent used on older carbs. I don't think it should be plugged completely. I would put something inside the end that would allow it to breath, but can be pulled out for cleaning.

PVC is Poly Vinyl Chloride for lawn sprinklers.

PCV is Positive Crankcase Ventilation

Since this picture was taken, I have gutted the air cleaner and fitted it with a dry filter. As you can see it is and was always a little wet and dripped on the valve cover. Here is where the PCV valve goes.

okay thanks, it makes sense. So does that mean i have to get rid of my little chrome filter and put the pcv valve there? So it won't work hooked up to the air cleaner? What do I do with the rest of the lines that are plugged right now? I know the little blue one goes to the vacuum advance and the ones on the intake go to the pcv valve. That leaves two that are unused.Thanks again.

Sorry guys, I'm trying to do this right. Is this right?

Yes blue for your Vacum adv. And Use the Black one for your
PVC.

Thank you. Do I need to use any of the other ones? Like the 2 red ones or the one I used to have the vacuum advance line hooked up to?

you can block them off.In the mean time i'll take a look at the stock 6 i have sitting here to see what it has. I'm not sure if it is all there or not. It has been cover ever since i brought it home,From a guy who pulled it from a 70s yr Nova.

It's not at all unusual for there to be 'extra' vacuum ports. Some of the ports may have a little more vacuum than others and may work better/worse for the vacuum advance. On some original cars, some vacuum lines went to the windshield wipers and other accessories. Worse case is you need one for the vac advance and PVC if you have a PVC port in your valve cleaner. If not, keep it plugged too, adding a PVC won't really help the engine run any better, it just pulls air from inside the valve cover and let's it go in the engine with the fuel mixture. If your car doesn't have one, you probably have a vented oil filler cap on the valve cover and you may see smoke coming from it once in a while...not a problem. Thing to remember on vacuum ports is to use it or plug it. You DON'T want any leaking vacuum lines or the car will run crappy.

Sounds good. I really do appreciate your time.
Today I hooked up the PCV valve like you told me and the vacuum advance and it runs a lot better. My problem is the car won't start on it's own. I usually have to pour gas down the carb. to get it to start. After a couple of times it will start and run fine. Someone told me it may be my fuel pump not pumping right.
Any ideas? thanks.

It could be a fuel pump issue Or the carb is not priming itself
(intake) meaning the excl. pump in the carb is bad.

I'll look at that, thanks.

I messed with a carb similar on a jeep, are you sure the big plug on top is vacuum,,???it could be a bowl vent,,I plugged one once, it created all kinds of havoc trying to fill the bowl, pull from the bowl etc,, I always wondered where one of the lines from the carbon canister went,,after the carb swap,,,I wrapped a hose around from the carb to the fire wall and put a differential vent on it,,,

Fingersix we are talking about the bigger one on the intake.If you go back and look at the photos you'll see which lines we are talking about.

Larry I got ya there,,, my pcv runs to the manifold on the face also,, I'm just refering to,, if that top one is a bowl vent and you plug it, strange things happen,, a common pontiac quad vent is outside the stock air cleaner, and the cleaner base has a indentation on it, to fit around the vent, many of times a new chrome air cleaner goes on top, and the first thing is to plug the big hole on top of the carb, no good,,that was from the pontiac ohc sprint forum,the quads from those six cylinders are hard to get so people try to swap later ones on them,,,the jeep thing rang true for that, it was a weber conv, with the vent plugged the jeep was a nightmare,, unplug it ,,smooth sailing,???
side-bar,, does anyone have trouble logging in,, the site never accepts my password????

Oh ok as for logging in No issues here.

Hey did you get the leak issue figured out? or fixed yet?

You mentioned fuel delivery problems. Being a 6 cylinder, the fuel pump might not be that hard to change. While your at it, get a new fuel filter just to feel better.

While you have the lines disconnected... blow air or suck on the fuel line going to the tank (tank to fuel pump) and the fuel pump to the carburator.

As far as Vacuum... do you have power brakes? cause they need vacuum too. I was just discussing vacuum in another area of the forum. There are lots of things a Vacuum Gauge can tell you.

I will try to find a picture chart that shows how vacuum can tell you things about your engine.
Safety First, Dave

Hey Larry,, my password didn't work now either,???
No I didn't play with the leak any more,,since the breakfast, I'm wondering if the fluid could of been anti-freeze, and it changes smell due to fuel vapor getting through the alumm???? naa probally
not,, I was looking for vac, gauge to hook to the water inlet to see if the channel is pulling vacuum while it is running,, broke my gauge playing with the vac. advance on the dist,,I've been trying to decipher between port or manifold vac. for the advance, and have read both side of the fence,,it is still confusing, but with the dist. on manifold vac.. my dieseling is gone, and it seems like the engine dropped some temp,, it's not August though,,,

I would get with Tim (if i was you) in regaurds to try and find out whats up with that.

Vacum to the dist is normaly ported Not straigh off the manifold
straight maifold vacum will normaly Pull the advacne full And it can over time put a hole in the advance diafram. So my guess is if it is doing so and your diesling issue is now gone.I would say you need a little more timing to start with.

On some vacum units you could put your finger under it and feel it move in and Out as vacum pulls on it. Un plug your vacum try and feel for the rod going into the dist. See if it pulls it at idle. If so You will need a ported vacum source Which should only pull as you come off idle.Another words while giving it the
gas.

I want to thank everyone who took the time to answer my questions. It really helped me. After all, it was my carb that was having issues. I originally rebuild it and apparently I didn't do a good job. I had someone else do it and they did a good job. Car runs good now. I am posting a new post about connecting my temp. line. My 250 has an electric water/temp connection but the 50 chevy had a mechanical one that went into the block. How can I connect this?

Hey Larry,, password did'nt work,, who is "Tim"???, and how do I get to him??,,,,
I'm going to mail you some articles on port verse manifold vacuum,,, they are way to long to reinterate,
Question, on your response,, I thought dieseling was created because the timing was already to far advanced,,???, and to much advance timing made the engine run hotter,,,so in theory I, pulled the vac. off the distributer, retarded the timing to 4 degrees advance, the idle was pretty erratic, in drive it would stall,,, hooked up the vac,,idle smoothed out with the advance on, and thats where I'm at,,I could go the other way,, change the vac. to port, and then crank up the advance mechanically till the idle smooths,,, the problem is I really don't know a base to start with, that comp cam 262,, where should I set base timing at,,and what springs should be used for total timing at WOT,,???
I started messin with this when I started to research the springs,, I see pictures of people using two different spring wieghts, and I couldn't figure out why,,??
I'll drop this stuff in the mail at lunch,,

Useing different springs in un matched sets is nothing new. Many
have done that for years. Some spring kits even come with different weights.

what does it do, to use two different spring wieghts??? at the same time,,,
...who is Tim,,,, my password again no worky,,,
...package is in the mail...

What seems to be the problem with your pasword?

Hi Tim,, I've seen Titen, but never put two and two together,,,,, basically when I log in it does not accept my password,, I have been doing case sensitive and all,,,so I get a temp to get in,,,

I think you can fix it by going to 'My Stuff/My Profile', while you are logged in, and change your password to one that you want.