Proform 850 Carb Help

[ghjedi]

I just put on my new proform 850 carb and I'm having some trouble with it.  Does anyone know how to adjust one of these carbs?  Of course, it came without any instructions.

The trouble that I'm having is it's hard to start (seems starved for gas) and won't stay running.  As soon as I give it a little gas, it immediately dies.  I then have to pump it once and restart, with the cycle repeating.  I have not tried to mess too much with the adjusting screws.

The setup for my 440 is: carb, gasket that it came with, adapter plate, gasket, intake manifold in that order.  It seemed fairly easy to install, but the one question I did have was the vacuum advance.  It looked it it could plug into one of two spots: at the front bottom in one of the 2 nozzles or at the side nozzle near the choke.  I tried both without much success.  Right now, it is plugged into the front bottom outer most nozzle.

Any tips would be much appreciated.

[Chryco Psycho]

you are too lean , possibly just from being cold , you need to check the float levels & try backing the idle mix screws out about 1/2 turn each until it warms up properly

[MEK-Dangerfield]

I'm surprised you can't even get it to idle. My first thought was the float level, which should be easy to see with the sight glass' on the fuel bowls. Does this carb have a choke? If so, maybe it's not open or closed enough.

I will have to get back to you about where to connect the vacuum advance. I know there were two nozzles down on the front corner of the base plate, but they were not for the same type of vacuum. I don't have my car stored here, so I'll have to check some time this week for you. In any case, even if you have your advance connected in the wrong place, this wouldn't be your problem with the car not idling now.


EDIT: I just took a quick look at mine, and you have your vacuum advance on the wrong nozzle. It goes on the one on the right if you are standing in front of the car facing the engine. I agree with Chryco that it sounds like a lean condition here, but if you are using an electric choke you need to have power to it for it to open, or possibly it needs adjusted to be closed a little more.   

[Chryco Psycho]

the vacuum advance should be connected to the ported vacuum so it should Not have any vacuum at idlle but should increase with RPM

[moper]

Just throwing this out there but you did plug on the PCV, right? No vacuum leaks?

[ghjedi]

Thanks for the tips guys and I'll try the adjustments that you suggest.  I know the fuel bowls were full because I could tell by looking through the see-through holes.  I'll try to take a photo tonight of my vacuum advance setup, as I know a picture will be most helpful.

To address the question about idling-- the car starts if I give it 1 pump of gas and then it starts to run very smooth for about 1-2 seconds before dying if I do not touch anything.  If it try to give it any gas whatsoever, the car immediately ties as well.   Do you still think it is too lean?  If so, do I back out all 4 screws?  It looks like there are 2 per side.

I likewise thought that the choke might be an issue (I have an electric choke) and I did notice that it does mostly shut when I first start it.  It does not seem to stay shut though, so it might need an adjustment to make it a bit tighter.  Does anyone know how to do this?   I've adjusted hot air chokes numerous times, but it looks quite different for

[ghjedi]

Just throwing this out there but you did plug on the PCV, right? No vacuum leaks?

I don't think I have any vacuum leaks.  The car did run smoothly for the 1-2 seconds that it did run!  I can't tell for certain until I can get it running for longer periods.

[ghjedi]

I'm surprised you can't even get it to idle. My first thought was the float level, which should be easy to see with the sight glass' on the fuel bowls. Does this carb have a choke? If so, maybe it's not open or closed enough.

I will have to get back to you about where to connect the vacuum advance. I know there were two nozzles down on the front corner of the base plate, but they were not for the same type of vacuum. I don't have my car stored here, so I'll have to check some time this week for you. In any case, even if you have your advance connected in the wrong place, this wouldn't be your problem with the car not idling now.


EDIT: I just took a quick look at mine, and you have your vacuum advance on the wrong nozzle. It goes on the one on the right if you are standing in front of the car facing the engine. I agree with Chryco that it sounds like a lean condition here, but if you are using an electric choke you need to have power to it for it to open, or possibly it needs adjusted to be closed a little more.   

Thanks MEK-Dangerfield.  To clarify, the vacuum advance does not go to one of the 2 lower ports at the base?  This is how it was setup on my prior carb (Edelbrock), but I did see the other port on the side of the carb and that is the one I think you are referring to, right?  I noticed that this side port is only on one side of the carb and not on the other side.

[MEK-Dangerfield]

Thanks MEK-Dangerfield.  To clarify, the vacuum advance does not go to one of the 2 lower ports at the base?  This is how it was setup on my prior carb (Edelbrock), but I did see the other port on the side of the carb and that is the one I think you are referring to, right?  I noticed that this side port is only on one side of the carb and not on the other side.

Sorry if I mislead you. The port I am talking about connecting the vacuum advance to IS on the base of the carb, but it's the nozzle to the right of the one you connected to. As Chryco mentioned, once your car is started, you will not feel a vacuum there at idle.

It does sound like your choke is working properly. In the future if you need to adjust it, there are 2 or maybe 3 screws that hold the choke pod to the carb that you have to loosen. You can then turn the pod towards the front of the car to lessen the time the choke is on, and of course, you can turn it to the left to get more choke if you find you need it. I wouldn't mess with that now....I think we have another issue.

Getting back to your statement of "knowing the fuel bowls are full"...They shouldn't be full. You should just barely see the fuel touching the bottom of the sight glass'. Maybe that is what you meant, but I just want to make sure maybe you aren't dumping fuel into your carb by having the float levels too high.

Hang in there, we'll figure this out.   

[ghjedi]

Okay, I had a 50-50 chance of picking the right vacuum port and of course I didn't   

I'll try the other and the more I read about carbs, I'm beginning to think moper is correct that there is a leak somewhere at the base of the carb that is killing it at idle.

Do you think that the adapter plate is an issue?  My carb won't bolt onto my intake manifold directly, but just curious if this carb works with an adapter plate.

[dodj]

How old is your fuel filter?

[ghjedi]

I just replaced it yesterday with a new one and fuel flow does not appear to be my issue (there is plenty of fuel in the fuel filter container.  I don't think the carb is starving for fuel, as when I manually open the throttle, I can see the gas flowing down into the intake.

[MEK-Dangerfield]

So you are trying to fit a square-bore carb onto on spead-bore intake with an adapter?

[ghjedi]

So you are trying to fit a square-bore carb onto on spead-bore intake with an adapter?

I don't believe so and sorry for being vague.  Previously I had an Edelbrock 1406 on an Offenhauser 360 manifold.  I left the Offenhauser on and also left the adapter plate on, as my new carb would not bolt directly onto the intake manifold without it, given the bolt spacing.  The adapter plate bridges the difference.  It is not a square-bore opening, but is the spread-bore patter.

[ghjedi]

Here are two photos of my carb setup. I'm going to switch the vacuum advance to the inner port and note that the photo below shows it connected to the outer port at the base of the carb.

Any other thoughts on what might be wrong?