Vacuum problems on my Carter afb

[Eakinsk2010]

I just bought a 1970 c10 from a guy who, its been a mess. It had a nasty quadrajet on it, but my boss gave me a Carter AFB 9635sa so I put that on there. I noticed I'm not getting any vacuum on my manifold or timed for my vacuum advance.

Today I went got an edelbrock 1477 rebuild kit and used it hoping to fix the problem but still no vacuum. What could be causing this?

It stumbles a bit sometimes taking off, and it has died while idling before, I figured it was a fuel/air problem. Could it be the lack of vacuum?

I'm not much of a mechanic, never worked much on cars. I actually bought the truck so I could learn some stuff. Guess I got my wish lol.

Sorry if my post is a tad erratic.

[geezer#99]

Is it a stock spreadbore intake?
If so an afb won't bolt on without having a huge vacuum leak.

[Eakinsk2010]

Originally Posted by geezer#99

Is it a stock spreadbore intake?
If so an afb won't bolt on without having a huge vacuum leak.

I don't know if its stick but it is spread bore, I got an adapter to run the afb

[Stocker]

Not sure if it was AFB or a different carb, but back in the Seventies some were made with a plastic body. The plastic would warp and you had to toss the carb b/c you could never fix the vacuum leaks.

[geezer#99]

You might need a fuel regulator set at 5 psi.
Afb's don't like more than that much pressure.
Do you have a pic of this carb/intake set up?

You're talking about a thermoquad Stocker. Body of the carb was phenolic resin.

[Stocker]

^^ That's it! Thanks for refreshing my brainpan...

[Eakinsk2010]

I'll take a pic of the intake and carb today.

[Wrenchbender Ret]

You must be measureing the vacuum at the ported vacuum outlet. It only has vacuum at part throttle. Hook up to the full vacuum outlet. It will have vacuum at idle & part throttle. An engine will not run without vacuum at the manifold.

[swamp rat]

Originally Posted by Wrenchbender Ret

You must be measureing the vacuum at the ported vacuum outlet. It only has vacuum at part throttle. Hook up to the full vacuum outlet. It will have vacuum at idle & part throttle. An engine will not run without vacuum at the manifold.

What Wrenchbender Ret said, it has to have vaccum or it won't run, vaccum is what polls the air fuel mixture to the cylindars, assuming it is a squair bore move your vaccum gauge to the vac port on the other side of the carb, Or even directly to the manafold, there should be a port location there as well.

Look at this pic, i believe its the same carb you have, notice the two vaccum ports one on each side, notice how the driver side port is lower than the other, that port is below the butterfly plates and is where the vaccum is at idle. The other port will only have vaccum at open low throttle conditions.

http://www.ebay.com/itm/EDELBROCK-CA...#ht_1365wt_916

[Eakinsk2010]

Originally Posted by swamp rat

What Wrenchbender Ret said, it has to have vaccum or it won't run, vaccum is what polls the air fuel mixture to the cylindars, assuming it is a squair bore move your vaccum gauge to the vac port on the other side of the carb, Or even directly to the manafold, there should be a port location there as well.

Look at this pic, i believe its the same carb you have, notice the two vaccum ports one on each side, notice how the driver side port is lower than the other, that port is below the butterfly plates and is where the vaccum is at idle. The other port will only have vaccum at open low throttle conditions.

http://www.ebay.com/itm/EDELBROCK-CA...#ht_1365wt_916

I can feel very week vacuum on the driver side port, and I don't feel any on the timed port or whatever it's called, the passenger side port even when I give it a low amount of throttle.

[Eakinsk2010]

Here's a pic

[leftybass209]

You wouldn't feel any vacuum at the time port because it's above the throttle plate. It is fuctioning correctly and needs to be capped.

[Eakinsk2010]

Originally Posted by leftybass209

You wouldn't feel any vacuum at the time port because it's above the throttle plate. It is fuctioning correctly and needs to be capped.

Oh OK, understood.

['68OrangeSunshine]

Get the Edelbrock Carburetor Owner's Manual. They'll send you one for free. Don't tell them you have a Carter AFB, say you have an Edelbrock 1406 "Performer". They won't give advice about Carters on the phone, but it's basically the same carb.
Also you have a nice looking 'CARTER AFB: Competition Series ' plate. Don't let carb cleaner get on that or it'll ruin the paint.

[swamp rat]

Where is the hose from the brake power booster hooked too? the manifold or the back of the carb? does not matter which but make sure which ever is not used is plugged, the port in the back of the carb is in the same location as the 3/8" hose on the front running to the valve cover, the ere is a port on the manifold runner as well.. While were at it there is a valve on the power booster where that hose hooks to it, make sure it also has a new rubber seal if its dried up.

When you say it has no vacuum, what are you checking it with a gauge? are you sure its a good gauge?

The port on the front driver side could possibly be plugged? take a can of carb cleaner and shove the tip all the way in the port, pull the carb and open the choke plate and throttle plate, give it a squirt and see if ya see it blow into the venturi..

It has to have vaccum or it won't run..

[Eakinsk2010]

Originally Posted by swamp rat

Where is the hose from the brake power booster hooked too? the manifold or the back of the carb? does not matter which but make sure which ever is not used is plugged, the port in the back of the carb is in the same location as the 3/8" hose on the front running to the valve cover, the ere is a port on the manifold runner as well.. While were at it there is a valve on the power booster where that hose hooks to it, make sure it also has a new rubber seal if its dried up.

When you say it has no vacuum, what are you checking it with a gauge? are you sure its a good gauge?

The port on the front driver side could possibly be plugged? take a can of carb cleaner and shove the tip all the way in the port, pull the carb and open the choke plate and throttle plate, give it a squirt and see if ya see it blow into the venturi..

It has to have vaccum or it won't run..

The power booster is hooked to the back of the carb. The port on the back of the intake manifold is going to my transmission vacuum line. They both feel like they're pulling plenty of vacuum.

Well I haven't hooked a gauge up to it, just sticking my finger over it to see if its pulling anything.

I had the carb dismantled for the rebuild and cleaned it up, shooting it with carb cleaner and air, none of the ports were plugged as far as I could tell. Pulling it off to double check won't hurt though.

[swamp rat]

Is your timing advancing when you rev the engine? Put a timing light in it and see if the marks move on the damper, the distributor hose is hooked to the correct port.

[swamp rat]

Havent looked at one of the rebuild kits for a while, is it possible to flip the lower body gasket upside down blocking a port? I'd have to look at the kit to see if the gasket is symetrical or not.