PVC Valve Removal

Hopefully someone can help me with this problem.

I would like to remove the vacuum hose that runs from the Carb riser to the PVC valve. Reason being is that I want to replace the aluminum riser or spacer with a fiber one to help reduce the heat from the intake manifold to the carb. The fiber piece does not have a place for the vacuum hose to connect.

My question is: If I remove this vacuum hose, where can I connect the PVC value or do I need to?

The engine is a stock 1970 302 with a stock 2 barrel carb.

More info:

The reason for replacing spacer: Bronco starts and runs great - after it's hot (running temp) it again starts fine if started within 5 to 10 minutes, however, if it's shut down for around 15 minutes or more it takes a bunch of cranking to start, also blows out black smoke after cranking and then starting. My theory is that the heat from the engine is overheating the gas in the float bowl causing some sort of vapor lock, I may be all wet, but no matter what I try with carb settings, etc. it still has the problem - hench my next trick is to try isolating the carb from the engine block heat with the fiber spacer but I'm not sure how to reconnect the PVC valve.

Thanks for any help you may give me

Bill

Try looking down the air horn (throat) of the carb after the 15 min. see if there's raw fuel setting down in the intake. (need a good flashlight) If it's wet...could be a (dirty) needle & seat, or float issue. (causing flooding)

Don't pump throttle..just hold pedal to floor while cranking.

If dry.... shoot some starting fluid (either) down air horn & see if it fires right up. If so, then fuel starvation.

In some cases heat will cause vapor-loc (usually in the fuel lines) but I don't think that's your prob.

Black smoke is usually flooding...

B B)

PS.. "where can I connect the PVC value or do I need to?"

I think you need it to keep the proper tune ...air fuel mixture.

Bully Bob said:

Try looking down the air horn (throat) of the carb after the 15 min. see if there's raw fuel setting down in the intake. (need a good flashlight) If it's wet...could be a (dirty) needle & seat, or float issue. (causing flooding)Don't pump throttle..just hold pedal to floor while cranking.

If dry.... shoot some starting fluid (either) down air horn & see if it fires right up. If so, then fuel starvation.

In some cases heat will cause vapor-loc (usually in the fuel lines) but I don't think that's your prob.

Black smoke is usually flooding...

B B)

PS.. "where can I connect the PVC value or do I need to?"

I think you need it to keep the proper tune ...air fuel mixture.

Click to expand...

Thanks for the reply Bully Bob, one more thing I should mention, the reason I believe the problem is heat related is because if the Bronco cools down, say in about 45 min to a hour, it has no problem starting, usually starts on the first turn over.

Your right about the PCV valve, it does run different with the hose blocked off, that's why I was wondering if there was another way to connect the PCV valve to another vacuum source - I guess I'll leave well enough alone for the time being since the engine really runs good except for the hot starting problem.

I'll be checking on what you suggested today.

Thanks again.

I have a similar problem with my 4BBL Holley. That will happen if I make the mistake of touching the gas pedal before starting to crank the engine over. If I keep my foot away from the pedal until I start cranking it is fine. It is definitely a flooding problem and as far as I can tell it is because touching the peddle will cause the dash *** to give a shot. One of these days I'm going to adjust that but for now if it happens, like BullyBob said just hold it to the floor until it starts and then wait for it to burn off the excess fuel. It always seems to happen when there is a Jeep owner near buy :blush:

You can't plug that line, it is not for vacuum but to complete the crank case ventilation path. The only alternative is to put a breather cap on both valve covers.

Good luck,

>-

Seabronc said.....,

"It always seems to happen when there is a Jeep owner near buy !"

Now that's funny...., & a ****** at the same time..! I also had that happen once..... Grrrr....

Wdetzi said...,

".....cools down, say in about 45 min to a hour, it has no problem starting, usually starts on the first turn over."

A warm eng. will evaporate pooled fuel in the intake plenum & below, in that amount of time.

One carb I had...I could look down the airhorn (eng. off) & see fuel dripping into the plenum. (It was a flek of debris stuck in the needle & seat.)

Bully Bob said:

Seabronc said.....,"It always seems to happen when there is a Jeep owner near buy !"

Now that's funny...., & a ****** at the same time..! I also had that happen once..... Grrrr....

Wdetzi said...,

".....cools down, say in about 45 min to a hour, it has no problem starting, usually starts on the first turn over."

A warm eng. will evaporate pooled fuel in the intake plenum & below, in that amount of time.

One carb I had...I could look down the airhorn (eng. off) & see fuel dripping into the plenum. (It was a flek of debris stuck in the needle & seat.)

Click to expand...

Thanks guys for all your information, this will save me a bunch of time by not fooling around with the PCV valve and fiber spacer! Now that I know what to look for maybe I'll find something fixable. Thanks again, ride safe, and "keep the sunny side up"!

Can you drill the spacer, and epoxy a ****** to it for the PVC hose? I did mine, but it's a 1" phenolic spacer that a guy at work make for me. see pics

76Explorer said:

Can you drill the spacer, and epoxy a ****** to it for the PVC hose? I did mine, but it's a 1" phenolic spacer that a guy at work make for me. see pics

Click to expand...

Thanks for the pictures and idea. That looks like what I may have to do - only problem, my spacer isn't quite that thick, but I'm going to give it a try, especially if nothing else helps my problem.

Did you install that type spacer because of a heat problem, and did it help?

wdetzi said:

Thanks for the pictures and idea. That looks like what I may have to do - only problem, my spacer isn't quite that thick, but I'm going to give it a try, especially if nothing else helps my problem. Did you install that type spacer because of a heat problem, and did it help?

Click to expand...

Yes, it always started right up when cold, but if you shut it down for more that 10 minutes after it got up to temp, it was a booger to start. I learned to just hold the pedal to the floor until it started. The spacer took care of that problem, but I still get vapor lock in 98 degree+ heat, and only if I get stuck in heavy slow traffic, and it doesn't shut it down, it only boggs it a litte above idle until I can get up some speed to cool her down, then she's fine. I belive that issue will be resolved with some re-routing of my fuel lines.

76Explorer said:

Yes, it always started right up when cold, but if you shut it down for more that 10 minutes after it got up to temp, it was a booger to start. I learned to just hold the pedal to the floor until it started. The spacer took care of that problem, but I still get vapor lock in 98 degree+ heat, and only if I get stuck in heavy slow traffic, and it doesn't shut it down, it only boggs it a litte above idle until I can get up some speed to cool her down, then she's fine. I belive that issue will be resolved with some re-routing of my fuel lines.

Click to expand...

That's good info, thanks a lot. I don't have a vapor lock problem while running, but I do have the hard start problem after it's shut down for over 10 to 15 minutes as you stated. If I start it after it has time to cool down or early morning, she'll start right up - that's why I assumed it was the carburetor over heating while sitting on top of the engine with no airflow.

You gave me new hope now, I'm definently going to be looking for or try to make a good insulator type spacer.

Thanks, and good luck with the vapor lock problem - if you don't already have an electric fuel pump, you might want to try installing one, that usually takes care of a vapor locking problem in the fuel lines.

I had the same problem on my 71' take the carb. off and pull the power valve cover if it's wet the valve is leaking and flooding the engine and only affects a hot or warm engine.

Good point...!!!!

I forgot about this....I've repl. many power valves...for this very reason..!

Good job 7br1....... /emoticons/[email protected] 2x" width="20" height="20" />