Farrar's car blog

[content22207]

You're sucking air, most likely at the intake ports (where the manifold mates to the heads). Spray them with carb or brake cleaner. Don't forget to shoot underneath.

If you pop the manifold off I bet you will find a damaged O ring.

Unless your manifold hold down bolts are just loose.

Of course there is vapor coming from the breather hose -- your engine isn't running.

Bill Robertson
#5939

[Farrar]

You're sucking air, most likely at the intake ports (where the manifold mates to the heads). Spray them with carb or brake cleaner. Don't forget to shoot underneath.

If you pop the manifold off I bet you will find a damaged O ring.

Unless your manifold hold down bolts are just loose.

Of course there is vapor coming from the breather hose -- your engine isn't running.

Bill Robertson
#5939

Bill, you're probably right, but the question is how. There's no way the bolts could have loosened themselves -- I haven't had the manifold off in ages. I had no vacuum leaks and the damn car was running rock solid and idling smoothly when I was driving it regularly several months ago. Then the fuel pump died. O-rings can't damage themselves, can they? Are there DeLorean fairies which circle the globe and cause vacuum leaks? We do seem to be plagued by the damn things no matter what fuel-delivery we're running.

And the carburetor still leaks fuel. But you noticed that, I'm sure.

Now I really AM going to bed. I need extra sleep -- I have to drive the car tomorrow, somehow.

Farrar

[opethmike]

I've found that a real good way to check for vacuum leaks is to take a fog machine that you would buy from a party supply store, take the front cap off, attach a vacuum hose to the little brass/copper nozzle, and then attach the other end to intake vacuum.

Seal off the throttle plates with plastic wrap, a cap, whatever. Turn the machine on and see where the smoke comes out.

[Farrar]

Of course there is vapor coming from the breather hose -- your engine isn't running.

What's it supposed to smell like? It smells like smoke to me.

Farrar

[content22207]

It will smell like the underside of a valve cover.

When the engine is running, PCV pulls those vapors into the carb base. You can put your finger over the breather hose and feel PCV sucking.

When you turn the engine off, the breather hose becomes a chimney to the outside world.

PCV_Vapor.JPG

Bill Robertson
#5939

[Farrar]

It will smell like the underside of a valve cover.

Check.

Okeydoke, I was just wondering if it might have anything to do with the coolant I found in the air cleaner housing the last time I drove the car.

Gonna look for an air leak around the intake manifold this afternoon before driving it. In any event, the car needs to be somewhere under its own power this evening. With any luck, the vacuum leak won't melt any of my new spark plugs.

Farrar

[Ron]

Farrar,
A question and word of advice, if I may:
Has that float been re-soldered? If so, get another one, its weight is fairly critical.
You should never EVER push down on or pop the needle valve side of the float with your finger.

[Farrar]

Farrar,
A question and word of advice, if I may:
Has that float been re-soldered? If so, get another one, its weight is fairly critical.
You should never EVER push down on or pop the needle valve side of the float with your finger.

Thanks for the advice. I don't know if the float has been re-soldered; I bought it from a store so I figured it was legit. The black plastic float that came with the carb was beginning to become porous, so I replaced it with this one last year.

When I have to remove the float to adjust it, I remove its clip with tweezers. My fingers are too big to get into that recess.

Just how delicate is the needle valve? I know it has a rubber tip, but it doesn't look damaged to me. Since one is supposed to adjust the float level "dry," how does one get the needle valve to seat without moving it down manually?

Farrar

[Ron]

Thanks for the advice. I don't know if the float has been re-soldered; I bought it from a store so I figured it was legit. The black plastic float that came with the carb was beginning to become porous, so I replaced it with this one last year.

The only reason I asked is that the soldering looked..um...shitty...as if the excess wasn't removed and it missed the weight check. I've seen them look 'ugly', but the amount and drip I see raised a red flag. Maybe nothing...you can measure and compare.
If nothing was done to it since it was running fine I wouldn't worrry about it, at least until you had it apart again...

Just how delicate is the needle valve? I know it has a rubber tip, but it doesn't look damaged to me. Since one is supposed to adjust the float level "dry," how does one get the needle valve to seat without moving it down manually?

Farrar

Very. There is always a warning about it in the kits if nothing else.
Usually, a ring will form around the tip rather than bust or crack it... (A very thin ring is natural, from the float pushing on it, eventually.)
You invert the carb to set the float, always. (Don't let someone talk you out of being precise here. Note the varying measurements for different vehicles, dozens of them for a given carb, given down to at least 1/64 = .015625 inch! The measurement is with the float's weight supplying the pressure (through the lever).)

[Farrar]

Maybe nothing...you can measure and compare.

How heavy is it supposed to be? It certainly seems to float just fine.

You invert the carb to set the float.

Ah HA! This was not mentioned in the instructions that came with my rebuild kit. I guess they figured anyone who is rebuilding a carb knows what he is doing; they were wrong, of course.

I will check the needle valve again tonight. When I looked at it yesterday, it looked brand new.

Thanks,
Farrar