"I can't get no..."

[Don L.]

...fuel to the carb - without what I consider to be excessive cranking and pedal stomping. (Sorry Mick)

I just installed my original carb after having it restored over the winter. I've been running an Edlebrock Qjet clone and it runs very nicely.

Anyway, on a cold start only, the original carb requires longer cranking, with a good bit more pedal stomping to get it cranked over. Much more than the clone, and more than I'd like.

Anyone have any tips or ideas as to what needs to be done to make the right carb run as well as the wrong one?

[Clem Z.]

Re: "I can't get no..."

...fuel to the carb - without what I consider to be excessive cranking and pedal stomping. (Sorry Mick)

I just installed my original carb after having it restored over the winter. I've been running an Edlebrock Qjet clone and it runs very nicely.

Anyway, on a cold start only, the original carb requires longer cranking, with a good bit more pedal stomping to get it cranked over. Much more than the clone, and more than I'd like.

Anyone have any tips or ideas as to what needs to be done to make the right carb run as well as the wrong one?

make sure the choke is closed completely and if your corvette has a return line from the fuel pump to the fuel tank make sure the carb has a filter with a check valve.

[Don L.]

Re: "I can't get no..."

make sure the choke is closed completely and if your corvette has a return line from the fuel pump to the fuel tank make sure the carb has a filter with a check valve.

Thanks Clem. A check valve seems like what the issue is, and what I was thinking.

It feels like the fuel is running back out of the carb after it rests. The choke is working very well, including fast idle. This only seems to occur after the car has sat for an extended period of time. When warm, it pops right over.

I am unfamiliar with the check valve you mentioned, but did notice a difference in contents between the filter housing on the clone and the one on the original. I've attached a photo of the inside of my clone's housing. Notice the black rubber part that the filter locates over. Might this be the check valve you mention? If not, please point me in the right direction.




Thanks again

[Stuart F.]

Re: "I can't get no..."

Don;

Sure looks like a check valve to me (nice manicure too). How is your accelerator pump actuation?

If you are really running into a return line situation, it is likely that it could happen under full throttle situations as well - where the float chamber runs dry and starves the engine because too much fuel is diverting back to the tank. I've run into this several times, but not on any early 70's cars. I cured this by inserting an old carb jet in the return hose to act as a restrictor. But I don't believe this is your problem now as the only thing you have changed is the carb, right?

Let's not forget the crappy fuel problem of today either, and it is now summer when it shows up the worst.

Stu Fox

[Jim T.]

Re: "I can't get no..."

Don what is the extended time that your Corvette sits and requires more cranking then when being used?
QJets have been known to leak the fuel stored in the fuel bowl into intake when not being used. The starter has to crank long enough to refill QJet.
Some have used JB Weld to patch up the leak.

Having the QJet leakage problem on my 1968 and 1970 Corvettes I installed Holley Spreadbore 6210 650's on both Corvettes in 1974. Instant starts and good gas mileage.
Both 6210's are double pumper Holleys. I have total control of when the secondaries open. My 68 327/350 M21 3:70 performs pretty good.

[Don L.]

Re: "I can't get no..."

Don;

Sure looks like a check valve to me (nice manicure too). How is your accelerator pump actuation?


Stu Fox

Stu: I'll tell my wife you liked her manicure. Ahh, just kidding.

Think the issue is isolated to the new carb itself, since all I need to do to get 'er to start up quick is switch the carbs back. It is happening with the new, but not the old carb. If the black rubber unit shown in my photo is the check valve Clem mentioned (boy, I sure hope it is), all I will have to do is swap filter housings. They look identical otherwise.

[Paul H.]

Re: "I can't get no..."

Don what is the extended time that your Corvette sits and requires more cranking then when being used?
QJets have been known to leak the fuel stored in the fuel bowl into intake when not being used. The starter has to crank long enough to refill QJet.
Some have used JB Weld to patch up the leak.

Having the QJet leakage problem on my 1968 and 1970 Corvettes I installed Holley Spreadbore 6210 650's on both Corvettes in 1974. Instant starts and good gas mileage.

I also went with the Holley spreadbore on my 68 427/390. Problem solved. Not a big fan of the Q-Jets even when they are right.

[Don L.]

Re: "I can't get no..."

Don what is the extended time that your Corvette sits and requires more cranking then when being used?
QJets have been known to leak the fuel stored in the fuel bowl into intake when not being used. The starter has to crank long enough to refill QJet.
Some have used JB Weld to patch up the leak.

Having the QJet leakage problem on my 1968 and 1970 Corvettes I installed Holley Spreadbore 6210 650's on both Corvettes in 1974. Instant starts and good gas mileage.

Seems like when only an hour or less, it starts promptly. If it sits for longer - usually long enough for the mechanical choke to coil out and work again, it needs to fill the carb back up before it'll start.

I like the clone carb plenty. It has plenty of power and at 14.5 mpg too. Just that I'm having it flight judged next weekend and am looking for the points.

[Stuart F.]

Re: "I can't get no..."

Don;

I think you have your finger on the problem with that check valve.

As for the Q Jets leaking, that is kind of an old tale now that most every good rebuilder checks for. It had to do with the main jet well plugs that sit in a chamber down in the base. Most rebuilders will put some extra sealer on them or use a plug that fills the cavity.

As for the Holley spread bores; I've had my fill of those. I don't like any carb that uses a gasketed surface below the fuel level. Also, those transfer tubes (primary to secondary) are prone to O-Ring seal leakage. No fun having the valley full of fuel. Then there is the air cleaner fit problem. A good Q jet will perform equal or better with half the fuss. Nothing like good old simple secondary dump instead of having to deal with an additional accelerator pump diaphragm, what with today's gas.

Stu Fox

[Clem Z.]

Re: "I can't get no..."

Thanks Clem. A check valve seems like what the issue is, and what I was thinking.

It feels like the fuel is running back out of the carb after it rests. The choke is working very well, including fast idle. This only seems to occur after the car has sat for an extended period of time. When warm, it pops right over.

I am unfamiliar with the check valve you mentioned, but did notice a difference in contents between the filter housing on the clone and the one on the original. I've attached a photo of the inside of my clone's housing. Notice the black rubber part that the filter locates over. Might this be the check valve you mention? If not, please point me in the right direction.




Thanks again

that is the check valve. the correct needle seat for a corvette carb is one with a openings below the fuel level to allow enought fuel into the bowl and the check valve is needed to prevent these from allowing fuel to run back into the pump.

[Patrick H.]

Re: "I can't get no..."

Thanks Clem. A check valve seems like what the issue is, and what I was thinking.

It feels like the fuel is running back out of the carb after it rests. The choke is working very well, including fast idle. This only seems to occur after the car has sat for an extended period of time. When warm, it pops right over.

I am unfamiliar with the check valve you mentioned, but did notice a difference in contents between the filter housing on the clone and the one on the original. I've attached a photo of the inside of my clone's housing. Notice the black rubber part that the filter locates over. Might this be the check valve you mention? If not, please point me in the right direction.




Thanks again

Don,

Do you have a side view of that same filter/valve combination?
I'm trying to picture it based on what you show above, but I'm not getting it.
And, I've taken enough Q-jets apart that I should know what it is.

Patrick

[Don L.]

Re: "I can't get no..."

Don,

Do you have a side view of that same filter/valve combination?
I'm trying to picture it based on what you show above, but I'm not getting it.
And, I've taken enough Q-jets apart that I should know what it is.

Patrick

Clem - Thanks! I'm going to swap them out. Let's hope it works.

Patrick - Wow. You caught me just in time. The Blackeberry hit me to show your post as I was getting my tools gathered. Hope this helps. I can/will share the details - and hopefully the cure - next weekend. You are coming, right?

It's kinda hard to get a good shot inside the housing to show the entirety of the valve. If you want to discuss, feel free to call @ 248.736.9798.

[Stuart F.]

Re: "I can't get no..."

Don;

If I see this right, this is the fitting that screws into the carb - behind which is the filter? Now, this fitting is from the clone and you will apply it to your original. Is there a gasket that goes over the fitting to seal on the carb body?

If these assumptions are correct, I'd say you're good to go Buddy.

Stu Fox

[Patrick H.]

Re: "I can't get no..."

Clem - Thanks! I'm going to swap them out. Let's hope it works.

Patrick - Wow. You caught me just in time. The Blackeberry hit me to show your post as I was getting my tools gathered. Hope this helps. I can/will share the details - and hopefully the cure - next weekend. You are coming, right?

It's kinda hard to get a good shot inside the housing to show the entirety of the valve. If you want to discuss, feel free to call @ 248.736.9798.

Don,

I've never seen a check valve built into the inlet fitting of a Quadrajet. My "assumption" is that what you have is a Edelbrock-inspired addition. Usually the "check valve" is just a rubber "flap" on the back of the paper fuel filter.

You can try this on your 72 but the guy doing Mechanical next weekend might note that it doesn't look like an original.

What kind of filter does your Edelbrock Q-jet use? Any pics of that too?

Patrick

[Don L.]

Re: "I can't get no..."

Don,

I've never seen a check valve built into the inlet fitting of a Quadrajet. My "assumption" is that what you have is a Edelbrock-inspired addition. Usually the "check valve" is just a rubber "flap" on the back of the paper fuel filter.

You can try this on your 72 but the guy doing Mechanical next weekend might note that it doesn't look like an original.

What kind of filter does your Edelbrock Q-jet use? Any pics of that too?

Patrick

OK. Transplant is complete. Re-assembled without leaks and started fine. Now we wait to see if it holds fuel. Film at 11:00 - TOMORROW.

And Patrick - there is no discernable difference between the two parts when viewing from the outside. Only the rubber within is on one and not the other. See attached photo of the housing without the valve. The paper filter is the same. It's now in, so I can't get a pic.

BTW, if you draw mechanical next week, just know that this didn't work and I put some NOS pixie dust on it to get it right .