Hard Starting Hot

[body bolt]

These days it's thankfully hard to find new fuel line that is incompatible with ethanol.

Originally Posted by Rich72C10

Well, I sure hope so - that is what I told O'Rileys what I wanted / needed. I even said, need fuel line for "normal" car ethanol fuel. He took me back, had me help match up the sizes and hold it to cut the length I wanted.

Gee, now you got me all worried that some fool box store is selling fuel lines that are not meant for gas that everyone gets!


Made me look up the part number on their website:

Gates Safety Stripe II Fuel Line/PCV/EEC Hose
Multi-purpose hose for use on return fuel lines, PCV and EEC systems, and for fuel return hose connections on diesel fuel injection systems. Approved for use with leaded and unleaded gasoline, diesel and gasoline blends of ethanol (E85), methanol and ethers (up to the legal limits allowed by the EPA).
Working Pressure (psi): 50 psi

[Rich72C10]

Got the heatshield in today and installed. Needed to cut a but around the old AC bracket (really need to take that off) and back by the vacuum periscope. 1st install was a epic fail, it leaked like the Titanic! I had used the supplied thin gaskets, so I swapped them out for my Fel-Pro 60255 gaskets. No more leaking after that!

Quick test drive to get things heat up, wanted 45 minutes. I said there is a little improvement in start up but nothing to write home about. But she did idled much faster/smoother. Though this is really needs multiple drives.

Oddly, I gained about .5~1 points in vacuum. No negative performance issues noticed while driving - everything seems fine, perhaps better as I am getting up to 15k.

[Carl Spangler]

So, what is the verdict on the post heat-soak startup?

I was sort of expecting a heat-soak temperature vs time graph also.

[Rich72C10]

ha, you are funny!

I'd say the heatshield isn't helping much post shut down and is only helping when the engine is running. Which I more or less expected.

I haven't moved to trying the 1/2 Birch spacer, I got kind of tired of pulling off my carb. Plus I am expecting my rebuilt one pretty soon, maybe by next weekend. Or I hope so, they asked for $$$ a week ago and I sent it right away!

So, this is on "ice" for a bit. Instead, I been having fun playing with my doors (seals), so it's not like I have been slacking ;-)

[Rich72C10]

I got my rebuilt carb back from QuadraJet Power two days ago. I have gone back to stock config for this carb, so no heat shield or spacers. Just the normal Carb Gasket between Carb and Manifold.

Twice where I thought I'd have hard starting after warm up, she started within 1/2 to 1 crank. So that seems interesting fix but this will take some time before I am really convinced.

I wished it was all rainbows and butterflies but its not. I have to say QuadraJet Power is not very helpful. Even with giving them the benefit of the doubt on how busy they must be, they lack helpful responses. Its like if they write more than 5 words some shock buzzer will zap them. Then good luck getting two responses in a day. My guess, they can't suffer fools / novices.

Anyways, I can't seem to get her drive decently while putting along normally. She is stubbly when giving little / regular driving peddle. If I punch her (near or at WOT), well hold on because she'll throw you out the door. I have resorted to carrying my screwdriver with me to tweak the mixtures screws a bit every 1000 ft or so - not really making progress. But I am going to keep at it - since I am sure I am just a idiot.

2nd problem - yesterday morning and today took me ages to get her started. It was like when I first installed the carb. So I am sure the gas is going away, I assume, from the bowl. My old carb never did this even after setting for days without being started - she has always been a happy cold starer. One of Quadjet Power's longer replies was:

Fuel can be backflowing after shut off and emptying the bowl, so it has to fill during initial cranking which is common. You can add a check valve to the filter, which is restrictive. Best long term remedy is adding an electric fuel pump for quick fills when key is turned on, like modern cars.

Okay, my Googling came up with more or less the same answer (other than leaking plug thingys or adding a electric fuel pump). I doubled checked my old carb, there seems to be no kind of check valve installed on the filter. I ordered one, it's only a few dollars, but why all of a sudden do I need one? Now I am risking adding a "restrictive" flow? Is there something in my older carb (which was made in 78) combating back flowing? I'd assume Quadjet Power could have suggested this but they completely ignored that part my of question. Then I can't believe the electric fuel pump suggestion... that seems extreme to me.

Over the weekend I'll keep my testing up but I have a feeling I am going to be defeated and have to take it to the shop down the street for a proper tune up. FYI - I'm at 12 degrees initial timing (I did try for a but 14 and 16 no help).

[Steeveedee]

It's a new fuel pump, so I doubt that the poppets in it are leaking already. I suppose that that is possible, though. IIRC, the check valve at the filter is there in case the vehicle is upside down and fuel doesn't siphon out of the tank. Do you get a lot of black smoke when you have this condition? You could perform the same check for fuel inside the manifold as you did before with the other carburetor.

[Rich72C10]

No, no black smoke and I agree the fuel pump shouldn't be my problem and its not like it could have went bad between one carb in the next. Though oddly, my Vacuum Gauge actually started reading 15hg with no vacuum applied during testing my new carb (POS, wasn't even 6 months old).

[RustyPile]

I've been working on Quadrajets since they first showed up. I was a mechanic before then. Over the years, I've put 'em on race engines.. I've put on F**ds.. I've put 'em on Mopars.. I've rebuilt probably a million of 'em (probably not, but is sure seems like it).. The Quadrajet is a well designed carburetor that works very well as designed and doesn't need any modifications, just the hands of somebody that knows how to make them work..

Let's look at this logically.. The "back flow" excuse is pure bunk.. Fuel cannot syphon from the carburetor back to anyplace.. Simple physics.. Only a few drops can make their way back through the need/seat, but certainly not enough to cause a no start problem.. The opening in the seat is above the fuel level and fuel cannot flow uphill.. IF your problem IS fuel loss from the reservoir, there are only 2 ways out.. One: evaporation... Two: leakage through the metering well plugs........

[body bolt]

RustyPile speaks the truth. I'm going with well plugs.

[Steeveedee]

Is the part number on your carb the one for your year truck? Please post it. Later model carbs don't have the well plug issue. It would help narrow down the problem, maybe.

[Rich72C10]

I find it doubtful the fuel evaporation in less than 10 hours, overnight in cool-ish weather. It surely cannot be plugs (I have read a LOT about them), unless it wasn't rebuilt correctly by Quadjet Power - they aren't supposed to be any other places better (unless you got one done by Lars).

I went to great length to get the correct 72 Qjet for my truck (the one I took off was from a 78 Chevy Truck 17058213). But here is my number: 7042208. Which now has been worked on by Quadrajet Power (modified to Performance II). You wouldn't believe what I spend on the carb and then to have it worked on. Not to mention 18 weeks of waiting (and the two before it getting the 7042208).

I thought I was on to something when I found the truck will idle now at ~600 RPM's with throttle fully closed.. it will not die anymore with throttle closed.

From Mark @QP

Carb can idle with them closed. It has bypass air built in and we richened the mixture based on your engine descriptions.

[RustyPile]

Originally Posted by Rich72C10

I find it doubtful the fuel evaporation in less than 10 hours, overnight in cool-ish weather. It surely cannot be plugs (I have read a LOT about them), unless it wasn't rebuilt correctly by Quadjet Power - they aren't supposed to be any other places better (unless you got one done by Lars).

I went to great length to get the correct 72 Qjet for my truck (the one I took off was from a 78 Chevy Truck 17058213). But here is my number: 7042208. Which now has been worked on by Quadrajet Power (modified to Performance II). You wouldn't believe what I spend on the carb and then to have it worked on. Not to mention 18 weeks of waiting (and the two before it getting the 7042208).

I thought I was on to something when I found the truck will idle now at ~600 RPM's with throttle fully closed.. it will not die anymore with throttle closed.

From Mark @QP

Originally Posted by Rich72C10

I find it doubtful the fuel evaporation in less than 10 hours, overnight in cool-ish weather.

The reservoir in a QJet holds only a few oz. of fuel.. Given the right vapor pressure, in a fully warmed up engine ALL of it will evaporate in a matter of minutes, no matter what the weather.. If this happens and it comes time to restart the engine, 1 or 2 strokes of the fuel pump puts enough fuel in that tiny reservoir for the engine to start, making one think evaporation has not taken place....

Originally Posted by Rich72C10

It surely cannot be plugs

And you know this how?? Do you know how to check for leaking metering well plugs??

I stick with my original diagnosis: Either evaporation or leaking metering well plugs.. Both can easily be checked if one knows how..

I can't vouch for nor complain against any of the aforementioned carburetor rebuilders.. I have no need of their services as I do my own carburetor work..

[Rich72C10]

Do I know for a fact / have checked - no because I really don't know this stuff. Which is why I spent the big bucks and sent it off to a Pro. I am pretty close to putting my old '78 Qjet on and calling this a (big) loss.

[Rich72C10]

I couldn't take it anymore and I am doing all I can not to throw the carb down my driveway LOL (actually I am crying laughing)! I put my old carb on and it really makes me appreciate it a lot more. I didn't change anything else, not even the timing (which is at 14 or 12 now). At least I know I can take off a carb and put it back on correctly.

The straw that broke my back is this darn whistling sound that is coming from inside of the this rebuilt carb. It happens right at where I want to be idling. You adjust the idle ~100 rpms either way and it goes away. Think "tea kettle" sound. And it is not coming from some leaking around the carb either.

Don't know what to do or what I did wrong asking for what I wanted done from Quadrajet Power :'(

[Carl Spangler]

The whistling sound is a vac leak in the carb. Check all of the gaskets.

If you do a google search you will find a LOT of threads about whistling quadrajets.

[RustyPile]

Originally Posted by Rich72C10

I couldn't take it anymore and I am doing all I can not to throw the carb down my driveway LOL (actually I am crying laughing)! I put my old carb on and it really makes me appreciate it a lot more. I didn't change anything else, not even the timing (which is at 14 or 12 now). At least I know I can take off a carb and put it back on correctly.

The straw that broke my back is this darn whistling sound that is coming from inside of the this rebuilt carb. It happens right at where I want to be idling. You adjust the idle ~100 rpms either way and it goes away. Think "tea kettle" sound. And it is not coming from some leaking around the carb either.

Don't know what to do or what I did wrong asking for what I wanted done from Quadrajet Power :'(

Sounds like the more you fix it, the broker it gets.. The base gasket is probably used up from all the back and forth carburetor changing...

[Rich72C10]

I agree its a vacuum leak, Quadrajet Power more or less said the same thing.

@Rusty - I used a brand new base gasket (and it's one of the thick / good ones) on Wednesday. I was not going to reuse a $5 gasket, plus they provided me with a new one. I actually have one or two more new ones in stock! I never want it to be a question about a gasket.

I did however reuse the "whistling" carb gasket when I installed my old carb about two hours ago, on purpose. No more whistling and I am back to normal driving. I do need to tweak things because I left my timing higher (they suggested I bump it up). Also I know my left mixture screw is not right as I took it out and eyeballed it back into place yesterday (long story why I wanted to look at it).

So either this carb has been modified so much that my engine can't handle or I got a bum rebuild...

[Carl Spangler]

Originally Posted by Rich72C10

I agree its a vacuum leak, Quadrajet Power more or less said the same thing.

@Rusty - I used a brand new base gasket (and it's one of the thick / good ones) on Wednesday. I was not going to reuse a $5 gasket, plus they provided me with a new one. I actually have one or two more new ones in stock! I never want it to be a question about a gasket.

I did however reuse the "whistling" carb gasket when I installed my old carb about two hours ago, on purpose. No more whistling and I am back to normal driving. I do need to tweak things because I left my timing higher (they suggested I bump it up). Also I know my left mixture screw is not right as I took it out and eyeballed it back into place yesterday (long story why I wanted to look at it).

So either this carb has been modified so much that my engine can't handle or I got a bum rebuild...

Man, what a bummer!

Before you throw that Qjet down the driveway check the torque on the screws holding this %(#@%^!@ together. The whistling sound is possibly from the lower throttle body gasket.

[Rich72C10]

I got a BFH sitting next to it ... I am going to sleep on it a few days. Well not on the actual carb, I don't want to be near it.

[ChevyGuyNC]

Originally Posted by Rich72C10

I got a BFH sitting next to it ... I am going to sleep on it a few days. Well not on the actual carb, I don't want to be near it.

Man, that really sucks Rich. After your experience I will not use QP when I do decide to have mine rebuilt. I'll use National Carb here in Jacksonville; one week turnaround and I can go right to them if something's not right.
I wouldn't let QP off the hook; if it's their fault, they need to make good on it.

When I got my truck, she ran like crap... turns out the choke was fully closed all the time! Not to mention poorly adjusted mixture screws, idle screw, timing set WAY too advanced, and more.

A very generous forum member close by in Daytona helped get mine running 98% ... just a little hesitation/stumble/bog if you really hit the gas that we couldn't get rid of, but otherwise she runs great, starts hot or cold, I can't complain.

[Rich72C10]

I am just venting, crap happens. There is never a perfect assembly line, someone always gets a bum item. It just seems it always happens to me LOL

My real problem is the support I am getting or the lack thereof. I also have the feeling I am suck in some kind of run around. It still may be my problem, in what I requested to be done or how I explained how my truck is setup (they build to your engine specs).

I am just so very bummed after sending in my carb back in January. It's like waking up for Christmas and you open you long awaited present and its hot steaming dog turds.

[Rich72C10]

Oh I forgot to report:

When out to the garage, 6am-ish and started my truck. I push the pedal one good time, then 1/2 to 1 key turn of the engine: She starts right up into fast idle. Does not die, just keeps running.

So the final issue I was having with my rebuild, gone with my old carb back into the truck.

[Rich72C10]

I am a glutton for punishment...

I decided to check all the screws, nearly all but two were loose. The bottle two being the worst, one was 2 1/2 turns loose before getting to snug. Though it is still whistling. I spray carb cleaner (which scared me) all around the carb (under the air horn). No change in anything, the whistling or RMPs. So I don't know what that means but I am sure it means something...

Though she did drive a bit better after snuging down the screws but still stumbly taking off / low end :'( Its a real shame, since if I give her good pedal / WOT I'm moving fast!

[RustyPile]

There are several causes for stumbling and hesitation.. Some are carburetor related, some are ignition related, and some are a combination of both. Make a wrong adjustment and the problem worsens. I'm confused from all the carburetor switching back and forth.. Which carburetor does the whistling?? Buncha loose screws?? To fully solve THAT problem, you need to change some gaskets.. Don't forget to clean passages again, those gasket particles went somewhere..

With all due respect, Richard... Your biggest problem is your lack of experience with and lack of knowledge of the art of tuning an engine and being able to recognize how/why a problem exists.. I've been doing it for over 60 years.. I'm pretty good at it but still not perfect. Stick with it, grasshopper.. You'll get it figured out..

[Carl Spangler]

Originally Posted by Rich72C10

I am a glutton for punishment...

I decided to check all the screws, nearly all but two were loose. The bottle two being the worst, one was 2 1/2 turns loose before getting to snug. Though it is still whistling. I spray carb cleaner (which scared me) all around the carb (under the air horn). No change in anything, the whistling or RMPs. So I don't know what that means but I am sure it means something...

Though she did drive a bit better after snuging down the screws but still stumbly taking off / low end :'( Its a real shame, since if I give her good pedal / WOT I'm moving fast!

Was the engine completely warmed up for the 'stumbly take off' test?

Here's another easy test:
Crack the thottle about half open and see how much side-play is in the throttle shaft. i.e. clearance between the shaft and casting. A proper rebuild would include drilling out the housing and pressing in a brass insert. If rebuilt properly there should be an 'interference fit' between the shaft and brass bushings. If not done properly this could be a source of air leak and whistle.