[jhein]

Originally Posted by Kenth

One has to realize our old carburetored cars uses atmospheric pressure and vacuum controlled devices to control engine management and to run.
And as the carburetor is vented to atmosphere at all times fuel WILL evoparate at shut-off.
NOT like a modern vehicle with closed fuel system computer controlled with electric fuel pumps preload the fuel system before "start".
Our old Pontiacs will NOT start as fast as the modern cars, especially with fuels that are composed for closed fuel systems.
Not always a bad thing as the engine will have oil pressure at the lifters when engine starts (if correct viscosity engine oil is used).

Also, how many enthusiasts have read the Starting The Engine procedure in their Owner Manual? From 1970 Pontiac Owners Manual:
COLD ENGINE
-Fully depress accelerator pedal- and slowly release. (to set choke closed). With foot off the accelarator pedal crank the engine by turning the key to the Start position (to fill carburetor with new fuel) and release when the engine starts.
If the engine starts, but fails to run, repeat above procedure.
When engine is running smoothly, the idle speed may be reduced by slightly depress the accelerator pedal and then slowly releasing.

A lost art!

Yeah, I know it won't start with a quick flick of the key and no other input like a modern car, and the starting procedure you describe is what I do. I understand the evaporation problem too. But what has me wondering is that it did not have cold starting problems before and now it does. Maybe this carb has a different needle and seat as mentioned, or something else. Don't know yet.

[Kenth]

Windowed or non-windowed inlet seat makes no difference as long as fully functional.
The non-windowed seat appeared 1975 in the M4-type Q.jets for better control of fuel slosh in the bowl.

An old Q-jet with leaking inlet seat, leaking well plugs, fuel percolating or flooding at shut off due to fuek lines too cloose to hot parts of engine may make the engine start easier when cold as the intake will be "primed" by the fuel that leaked into it.
A newly properly maintainanced Q-jet wont have those issues and may not start as easy.

[Formulabruce]

Seriously, How many people actually " Fully depress , and slowly release the accelerator pedal", JUST ONCE ????
Be honest......
I manually set choke under hood and pour in some fuel. Hit the key. Engine Usually runs long enough to pump fuel into bowl and keeps running
on high Idle.
Have worked in a GM dealership and watched people, especially men, and they "almost" always do 2 things related to cars and bikes.
1. Pump the gas pedal like they have to suck fuel out of a well thats down 20 ft below the ground.
2. Rev the engine up and down and slip the clutch on and off as if they need to help get the car or bike rolling, or are scared to let the clutch.
Yeah Slipping the clutch for NO reason.
Have had to change carbs, or carb bowl section many times for excess wear, and even tried the springs on the accel pump seal. Wear is bad when its dry.
Have had to change clutches WAY prematurely due to slipping by owner.

[unruhjonny]

Originally Posted by Formulabruce

Seriously, How many people actually " Fully depress , and slowly release the accelerator pedal", JUST ONCE ????
Be honest.....

When I got my car running properly, and regularly drived it, I did exactly as per the owners manual.

I bought my owners manual as an NOS Canadian printing many years ago, and spent time reading it over and over...
Asking prices for these (the English version that is) now are plain nutty.

[Formulajones]

Couple cars here I don't even use chokes on and they still start pretty easy when cold outside. Usually pump the throttle a couple times and 3-4 crank revolutions and it'll fire to life. Don't have to monkey around very long to keep it running either. Usually will idle on it's own within a minute of running without the need for a choke.

If cars are more finicky than that then there are some tuning issues to be addressed. Usually not enough idle timing (assistance with vacuum advance is a big help) or the idle circuits on the carb are way too lean (I find this all the time with todays fuels and stock carburators). Using todays fuels I find the idle circuits need to be fattened up to be happy.
Usually starting issues are a combination of both of these scenarios.

If you have a dry carburator that's a completely different problem. Gas isn't going to evaporate in 2-3 days, it just isn't. I don't even have an empty carb after 2 weeks of sitting. I've even left the nomad sit for a couple months and when it comes time to move it, I only have to crank it for a few seconds and the fuel pressure gauge comes right up and it fires off.

It just sounds to me like you either have a carb that leaks, a fuel pump that drains back, a fuel pump that looses it's prime, or maybe a rubber line somewhere sucking air, or maybe a fuel system that doesn't vent properly and as it cools off it sucks fuel back to the tank, or some other strange anomaly.

[98 SNAKE EATER]

So I've been lookin into other electric pumps apart from the Airtex I posted before....


Contacted Facet, who supplies pumps for Holley and they suggested their 60106 POSI-FLO, which is the same thing as Holley's Mighty Mite 12-427







Question

Would I have any issues mounting one of these pumps vertically?

I'd want it to be completely hidden without cutting any of the hardlines, so I was thinking about just extending the rubber lines and mounting it behind the quarter kinda like this (some high quallity rendering, I know)

[Formulabruce]

Does that need a relay though? It cant draw much current? Great Location Idea.. really like it .

[unruhjonny]

if you want it out of sight, why not put it somewhere near were the hard lines are connected together (with sections of rubber hose) in front of the tank?

[70TA-RAIII]

It looks like 1.5 amps so you should be good without a relay. Toggle switch or tie to ignition switch.

[Formulajones]

Electric pumps, to be as effective as they can be, need to be as close to the tank as possible. They are excellent pushers but terrible suckers. Which is why generally with an electric they recommend having a much larger pickup line in the tank vs the feed line to make life easier on the pump.

[98 SNAKE EATER]

Relay not required as long as the switch is rated to handle it, however, i use a relay for just about every circuit I wire up (force of habit)

I also like to use the smallest buttons/switches to keep things hidden or at least look OEM

As for pump location, as FJ said, its generally better for the pump to be as close to the tank as possible and as low as possible (which is why you see many track cars with a fugly pump hanging down low behind a tank)

I have a HUGE 250GPH pump on my Road Runner and hate the way it looks, but there's no hiding that monster.

That being said, with the minimal use this pump will see, I think anywhere in the system will just be fine for priming

[71GP76TA]

That car always had carb problems. I ran a reman service replacement on it for a while and it ran better. The carb I sold it with is the original RAIII 4 speed carb original to the car. I kept the service replacement.

I rebuilt the original carb twice. It'd run better for a while.. then go back to running crappy again. I was afraid of sending it out to a professional as that is a very rare and expensive carb. I was afraid it'd get lost.. or I wouldn't get the right carb back..

It always started with a couple pumps if it sat for a week or two and would go to high idle and kick down.. Any more time than that it took some cranking and pumping to get it going. Wasn't a big deal to me... just an old car..

When its running right.... that car is a screamer... it rips!

[98 SNAKE EATER]

Originally Posted by 71GP76TA

That car always had carb problems. I ran a reman service replacement on it for a while and it ran better. The carb I sold it with is the original RAIII 4 speed carb original to the car. I kept the service replacement.

I rebuilt the original carb twice. It'd run better for a while.. then go back to running crappy again. I was afraid of sending it out to a professional as that is a very rare and expensive carb. I was afraid it'd get lost.. or I wouldn't get the right carb back..

It always started with a couple pumps if it sat for a week or two and would go to high idle and kick down.. Any more time than that it took some cranking and pumping to get it going. Wasn't a big deal to me... just an old car..

When its running right.... that car is a screamer... it rips!

Happen to know if it has windowed seat in it currently?

Apart from the bowl leaking down, I haven't had any issues with it

Ordered up a high flow non-windowed seat for it, but if the electric pump fixes the initial start problem, I probably won't tear into it.

[71GP76TA]

Originally Posted by 98 SNAKE EATER

Happen to know if it has windowed seat in it currently?

Apart from the bowl leaking down, I haven't had any issues with it

Ordered up a high flow non-windowed seat for it, but if the electric pump fixes the initial start problem, I probably won't tear into it.

I don't remember.

I was having problems with hesitation when i put my foot in it. After I rebuilt the carb it was fine but eventually went back to doing the same thing. Probably kept me from hot rodding it.. LOL..

[Formulabruce]

Originally Posted by 71GP76TA

I don't remember.

I was having problems with hesitation when i put my foot in it. After I rebuilt the carb it was fine but eventually went back to doing the same thing. Probably kept me from hot rodding it.. LOL..

This sounds a lot like the "bore" the pump plunger travels in is worn.
A new plunger and seal ( usually with a sealing spring) will make it ok for a while, but eventually back to leaking by on a hard throttle push.
The wear is at the top, first 1/2 inch of travel.
Had a bunch of these on warranty and that's how original carbs got replaced on many cars.

[Kenth]

How would the soft rubber or leather skirt of an accpump plunger wear out the zink alloy or aluminium accpump bore, and within the warranty time?
Never seen this on 40-50-60 years old carburetors with hundreds of thousands of miles on them.

[Formulabruce]

Originally Posted by Kenth

How would the soft rubber or leather skirt of an accpump plunger wear out the zink alloy or aluminium accpump bore, and within the warranty time?
Never seen this on 40-50-60 years old carburetors with hundreds of thousands of miles on them.

Pumping the piss out of a car that wouldnt start for a variety of reasons. ( could be anyone, but I have seen it first hand many many times)
Zinc, and or Aluminum is NOT very hard.
Usually the upper part of this area would wear the most as well as the hole in the air horn. This was Not just Q jets, 2bbl and Mono Jets did it as well.
You may not be able to tell by looking, and the rubber/leather skirt was pretty forgiving. Gm eventually put springs in these to increase the pressure to the side wall. This did make up for some of the wear.
Worn carbs, the problem comes back, and so does the customer, to the dealership.
Just something to look at Carefully and up close next time you have it apart.
Usually scoring and discoloration is present, usually on the side facing the
Fulcrum of the plunger lever up top.
I can envision more wear taking place now, vs then with fuel evaporation taking place.
Just something to carefully look into if you have it apart.

[71GP76TA]

Originally Posted by Formulabruce

Pumping the piss out of a car that wouldnt start for a variety of reasons. ( could be anyone, but I have seen it first hand many many times)
Zinc, and or Aluminum is NOT very hard.
Usually the upper part of this area would wear the most as well as the hole in the air horn. This was Not just Q jets, 2bbl and Mono Jets did it as well.
You may not be able to tell by looking, and the rubber/leather skirt was pretty forgiving. Gm eventually put springs in these to increase the pressure to the side wall. This did make up for some of the wear.
Worn carbs, the problem comes back, and so does the customer, to the dealership.
Just something to look at Carefully and up close next time you have it apart.
Usually scoring and discoloration is present, usually on the side facing the
Fulcrum of the plunger lever up top.
I can envision more wear taking place now, vs then with fuel evaporation taking place.
Just something to carefully look into if you have it apart.

Never thought about that.. (duh).. I'm guilty of pumping the sh** out of it when it wouldn't start... I'm sure I didn't help matters any.

[98 SNAKE EATER]

Originally Posted by 71GP76TA

I don't remember.

I was having problems with hesitation when i put my foot in it. After I rebuilt the carb it was fine but eventually went back to doing the same thing. Probably kept me from hot rodding it.. LOL..

I haven't noticed any hesitation, but she did respond better to a little more timing after I installed the Breakerless setup


Some random dash cam footage just rippin around a bit

https://www.youtube.com/watch?v=nfTsxIxwyIY

Originally Posted by Formulabruce

Pumping the piss out of a car that wouldnt start for a variety of reasons. ( could be anyone, but I have seen it first hand many many times)
Zinc, and or Aluminum is NOT very hard.
Usually the upper part of this area would wear the most as well as the hole in the air horn. This was Not just Q jets, 2bbl and Mono Jets did it as well.
You may not be able to tell by looking, and the rubber/leather skirt was pretty forgiving. Gm eventually put springs in these to increase the pressure to the side wall. This did make up for some of the wear.
Worn carbs, the problem comes back, and so does the customer, to the dealership.
Just something to look at Carefully and up close next time you have it apart.
Usually scoring and discoloration is present, usually on the side facing the
Fulcrum of the plunger lever up top.
I can envision more wear taking place now, vs then with fuel evaporation taking place.
Just something to carefully look into if you have it apart.

I'm actually looking into a replacement accelerator pump

Figure I'd replace it if/when I swap out the non-windowed seat

Which shaft length do I go with?

https://quadrajetparts.com/quadrajet...-c-128_22.html

[Kenth]

1967-74 Pontiac Q-jet, except 455S.D., uses 2.745" length pump assembly.
455S.D. uses a 2.556" pump assembly.
1975-79 uses a 2.572" pump assembly w/garter spring.

And, pumping the pedal is never a good thing for various reasons, unburnt fuel flushing oil-film in cylinders is one, leaving the seal at bottom of pump bore another, but it will seldom if ever wear the bore out.