This quadrajunk is killing me! I have a very low mileage 78 with the L-82 package, beautiful, but it suffers from extreme hard cold start. So bad I often have to pour gas down the carb. The car runs great and starts right up once it has run for a while. the bowls seem to go dry and it takes too much effort to draw fuel into them??? Do I just replace the Q-jet or upg to F/I? Effect on value? the car is all original as is. Thoughts?

 

Lots of people here love te Q jet. I would suggest searching the forum for a member named LARS. My understanding is he is the MAN when it comes to those things. He probably could help you out trying to fix it before spending lots of money on a new one.

 

I would contact Lars on this forum who is an expert Qjet rebuilder and tuner OR Holley 4175 Qjet replacement 650 CFM vacuum secondary Spreadbore (I have had this one since 1985)-expensive though now $500. I would get the Qjet fixed by Lars

 

Hi Jb,
Welcome!
First post!!!
Do you know if the choke is setting properly?
Are you following the instructions in the Owner's Manual for the procedure to start the engine when it's cold….. it's quite different from starting our contemporary fuel injected engines?
Regards,
Alan

 

What is the most important thing to you?
Keep it original?
Send your Qjet to LARS, let him rebuild it and enjoy like it was new (or better).

Modify to FI?
Lots of advantages to going to an FI system but the cost could be much higher.
It could offer better performance and fuel economy.

As far as effecting the value of your car?
In the end you have to have a car you are happy with.
When you sell it, it all depends on what the buyer is looking for.
Keep the Qjet on the shelf and give to the buyer so he can convert it back if he wishes.

 

For what it is worth:

Unless you want to spend a lot of money and have to deal with a lot of modifications...I would get the QuardaJet rebuilt correctly.

PLEASE excuse me but I am not attacking your and your ability to start your car....but...a lot of it can depends on HOW you are trying to start the engine after it has set for a few days and it is cold.

On some QuadraJets...if the car has set for few days....and you go and take off the air cleaner and manually move your accelerator linkage and DON NOT see fuel squirting in the primaries. Then ..this is telling me that the fuel bled back out of the bowl....and what may need to be done is to turn the engine over for a few seconds (4-6) so the bowl can fill back up with fuel. Then...press on the accelerator pedal and then see if your get a good fuel stream. The try to crank the engine.

When a person actually take the time to do all of this..they will then understand what it takes to get it to start when COLD...because there is no absolute procedure...because...if the car has sat for along time...your accelerator pump in your carb can loose its prime. and may take a few more presses on the accelerator pedal to actually get fuel to squirt out.

The fuel is being forced into the bowls by the fuel pump..and what I wrote above can help you clarify what you have going on.

I tell my customers to do this. See what it does when it has sat for ONE day.,..then TWO days and so on...so they can see what is happening.

And many of then call be back and were shocked in what they have found and now know that it was the starting / cranking procedure and not the carb or tune-up because they actually saw what was going on....and this is all due to we have been spoiled by fuel injection engines..and have forgotten the 'procedure' to crank a carbureted engine that may have sat for along time..

Also all of this may be totally pointless due to I have no clue if the 'cold start' problem just started to happen ...or if it has been like this for some time.

YES and improper choke setting/adjustment can cause for this EVEN if your have good fuel squirting into the primaries.

And there can also be other things wrong that can cause for the engine to be hard to start when it is cold...but does great when it is cranked at operating temps.

DUB

 

Will a Holley affect the value of the car? Heck yes! It will make it worth more!
Holley - Holley- Holley and never look back. Easy to work on, easy to find parts and they look awsome sitting on a Edelbrock. Just my humble opinion.

 

BUT...keep in mind that Holley is not a simple install.

Taking into account the air cleaner base more than like will NOT fit correctly...the factory bracket for the accelerator cable and transmission kick down cable will not work and need to be modified or something else 'figured out. The vacuum fitting in the top of the intake
in the #8 intake runner might now be effected. The choke may now need to be looked at.

The fuel line going into the front of the Holley...(depending on which one is purchased) will need to be looked at.

The vacuum going to the power brake booster is something else that will come up...which...once again...depends on which Holley is purchased.

And finally...checking to see what the vacuum is on the engine is so the power valve in the Holley is the correct one needed....because you never know.

Lastly...is the actual clearance under the hood (between the hood and air cleaner) when you shut the hood. If the engine has the dual snorkel factory air cleaner...and you loose that and have to put on an open element type...and then have to run a shorter air filter....to me...it makes no sense going through all that...instead of keeping the QuadraJet and having it set-up correctly. BUT...that is my opinion.

DUB

 

had my qjet and dissy rebuilt by Lars 3mths ago,

was on my old engine, then it had a mild'ish rebuild, new heads, more comp and it still works flawlessly,

just made 410hp/405ft/lbs with timing at 32* with the qjet.

highly recommended , even from the other side of the world....

 

Dub,

Just an FYI that the Holley 4175 is a direct bolt n replacement for the Qjet:

https://www.summitracing.com/parts/h...waAs0wEALw_wcB

I have this one on my 78 C3 and have since 1985...it is a direct bolt on. I would get the OEM Qjet rebuild/tuned by LARS if it was me to keep it original, if I was doing it today...Love the holley though....

 

I originally put a 4175 vac secondary on my '69 several years ago. Bolted on with no mods other than I had to raise the aircleaner base 1/4" with a spacer to get it to clear the secondary diaphragm.

After my recent engine refresh I changed to a 4165 double pumper and had to get an aftermarket drop base because the secondary lever hit the stock breather tube and I didn't want to cut the original.

I love the Holley spreadbore series. Very easy to tune. The issue is that most people do not tune them and just bolt them on. That is a recipe for a bad experience. Holley assumes you are not bolting on to a stock engine and you have made some performance improvements such as a cam and headers, as well as they are tuned a 70 degrees at sea level. That means it will run rich for most people.

The 4165 (at least mine did) comes with a 62 primary jet, an 83 secondary jet, 25 primary squirter, a 37 secondary squirter, and a 6.5 power valve. When I bolted it on the engine ran fine overall but was very rich at idle, very rich at cruise, lean at WOT and there was a slight hesitation at transition from primary to secondary.

I have a stock L48 cam and stock manifolds. After some quality time with an O2 sensor (also love the bolt-on O2 bung from FiTech!) I changed to an 8.5 power valve, 59 primary jet, 89 secondary jet, and a 40 secondary squirter. Also adjusted the idle circuit screws and now all is great with the world.

Friends don't let friends bolt on a Holley with tuning out of the box.

 

While I personally love the Holley, In your case it seems you might just want to try and fix the leak. A $5 tube of JBWeld is all you might need to seal a pressed in plug.


See:

https://en.wikipedia.org/wiki/Quadrajet

http://www.superchevy.com/how-to/eng...ike-it-should/

 

If you have the money, by all means upgrade to FI. Store the qj until you sell the car.

 

On a properly tuned engine how the engine initially fires has little to nothing to do with the choke.
I run with no choke and it never has any issue firing up.

After it fires up now the choke comes into play with how it will idle while cold.

The fuel bowl on these carbs are open bowls. That means exposed to the atmosphere. This being the case fuel easily evaporates out of the bowl.
You may have no leaks in your bowl, but after running the car there is significant heat remaining from the engine that facilitates evaporation. Add to that an extended time of no running the fuel continues to evaporate from the bowl.

So next time you go to start your bowl may be low or empty depending on how long it sat.

Crank the engine for 10 seconds and the fuel pump should fill it sufficiently to now pump the throttle say 3 to 5 times and then it should fire up due to accelerator pump introducing fuel from you pumping the throttle.

Choke plays little to no part in this process.

 

Thanks for the detailed reply. I have had the vette since 2001, and like most carbureted vehicles it was always a tough first cold start. when things are working correctly it would take 3 or 4 tries of the starter. the first to bring fwd fuel to the bowl then it would start right away. Now however I can try over and over until the starter says NO MAS. Throw less than an ounce of gas down the throat and immediate start and it will generally keep running. I had a local mechanic rebuild it but to no avail...no better. The carb works well once running and restarts with no problem. Folks have recommended someone named Lars but I haven't connected yet.

[QUOTE=DUB;1595929713]For what it is worth:

Unless you want to spend a lot of money and have to deal with a lot of modifications...I would get the QuardaJet rebuilt correctly.



PLEASE excuse me but I am not attacking your and your ability to start your car....but...a lot of it can depends on HOW you are trying to start the engine after it has set for a few days and it is cold.

On some QuadraJets...if the car has set for few days....and you go and take off the air cleaner and manually move your accelerator linkage and DON NOT see fuel squirting in the primaries. Then ..this is telling me that the fuel bled back out of the bowl....and what may need to be done is to turn the engine over for a few seconds (4-6) so the bowl can fill back up with fuel. Then...press on the accelerator pedal and then see if your get a good fuel stream. The try to crank the engine.

When a person actually take the time to do all of this..they will then understand what it takes to get it to start when COLD...because there is no absolute procedure...because...if the car has sat for along time...your accelerator pump in your carb can loose its prime. and may take a few more presses on the accelerator pedal to actually get fuel to squirt out.

 

Here's one more vote for getting your original rebuilt by Lars. Properly setup, the quadrajet works just fine. Lars probably rebuilds these things in his sleep, and he runs the carb on a test engine to verify warm and colds starts.

Fuel injection would be 'cool', but when I looked into it, there was a lot more involved than just bolting it to the intake...not to mention it will probably run you at least a grand or more by the time you have it all completed.

 

[QUOTE=DUB;1595929713]For what it is worth:

Unless you want to spend a lot of money and have to deal with a lot of modifications...I would get the QuardaJet rebuilt correctly.



PLEASE excuse me but I am not attacking your and your ability to start your car....but...a lot of it can depends on HOW you are trying to start the engine after it has set for a few days and it is cold.

On some QuadraJets...if the car has set for few days....and you go and take off the air cleaner and manually move your accelerator linkage and DON NOT see fuel squirting in the primaries. Then ..this is telling me that the fuel bled back out of the bowl....and what may need to be done is to turn the engine over for a few seconds (4-6) so the bowl can fill back up with fuel. Then...press on the accelerator pedal and then see if your get a good fuel stream. The try to crank the engine.

When a person actually take the time to do all of this..they will then understand what it takes to get it to start when COLD...because there is no absolute procedure...because...if the car has sat for along time...your accelerator pump in your carb can loose its prime. and may take a few more presses on the accelerator pedal to actually get fuel to squirt out.

I agree with the above, we have been spoiled by many years of fuel injection, and have forgotten the difference of the old carbureted engines, should there not be any problems with the Q-jet, proper starting procedures help. Should it need repairs, I'm not sure I would self-repair it, without a full understanding of it's total workings risking doing more damage if any than may already exist.

I must say I've had mine rebuilt by Lars a couple of years ago with great satisfaction and no problems to date, I feel it was money well spent, and with the reminder of how the old cars start all is good.
I would recommend this. I think many Q-jets get a bad rap, from miss-information, and faulty careless repairs.

PS. If I'm correct I believe the float bowl is also open to the atmosphere which would add to some evaporation over time, but I could be wrong.
Best of luck with your decisions,
Brian 79

 

The end result was worth it to me but there was a bit of figuring things out as you noted and what worked best but it wasn't that hard to do (on a Team G). That's a 4"X14" air cleaner on top of a Team G intake. There is still a full 3" gap between the lid top and bottom on the inside. It fits under the stock '76 hood.

 

I put one of these on a guys Corvette a few years ago...but he changed the air cleaner and the hood was not stock.

Are you still able to us the factory air cleaner...under an original hood???

DUB

 

I am NOT against anyone wanting to make changes to what they have. Heck..I get paid to do it for customers who can not do it themselves.

All I was wanting to point out is that many times...some modifications will need to be made....and a person is not going to take a Holley right out of the box....remove the QuadraJet and bolt on the Holley and ALL is done and perfect. It just does not work that way. Something is going to halt this process....such as accelerator cable mount brackets and so on.

DUB