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-   -   Carb gaskets question… (https://forums.maxperformanceinc.com/forums/showthread.php?t=865220)

Mook 03-13-2023 06:54 PM

Carb gaskets question…
 
2 Attachment(s)
Hey Guys…. Quickfuel 850 double pumper with electric choke on my 468 stroker. Carb does fine at initial cold start up. After a drive and sitting for more than 40 or so minutes, the car is very hard to start. Would have to floor the gas pedal to get it to start and when it starts is a big cloud of smoke. Even after a short 15-20 min the car wont’t start without pumping the accelerator. I took bowls off…. Did not see any trash, tried my best to clean out the meter and blocks with car cleaner, spray, and compressed air. Replaced gaskets, and notice how much buildup was on the interior gaskets between a medium block and the body. (See pictures) How bad are these gaskets, could those cause any issues? Bowls levels just about dead center…..

Thx…

25stevem 03-13-2023 07:30 PM

That’s a hard start condition due to fuel leaking out of the carb and into the manifold plenum,. That’s the only reason you would need to hold the throttle blades wide open to get enough air into the motor to lean it out and get it to restart.

Your gaskets look ok, but take a real close look at the main body behind the power valves .

Do you see any marks left by the power valve where it’s touching the main body?
If so this is due to too thick a power valve gasket and the expansion of the parts when hot unseating fuel passage areas that should be sealed.

Half-Inch Stud 03-13-2023 07:56 PM

Old over-winter fuel ?

Tom Vaught 03-13-2023 09:43 PM

Quote:

Originally Posted by 25stevem (Post 6414237)
That’s a hard start condition due to fuel leaking out of the carb and into the manifold plenum,. That’s the only reason you would need to hold the throttle blades wide open to get enough air into the motor to lean it out and get it to restart.

Your gaskets look ok, but take a real close look at the main body behind the power valves .

Do you see any marks left by the power valve where it’s touching the main body?
If so this is due to too thick a power valve gasket and the expansion of the parts when hot unseating fuel passage areas that should be sealed.

Sorry. I totally DISAGREE. The Blue gaskets are crap. Time for replacement.

Tom V.

Mook 03-13-2023 10:07 PM

Quote:

Originally Posted by 25stevem (Post 6414237)
That’s a hard start condition due to fuel leaking out of the carb and into the manifold plenum,. That’s the only reason you would need to hold the throttle blades wide open to get enough air into the motor to lean it out and get it to restart.

Your gaskets look ok, but take a real close look at the main body behind the power valves .

Do you see any marks left by the power valve where it’s touching the main body?
If so this is due to too thick a power valve gasket and the expansion of the parts when hot unseating fuel passage areas that should be sealed.

The first time I opened the carb, the power valve was loose….. thought that was the problem….. changed it to a new #65 valve, but did not change the gaskets….SMDH! The only gasket I have not looked at is the base-plate. I will go back and check behind the power valve for marks.

Thx

Mook 03-13-2023 10:09 PM

Quote:

Originally Posted by Tom Vaught (Post 6414256)
Sorry. I totally DISAGREE. The Blue gaskets are crap. Time for replacement.

Tom V.


Yes sir changing those gaskets asap!

Thx

Mook 03-13-2023 10:11 PM

Quote:

Originally Posted by Half-Inch Stud (Post 6414246)
Old over-winter fuel ?

Don’t think its the fuel…. Replaced tank, all new fuel mixed with 110

Thx

25stevem 03-14-2023 06:22 AM

Tom you really seem to like to contort what I say, and put words in my mouth!

I never posted that those gaskets where the end all be all now did I?

By the same token I never suggested to the OP to not replace them, in fact every time I take a Holley type car apart I replace the gaskets unless I am at the track and don't have any new ones.

When have to use the blue gaskets I coat both mating surfaces with a light film of synthetic wheel bearing grease so that if and when I do have to disassemble the Carb the gaskets do not rip of there outer layer.

All I commented on was the remains of How the contact pattern looked, ok there Tom.

I would appreciate it if you stop this pattern of behavior and go back to standing on your soap box and shouting that your a Engineer.

Formulajones 03-14-2023 09:55 AM

For what it's worth, I've never had any issues with the blue gaskets over the years using them. I apply a stick of deodorant to them. It just leaves a waxy film that doesn't harm the carb and it's small and easy to carry to the track in my box of holley parts.

As far as your fueling problem, generally if you have one of those meter block gaskets that aren't sealing, you'd have a fuel flooding problem constantly while running, usually dripping off the boosters all the time, not just after shutdown.

My guess is your heat soak issue after shut down is just that, it's heat soak related. More than likely you'll find several solutions such as how hot you're running the car before shut down (engine temp) will have an affect, or whether or not you run a fuel return line. Whether you use a heat cross over or not. A thick or thin baseplate gasket or some form of heat insulator or spacer, or even a heat shield. A whole myriad of things will affect heat soak after shut down and it's usually a combination of a few or all the above to cure it.

Just some things to look at.

chuckies76ta 03-14-2023 10:31 AM

Do you think a lite coat of Vaseline is also OK on these gaskets? Thanks

77 TRASHCAN 03-14-2023 10:51 AM

Quote:

Originally Posted by Formulajones (Post 6414323)
For what it's worth, I've never had any issues with the blue gaskets over the years using them. I apply a stick of deodorant to them. It just leaves a waxy film that doesn't harm the carb and it's small and easy to carry to the track in my box of holley parts.

As far as your fueling problem, generally if you have one of those meter block gaskets that aren't sealing, you'd have a fuel flooding problem constantly while running, usually dripping off the boosters all the time, not just after shutdown.

My guess is your heat soak issue after shut down is just that, it's heat soak related. More than likely you'll find several solutions such as how hot you're running the car before shut down (engine temp) will have an affect, or whether or not you run a fuel return line. Whether you use a heat cross over or not. A thick or thin baseplate gasket or some form of heat insulator or spacer, or even a heat shield. A whole myriad of things will affect heat soak after shut down and it's usually a combination of a few or all the above to cure it.

Just some things to look at.

Old Spice??? Lol...

What color are the Holley gaskets, that are supposed to be the best for not sticking?

Tom Vaught 03-14-2023 11:47 AM

Simple concept. SWOLLEN GASKETS ARE POSSIBLE "LEAKING GASKETS".

It is obvious to any carb guy looking at the gaskets that the gaskets needed to be replaced asap.

So why was that recommendation not made and left out of the post?

The other thing is I have run the same blue gaskets at the track with multiple metering block removals with no issues. BUT when the gaskets are obviously swollen that should be an immediate repair before going farther with tuning. High Potential fire hazard.

Blue gaskets vs the other brown gaskets, etc have the best non-stick performance.
But they do swell and need to be replaced over time.

As far as the other comments, everyone has an opinion and can post it.
One fact is worth 10,000 opinions. I am passing on valid facts vs starting urination contests.

Tom V.

Formulajones 03-14-2023 02:07 PM

Quote:

Originally Posted by 77 TRASHCAN (Post 6414334)
Old Spice??? Lol...

What color are the Holley gaskets, that are supposed to be the best for not sticking?

LOL I'd have to look but yeah it's probably a stick of Old Spice or Brute :D

Me personally, I have no issue with the blue gaskets, I can reuse them 4-5 times as long as I'm coating them with deodorant. Really depends on how long it's been together. If it's been a few years and a few thousand heat cycles I just plan on replacing them.

Or like Tom said, the brown ones are also ok, but again, I rub them with deodorant. It just depends on which ones I find and how much I've stocked up on them. It doesn't matter to me either way.

Formulajones 03-14-2023 02:11 PM

Quote:

Originally Posted by chuckies76ta (Post 6414330)
Do you think a lite coat of Vaseline is also OK on these gaskets? Thanks

Vaseline won't hurt anything and would dissolve upon fuel contact anyway. It's just a little messier to use.

I just like the wide stick of deodorant because I can swipe it on pretty quickly and easily, slap the cap back on and toss it back in the holley box. It just acts like a wax to keep the gasket from sticking for a while, and again the excess dissolves with fuel.

Either way there is no worry of clogging any fuel passages with it or any other kind of harm to the engine.

chiphead 03-14-2023 03:44 PM

My qf750 is doing the same thing. Hard starting when hot like it was flooded. I found that my throttle plate settings were jacked up due to trying to lean it out. I've rebalanced the plates and reducing the IFRs to lean it out. I think the QF carbs are pig rich on mild engines. 33ifr and 70iab stock.

JSchmitz 03-14-2023 04:00 PM

I don't like the blue gaskets either. Brown non-stick gaskets for me.

But your problem statement seems to contradict itself. On one hand you say that you have to floor it to get it to start. That's a flooded condition. Then you say that you have to pump the gas to get it to start. That's a lean condition. I'm gonna guess that you need to replace the needles and seats. Let it set for five minutes after it's warmed up. Now look down in the venturis and see if there's gas dripping from the boosters. You can check the inlet valves if you have a hand vacuum pump. Take the carb off and empty the gas out. Then turn it upside down and see if they hold vacuum.

Mook 03-15-2023 06:37 PM

Quote:

Originally Posted by JSchmitz (Post 6414393)
I don't like the blue gaskets either. Brown non-stick gaskets for me.

But your problem statement seems to contradict itself. On one hand you say that you have to floor it to get it to start. That's a flooded condition. Then you say that you have to pump the gas to get it to start. That's a lean condition. I'm gonna guess that you need to replace the needles and seats. Let it set for five minutes after it's warmed up. Now look down in the venturis and see if there's gas dripping from the boosters. You can check the inlet valves if you have a hand vacuum pump. Take the carb off and empty the gas out. Then turn it upside down and see if they hold vacuum.

Yes sir you make a good point! It does seem to contradict myself…….
Usually I have to floor it after lets say arriving at a car show at 6am and the car is parked till 11:30 am….

The times when I had to pump it would be after engine had run then sits for 15-20 min or so….. in that situation I would think the engine should restart without pumping?

I will….run the engine then Let it set for five minutes after it's warmed up. Now look down in the venturis and see if there's gas dripping from the boosters. The needles and seats had been changed lately.. at least one, I am willing to replace them both to make sure!

Thx

Mook 03-15-2023 06:39 PM

Quote:

Originally Posted by chiphead (Post 6414391)
My qf750 is doing the same thing. Hard starting when hot like it was flooded. I found that my throttle plate settings were jacked up due to trying to lean it out. I've rebalanced the plates and reducing the IFRs to lean it out. I think the QF carbs are pig rich on mild engines. 33ifr and 70iab stock.

I will look into the throttle plate…. The carb ran great for years then slowly began to give me problems

Thx

Mook 03-15-2023 06:42 PM

Quote:

Originally Posted by chiphead (Post 6414391)
My qf750 is doing the same thing. Hard starting when hot like it was flooded. I found that my throttle plate settings were jacked up due to trying to lean it out. I've rebalanced the plates and reducing the IFRs to lean it out. I think the QF carbs are pig rich on mild engines. 33ifr and 70iab stock.

Quote:

Originally Posted by Formulajones (Post 6414371)
Vaseline won't hurt anything and would dissolve upon fuel contact anyway. It's just a little messier to use.

I just like the wide stick of deodorant because I can swipe it on pretty quickly and easily, slap the cap back on and toss it back in the holley box. It just acts like a wax to keep the gasket from sticking for a while, and again the excess dissolves with fuel.

Either way there is no worry of clogging any fuel passages with it or any other kind of harm to the engine.

Never used anything to coat the gaskets…. Will def look into doin that moving forward … thx

Mook 03-15-2023 06:47 PM

Quote:

Originally Posted by Tom Vaught (Post 6414346)
Simple concept. SWOLLEN GASKETS ARE POSSIBLE "LEAKING GASKETS".

It is obvious to any carb guy looking at the gaskets that the gaskets needed to be replaced asap.

So why was that recommendation not made and left out of the post?

The other thing is I have run the same blue gaskets at the track with multiple metering block removals with no issues. BUT when the gaskets are obviously swollen that should be an immediate repair before going farther with tuning. High Potential fire hazard.

Blue gaskets vs the other brown gaskets, etc have the best non-stick performance.
But they do swell and need to be replaced over time.

As far as the other comments, everyone has an opinion and can post it.
One fact is worth 10,000 opinions. I am passing on valid facts vs starting urination contests.

Tom V.

I will replace those gaskets asap… as far I know those gaskets at 6-7 years old…

Thx


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