Carb Floats

[Krooser]

Doing some plannig on my newly aquired 850 Holley methanol carb.

It presently has two different style floats...one is a white platic Holley brand...the other the standard style float.

Can anyone recommend using the split style floats I see in some catalogs? The black floats with two seperate floats. I would think I'd get a bit more fuel capacity in the bowls with this style.

Good? Bad? Useless? Gimmick?

https://www.jegs.com/i/Holley/510/216-22/10002/-1

[ProPower engines]

Doing some plannig on my newly aquired 850 Holley methanol carb.

It presently has two different style floats...one is a white platic Holley brand...the other the standard style float.

Can anyone recommend using the split style floats I see in some catalogs? The black floats with two seperate floats. I would think I'd get a bit more fuel capacity in the bowls with this style.

Good? Bad? Useless? Gimmick?

https://www.jegs.com/i/Holley/510/216-22/10002/-1

Having used methanol for 40 years I have never seen the dual side hung float in the link for the 4150 series carbs yet.
I do not know how well they will control the fuel in the bowl for the needle to seat and with the higher pressures and volumes used with an alky system I would prefer the black nitrophyl floats. I never had an issue with them ever

the other question is what fuel pump are you planning to run?? belt driven or electric? And what bypass do you have for a return line to the tank?

I would run a fuel log for extra volume at the carb rather then try those dual floats.
Brass floats can bend in the center if you get the fuel pressure to high during tuning causing the system to pour fuel in the engine from a stuck float. seen that lots in both circle track and drag applications.

[turbo camino]

If the white plastic float isn't cracked where the arm attaches to the float body, you should make a little fitted velvet stand for it and put it in a display case, as it's likely the last non-cracked one on the planet.

[Krooser]

Doing some plannig on my newly aquired 850 Holley methanol carb.

It presently has two different style floats...one is a white platic Holley brand...the other the standard style float.

Can anyone recommend using the split style floats I see in some catalogs? The black floats with two seperate floats. I would think I'd get a bit more fuel capacity in the bowls with this style.

Good? Bad? Useless? Gimmick?

https://www.jegs.com/i/Holley/510/216-22/10002/-1

Having used methanol for 40 years I have never seen the dual side hung float in the link for the 4150 series carbs yet.
I do not know how well they will control the fuel in the bowl for the needle to seat and with the higher pressures and volumes used with an alky system I would prefer the black nitrophyl floats. I never had an issue with them ever

the other question is what fuel pump are you planning to run?? belt driven or electric? And what bypass do you have for a return line to the tank?

I would run a fuel log for extra volume at the carb rather then try those dual floats.
Brass floats can bend in the center if you get the fuel pressure to high during tuning causing the system to pour fuel in the engine from a stuck float. seen that lots in both circle track and drag applications.

I'll be running a belt driven fuel/power steering pump driven off the flywheel.

I have a fuel log with a -8 return line to the fuel cell with a regulator.

That white plastic float seems kinda chintzy... maybe put it in the Holley museum?

[jsgarage]

Maybe I'm unlucky, but I've had hollow brass floats desolder and fall apart from engine vibration, and we know they can collapse in a high vacuum enclosure with power adders. As was mentioned, the solid black foam-like floats, coated with fingernail polish to seal the pores, have given no problems. Hollow plastic or brass CAN give problems in some cases.

[Krooser]

If the white plastic float isn't cracked where the arm attaches to the float body, you should make a little fitted velvet stand for it and put it in a display case, as it's likely the last non-cracked one on the planet.

Well that float is OK... going to send it to the Holley museum.

Those dual floats I spoke of are for another style Holley carb...Model 40? The listing in Jeg's was a mistake... which is OK. I'll get a couple nitrophyl floats and going to try jet extensions for the rear bowl.

[MadBill]

...I have a fuel log with a -8 return line to the fuel cell with a regulator....

Apologies for the O/T excursion, but although many companies offer them, the use of a fuel log, i.e.a relatively large fuel volume adjacent typically to a dual inlet Holley-style carb, ignores one important reality, namely that liquids are incompressible so it doesn't matter if the fuel line/log alongside the carb is 0.375" or 1.375" diameter; unless it has an internal membrane-isolated air volume like the pressure tank in a well water system, it will have zero capability of damping out rapid pressure fluctuations, momentary fuel deliver sags, etc.

It will however offer a larger surface area for heat absorption and vapor lock...

[Krooser]

...I have a fuel log with a -8 return line to the fuel cell with a regulator....

Apologies for the O/T excursion, but although many companies offer them, the use of a fuel log, i.e.a relatively large fuel volume adjacent typically to a dual inlet Holley-style carb, ignores one important reality, namely that liquids are incompressible so it doesn't matter if the fuel line/log alongside the carb is 0.375" or 1.375" diameter; unless it has an internal membrane-isolated air volume like the pressure tank in a well water system, it will have zero capability of damping out rapid pressure fluctuations, momentary fuel deliver sags, etc.

It will however offer a larger surface area for heat absorption and vapor lock...

These tandem (power steering/fuel) belt driven pumps offer some good volumes of fuel and seem to have pretty steady pressure. I don't think most guys run more than 8 or 9 lbs. of pressure. The regulators generally run on the back side of the back on the return line.

I also have an older style regulator than mounts under the carb but it seems they tend to build too much pressure at WOT causing issues.

This is my first go-round with alky since the 60's when I helped a couple guys on their coupe modifieds that ran alky and stack injectors. Those were pretty finicky.
http://www.kse-racing.com/images/newpro ... 21-002.pdf

[ProPower engines]

I used a barrel valve attached to the linkage so it was able to be at a lower pressure for start up and slow driving through the pit area as most guys do.
There is several adjustable regulators with a bypass that we use as well. the issue is getting the Fuel pressure right and bypassing the rest. We run between 12-15 lbs WOT under load with an 850 carb but a drag deal will need some extra
tuning to be right. best to do on a dyno to get it real close to avoid hurting anything.