Float setting?

[Jimpala]

Hello,my carb kit tells me 15/32 is the proper float height, could that be too much fuel in the bowl,as the air horn gasket is seeped in fuel?I notice the seeping of the air horn gasket starts on the corner where the black plastic cup is. And it seems to flood after shutting off when warm?

Is 15/32 right?? My carb # 17059218. I pulled off the top air horn assembly and noticed the black plastic cup was full to the top as well.I've sealed my bowl plugs,too.

Does anyone know the proper level off hand?? Thanks,Jim

[Ethan1]

 Welcome to CHP!

 The stock float setting for that carb is indeed 15/32".

[omaha]

 15/32 is a big number. usually floats are set at ~1/4 inch. does this application have a small float? (that's the only thing that I think would have that low of a setting. (that setting is low, not high). might be too low of a setting. Hard to keep the needle on the seat when the bowl is next to empty.  I think some investigating is in order. (maybe I am wrong but I have never heard of a setting like that. Is it measured the same as usual for floats? From the top of the casting to the toe of the float with slight pressure on the needle? Does this carb have some type of strange float that is uncommon? (I wouldn't think so) As far as the wetness goes, could be that the small "clip" on the needle is hanging off of the float arm in the wrong  position. (causing the needle not to "seat" properly) (the small clip hangs off the edge of the metal arm NOT in the middle...{get the book it has a good picture}... or just get rid of the little clip altogether... not really needed if car used regularly)

[Jimpala]

Hello Omaha,
Yes I've confirmed the float level is 15/32"and confirmed this in 2 different quality kits.Yes it's the smaller float,brand new nitrophyl.I've also confirmed float/needle clip attached correctly.I've rebuilt many Rochester 2 and 4 bbls over the years.
I feel confident the carb is fine.I just went through it.
After searching around on this very informative forum,I saw a comment by Cliff,stating that some of the new standard oem style mechanical pumps are manufactured with too high a fuel pressure! I'm running a '76 stock 350,nothing fancy.BUT....I did just replace the original AC Delco fuel pump as part of this fuel system freshening up.
I'm thinking I need to rig up a piece of hose to the inlet hard line at carb,and stick the head of my fuel pressure test guage to it and simply crank her over.It should not exceed 6-7 during cranking?And running pressure maybe slightly lower? My thoughts,Jim

15/32 is a big number. usually floats are set at ~1/4 inch. does this application have a small float? (that's the only thing that I think would have that low of a setting. (that setting is low, not high). might be too low of a setting. Hard to keep the needle on the seat when the bowl is next to empty.  I think some investigating is in order. (maybe I am wrong but I have never heard of a setting like that. Is it measured the same as usual for floats? From the top of the casting to the toe of the float with slight pressure on the needle? Does this carb have some type of strange float that is uncommon? (I wouldn't think so) As far as the wetness goes, could be that the small "clip" on the needle is hanging off of the float arm in the wrong  position. (causing the needle not to "seat" properly) (the small clip hangs off the edge of the metal arm NOT in the middle...{get the book it has a good picture}... or just get rid of the little clip altogether... not really needed if car used regularly)

[Ethan1]

Hello Omaha,
Yes I've confirmed the float level is 15/32"and confirmed this in 2 different quality kits.Yes it's the smaller float,brand new nitrophyl.I've also confirmed float/needle clip attached correctly.I've rebuilt many Rochester 2 and 4 bbls over the years.
I feel confident the carb is fine.I just went through it.
After searching around on this very informative forum,I saw a comment by Cliff,stating that some of the new standard oem style mechanical pumps are manufactured with too high a fuel pressure! I'm running a '76 stock 350,nothing fancy.BUT....I did just replace the original AC Delco fuel pump as part of this fuel system freshening up.
I'm thinking I need to rig up a piece of hose to the inlet hard line at carb,and stick the head of my fuel pressure test guage to it and simply crank her over.It should not exceed 6-7 during cranking?And running pressure maybe slightly lower? My thoughts,Jim

 Which kits/parts did you use?

[Jimpala]

Tonight I took fuel pressure reading off the new fuel pump....10psi. Repeated the test 3 times,even bled any air from test line to be sure of accuracy.

This is frustrating.Never would have guessed a correct pump,application wise,would put out twice the psi of orig pump! I need to find a stock oem look pump that specifically states btw 5-6 psi and approx 40gph.

Maybe I'll get lucky and find an nos ac delco or carter.

Thanks much Cliff for your comment about these new pumps and their psi out put! Jim

[von]

I can confirm the aftermarket pump problem. Two different new off-brand pumps from the chain parts store put out 9-10 psi on my '69 350 Chevy. An AC Delco pump fixed it.

[68 Firebird]

Von can I ask where you got the AC Delco fuel pump.  Was it online or from a dealer.
Having trouble finding one in my area of NJ.  Sometimes easier to order online.
This would be for a 68 Firebird 400
Gerry

[von]

I believe I got it from Classic Muscle, ordered on-line (www.oldmusclecars.com). It was for a Chevy 350. I don't now if they sell Pontiac parts but since they're a GM dealer they might. Try their website.

[Cliff Ruggles]

The factory float settings are often pretty "low" on the later carburetors.  They were based on the original applications tuning requirements, fuel pressure, etc.  Many later model set-ups used higher pressure pumps, and return systems to keep more fuel in circulation (cooling). 

I would also add here that none of the over the counter rebuild kits will contain a good high quality needle/seat assembly, they aren't even the correct size for the carburetor number.  Ethanol will quickly find a new part that isn't made of a good quality flouroelostomer.  This also effects fuel level, float setting, etc, at any give pressure.  We've also vacuum and pressure tested a lot of the seats and many aren't holding. 

Just another reason why we stepped up the quality of our parts in recent years, and we have ZERO issues with any of our parts in this new fuel.....Cliff

[Jimpala]

I just ordered one of your viton needle/seat assemblies,Cliff.Would you suggest raising my float setting up to 1/4" versus the stock oem 15/32"? Would the 1/4" setting help handle my higher than desired fuel pump pressure of 7lbs. I did just find a nos ac delco #40987 pump and it's on it's way.Hopefully this new pump will bring me down to 5-6psi. My carb#17059505.It sits on a stock '76 350. Thanks,Jim

The factory float settings are often pretty "low" on the later carburetors.  They were based on the original applications tuning requirements, fuel pressure, etc.  Many later model set-ups used higher pressure pumps, and return systems to keep more fuel in circulation (cooling). 

I would also add here that none of the over the counter rebuild kits will contain a good high quality needle/seat assembly, they aren't even the correct size for the carburetor number.  Ethanol will quickly find a new part that isn't made of a good quality flouroelostomer.  This also effects fuel level, float setting, etc, at any give pressure.  We've also vacuum and pressure tested a lot of the seats and many aren't holding. 

Just another reason why we stepped up the quality of our parts in recent years, and we have ZERO issues with any of our parts in this new fuel.....Cliff

[StillLearning]

I finished a 1983 Quadrajet with Cliff's parts and advice. The first float setting I tried was about 5/16". Way too high-gas everywhere!  Went to 15/32" and it solved several running problems. The carb now works great!  This allows me to work on jeweling in timing and advance without worrying about an over-rich fuel system.

[Jimpala]

That is interesting,StiilLearning. In Cliff's book at bottom of page 25 and top of page 26 he states that it's best to use stock oem float settings unless building for hp. Jim

[StillLearning]

I don't pretend to have Cliff's knowledge regarding Q-jets, but I have been rebuilding them off and on since the late sixties. Float setting close to or a little lower than spec has always worked for me.  One thing I would add based on personal experience is most running problems are not related to just one thing. For instance if running rpm timing and advance are not right no amount of carb tuning will cure the problem. Generally speaking, carb doesn't affect timing, but timing can sure mess up how a carb works. Just a thought.

[Jimpala]

Same here been at it a long time as well.Agree,engine perf starts with timing.Also today,I've noticed all these new oem replacement fuel pumps all seem to put out much higher pressure than they did even 5-6 years ago.I'm battling this issue right now on a stock '76 low mile 350 sbc.I've bought 7 "Stock" oem style pumps from all the popular places.ALL are putting out 8-13 psi! We know Q-jets are happy btw 4-6psi.I've given up on these new pumps they are all made in China,Mexico or Milaysia. I am looking for an NOS AC Delco pump.Not that it will last long with today's fuel and any poss diaphram deteriation,but I am frustrated.........  Jim

I don't pretend to have Cliff's knowledge regarding Q-jets, but I have been rebuilding them off and on since the late sixties. Float setting close to or a little lower than spec has always worked for me.  One thing I would add based on personal experience is most running problems are not related to just one thing. For instance if running rpm timing and advance are not right no amount of carb tuning will cure the problem. Generally speaking, carb doesn't affect timing, but timing can sure mess up how a carb works. Just a thought.