6 bbl center carb fuel level too high?

[jordan]

I noticed my 440 six bbl gas milage drop by %25 on my last 2 tanks.  The last time I drove it, it would fall flat, sputter and backfire through the carb whenever I gassed it enough to kick in the outboard carbs.  But it ran OK, but not perfect when I just stayed on the center carb.  At least well enough to make it home. 
Today I started it up to get gas into the carbs but not warm enough to evaporate the gas out of the carbs.  I pulled the sight plugs of my outboards first and the gas level was at the bottom of the hole.  Then I removed my center carb fuel level sight plug and gas came out.  As I watched, gas continued to come out slowly as it just sat there with the engine off.  I run a stock mechanical fuel pump. 
  My first question is why would gas continue to drain out of the center and not the ends?  I am assuming my float is not closing all the way, but is my fuel line still pressurized after I shut off the motor?  Any ideas of what to look for when I pull the carb?  My first thought it the fuel inlet/float seal.  It could be that my float is stuck against my jet plate, maybe?   And lastly, a couple of friends mentioned it could be my power valve.  Im not sure.  What will it look like if it is bad?  I just put a new 2.5 in 600 miles ago when I set the carbs up with the distributer.  I don't have much vacuum at idle.  I don't want to wash my cylinders with the flooding.  Do I need to change my oil?
  I appreciate any info you guys can give to steer me in the right direction.  I wouldn't have the car I do if it wasn't for this great family of E-body owers. 

[734406pk]

Have you tried adjusting the float level on the center carb? If fuel is running out of the sight plug, it is too high. Also the power valve has nothing to do with float level. You may have a leaking needle and seat on your center carb, but if so that can be replaced with the carb on the engine.

[Chryco Psycho]

or dirt in the needle & seat so it will not fully close off

[jordan]

I pulled my center carb and opened the bowl.  I didn't see anything obvious.  I did see that the float cannot hit on the jet plate in front of it.  I did not see any dirt in the needle/seat area, but it doesn't mean it wasn't there.  I pulled the needle assembly and blew it out with air and put it back in.  I did figure out how to set the fuel height in the bowl.  I set all of them just a little below the sight plug so no fuel runs out.  I can always adjust that in the future if needed.  I took it out for a quick ride around the block and had no fueling issues.  The secondaries open and it just takes off with no hesitation, and no backfiring through the carb.  I am not sure what I fixed, other than taking it apart and putting it back together again, but it seems to work right now.  I will have to do some driving to see if my gas milage comes back up to almost 10MPG.  I hope there isn't another issue that I cannot see lurking under there somewhere.  At least it works for now.  Thanks guys. 

[734406pk]

Good luck!

[Chryco Psycho]

 

[jordan]

i think I am going to run the 6bbl for another season and see if it stays set or if I am always having to mess with it.  I really like the stock look and cool factor.  Although.......If I sell my current set up along with my other set of mechanical linkage carbs, it would go a long way $$$ towards a 6bbl fuel injection system.  Hopefully those self learners will keep me from tweaking the tune very often. Plus the added power and drivability should be worth it.

[Chryco Psycho]

I would be all over the EFI route !

[jordan]

I took the cuda for a drive recently and it was total crap again.  I pulled the sight plugs and this time the rear carb was way too full.  I don't know if I maybe didn't set the height correctly, but it was still too full.  I spent the evening setting my float height.  I thought I would keep it easy and disconnect the coil wire and crank it for a few seconds to fill the carbs.  When I was finally done, I replaced the coil wire, and it didn't fire.  I pulled a plug and it was totally flooded.  I will wait till tomorrow and try again.  If no go, then I pull all the plugs and blow air, and start over.  I can't really determine anything until it runs again. 

Now this really has me thinking about fuel injection!  Im going to start saving and get a set up like mjs73.  That six pack FI looks sick!!!

[Chryco Psycho]

You could have other issues like a filter disintegrating or the fuel sock in the tank letting debris get through into the carbs & messing with the needle & seal assy . A friend of mine considers carbs to be a controlled fuel leak , EFI is so much more accurate , this is the main reason engines last 300,000 miles now not 100,000 as the cylinder & rings do not wear out with all the excess fuel from carburation . EFI is not cheap though & you really need to understand tuning to get the EFI set up correctly unless it is self learning .

[jordan]

My entire fuel system is new.  Not saying there isn't a problem, but I am not suspecting disintegration.  I hope its just a easy fix and not something like Tommy had to go through.  Ill keep after it until the snow flies.

I hate posting about this problem because of the feedback to go to FI.  I have spent some time researching it this past week.  Just one step short of making a phone call.  I need to wait, save some money, and get these carbs figured out.  Then I will switch.  Hopefully soon.  I am paranoid about washing the cylinders and killing my motor!

[Chryco Psycho]

I have the same system on my 512 CI , I cannot affrd EFI .
 The disintegration was just a suggestion , I set up an AAR back in 78 , it has changed hands 3 times but is has not been touched since & never has a problem , others I have seen with similar problems you are having needing the needle & seats cleaned constantly but why ?
 Holley has approx 20 different types of needle & seat assy , some are viton some all metal in different sizes for increased fuel flow possibly switching them out would help you . Make sure the floats are not leaking & holding fuel although I doubt it as it is not the same carb with the problem .
 The problem with setting the levels is when you adjust down the fuel has nowhere to go so you need to set it low to push out some fuel & adjust upward but if it over full this is not the issue .
 The EFI system I built I use 3 fuel lines with external fuel pumps in line , 2 - 3/8" lines forward with a Walbro inline pump in each & connected 1 to each fuel rail , then I twinned the return line into 1 - 3/8" line back to the tank , we dynoed this at 702 gross HP with a single 1200 cfm T body

[jordan]

I didn't drive the car for a month or so this summer because I went on holiday in Europe to drive motorcycles.  When I came back, I was stuck on the motorcycle adrenalin so the car sat.  When I finally got in it, it ran poorly.  Could it get leaky from sitting for a few weeks, and if so, why is a great question.  I looked at my seats, an nothing appears wrong.  I didn't see any debris in the bowls.  I took it apart once, and it ran great.  Then sits for a bit, and runs like crap.  I may end up replacing all the needles and seat assemblies since they are cheap.  I see there are so many different kinds.  How do I know which one to use?

[Chryco Psycho]

I prefer to use the non viton , all steel ones as they will not deteriorate with the ethanol in the fuel too large is not a problem , too small could be

[jordan]

I couldn't get my car started after setting the bowl height with the coil wire pulled and turning over the motor to fill the carbs.  I suspected that I flooded the engine.  I went out this after noon and tried again.  No firing at all.  So I pulled all the plugs, blew air into them to dry them, blew air into the cylinders, and tried again.  Nothing!  I couldn't imagine that I killed all the plugs.  So I did some checking with a friend.  No power out of the coil.  I disconnected my rev n nator ignition, attached the orange box, and it fired up instantly.  This is what really gets me.  I work on the fuel system, and try to cure a problem.  Then the electrical ignition system craps out.  I can't get a break.  I did a quick timing check and checked my float heights and all is well.  Now I have to see what the deal is with my ignition.  I will drive it tomorrow to see if it overfill the carbs.  After I warmed it up, I checked the sight plugs and it is at the correct height: spilling over when the car is rocked side to side. Hopefully that is fixed. It is never easy.