Holley 650 DP Flooding

[mal67]

Hi Guys,  I am looking for some suggestions to pass on to my mechanic.

I have a brand new Holley 650 Double Pumper fitted to a brand new Windsor 302 via a Wieand manifold.  I am having ongoing issues with the carbie flooding badly at idle or very low revs.  It floods so badly that the car becomes impossible to drive at town speeds.

The car has been back to the workshop about 4 times to get this issue addressed.  Float levels have been checked and adjusted several times, but the problem persists.

Each time it comes away from the workshop it runs fine for an hour or two and then returns to flooding again.  Initially we thought foreign matter from the tank, but a new inline fuel filter has not fixed the problem.

I have tried searching the site, but can see no mention of similiar problems.

What other things should we be looking at ?  

[booah]

Whats the fuel pressure?
Does the engine have excessive movements in the mounts?
Have the throttle plates been set up off of the carb?

[mal67]

Hey booah,

Don't know what the pressure is, but it can be checked.  Could that cause an intermittant problem do you think ?  What pressure would you suggest is correct ?

I do not believe there is excessive (any) movement in the mounts at all, but I see your thinking and will get it checked.  I don't understand about throttle plates.  Can you explain a bit further please.....?

Something I forgot to mention initially, is that a couple of times, when the flooding has not been severe, it has actually come good without the intervention of my mechanic.

Mal

[Frank70]

Sounds like you need to take it to someone who understands Holleys.

I worry when i hear the words " I am looking for some suggestions to pass on to my mechanic."

I see you are in NE Vic - I take mine to a guy in Moorabbin - Power Up performance. He had been doing Holleys for 20 years.

A bit far for you , I know, but if you need it sorted , they will do it.

Cheers,
Frank.

[mal67]

Hi Frank,

Yes, I am thinking it may come to that myself......  After my recent experiences though, trying to drive it in city traffic is a very daunting thought !!!!  :banghead:

[booah]

I just bought a brand new carb off of Frank and all I had to set up was the fast idle with the choke on. There should have been instructions for initial set up that came with the carb. Leaving the carb out of the equation, it sounds like an introduced problem, fuel pressure, quality, vacuum leaks, you get the idea. If its new the floats should be sound and its intermittant so, take Franks advice, holley tuner.

[Frank70]

Mal,

Does your 650 have mech secondaries ? If so, check the secondary linkage to see if they are coming on at part throttle.
Would imagine that would give a flooding like symptom.

Cheers,
Frank.

[mal67]

Hi Frank,

Yes, they are mechanical secondaries.  At one point, we certainly did have one of the secondaries "dripping" at idle. I checked this yesterday and I believe this is not the case now.  While actually watching the carb with the air filter off yesterday, the car idled sorta okay for about 30 seconds and then fuel suddenly bubbled up through the overflow and the engine died instantly.  The next time I tried it, I had an idle for about 20 seconds before it died.  I did not see any fuel bubble out of the overflow the second time though.

Vacuum leaks as suggested by booah is an interesting thought too.  

Thankyou gentlemen !!  

Mal

[Frank70]

You could try the Holley tech support line : +1 270 781 9741 during US  business hours. Hours are 8:00am - 6:00pm CST
Mon to Fri.

If it's a new carby , then it might be an idea to register it first online.

Cheers,
Frank.

[mal67]

okay, thanks Frank.  Would never have thought of that.......

Mal

[shaunp]

Does it have a phenolic spacer under it, may be boiling the fuel,and not flooding at all. Other wise it's dirty fuel or too much pressure, did you put the filter right at the carb?

[mal67]

Hi Shaun,

No, there is no phenolic spacer.  The engine runs at about 80 to 85 degrees C.  Would that generate enough heat to be an issue ?  The fuel pump pressure has not been measured at this point.  The filter is fitted on the inlet side of the fuel pump, and right beside it.  Your thoughts ????

This is the latest.  He has just returned the keys to me and tells me that he pulled the carbie and found some tiny flecks of rubber in the bowl.  Maybe this got in there before the filter was added ?  Crossed fingers that it is as simple as this, but past experience makes me wary.  :mad:

Thankyou for your suggestions.  

I'll give it a run tonight and report the outcome.

[shaunp]

Put the filter at or as close as you can to the carb, to minimse and rubber crums for hoses, pump etc. You did use an old bit of fuel line did you. Put a spacer under it regarless, the cooler the carb the better it will go. 1/2 inch will be fine, 1inch if the the bonnet will still close. They are pretty cheap.
Holleys need really clean fuel, if the metering block getts crap in it, it will be a dog.

[mal67]

Thanks Shaun, thats interesting info.  Who knows how old the fuel line is, it sounds like it should be replaced from tank to pump then.  From pump to carbie is all new.  Saying it will run like a dog pretty much describes my experience over the past 3 or 4 weeks........ :banghead:

Mal  

[shaunp]

I was more reffering any old rubber line. I'm not convinced it's fixed, rubber in the bowls won't make it flood as it's already passed the needle and seats, but it could get in and block up the metering block.

[mal67]

okay Shaun...... Thanks, I did not completely get your point but do now.  I will discuss this with him....    

[CPU]

From http://www.bob2000.com/carb.htm


[align=center]
Common Problems
Lots of folks have been emailing me with some common problems, so here are some tips for fixing these common problems.
[/align]

Gas is flowing out of places it shouldn't.

This is most likely due to a bad float valve, bad float, or excessive fuel pressure.  The first step is to check the fuel pressure, which should be between 4 psi and 7 psi.  If the fuel pressure is correct (or you have no reason to believe that it has changed on an existing setup such as an old stock mechanical pump), either the float has sunk, or there is a problem with a float valve.  ................

I had this problem decades ago.  Old rubber debris was getting stuck on and off in the needle and seat of the float of a new Holley and either the engine would die from lack of fuel or it would overflow (flood).

Cause:  When the carby was changed the old fuel lines were disturbed and bits of rubber moved through the old fuel lines and into the carby.

Remedy:  Pulled carby down, removed needles and cleaned out seats.  Replaced fuel lines and flushed system.  Inserted fuel filter next to carby.  (I was always taught to NEVER EVER put a fuel filter on the suction side of a fuel pump.  This is a topic for another discussion)

Don't know what model you have but HERE is the tech sheet from Holley on the MODEL 4150 ULTRA HP SERIES.
{P/N 0-80674 (650 cfm), 0-80675 (750 cfm), 0-80676 (950 cfm)}

Might be something else is your problem but thought this may help

Kind Regards
CPU

PS

Sintered bronze fuel filter inserts are almost a must with Holleys.
[img=700x525]http://i24.photobucket.com/albums/c17/CFrance/IMG_0044.jpg[/img]

I'm not a qualified mechanic.  Above comments are only from my own observations and information gathered from the net.
CPU

[Glen68]

Here is my 2 cents from running holleys many many years ago and I don't think that they have changed much since.

Clean fuel so filter as near as possile to the carby. Check bowls for cr@p. If cr@p try to determine where cr@p is from and fix it.

They have an inherent problem with the standard needle and seats. No more than 4 to 5 lbs fuel pressure or you will simply push pass the needle even with the float closed. The viton (I think) coated needles are better but I have still seen them and the brass ones actually fail and fracture from too much fuel pressure.
Holley’s are a very BASIC carby. Set floats with engine running at idle and bungs out. (Fire extinguisher at the ready). Some people try to set this engine off with electric fuel pump running. (NO GOOD)For the street wind out the seat adjuster until fuel just starts to flow out the hole and then back up at least 1/4 turn.
If you pull the carburetor off do not adjust anything on it and I will be able to go through some very basic checks with you.
You can U2U me if you like. Cheers Glen.
I am with CPU :)

[Trans-Am]

A further 2 cents worth...

Make sure that the 'Curb Idle Discharge Port' which is found at the bottom of the throttle bore's within the carburettor's base plate has the correct amount of spacing between the edge of the throttle blade and the machined transfer slot or else it will just dump fuel at idle into the inlet plenum of the manifold, flooding the engine and fouling the plug's.

The initial setting of the closed butterfly position will vary slightly between carburetor model sizes
and fuel types. Most carburetors will have the butterflies adjusted with a small length
(approximately .020", looking like a square) of the idle transfer fuel slot visible below the bottom
edge of the butterflies.

Hope this helps...


Cheers,

Trans-Am:cool:

[fordtj69]

hey trans am
you are good at changing plugs or crying about doing it :rol:

[mal67]

Hi Glen68, CPU, Trans-AM,

Thankyou very much for your input !!       Most of it is far too technical for me, but I will certainly pass all this info along to my mechanic.  There is an ongoing theme here from pretty well everyone; Holley's need clean fuel !!

As mentioned, I have a filter on the inlet side of the pump.  Would there be an issue with adding an extra filter before the fuel line splits to feed the primaries and secondaries ?

The car run okay on a 20 to 30 minute run last night, but I know from excperience that this doesn't mean it is fixed.  I have also noticed a tendency for the car to stall when pulled from park back into drive.  The engine loses revs and then dies over about 15 to 20 seconds.  Is that a related problem do you think ?  

Tips for the cup ?????  

Mal  

[Envy 68]

G'day Mal,

For me ....Box Trifecta...Top two favourites plus outsider...:rub:

[mal67]

hmmmmmm........ Very Scientific Envy !!!  lol    

Horses and Engines .... two major mysteries to me !!! oh, and Holley Carbies !!!    

[Envy 68]

  :violin:Well my theory didn't work......lucky I didn't waste any money then hey

[mal67]

Well, you were right Shaun.... its not fixed !!  :banghead:   Same problem after about 60 minutes of driving.....