This is in regards to my Holley dual feed VS. When I shut my car off, fuel begins to leak down and drip from the vacuum secondary linkage. It feels like it is coming from the passage directly under that area. The carburetor was recently rebuilt and it did this both before and after. When I run the car, it immediately stops leaking. I figured that my rear fuel level was out of adjustment but it is still dead on. The needle and seat have also been replaced. I have an in tank electric pump with a return regulator. Fuel pressure is set to 5psi, as it's always been. So, open to any thoughts as to why fuel would be drawn past when the needle and seat are not leaking, the fuel level is properly set, and fuel pressure is at an acceptable level?

 

It still leaks when the car is running; WORSE in fact; but the vacuum in the area makes sure that the fuel goes INTO the intake, not OUT of it.

Still leaks, you just ... don't see it. But your pocketbook does.

Problem isn't the needle and seat. More likely, it has to do with the sec power valve.

 

The secondary does not have a power valve, It has the factory plug in place.

 

You sure? Not too many Holleys come from the factory with a plug. In fact I don't even know of any. (unless it's a 4010 or some such, i.e. not really a "Holley" regardless of what's cast into the side)

But even so, it would have a gasket.

 

The original reason for me pulling the carb apart was because I thought that it HAD to be the secondary pv causing that problem. I was very surprised to see a plug but none the less I'll pull the rear block off to double check that I replaced the gasket

 

It's easy to get them "off center" when installing. I hold the metering block directly above the PV/plug as I screw it in to avoid these kinds of problems.

Also, don't use the hard plastic PV gaskets like supplied in AED kits. Use the fiber Holley-style gaskets.

Other than that, start looking for cracks in the metering block. Especially the kind that only open up when you screws things down tight into them.

 

I just pulled my 570 off in December and mine is blocked off as well.

There's only jets getting screwed into the block and they shouldn't be torqued to where they would distort the metal.

On your metering block, are the ridges, casted into the block, intact? Is there any damage on the base side of the metering block to where fuel might be leaking past?

Have you checked the flatness of the mating surface on the main body? Take a straight edge and check cross corners as well as horizontal and vertical. Now that I got my 570 apart I noticed that the bright finish on the main body even covers the metering block area which is usually a machined flat surface on other carbs. the finish on my avenger is rough but not causing problems...

...for now.

 

When I pulled the rear block from the main body, the surface area was in better condition than I thought it'd be. The surfaces were flat and the carb actually looked like it had been rebuilt prior, which was news to me. I was almost certain that it was going to be a torn PV gasket causing the problem...but not so lucky.

 

Now that you said it was rebuilt previously I wonder if they overtightened anything and cracked the metering block. I haven't seen one cracked but being a cast piece I'm sure it can happen.

 

Bestracing when you took your 570 apart, did you have a pv plug in the secondary or did it appear to be the outline of the shape etched into the cast but no actual cut made?

 

Why don't you just post up the List # of the carb (stamped in the airhorn) and I can tell you if it was originally equipped with a secondary-side PV.

Most of my Holley double-pumpter carbs I delete the secondary-side PV anyway since they're almost always open by the time you are digging into the secondaries.

Secondary-side PVs are really rare on a Vac Sec carb, for obviousl reasons (you're already at or near WOT when they are in use).

 

80570. I appreciate it, Damon. From what I have come across it came factory without one on the secondary side. Wishful thinking maybe I have a bad float but I guess next step is to check for cracks in the block.

 

Mine is raw cast in that area and not machined and tapped for a PV. One thing I did find is that the primary bowl gasket wasn't installed right from the factory. The thin section along the bottom under the jets was pushed up and I had a very tiny leak. It didn't stain the manifold but there was about a 3/8" spot on the underside of the metering block and bowl where the gas leaked out and evaporated.

Mines still apart so I can get pics of it. Holley's web site says the secondary metering block is "Not Serviceable" and doesn't list a P/N

 

He has an Avenger 570 (80570) and they don't have a PV.

The main difference on the Avenger Series compaired to 1850 series:

Has center hung float fuel bowls, dual inlet
Has a secondary metering block instead of metering plate, not machined for a PV or idle screws
Secondary fuel bowl is casted like a DP but the accelerator pump is cast shut and not machined.
Main body, metering blocks and fuel bowls are bright dipped.
Quick change Vac Sec spring housing already installed

 

Yes apparently they don't sell a single sec metering block for our carb, which doesn't make sense to me. So, if you have a crack in your sec block what exactly would they like you to do about it...lol

 

Would it be the same as the universal replacement/upgrade secondary metering block? When I've done conversion from secondary metering plate to secondary metering block that's what I've used. But always on a "plain 'ol Holley", not one of the Averger or other tuner carbs.

 

Avenger is a Holley carb.

Now for some pics. First set is the secondary metering block. This is of the jet side, notice no hole for acceleration pump and the PV area still has casting material in it.



This is on the PV side again no acceleration pump hole



The idle circuit is not machined



Secondary fuel bowl,





Primary side for compairson





Secondary side of main body

 

That's actually a good point. I'll have to check on that OR if anyone knows and can beat me to it..

Thanks for the pictures, bestracing. Through the pictures, comparitively speaking, our blocks and main bodies appear to be in the same condition but that's not saying much until I pull it off and check for cracks. I should have time to tinker with it at the garage tomorrow so we'll see...

 

Just a little update: I didn't get to start the car at all but with just priming the electric pump a few times earlier, fuel started to leak out the throttle shaft area. I noticed that the secondary blades appeared to have fuel on them as well.

Now, for whatever the reason may be, fuel isn't being transferred from the primary bowl to the booster. My car just doesn't like me this week.

 

The only way I would see fuel leaking out of the boosters is the fuel level is too high in the bowl.

Also check and see if you have any play in the throttle shafts. One of the most common problems with Holley carbs is worn throttle shaft bushings and seals.

 

Maybe the float is bad and submerging with fuel..probably not but I guess it couldn't hurt to pull it and check it out.

 

I've seen metal floats get pin holes in them and fill up with gas in other applications. Haven't had it happen on a car .....yet.

Are you sure the fuel level is adjusted to where the fuel is at the bottom of the sight hole? Do you still have your clear sight plugs to verify the fuel level while the car is running and see if fuel is leaking past the needle valve after the car is shut off?

I've always start low with the fuel below the hole and then work my way up to the proper setting.

 

Yeah I set it way low to start with and it's still leaking. I haven't checked to see if fuel is leaking by the needle, I replaced them and it still leaked after. I guess it couldn't hurt to check the new needle though

 

I know what, how about driving to Ky and bleed the brakes on my sons Grand Am and I'll fix your carb LoL

 

Hey I'll GIVE you the 570 if you come and fix the awful leak in my youngest sisters 96 Contour..It's making a mess of my driveway lol.

 

Sorry I don't work on Ford's I'm afraid I'd pick up some nasty habits like not making any power, having my car Found On Road Dead or having the need to Fix Or Repair Daily.....

.....I'm getting too old for that stuff

 

Here are a couple of pictures. The idle circuit looks like it was machines and in the other picture, right above my finger that stud appears to be broken off..Didn't notice that before.

 

That stud is to help keep the gasket aligned.

I don't know why someone would want to open the idle screw adjustment passages because the main body doesn't have the passages or idle circuit slots for it. I'm guessing this was used when you got it, right? I bought mine new in 2005.

 

Yes I got it a couple years back from a mechanic friend of mine for free. I dont know why he would open the circuit. But since the main body doesn't have the passages, this isn't my cause of the leak obviously, correct?

The float had no pin holes in it either and the fuel bowl level is still correct after re checking for the 10th time..This is getting frustrating.

 

With the main body blocking the idle passage there shouldn't be a way for fuel to get into the throttle body area. Although fuel could come out of the metering block there at where the mixture screw would be.

For fuel to come out of the discharge nozzle fuel has to go through the jets first into the metering block's main fuel well. Through the negative pressure at the venturi and the high air bleed the fuel is then sucked up and through the discharge nozzle. The only other way I see fuel coming out of the discharge nozzle is if the fuel in the bowl is above the entry tube of the discharge nozzle or if there is a problem with the air bleed circuit and you start a siphon through the discharge nozzle. see diagram on page 3 here--> http://www.holley.com/data/TechServi...ech%20Info.pdf

 

The fact that it will leak if I JUST prime the pump a few times and that's it is something I've never seen before.

Anyways, I'm gonna get the carb back on when I can and mess with it some more

 

Well the float could be set right but the inlet valve could have problems. You can check the inlet valve using compressed air set to 5-6psi and move the float up and see if air is leaking past.

Other than that the only thing left is a bad metering block.

 

I checked the inlet valve yesterday when I had the carb on my work bench and no air leaked past..Worst case scenario I guess I track down this crack in the metering block and bite the bullet and get a new block.

 

Well I would think if you could borrow someone's secondary metering block from a DP it should work for a fuel pump prime test since all the other ports are blocked off by either the fuel bowl (accel pump) or the main body (idle circuit) and the PV shouldn't matter since it's not open because it's not running. Better than just throwing money at it. Best of luck to you and let me know how this turns out. I'd like to know

 

I'm actually going to take the secondary metering block off of my DP and do just that..Thanks for the brainstorming help and I will keep posted until the damn thing is fixed!

 

Little update: Swapped metering blocks with my DP to do the prime test and sure enough the symptoms are still there. I'm stepping away from it for a bit because I need to get my body work done and this is greatly hindering me getting my car back together for the spring!

 

Looks like your problem is in the main body. I haven't compared my 600 main body to my 570 so besides larger bores I'm not sure what differences there are. Time for me to tear into my rebuilt 600 and compare it to the main body on my 570. Might be able to find a used 600 really cheap (I got one for $15 not too long ago) repair the throttle shaft bushings and swap the metering plates, fuel bowls and quick change VS top from the 570 to the 600.

I'll post pics for you just as an FYI and for others.

 

I've got a couple of old 600s in the garage that I could take the main body from. IIRC the throttle shaft bushings were still good on the 600's. I'll swap the plates, bowls, and my QFT Vs unit on and see what happens. Post pics of the main body if you end up tearing your 600 apart but if you don't no worries man!

 

Just a little update: I got the 600 converted to the 4150 style and it appears that the main body of the 570 was in fact the problem. So far, no leaks. I'd like to get it tuned and all set tomorrow and make a video but we're getting 16-24 inches of snow tomorrow so that's not looking too promising.

 

Glad to hear you fixed it!
Stay safe--- looks like Nemo has a BAD ATTITUDE!!

 

I guess we'll see in the morning! Got called into work tomorrow morning because of this damn storm so it better have a mean bite behind that name!!

 

Good to see you got it fixed. I haven't forgot but I haven't been on here for awhile. Got swamped at work, sick and having to fix my sons Grand Am again.

 

Yes life has been busy lately; 3 feet of snow later and I finally made it back to the garage and there is a leak coming somewhere from the rear fuel bowl that I haven't had time to fix yet/ Probably a gasket issue

 

Well I looked at both main throttle bodies and the only difference on the secondary metering side between the two is that the Avenger doesn't have the casting for the accelerator pump in the main body and the 600 did. Still neither one uses a secondary accelerator pump/squirter so it doesn't really matter.

Decided to sell my 600 locally and I'm working on getting my T/A back together and running for the season.