Holley Question?

[Anonymous]

Cars been running rich lately for some reason If you have a vacuum leak, will it cause it to run rich or lean?

Plugs dont look too bad, not black or carboned up but not tan either, but stand behind the car and it smells really rich like water your eyes rich!

Running a 4.5 power valve (switching back to a 6.5) and running 69 jets. Also using a .028 squirter. Only reason I switched was to see if I had a blown power valve...didnt seem to make a differeance except it drives better with the 6.5 one.

Float level seems to be allright too....just at the bottom of the sight plug.

Trying to sort out the rich problem then I need to do some more tuning because i have a massive bog now since I switched gears on take off....

This is a 500 cfm Holley...Ran good a couple of months ago...nice tan plugs.

Thanks,

Doug

 

[Anonymous]

a vaccum leak should cause a lean condition, more air leaking in. you say when you stand behind the car yoiu can smell it, so I assume it is rich at idle, any idea how it is when you upen up the throttle?

also I am running #53 holley jets in my autolite 2bbl

 

[Anonymous]

a vaccum leak should cause a lean condition, more air leaking in. you say when you stand behind the car yoiu can smell it, so I assume it is rich at idle, any idea how it is when you upen up the throttle?

also I am running #53 holley jets in my autolite 2bbl

Yep, its running rich at idle. Dont know if its running rich when you rev it up.

Thanks,

Doug

 

[wsa111]

Doug, can you screw in both idle screws & the engine still idle???

If so you are getting extra fuel from somewhere, blown power valve, but you have replaced that, I run a 8.5 power valve & that elimated all flat spots off idle & part throttle, but my metering block is calibrated leaner.

Pull the float out & see if the nitrophyl is too heavy or if you have a brass float is it leaking fuel to make it too heavy??

Replace the needle & seat & lubricate the o'ring with vasoline when installing on the float bowl.

Make sure you have a good accerator pump shot??

Blow out all the air bleeds in the main body & where they go to in the metering block.

I,m sure you used new gaskets between the metering block & the main body. Just looking for areas of leaking fuel into the intake.

Give a shout if you find the problem or still have the rich condition.

Make sure your vacuum advance is working & is tapped into manifold vacuum at idle, this is essential with any engine with a lot of camshaft.

Let us know what you find. Bill

 

[LEROY POLL]

DOUG


.....A VACUUM LEAK WILL MAKE THE POWER VALVE OPEN. WHAT IS YOUR VACUUM LEVEL? SMOOTH VACUUM IS WHAT YOU WILL NEED WITH A CAM THAT HAS LOW VACUUM. IF THE VACUUM DROPS IN A 10 SECOND TIME INTERVAL YOU WILL BE GETTING A POWER VALVE THAT OPEN JUST ENOUGH TO GIVE YOUR PROBLEM. IF YOU RAISE THE IDLE AND IT SMOOTHS OUT AND THE RICHNESS SMELL GOES AWAY THEN THAT COULD BE YOUR PROBLEM.

.....SOMETIMES LOOSE,OR OVER TIGHTENED POWER VALVE WILL NOT SEAT. THIS WOULD BE SOMETHING TO CHECK ALSO.

.....HOPE THIS HELPS.

LIVE IN GRACE

LEROY POLL

 

[wsa111]

Doug, Leroy has a good point on fuel leaking from the power valve gasket right into the vacuum port behind the power valve.

However the power valve only controls the extra amount of fuel to the main venturi, it is not even connected to the idle & transfer circuit in the metering block.

I have found that with these small six cylinder engines a 7.5 or better yet an 8.5 power valve will enrichen the mixture between after the idle & transfer slot till the main venturi has sufficient flow to cover up this lean hole.

Good luck on finding your internal fuel leak.

 

[Anonymous]

Had a chance to check a few things tonite. I can screw in either of the idle mixture screws and it will quit so I readjusted them to get the highest smoothest rpm possible. They are around 2 1/4 turns out.

Lowered the float level just a tad so it just is on the verge of running out the sight plug but not quite. It has a brass float and there is no fuel in it.

Tested my vacuum on my intake port and it is reading anywhere between 7 and 8 inches of vacuum. Tested it with another gauge and it still reads between 7 and 8 inches of vacuum.

It is fluctuating so maybe its hitting 6.5 inches and opening the power valve at idle? Maybe I need to try a 5.5 power valve.

Vacuum seems a little low IMO?

Thanks,

Doug

 

[wsa111]

Doug, you need to raise your curb idle speed in neutral to 1100 rpm's & then put it in drive & it might drop to 750-850 rpm area, that is where you need to keep your curb idle especially with the 110 camshaft lobe center.

The power valve has no effect on idle, unless it has a mechanical fuel leak.

Try the 7.5 power valve cause as soon as you open the throttle thats where the main fuel discharge comes in, if the power valve does not open in time you have a lean hole in the fuel mixture.

I assume you are using the brown accerator pump cam that came with your 4412. If not you need the pump shot from that pump cam, you can even try .030 in your squirters if you still have a flat spot.

Check your vacuum guage at 1400 rpm's and see what it reads?? I'm sure it will go to 13-14" & thats way above your power valve rating.

Keep in touch.

 

[Anonymous]

Bill,

with the loose convertor, it idles at 900 and only drops to 750 in drive so I think that should be allright

I'll check tomorrow night to see what pump cam I have. It does have a bit of a flat spot like you described. I have a .028 squirter in it right now and I have .030, .032, .034 & .036 squirters out in the garage so I'll try the next size bigger and see how it drives.

I'll check out the vacuum at a higher rpm like you said tommorrow night.

Any thoughts on jets? Running 69's right now.

Another question?

You said,

Make sure your vacuum advance is working & is tapped into manifold vacuum at idle, this is essential with any engine with a lot of camshaft.

Whats the difference on how you run the advance vacuum?? Right now I'm running it off the advance port on the holley.

Thanks!!

Doug

 

[wsa111]

Doug, with a wild cam, hook up the vacuum advance right to manifold vacuum.

This will up your idle speed by 200-300 rpms, adjust as necessary, don't make a squiter change till you do the vacuum advance deal.

If this eliminates your hesitation, you can try a 68 jet, thats what i'm running & my throttle response in the hot weather is instant.

When you get past this obsticle, send me a pm and i would love you to try the same modified metering block that i have. Bill