Holley question

[EMSjunkie]

I have a Holley 600, elect. choke, 4160 series, list # 1850. your basic aftermarket Holley. Mikej touched on my problem in an earlier post about the Edelbrock problem.

It runs REAL rich at idle. I mean catch a buzz after 2-3 min. of idle.
burns the eyes and nose.  

Mikej suggested the throttle plates are open too wide. I checked mine, and yup, seems like they are open quite a bit. tried to adjust them by backing off the set screw under the elect choke pot. didn't make any difference.

now what?  I checked my Holley book, it is kinda vague in this area.  :?

can someone take me to school on how to lean out a Holley at idle.


Thanks

Vance

[Jokester]

Blown power valve!  It must have sneezed once.  While you're replacing it install an anti blow up kit in it so it doesn't happen again.

.bjb

[EMSjunkie]

Blown power valve!  It must have sneezed once.  While you're replacing it install an anti blow up kit in it so it doesn't happen again.

.bjb

NO KIDDING!!!!

I just replaced it when I re-jetted the carb  :x

guess I got a bad one.  :oops:


Thanks for the info.

I really appreciate it


Vance

[Pep]

Also...if you have a big cam, the standard power valve will overcome the vacuum and open at idle.

[EMSjunkie]

Also...if you have a big cam, the standard power valve will overcome the vacuum and open at idle.

its not a huge cam, but it is kinda healthy.
somewhere in the neighborhood of .485 lift and around 270-280 duration.

least I think that is the cam I put in, but it sure sounds like the
cam that was in it when it was in my stock car  



Vance

[topless]

Hello, there are power valves available with different values. With a performance cam you can add one with a lower vacumn value so it won't open so early. It is harder to keep vacumn up at idle with high performance cam. Hope this helps, Topless

[C9]

Also...if you have a big cam, the standard power valve will overcome the vacuum and open at idle.

its not a huge cam, but it is kinda healthy.
somewhere in the neighborhood of .485 lift and around 270-280 duration.

least I think that is the cam I put in, but it sure sounds like the
cam that was in it when it was in my stock car  



Vance

That's a fairly big cam for the street.

On a 454-455 size engine it will pull about 10-12" of vacuum at idle.
Assuming you have the idle speed down to 600-650 or so.

Stock cams will pull 18-19" of vacuum at a 600 rpm idle in the same size engine.

[EMSjunkie]

OK, I put a vacuum gauge on it tonight

12 inches Hg at idle, approx 800-850 rpm

tried 4 different power valves tonight.
same results.  1-2 min. and I gotta evacuate the shop.

now what?  :?


Vance

[Mikej]

Vance, maybe you already post this but what is your motor, timing, and are you on the port vaccuum or manifold ? I just switched from an Edelbrock to a Holley last year and haven't done much to it but set the idle and change jets. The edelbrock had the problem I described. Can you change your idle speed with the Idle screws? Also on my holley if you change the front butterfly setting who are suppose to change the secondary also.

[EMSjunkie]

Vance, maybe you already post this but what is your motor, timing, and are you on the port vaccuum or manifold ? I just switched from an Edelbrock to a Holley last year and haven't done much to it but set the idle and change jets. The edelbrock had the problem I described. Can you change your idle speed with the Idle screws? Also on my holley if you change the front butterfly setting who are suppose to change the secondary also.

Hey Mikej, its a small block chevy, .030 over, 76cc heads, stock hei,
timing set at about 10-12 degrees btdc at idle.

not really sure about the cam specs. I think the one I put in was around
.485 lift and around 270-280 duration, if thats the one I put in, but at idle,
is sure sounds like the cam I ran when the motor was in my stock car.

it has 12 inches Hg at idle from the manifold port at the rear of the intake, where you pull vacuum for the auto tranny and power brakes.

the air / fuel bleed screws don't affect the idle until you screw them all the way in, then it will try to die.

I thought I knew a little about Holleys, guess "little" is the key word.


Thanks for your help.

Vance

[C9]

An off the wall thought, but is it possible the carb has a nitrocellouse float instead of a brass one?

Holley used the nitro floats in their late two barrels.
The nitro soaks up some of the stuff in modern gasoline and doesn't have the buoyancy required to keep the needle closed.

Even with the proper float setting - as done on a dis-assembled carb - you'll have a too high float liquid level since the float is riding low.

A high float - or a sunken one - means added richness and if the float is at an extreme high it can flood the engine while it's running.

It's possible for brass floats to develop a pinhole in the solder and drown as well.

Did you check the float level?

Isn't the screw under the electric choke for adjusting the secondary throttle blades?

I see where you tried four different power valves.
Were they all rated at the base level - like for a stock engine - or did you have some rated for a lower vacuum level?

If I remember right, you should be running a 7 or 8" power valve for the vacuum levels you're running.

Looks as well like the carb was taken away from the base settings due to the blown power valve and when the new valve was installed the incorrect base settings were still there.
Double check the power valve rating and if it's ok and return the carb throttle blades to the base setting and see what you get.

What kind of fuel pressure are you running?
If you're running a racing electric fuel pump without a regulator, more than likely that's your main problem.
4-5# fuel pressure should do it.
Don't guess at it either, test it with a pressure gauge.

[entodad]

If I remember right you should be running a power valve with a vacuum rating of one half of your idle vacuum minus two or in your case about a 4.

However what do I know, I have been fighting the same problem with a 450 cfm holley on a 283 chevy.  It runs fine once it starts but when you turn the engine off, there is a nice cloud of fuel vapor that flows out of the carb.  It did have a blown PV, we replaced it with a 6.5 (supposedly that is right with a stock cammed engine with an edelbrock single plane manifold), maybe not though.

It has gotten to the point, that I just purchased a holley projection unit and will soon install it with the closed loop O2 sensor.  If that works to my satisfaction, then I will replace the carb on my 67 camaro convertible as well.
Doug

[EMSjunkie]

Thanks for the info guys, I really appreciate it.

the power valves I tried were some I had laying around.
not sure of their ratings, I couldn't find any discernable markings.

gonna go to the parts place Monday and get a new power valve.
probably a 6 and an 8 just to be sure.

there has to be something I'm missing, I've never had a Holley
kick my hiney this bad yet.

I'll keep you posted.


Vance

[Fat Cat]

Thanks for the info guys, I really appreciate it.

the power valves I tried were some I had laying around.
not sure of their ratings, I couldn't find any discernable markings.

gonna go to the parts place Monday and get a new power valve.
probably a 6 and an 8 just to be sure.

there has to be something I'm missing, I've never had a Holley
kick my hiney this bad yet.

I'll keep you posted.

Vance

according to this page you want a power valve with -2 Hg not half-2. There is also a description of where the power vavle is marked for its opening value.

[entodad]

mea culpa,
you're right it is lowest steady vacuum minus two.  Don't know where I got my misinformation from...I must be suffering from CRAFT...can't remember a freaking thing
Doug