Only one thick gasket.



-Gary Burnette-

On the holley power valve do you guys know is there just one gasket between the valve and the metering block?

Unless you go early style with 2 PV's like on the '57 t-bird carbs.

Ted you are the man. thanks for the advice. I found last night that I had a 4.5 power valve in this 600 cfm carb. I think its the cause of my hesitation. I'll be going with a 6.5 to see how it acts. I have around 11-12 inches vacuum at idle.

As a general rule, concentrate on primary jetting for ‘drive around’ jetting.  Secondary jetting is typically better left alone or made richer to provide a cushion again being too lean under full throttle conditions.  Being at a higher altitude will simply require driving and making adjustments based on those driving tests.  Making changes without driving can have you going a completely opposite direction than what is actually needed.
  
  It’s recommended to first try any carburetor with the factory supplied jetting.  Assuming the manifold vacuum at idle is no lower than 9-10” Hg, then the factory #65 power valve will be adequate.  Some of the Holley 600’s come with a #25 (0.025”) accelerator pump shooter and these do prove to be on the small side when a larger than stock camshaft is involved.  The #31 shooters tend to be a better starting point in these cases but depending upon the camshaft, shooter size could jump to a #37 or larger.  Jetting is best tried with the ‘as supplied’ jets and then go from there.  Leaning the overall fuel mixture by way of jetting does bring on the potential for a dead spot or hesitation which then requires an even larger accelerator pump shooter in which to compensate.  Float levels on both bowls are important on the 4150/4150 Holley carbs and being too high or too low on either fuel bowl can lead to jetting changes that may not be necessary.

Lorena, Texas (South of Waco)

There is some leeway for the jets you use.  As long as it is not too rich or worse, too lean, it will be fine.



Lawrenceville, GA

One other question. Is there any problems with jetting the secondaries down a bit and leaving the primaries stock ( which is one stage rich for me in Co ). Seems to run better rich.

Any thoughts on this thing... https://www.quickfueltechnology.com/carburetors/street/slayer-series/slayer-series-carburetor-450cfm-vs.html

Which carb??  Open that can of worms... Still all about tuning.
I went from a 600 Holley to a 450, and now a 600 Eddie , despite lots of tuning there was no real revelations. "I think " The Eddie has a little bit better mid range that's about it..



"Came too close to dying to stop living now!"

Thanks you guys. I am not able to get into he carb until tomorrow night. I will post updates for sure. Keep the suggestions coming. One other question. For best performance in my set up .. Holley or Eddy?