Holley 600 Questions

Knucklehead · Post by **Knucklehead** » Fri Jun 06, 2014 5:10 pm

Ok. My son and i rebuilt the 360 in his Wagoneer. Stock everything except for a Lunati Voodoo 64501 Cam, Edelbrock Performer and a 600cfm Vac. Secondary Carb. He also put on a set of Hedman Long Tube Headers.

http://www.lunatipower.com/Product.aspx?id=1481

My questions relate to tuning the carb. We live in Omaha Ne. for reference. I need a good starting point for the Power Valve and carb jets both Primary and Secondary. My son rebuilt the carb using a Holley Rebuild kit and the jets that were in it. Right now, it runs like crap. VERY rich at idle to the point of dying out if you don't blip the throttle.

haminawag · Post by **haminawag** » Fri Jun 06, 2014 6:06 pm

It would help if you knew what's in the carb now, but I understand your not wanting to pull it apart just yet. If it were mine I'd start by trying to achieve a baseline for tuning the carb because you're going to have other adjustments to consider like accelerator pump arm gap, vac secondary spring rate, etc. I'm assuming this'll be the Holley 4160 or similar series square-bore carb., and that you installed the cam straight up, if so I'd start with #50 jets, and a 3.0 power valve, set the cold choke opening at 1/8", and the accel. pump lash at .005, the vac sec spring should be the green spring, float settings per spec, curb idle, and fast idle to factory specs. Get this combo tweaked to run well then very gradually step up or down on the jets one size at a time, be sure to read the spark plugs so you know what's going on in the combustion chambers, this ought to get you going, but you'll probably not want to go beyond a #55 jet and a 2.5 PV. Let us know how you do.

acct21 · Post by **acct21** » Sat Jun 07, 2014 4:02 am

Why such a low PV opening pressure? If the rebuild is fresh, that engine should pull way over 15-18 inches of vacuum at idle. With a 2.5-3 PV would the PV circuit ever open?

jaber · Post by **jaber** » Sat Jun 07, 2014 7:13 am

Altitude plays a big part in this. When setting mine up, I got fortunate enough to stumble onto a parts man that had just gone through this and knew what I needed. We are 5200' and new carbs are set @ sea level. I dont have the #s in front of me, but can look to see if I can find them. Havent played with my carbs in a llllooooonnnngggg time.

Knucklehead · Post by **Knucklehead** » Sat Jun 07, 2014 9:00 am

FYI, Omaha is 1090' above sea level.

serehill · Post by **serehill** » Sat Jun 07, 2014 3:33 pm

The power valve rule of thumb the PV number should be half of the vacumn number at idle. If Idle vacuum is 12 & with that cam that would be close you should us A # 6 PV.

should be fine at that elevation.

Knucklehead · Post by **Knucklehead** » Sat Jun 07, 2014 9:37 pm

Anyone have a link to the accelerator pump springs? The one on the crab now is Red and cannot seem to find them.

serehill · Post by **serehill** » Sun Jun 08, 2014 6:31 am

http://www.summitracing.com/parts/hly-2 ... 7AodWAwAdw

Herk · Post by **Herk** » Sun Jun 08, 2014 8:39 am

Assuming your 600 is a Holley 1850 which should be just about perfect for that combo right out of the box. If it was purchased "used" or had been previously "tuned" the first step I would do is put it back to the original configuration. Here's a handy guide to establish a good starting point with Holleys: http://holley.com/data/TechService/Tech ... isting.pdf

Plenty of other great info on the Holley site.

The accelerator pump spring is probably not your problem...

Knucklehead · Post by **Knucklehead** » Sun Jun 08, 2014 8:58 am

Thanks for the link. The carb was purchased used, so I have no idea what was done to it previously. Unfortunately when my son rebuilt it, he did not check the jet sizes etc so I have no idea whats in there. Also thinking of just putting a Truck Avenger on it. Would a 670cfm be to much carb, or would the 470cfm be a better option?

csuengr · Post by **csuengr** » Tue Jun 10, 2014 7:13 am

Best way to tune a Holley is throw it out a buy an Edelbrock.

Knucklehead · Post by **Knucklehead** » Tue Jun 10, 2014 7:16 am

And then i have Edelbrock tuning issues. That would be kind of like jumping out of the frying pan only to end up in the fire.

Both have their issues. Best solution by far is to dump both and throw on a junkyard Fuel Injection setup. Might go down that path in the near future.

csuengr · Post by **csuengr** » Tue Jun 10, 2014 1:50 pm

They have to be tuned (sometimes) also. Especially on a modified engine.

haminawag · Post by **haminawag** » Wed Jun 11, 2014 6:18 am

Knucklehead wrote:Thanks for the link. The carb was purchased used, so I have no idea what was done to it previously. Unfortunately when my son rebuilt it, he did not check the jet sizes etc so I have no idea whats in there. Also thinking of just putting a Truck Avenger on it. Would a 670cfm be to much carb, or would the 470cfm be a better option?

Yeah, I was guessing it was a used carb., that's why I mentioned establishing a baseline setting. None of the info. myself or anybody else has given will do any good if the previous owner drilled out the air bleeds in the venturi body, also if they drilled any of the passages in the primary or secondary metering block you'll at least be able to replace that.
Used carbs. are a real craps shoot, I won't touch them. The reason I suggested such a small (numerically) power valve is because most carbs PVs are set to open WAY too early which is just a waste of fuel and, ultimately, bottom end torque, but run what works best for your truck. A stock 350 c.i. engine at 6500 RPM only draws about 490 CFM, so it's pretty easy to see that a stock 360 that will probably never see 4500 RPM doesn't need much carburetor, this is why AMC put 500 CFM 2 barrels on them, unless you're needing more for a performance application a 600 CFM Holley ought to work just fine, but they can be a tuning nightmare unless you're a Holley guru, or unless you become one the hard way.

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