Aaron-74

Today I slapped my Holley on my shop teachers 350HP truck motor. And we tried for two ours to get the damn thing to lean out enough. It went through 3 GALLONS of gas in 30-40 minutes at IDLE!! We turned the idle air screws all the way in, turned the floats all the way to the point where it killed the motor and it still ran to rich. The weird thing is that, that same carb was on the truck 8 weeks before and it ran beautiful....sang like a true beast. All I've done since is rebuild it (just replaced gaskets) and didn't change anything what-so-ever. And my teacher is a Holley expert. Just for some odd reason we can get it to lean out. I think my meetering block is hosed. We didn't changet the jets or anything so we don't know what the problem is. But, I'm trying to get a job at AutoZone so, I can get a new chrome Holley 600 for 216$ and 180 on an employee discount.


[Modified by Aaron-74, 4:23 PM 3/22/2002]

Barry's70LT1

A bad power valve will give that exact same problem. Also, I assume the metering block gasket is the correct one for that carb.
If the float levels are fine, then I would change the power valve.

Someone may have another suggestion, but I can't think what else it might be.
Barry

QuickVet

sounds like you have only begun working with that carb. i would have changed the jets first if it is running that rich.

Aaron-74

But we don't get it..is ran on that exact same motor the exact same jets and power valve.....So, we nother really don't get what's happening.

QuickVet

the weather :yesnod: or mabey the timing :yesnod:


[Modified by QuickVet, 6:18 PM 3/22/2002]

bence13_33

Have you checked the power valve to make sure it's good? A bad power valve on a Holley will do strange things. It only takes one backfire to ruin a power valve...

Stingy74

Insuffecient idle vacuum will make tuning a Holley a nightmare. Perhaps the test engine is leaking vacuum somewhere?

BeachinVette

I agree a bad power valve. I had the same thing happen just a couple weeks ago. I have an extra brand new one if you want it. They are cheap though. I was getting 4 mpg. while the car was idleing It would burn your eyes with a 10 mph wind out in the drive way. We still don`t have any misquitoes (SP).

You will find that will be your problem


Bob

Aaron-74

Yeah, now that I think about it, it could be the power valve. With the motor running for about 5 minutes my eye's burned so bad it made them tear. It COULDN'T be a vacuum leak. The motor is brand-new and there is sealant every where that i can safely be. And we aslo checked and closed all ports that could be a leak. It's a new power valve though, and it was running real rich even before it back-fired. It could be the power valve, but i don't see how since it was doing that before anything happened that could cause it to go back. Hopefully I'll get this job and solve the problem in no time flat.

clem zahrobsky

what is the LIST# on the front of the choke housing,knowing that we can see what you have and what should be in the carb. when you rebuilt it did you compare the gaskets you took off with the ones you put on because using the wrong gaskets will cause this problem. :chevy


[Modified by clem zahrobsky, 10:21 PM 3/22/2002]

Barry's70LT1

[QUOTE] It's a new power valve though, and it was running real rich even before it back-fired. It could be the power valve, but i don't see how since it was doing that before anything happened that could cause it to go back. /QUOTE]

The wrong power valve will also cause this problem. Power valves are rated for different vacuum levels. If you replaced the power valve with one that is rated higher than the engine's vacuum, then the power valve will never close, which causes the rich condition.
Was the number on the new power valve the same as the one removed.???

Aaron-74

Aaron-74

Actually, dumb assed me didn't check that. It came in the re-build kit. So, I figured it was the correct power valve. If I could get the correct power valve number, that would be GREAT. I need to find my Holley rebuild box around here because It's got the right one in it...or the origanal one.

The Dude

R80457-1

4160.
600 CFM.
Renew Kit: 37-119
Trick Kit: 37-993
Primary & Secondary Needle and Seat: 6-506
Primary Main Jet: 122-64
Secondary Main Jet (or plate): 134-39
Primary Metering Block: 134-128
Secondary Metering Block: 134-39
Primary Power Valve: 125-65
Primary Discharge Nozzle: .031"
Secondary Nozzle Size (or spring color): Black
Primary Bowl Gasket: 108-83-2
Primary Metering Block Gasket: 108-89-2
Secondary Bowl Gasket: 108-90-2
Secondary Metering Block Gasket: 108-90-2
Secondary Metering Plate Gasket: N/R
Primary Fuel Bowl: 134-101
Secondary Fuel Bowl: 134-105
Throttle Body & Shaft Assembly: 12R11240A
Venturi Diameter (Primary): 1 1/4"
Venturi Diameter (Secondary): 1 5/16"
Throttle Bore Diameter (Primary): 1 9/16"
Throttle Bore Diameter (Secondary): 1 9/16"

Aaron-74

where is the number on he power valve???

QuickVet

directly on the power valve. you should see a 6 on one side and a 5 near it. if it is a 6.5. they should be printed right on the P.V.

Aaron-74

The only number on the power valve that I've got is 87.5 it's on the bronze tip.

Barry's70LT1

Hi, here is a picture of three power valves. a 6.5, a 4.5, and a 10.5. The 10.5 is very hard to see. Hope this helps.
Barry

bigvette1

All I would like to add Aaron - 74: put a vacuum gauge on the manifold at idle and see what you are pulling. An incorrect P.V. or a damaged one that is around or below mainifold vacuum will start leaking fuel and ---- very rich.
One other thing is make sure the secondaries are not slightly open, idle gets screwed up PV pulls in etc. Just give them a slight push with a screw driver to make sure they are shut.

fontking1a

Can you find the old power valve? If it's not that, you may have one of the gaskets installed incorrectly. All those little holes mean things and if you plug one up or expose one that shouldn't be exposed, it will cause you problems. Also, did you check your accelerator pump and follow the instructions for clearance?