Power valve 4100

Power valve 4100

Joined: February 12th, 2009, 1:41 am

November 21st, 2010, 11:38 pm #1


What power valve would be the appropriate one for the Auyolite 4100 480cfm. I have a 6.5 Holley valve installed and the one that I had removed looked a bit different. Should the 6.5 work or do you need the one from a rebuild kit specific to the carburetor. I am just about to bolt it on , but the snowfall may stop my road test.


Greg
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Joined: April 16th, 2010, 1:42 am

November 22nd, 2010, 1:42 am #2

Stock for a mustang would be Plain (8.5) or Green (7.5) at altitude. Depending on your cam and other mods to your engine the 6.5 may be just fine, if it's just stock then you may need to go up a size or two.
Holley power valves are interchangeble with the autolite ones.
Last edited by Oldskool1 on November 22nd, 2010, 1:47 am, edited 1 time in total.
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Joined: February 12th, 2009, 1:41 am

November 22nd, 2010, 3:48 am #3


Will running the 6.5 compared to the 8.5 have the fuel transition at a faster rate. And does the valve help if there is a hesitation. I believe I have a couple of plain valves from some kits.


Thanks
Greg
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Kurt
Kurt

November 26th, 2010, 4:02 pm #4

It is my understanding that the power valve, which is normally held closed by manifold vacuum acting against it's spring tension, will open when manifold vacuum rises to the level marked on the valve.

At idle (higher manifold vacuum), the valve is closed.
When power is needed, such as under acceleration or climbing a hill under acceleration, the valve opens due to the decrease in manif. vacuum.

The opening occurs when vacuum reaches the value stamped on the valve, (8.5 or 6.5 etc).

This would mean that the higher number valve will open sooner rather than later than the lower numbered valve.
The higher numbered valves have stronger springs, which open at higher vacuum numbers.

If you want to speed up the transition, you will want higher numbered valve. Probably best to start with the specified number for your carb, then try higher number if you feel transition not soon enough.

Keep in mind, a hesitation may be caused by too rich as well as too lean mixture. you will have to determine which is occuring by how the car acts - lean or rich.

My 2 cents - Kurt.
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Joined: February 12th, 2009, 1:41 am

November 26th, 2010, 11:54 pm #5


Great info Kurt. I may have some other issues, but thought I would start with something simple to change. I measured my vacuum at idle and it was a steady 18.


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Greg
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Joined: December 30th, 2005, 8:04 pm

December 4th, 2010, 5:42 pm #6

What power valve would be the appropriate one for the Auyolite 4100 480cfm. I have a 6.5 Holley valve installed and the one that I had removed looked a bit different. Should the 6.5 work or do you need the one from a rebuild kit specific to the carburetor. I am just about to bolt it on , but the snowfall may stop my road test.


Greg
I find more sensitivity to these than to 1" of when the power valve opens:

1. What carb do you have? eg c6af-f on the tag, or 6a-f on the driver's front carb foot, etc. 1.08 or 1.12?

2. What jets are in the primary and secondary?

3. And as long as you have the pvalve out, can you measure the two PVCR holes (Power Valve Channel Restriction).

Sometimes the PVCR are too small, and if richer jets solves the problem (but eats more gas) then you can drill out the PVCR's, put the lean jets back in, keep your gas mileage up but it will be happy with your foot in it as well.
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Joined: February 12th, 2009, 1:41 am

December 4th, 2010, 6:35 pm #7



The carburetor is a 108, with a stamping of C5ZF E. I believe the jets are 48 primary , but can't get the secondary's out.



Greg
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Joined: February 12th, 2009, 1:41 am

December 4th, 2010, 6:39 pm #8



I think the secondary's are 58's

Greg
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Joined: December 30th, 2005, 8:04 pm

December 5th, 2010, 1:11 am #9


See pictures below.
Is there a hole like this in yours, in each main body bore just below the booster flat area?

http://www.network54.com/Forum/88781/th ... rb+Secrets

Also, do you have any richer jets to try?
Your setup sounds kinda lean to me, I had a similar one, jetted the secondaries up 5 sizes and it ran a lot quicker.
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Joined: February 12th, 2009, 1:41 am

December 5th, 2010, 4:50 am #10


My carb doesn't have those holes.I believe those holes were modified by Pony carbs. I do not have any jets to bump up the secondary size.


Greg
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