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post #1 of (permalink) Old 02-28-2002, 08:55 PM
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Power Valve #\'s (specifically for MC2100)

I have two power valves for my MC2100.

The first is marked 162 on one side of the 8 sided flats used to turn it in and out and 2L8 on
the opposite side.
The other is marked 167 on one side and the others are blank.

Both are two stage valves. I have gone to the Holley web page as the carb was rebuilt by
Holley they say the valves will be marked with two digits example (65 means opens at 6.5
inches of vacuum) they say they offer two stage valves as well, but do not say how they are
sized. Does anyone have information on what my numbers may mean?
Also which power valve are those with MC 2100s of 258s running. I am currently getting
vacuum readings to get the right valve, but would be interested in others experiences. Mine
seems to run better with the valve marked 162 and 2L8, I am only got the other because it
came in a rebuild kit from NAPA.

Also does anyone know if motercraft power valves are interchangeable with Holley ones?

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post #2 of (permalink) Old 02-28-2002, 11:07 PM
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Re: Power Valve #\'s (specifically for MC2100)

Those are not Holley part numbers. I have no idea what they mean or what the opening on them is...

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post #3 of (permalink) Old 03-01-2002, 12:32 PM
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Re: Power Valve #\'s (specifically for MC2100)

The two stage power valve I got from a rebuilder was marked #16. I was advised this means it opens at 16" Hg. That must mean the first stage of enrichment. I have one in my hand that I pulled out a stock 304 mc2100 1.08 model and it's marked 7 on one side and A6 on the other. From the length of it, it looks like a two stage. I have wondered if it's possible to adjust these things ourselves. They are threaded at each end,and possibly the pre-load on the spring sets the tension, and would affect the point of opening of the two stages. I've never been able to unscrew one though. I even tried heat, which no doubt would have destroyed the rubber parts, and i still couldn't unthread it. The old ones are either corroded or lock tighted. If you get any info on where to obtain power valves of various opening values, be sure to post what you find out. I'd also be interested in finding out how to order jets to do some experimenting in tuning.


84 CJ7, 258, HEI, M/C 2100 carb, 5 inch lift, RS9000's, 33x12.5 BFG M/T's, 4.56's and Detroit softlocker, full cage & belts, Xenon flares, Dana 44 rear, GM dual diaphragm brake booster
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post #4 of (permalink) Old 03-02-2002, 10:22 PM
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Re: Power Valve #\'s (specifically for MC2100)

I drove around to day in the jeep to get vacuum readings for a new power valve.

Cruse in 1st to 4 th gear: 15 in Hg
Cruse in 5th gear: 7 in Hg
Moderate acceleration in 1st to 4th: 7 in Hg
Heavy acceleration in all gears: 4 in Hg
Idle: 19 in Hg

I would like to find a 2 stage valve opening at 12 or so and the second stage at about 5. This
should keep me out of the power valve in all but 5 th gear and that should change when I
regear the diffs. I am however still looking for a source for Motorcraft/ Autolite Power
valves. I have attached a drawing of the 2 stage Power valve and would be interested If
anyone could compare it to a Holley 2 stage Power valve, and note any differences, I would
appreciate it. Its a long shot but they may be the same.
I managed to remove the top end cap off the top end of my spare power valve and a
spring and some kind of little piston came out. The rest of the mechanism seems to be under
the bottom end. I could not get the bottom screw out and was not willing to use heat since
the jeep seems to like this valve better. I put the top screw back in to the same point, I do not
want to adjust it my self until I have had one all the way apart and know how it works. the
one I am currently running marked 167 seems to flat spot on acceleration at about 10 in Hg.
During this flat spot if I pull the choke the jeep accelerates. I suspect that this power valve
does not open till much lower and that is why pulling the choke (richening the mixture)
causes acceleration.

TiminMb, I would be suppressed if the 16 on your power valve means it opens at 16 in Hg.
Holley lists there valves on there web page and the highest they list is 12.5. I know they
may be different valves but it is hard to imagine that much difference. Who knows I am just
speculating. On your search for main jets I sent a parts request to
http://www.carburetorfactory.com/ about 4 months ago and they informed me that
they have them in sizes 38 and up for $7.00 a pair. They also have a nice carb identification
page that can be useful. I have sent a request as to what if any power valves they have and
am waiting for a response. I will post what I find out.


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post #5 of (permalink) Old 03-03-2002, 11:02 AM
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Re: Power Valve #\'s (specifically for MC2100)

*I would like to find a 2 stage valve opening at 12 or so and the second stage at about 5.*

Holley P/N

P/N, 1st Stage Opening, 2nd Stage Opening
125-208, 10.5, 5.5
125-213, 11.5, 5.0

125-212, 12.0, 6.5
125-215, 10.5, 6.0
125-218, 11.0, 5.5

So many cats, so few recipes...
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post #6 of (permalink) Old 04-20-2002, 11:34 AM
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Re: Power Valve #\'s (specifically for MC2100)

I can tell you definitively that the holley single stage valves will work. I will have a two stage next week and if i find that i have a cover that will work on my 83 mustang 3.8( which does by the way have the 1.08 2100) I will be trying it out. Brendan
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