I'm trying to conquer the learning curve here so bear with me. My questions are: What indictators let you know when you are in the power valve on a Holley 1920. I'm trying to identify my distributer weights and springs. I have a short heavy spring with 4 coils. The light spring I cannot identify. No colors to go by. Its from a 79 diplomate. I see some numbers in the wieghts. Lots of 9's but its hard to read the whole thing. I've got a new nylon gear installed and will be using a new 8.5r vacuum can so I'm trying to ballpark what to expect from my mechanical advance.
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BMW K1200RS

For the power valve, you need to know what it's rated at (8.5,10.5,whatever) and then install a vacuum gauge.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

The power valve on a 1920 should kick in around 6" of vacuum. Do as emsvitil says, and get a vacuum gauge. Hook it up to manifold vacuum (not on the #6 runner though, otherwise you will get "pulses" when that valve opens). I hook mine right to the base of the carb (not the PCV port though, mine has an extra port on the other side).

The easiest way to tell in my experience is to drive uphill around 55-60 mph, and then progressively step down on the throttle. When it hits the power valve, you will feel the increased acceleration, then note where the vacuum gauge is pointing.

~THOR~

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1984 D100 Shorty Custom
Certified Auto Appraiser - RevItUp Classic Appraisals
President - Cherry City Bombers CC
Part of Tyrde-Browne Racing

Manifold vacuum around 6 in Hg. Got it. I'll have to get the new Electronic ignition up and running to get enought timing to feel the additional power.

The vacuum can that came on the distributor was the 11r. I don't know if that is the correct can.
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health store

3874876... late model distributor for super sixes (and very late model 1 barrel cars)... should have a 9r governor, short loop 4 coil primary spring... and an 11R vacc. can for good mileage...
set at 10-12 BTDC initial.

-D.idiot

I hook the vacuum can to manifold vacuum? I thought it was venturi vacuum. Reason I ask is what I thought may be the adjustment screw for air bypass that is seized up is in the same location as where the venturi vacuum line fitting is in the holley 1920 carb figure 4. Could I have a screwed in plug instead of the correct vacuum fitting? How can I get a venturi source now?

I did sone calculations on rpms at cruise in this truck and I get around 2500-2700. At 2700 I'm going 70mph with 31inch tires and a 3.55 differential. Its more comfortable to run at 2500 rpm so will I be able to utilize the 22 degrees of vacuum advance a 11r would give me in a truck with tall tires? My primary goal is improving mileage. Any help with a wiring diagram pertinent to my electronic igition comvertion for an 87 d100 would be great.
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buy digital scale

I believe THOR meant to use manifold vacuum for the vac gauge, not the vac advance can. Vac advance needs to be ported or you'll be getting advance when idling.

Nat

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1970 four-door Dart, 225/A-904/2.45 gears. 0-60 in twenty three minutes!

Agreed, use the ported vacuum line off the 1920 to the pod, not manifold vacuum. The 11R pod will give you much better mileage as DI has pointed out. I have found that unscrewing the can about 3 turns will turn off the pod at idle so you can get consistent base timing. That way when you crack the throttle you get a healthy hit of torque.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Has it been a year already? Wow! Finally got my timing light back and looks like I'm right on the money for timing. I've adjusted the tranny kickdown to fix early shifts and I'm in good shape. All these correction briing me back to the power valve again. It does seem to be kicking in a bit early, if I'm right. I don't know if I'm getting more acceleration but the engine definitely gets a more angry louder sound to it. I'm putting the vacuum gauge back on it to be sure but I'd venture to guess its coming in around 7 instead of six. Now that it holds shifts longer I don't need it coming in so early. Its difficult to stay out of it. Any thoughts?
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herbalaire vaporizer

Let's see what numbers the vacuum gauge shows at the varoius rpms (idle, cruise, etc). Then document what your seeing and experiencing.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Looks like its coming in around 5. I spend a lot of time around that # is why I thought it was coming in early. It maxes out around 9-10 if I'm extremely light on the throttle. At speed I'm at 7 on level smooth road without a head wind. Thats at about 55-60mph.
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List of engines

What does the vacuum gauge show at idle?
If your at these vacuum levels you got some serious problems......like dragging an anchor???? over geared or an a extremely lean jetted carb to where your on the power valve all the time.

What jet are you running???? You may want to consider going to a #60 jet or larger. That should help keep you out of the power valve.
With this condition you must be under 10 mpg......

Vacuum at cruise should be from 12 to 16" or higher.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Few basics:

• Bunch of info and links to Holley 1920 tune-and-mod threads here

• What exact 1920 is this you're working on? What's the type (or "list") number? Should be four digits, possibly followed by some letters. Find it on the top or front surface on the passenger side.

• Careful which vacuum port you're using if it's a 1973 1920. That's the only year for 1920s with a venturi vacuum tap, which is used for the EGR system. It's not the same as "ported vacuum", which all 1920s have, down at the base, which is where the distributor vacuum advance line hooks up.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Last mileage I checked was pretty bad--near where you said. The gauge was T-d off of the ported vacuum port so I read 0 vacuum when I'm at idle. Yeah, it kinda feels like I'm pulling an anchor. Stamp on the carb says 6156 if that helps off of a duster donor I think. Rear diff is the stock 3.55 that came with it new. Its not making noise and the diff oil looks good. I've got this truck lightened up alot with lighter aluminum wheels, no bumpers, no spare or onboard jack so it should be optimized there. I had a real problem fouling plugs out due to a choke problem and the idle mix screw was past 4 turns. I think its around 1.5 to 2.5 turns now. I haven't checked the mileage since I made the kickdown linkage longer and installed the vacuum distributor, but so far it doesn't look much better. I thought for sure the timing would bring the power back but it hasn't. It
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BMW F800S history

6156 is a 1972 Federal-emissions 225/automatic carb. What is its history? If you're getting really rotten mileage despite all the tune-up components being in good shape, the carb could be in bad shape (i.e., worse than can be restored with a simple cleanout-and-gasket-kit). On the other hand, it might not be terminal; have you replaced the float?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.