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Jet numbers in 1945
https://www.slantsix.org/forum/viewtopic.php?t=13540		 Page 1 of 2
Author:  ceej [ Fri Jul 01, 2005 4:26 pm ]
Post subject:  Jet numbers in 1945
Pulled the 1945 Carb down. The main has 612 on it. Is this a 62 or something else?

CJ
Author:  ceej [ Fri Jul 01, 2005 6:41 pm ]
Post subject:  Power Valve
My kit came with two power valves that look identical.
One has 56-7 and 04F1 on the package

The other has 56-13 and 04C1 on it's package.

I can't see any difference between the two, and the instruction sheet is no help.

Any ideas?

CJ
Author:  emsvitil [ Fri Jul 01, 2005 6:50 pm ]
Post subject: 
As a wild-ass-guess I'd say one opens at 7" of vacuum and the other at 13" of vacuum..................
Author:  emsvitil [ Fri Jul 01, 2005 7:10 pm ]
Post subject:  jets & valves
Found my book on Holleys (doesn't mention a 1945) but it does mention their naming conventions.............

The Jet is a 61 close-limit jet. The jets can be 611, 612, 613.

The third digit is if the jet flows lean (1), middle (2), or rich (3).
There can be a 1.5% difference in flow between each of the 3 jets, or a flow range of 4.5%. There can only be at most a 1.5% flow difference between jets marked the same (i.e. a lean 612 vs a rich 612). The 2 digit jets could have a 3% difference between jets with same markings.


And the second number on the power valve is the inches of Hg that it will open up (not so wild after all).

If you're basically stock, I'd use the -12. (you want your idle, and cruise manifold vacuum to be higher than your power valve)
Author:  emsvitil [ Fri Jul 01, 2005 7:47 pm ]
Post subject:  whoops...
change -12 to -13.........

I'm not so sure about what to use anymore (searching around the internet)

I found places that say use about 2" less than idle vacuum, and some place else was dividing the idle vacuum by 2 then taking off the 2"......

The -7 will run leaner than the -13 and takes more of a vacuum drop to open (takes more throttle to have it enrich the mixture).
Author:  emsvitil [ Fri Jul 01, 2005 7:50 pm ]
Post subject:  Try this.........
http://www.holley.com/TechService/FAQ.a ... Carburetor
Author:  Craig [ Fri Jul 01, 2005 8:15 pm ]
Post subject: 
Quote:
As a wild-ass-guess I'd say one opens at 7" of vacuum and the other at 13" of vacuum..................
Ummm.... no! not on the Holley 1945 carbys. The power valve calibration is built into the vacuum piston and spring in the carburetor top. There is a lead plug on the top of the carburetor with a threaded adjuster under it to adjust the calibration at the factory. Don't mess with it.
Quote:
My kit came with two power valves that look identical.
One has 56-7 and 04F1 on the package

The other has 56-13 and 04C1 on it's package.

I can't see any difference between the two, and the instruction sheet is no help.

Any ideas?


What kind of kit is this that comes with two power valves. Find yourself a micrometer and measure the little poppet of the power valve. You shoud find the old original one from the carb (if no one replaced it in the past) is straight on the bottom end (fat part) then about half way up it starts to taper smaller a few thousands of an inch. The replacement power valves I have seen are not tapered. This tapered power valve stem is what makes it a "gradient power valve" along with the long stroke of the vacuum piston and spring that operates it. This operates similar to a metering rod you would find in a different carburetor.

Post some pictures of these power valves if you can and tell us if they are tapered or not and how much.[/quote]
Author:  ceej [ Fri Jul 01, 2005 8:27 pm ]
Post subject: 
Thanks for the replies. As I haven't taken a manifold vacuum reading, I don't know what normal is. Any thoughts? 1bbl , auto, 1974.

CJ
Author:  ceej [ Fri Jul 01, 2005 8:45 pm ]
Post subject: 
OK, both are tapered.

The Taper on the -7 is about .050"

The Taper on the -13 is about .060"

This is subject to poor lighting and questionable eye sight. I double checked them and the taper is about 1/100th longer on the -13.

As I've been having power issues, and don't know the vacuum readings on this engine, any thoughts?

The Kit covers multiple applications of the 1945 and other carbs.

The power valve that was in the carb is pretty close to .060" As it has been apart before, I don't know if it the correct power valve for the application.

Thanks again,
CJ
Author:  hitokage [ Fri Jul 01, 2005 9:26 pm ]
Post subject: 
Quote:
What kind of kit is this that comes with two power valves.
When I got some GP Sorensen rebuild kits for my 1945 one of them came with two, and the other came with three power valves. Both kits had the same part number. The first kit they were two different sizes. The second kit had two that appeared to be identical, and the third was a different size. My car seems to run decent with the one I chose - after I replaced the first one I bent putting the top cover on.

Steve G.
Author:  ceej [ Fri Jul 01, 2005 9:35 pm ]
Post subject: 
So the long taper will run leaner? I may stick with the 61 Main and use the short taper to attempt to richen the mid up. Does this make sense?

Am I going about this right?

CJ
Author:  Craig [ Fri Jul 01, 2005 9:41 pm ]
Post subject: 
Quote:
OK, both are tapered.

The Taper on the -7 is about .050"

The Taper on the -13 is about .060"

This is subject to poor lighting and questionable eye sight. I double checked them and the taper is about 1/100th longer on the -13.

As I've been having power issues, and don't know the vacuum readings on this engine, any thoughts?

The Kit covers multiple applications of the 1945 and other carbs.

The power valve that was in the carb is pretty close to .060" As it has been apart before, I don't know if it the correct power valve for the application.

Thanks again,
CJ
I don't think you measured the proper place. A picture for you would help. I don't have a picture right now. It's the fat part that has a very slight taper to it, then further up it makes a sharp taper to the skinny part of the stem which I think is what you actually measured. The taper I am talking about, you can not see with your eyes.
Author:  ceej [ Fri Jul 01, 2005 9:53 pm ]
Post subject: 
Ah.
The 7 has a taper of 1/1000th

The 13 has no taper.

Now for the full comparison.
The original has 1/1000th taper. It starts at 0.101" and tapers to 0.100"

The 7 Tapers from 0.102" to 0.101"

The 13 is 0.100" not tapered.

What does this mean? I don't have anything I'm comfortable measuring the ID with.

Still kind-of points to the -7.

CJ
Author:  Craig [ Fri Jul 01, 2005 9:59 pm ]
Post subject: 
I'll have to try and find some old power valves here to look at , It's been some years since I had to study them.
Author:  ceej [ Fri Jul 01, 2005 10:17 pm ]
Post subject: 
I was re-reading the Holley tech stuff. They say; "To properly size a power valve, take a vaccum reading at idle and if it is above 12" for a standard transmission a 6.5" will be safe to use. For automatic transmissions take a vaccume reading in gear at idle and if the vaccum is below 12" divide that in half for proper size. Example 9" of vaccume in gear at idle will require a 4.5" power valve. "

Soooooooo I need to know what typical manifold vacuum is for my 225, automatic tranny at idle. That should tell the tale. As they don't go into any detail for above 12", I don't know what the formula is for higher manifold vacuums. This vehicle should have the stock cam.
use the 7? I don't think my vacuum is above 12" at idle. But I really don't know.
Back to the vacuum question. What, typically should I be seeing at idle, in gear, on the manifold. I would think less than 12, pointing me at the -7....? Or is this number now something different?

I'm learning. I'm not sure what I'm learning, but there it is.... :shock:


CJ
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