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Bigger Jet for Holley 1945
https://slantsix.org/forum/viewtopic.php?t=27139
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Author:  75plyduster [ Mon Feb 11, 2008 7:00 pm ]
Post subject:  Bigger Jet for Holley 1945

Does anyone know where I can get a bigger jet for my 1945 holley on a 1975 225?

Author:  Aggressive Ted [ Mon Feb 11, 2008 7:28 pm ]
Post subject: 

Sure, just about any Auto Parts store that carries Holley carbs. Schucks, Napa, ma and pa auto parts, etc... or off the web, Summit Racing, Jeg's, etc..... It takes the same Holley Jet as the bigger Holley racing carbs.

What size is in yours?
How big do you want to go?
all mine had a #60

Author:  75plyduster [ Tue Feb 12, 2008 4:55 am ]
Post subject: 

Would this work?

http://store.summitracing.com/partdetai ... toview=sku

Author:  Aggressive Ted [ Tue Feb 12, 2008 6:57 am ]
Post subject: 

Yes, that is exactly what I was referring to.

Author:  DusterIdiot [ Tue Feb 12, 2008 6:57 am ]
Post subject:  Yep...

Those jets will work, but I'd bet you can get a better price at your local autoparts store than buying from summit on one small item...

-D.Idiot

Author:  75plyduster [ Tue Feb 12, 2008 8:25 am ]
Post subject: 

I was getting other things too. Will the bigger jet affect gas mileage much?

Author:  Aggressive Ted [ Tue Feb 12, 2008 8:39 am ]
Post subject: 

Yes, technically each jet size larger is a 4.5% increase in fuel flow.
If you drive less aggressive you will be ok, but if not, then expect to burn a little more fuel.

Author:  75plyduster [ Tue Feb 12, 2008 10:03 am ]
Post subject: 

Do you think its worth it?

Author:  Aggressive Ted [ Tue Feb 12, 2008 10:20 am ]
Post subject: 

That is a very subjective question that you can get allot of different answers on. From my experience with a couple of 1945's, I would say no.
I have collected quite a few jets and have tried them in the 1945. I never saw any drastic improvements in HP from jet changes, just worse mileage. You can try it and see, maybe your results will be better.

Doc was the main influence on me for making the switch to the 1920. For some reason the 1920 Holley EconoMaster has been very responsive to the subtlest jet changes that I never felt or was able to log with the 1945 (I have a vacuum gauge and tach for reference).
The jet changes are much quicker to do on the 1920, less than 5 minutes were as with the 1945 you can damage the accelerator pump and gasket very easily popping the top several times to make jet changes.

Hope this helps.

Author:  Rust collector [ Tue Feb 12, 2008 10:27 am ]
Post subject: 

What makes you think you need a bigger jet???

Author:  75plyduster [ Tue Feb 12, 2008 10:30 am ]
Post subject: 

Nothin I was just going to rebuild my carb soon and while I was at it I was thinking about putting a new jet in to see if I got any extra power.

Author:  Jopapa [ Tue Feb 12, 2008 11:06 am ]
Post subject: 

On the subject of jets, what's the typical ideal size for a 1945 for a compromise between performance and economy? I'm about 1000 ft above sea level where I live.

Author:  Aggressive Ted [ Tue Feb 12, 2008 1:53 pm ]
Post subject: 

My 1945 carb's came stock with a 612 jet. They got between 18 and 22 mpg at best. With a #60 jet I hit 23 mpg once but never was able to repeat that again over the following three years. Most of the time I was in the power valve too much so ended up with lower overall mileage. If you drive like a grandma, not very fast in town, it would be fine. For today's real world driving with the need to accelerate quickly up to speed on freeways, especially in the hilly Seattle area, it was not practical. A #62 was more responsive, but average mileage was 20 mpg.

Author:  DusterIdiot [ Tue Feb 12, 2008 5:00 pm ]
Post subject:  Yep...

Quote:
On the subject of jets, what's the typical ideal size for a 1945 for a compromise between performance and economy? I'm about 1000 ft above sea level where I live.
The 1945 came with two sizes for jetting...

In 1974 it came with a #58 which was wayyyy to lean for the job...
Sometime about 1975-ish they upped the number a bit and by 1976 it was a 612 (#61) close limit jet to maintain that flow control for ever tightening emissions...

61 is about the limit for the 1945, you can go up to a 63 but at that point it will just be a lot of gas and less mileage...

-D.Idiot

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