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  #16 (permalink)  
Old 06-12-2012, 07:43 PM
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Quote:
Originally Posted by Freddyfingaz83
Interesting. I gotta hit junkyard for that qjet for my modified 454.
There is a little-known Q-jet you might luck into for cheap because it fools a lot of guys into believing it's a computer controlled carb. These carbs work basically the same as any non computer controlled carbs, except for having the dual accelerator pump connector on the top. More here.

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  #17 (permalink)  
Old 06-12-2012, 07:54 PM
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Since we are changing subjects. I do have other question. I bought used Med modified 454 with Holley and I want to change it to qjet. But problem is past owner didn't give me any information on those modified jobs on my 454. What's best way to calibration qjet for it without any information? By playing with meter jets, power piston spring and floaters until I find best combination?
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  #18 (permalink)  
Old 06-12-2012, 08:06 PM
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Quote:
Originally Posted by cobalt327
There is a little-known Q-jet you might luck into for cheap because it fools a lot of guys into believing it's a computer controlled carb. These carbs work basically the same as any non computer controlled carbs, except for having the dual accelerator pump connector on the top. More here.
Thanks!
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  #19 (permalink)  
Old 06-12-2012, 08:09 PM
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Quote:
Originally Posted by Freddyfingaz83
Since we are changing subjects. I do have other question. I bought used Med modified 454 with Holley and I want to change it to qjet. But problem is past owner didn't give me any information on those modified jobs on my 454. What's best way to calibration qjet for it without any information? By playing with meter jets, power piston spring and floaters until I find best combination?
If you are new to Q-jets, I would recommend starting by getting a copy of Cliff Ruggles' book. Then based on the Q-jet you were working with and the engine vacuum (to determine roughly how much cam the 454 is running), choose the appropriate recipe outlined in the book.

There are a couple pages on the Q-jet and carbs in general over at the Crankshaft Coalition wiki.
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  #20 (permalink)  
Old 06-12-2012, 08:21 PM
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Quote:
Originally Posted by cobalt327
If you are new to Q-jets, I would recommend starting by getting a copy of Cliff Ruggles' book. Then based on the Q-jet you were working with and the engine vacuum (to determine roughly how much cam the 454 is running), choose the appropriate recipe outlined in the book.

There are a couple pages on the Q-jet and carbs in general over at the Crankshaft Coalition wiki.

Forgive me, I'm little slow. I do have this book and did see those recipes. But I'm not sure which one to start with because I need to to determine roughly how much cam the 454 is running and how big cid it is. All I know is owner said it is about 10% larger. Displacement and has RV camshaft with full length headers and using powerglide. How can I determine it without tear 454 apart?
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  #21 (permalink)  
Old 06-12-2012, 09:51 PM
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Quote:
Originally Posted by Freddyfingaz83
Forgive me, I'm little slow. I do have this book and did see those recipes. But I'm not sure which one to start with because I need to to determine roughly how much cam the 454 is running and how big cid it is. All I know is owner said it is about 10% larger. Displacement and has RV camshaft with full length headers and using powerglide. How can I determine it without tear 454 apart?
"10% larger" would still be a mild cam, relatively speaking. If the engine runs, put a vacuum gauge on it and you can get a rough idea of the cam by the vacuum.

If it doesn't run I would go w/one of the milder Q-jet builds. I'm unable to comment further as I don't have his book in front of me so I don't know what he recommends in his recipes, other than generalities.

Be sure to set up the distributor w/a performance curve.
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  #22 (permalink)  
Old 06-12-2012, 11:24 PM
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Quote:
Originally Posted by cobalt327
"10% larger" would still be a mild cam, relatively speaking. If the engine runs, put a vacuum gauge on it and you can get a rough idea of the cam by the vacuum.

If it doesn't run I would go w/one of the milder Q-jet builds. I'm unable to comment further as I don't have his book in front of me so I don't know what he recommends in his recipes, other than generalities.

Be sure to set up the distributor w/a performance curve.

Ok where connect vacuum Gage to? It's running and I still do need to curve my dis.
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  #23 (permalink)  
Old 06-13-2012, 09:15 AM
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Quote:
Originally Posted by Freddyfingaz83
Ok where connect vacuum Gage to? It's running and I still do need to curve my dis.
Find a vacuum port on the carb that has vacuum when the engine is idling. If it's a Q-jet carb, don't use the port that was used for the EGR valve, it will not register the same vacuum as a manifold vacuum port, but it will show some vacuum at idle. Usually the ports on the baseplate will be manifold- but not always every one of them. A sure thing is to use the port that feeds the choke pull off. Replace it when you are done.

If you have an Edelbrock, use the driver side port. If you have a Holley us a port on the baseplate. More on vacuum port locations, etc. here.
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  #24 (permalink)  
Old 06-13-2012, 03:45 PM
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Quote:
Originally Posted by cobalt327
Find a vacuum port on the carb that has vacuum when the engine is idling. If it's a Q-jet carb, don't use the port that was used for the EGR valve, it will not register the same vacuum as a manifold vacuum port, but it will show some vacuum at idle. Usually the ports on the baseplate will be manifold- but not always every one of them. A sure thing is to use the port that feeds the choke pull off. Replace it when you are done.

If you have an Edelbrock, use the driver side port. If you have a Holley us a port on the baseplate. More on vacuum port locations, etc. here.

Ok Thanks you. I didn't know that vacuum gauge can guess what type cam engine is running on. After I got my reading then what? Where's chart?
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  #25 (permalink)  
Old 06-13-2012, 03:57 PM
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Quote:
Originally Posted by Freddyfingaz83
Ok Thanks you. I didn't know that vacuum gauge can guess what type cam engine is running on. After I got my reading then what? Where's chart?

I was going do this process to confirm my type cam.

http://www.crankshaftcoalition.com/w...otor_assembled

But if there's easier way then I'm interested to do. Because my 454 in my 63 impala really doesn't have any good clearance room to work with. It's difficult tight spot to work around. Lol. But many Thanks for all your information's. They are very helpful.
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  #26 (permalink)  
Old 06-13-2012, 04:20 PM
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Quote:
Originally Posted by Freddyfingaz83
Ok Thanks you. I didn't know that vacuum gauge can guess what type cam engine is running on. After I got my reading then what? Where's chart?
The vacuum reading is only to get an idea of the camshaft specs by how much idle vacuum the engine makes. It will not tell you what the lift is, or the exact duration numbers, or anything exact about the cam specs.

If the idle vacuum is 20 to 17, I'd call it a basically stock cam- from a duration/overlap standpoint. Meaning the engine should idle pretty smoothly, and a PP spring of around 8 in/Hg would be a decent choice. Less vacuum at idle = less PP spring rating. Edelbrock sells a set of PP springs: golden (4" Hg), orange (5" Hg), black (6" Hg), and yellow (8" Hg).

If the vehicle is driveable, you can check the vacuum under various driving conditions and you would be able to select a PP spring based on what vacuum you see when the engine is under a load.

If the engine is running good w/the spring and jetting, metering rods, etc. that's in it now, just leave the same parts in it when you rebuild it.
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  #27 (permalink)  
Old 06-13-2012, 04:24 PM
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Quote:
Originally Posted by Freddyfingaz83
I was going do this process to confirm my type cam.

http://www.crankshaftcoalition.com/w...otor_assembled

But if there's easier way then I'm interested to do. Because my 454 in my 63 impala really doesn't have any good clearance room to work with. It's difficult tight spot to work around. Lol. But many Thanks for all your information's. They are very helpful.
Doing as that article says is certainly an option. But in this case, you really aren't (at least I didn't think you were) concerned w/the lift numbers, etc.

But in any event, if the engine is running good, leave the jetting and PP spring as-is and just rebuild it if it needs freshened up and cleaned.
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  #28 (permalink)  
Old 06-13-2012, 06:29 PM
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Quote:
Originally Posted by cobalt327
Doing as that article says is certainly an option. But in this case, you really aren't (at least I didn't think you were) concerned w/the lift numbers, etc.

But in any event, if the engine is running good, leave the jetting and PP spring as-is and just rebuild it if it needs freshened up and cleaned.

Sound good.
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