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VACUUM AT IDLE #1092151
10/10/11 02:55 PM
10/10/11 02:55 PM
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Moparnut426 Offline OP
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What kind of numbers are you guys getting at an idle? Heres my dilemma, no ports on the carb to test it. have 1 port in intake plenum, and I am only getting 5.5-7 at an idle, and it goes up as I crack the throttle.

What rpm do you guys test for to set the power valve

Kasey

Re: VACUUM AT IDLE [Re: Moparnut426] #1092152
10/10/11 03:45 PM
10/10/11 03:45 PM
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maximum entropy Offline
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i have less than 3" @ idle. power valve selection isn't nearly as critical as some would lead you to believe. it doesn't affect idle mixture at all, only the main circuit. i still run a 65 pv with no problem. more important would be your cruise vacuum. mine is ~15", meaning the power valve is closed (as it should be) at cruise.


for what is the good life if not doing things thoughtfully?
Re: VACUUM AT IDLE [Re: maximum entropy] #1092153
10/10/11 03:54 PM
10/10/11 03:54 PM
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Moparnut426 Offline OP
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I have 15 at 3k, I dont have a power valve, and I am running very fat down the road. Only 8.5 mpg, just checking things out, and I am gonna tune the secondary idle adjustment down cause now I know its rich. Just trying to get this carb figured out.
thanks

Re: VACUUM AT IDLE [Re: Moparnut426] #1092154
10/10/11 04:20 PM
10/10/11 04:20 PM
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St. Clair Shores, Michigan
bigsbigelow Offline
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If you want better cruising mileage you need a power valve.


Ryan "Bigs" '73 Duster (BLKDUST) - Black, 100% factory sheet metal, flat hood, 346 cid, J Heads, and a bench seat. http://s268.photobucket.com/albums/jj1/bigsbigelow/ Best to date: 12.40 @ 109 mph
Re: VACUUM AT IDLE [Re: bigsbigelow] #1092155
10/10/11 04:27 PM
10/10/11 04:27 PM
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maximum entropy Offline
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Quote:

If you want better cruising mileage you need a power valve.



correct. get a power valve in that thing! oh, and don't forget to jet down on the primary side (assuming you'll have a power valve on primary only). 8 numbers down should do it.

Last edited by maximum entropy; 10/10/11 04:29 PM.

for what is the good life if not doing things thoughtfully?
Re: VACUUM AT IDLE [Re: maximum entropy] #1092156
10/11/11 10:36 AM
10/11/11 10:36 AM
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Moparnut426 Offline OP
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Wha spread does a guy usually run as for jets, Like 80 rear, 70 fronts?

os it 10, 8, 6?

Just curious.

Re: VACUUM AT IDLE [Re: Moparnut426] #1092157
10/11/11 11:10 AM
10/11/11 11:10 AM
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Taxes & Virus's R-US, NY
Dragula Offline
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Quote:

Wha spread does a guy usually run as for jets, Like 80 rear, 70 fronts?

os it 10, 8, 6?

Just curious.




Spread them to start off with at 8...It may go as high as 10 on the spread, but usually 8-9 jets between them.


'70 Cuda,...605 EFI Hemi Street Car (6.20 best pass, 1.33 60ft)
https://www.youtube.com/watch?v=WYw6RA-k5Bk (6.25 at 108.75mph from inside car)
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https://www.youtube.com/watch?v=JCvfzsC4NgM (9.9)

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https://www.youtube.com/watch?v=Znuo3jMUXTk
Re: VACUUM AT IDLE [Re: Dragula] #1092158
10/11/11 11:21 AM
10/11/11 11:21 AM
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Moparnut426 Offline OP
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Thanks, Ill try that.

I ended up with a 70 front, and a 78 rear, and a 7.5 pv. Im also going to step it up on the plug heat range from a ngk 8 to a ngk 9 or 10.

Kasey

Re: VACUUM AT IDLE [Re: Moparnut426] #1092159
10/11/11 11:38 AM
10/11/11 11:38 AM
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Blown61 Offline
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Think of the pv as a switch, when the vac drops below what it is rated it opens, you could pull a vac gauge into the car and see what your cruise vac is and tailor your pv to open once you get into the gas and the vac drops below your cruise vac reading. That is how I tune mine.

Re: VACUUM AT IDLE [Re: Moparnut426] #1092160
10/11/11 12:06 PM
10/11/11 12:06 PM
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Racer33 Offline
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Kasey, if memory serves me the bigger the number on an NGK plug the colder the heat range. Maybe someone with more experience than me can chime in on that.

Re: VACUUM AT IDLE [Re: Racer33] #1092161
10/11/11 12:21 PM
10/11/11 12:21 PM
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Moparnut426 Offline OP
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HOTROD,,, AKA racer33.. Ya finally made it on here.

Welcome aboard!

Last edited by moparnut426; 10/11/11 12:22 PM.
Re: VACUUM AT IDLE [Re: Moparnut426] #1092162
10/11/11 12:48 PM
10/11/11 12:48 PM
Joined: Mar 2007
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Moparnut426 Offline OP
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I was thinking backwards again, As usual..... Ive been reading other places that the 9 or 10 is what I should be running. Heres a youtube I found on plugs from NGK. Pretty nice.

Kasey

http://www.youtube.com/watch?v=LbR75wq9nmM







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