Changing jets question?
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From: kennett square,pa,us
Changing jets question?
If I want to change the air/fuel ratio, my existing jets are 70 & 77, do I,
Change all four?
Change only two?
If two Which two? Primary or secondary?
Thanks.
Change all four?
Change only two?
If two Which two? Primary or secondary?
Thanks.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
Re: Changing jets question? (bud snyder)
Hey Bud, What do you want to correct. If the A/F ratio is off at a cruise change the primary ones. If it is for wide open throttle change the secondary and you might need to change the primary. But if the cruising is right on I would just change the secondary. Idle A/F is controlled by the idle adjsuting screws mainly. I have considered getting a A/F gauge to moniter all this so I can tune the car but as you know I have other problems right now
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From: kennett square,pa,us
Re: Changing jets question? (Gordonm)
Gordon,
I did the primeries up from 70 to 72 and it doesn't like it!
I will change the seconaries and see if that works.
At the speed shop where I got the jets they suggested doing the primaries, I think because they are so far apart 70 & 77. Usually Holley jets are closer than that, but Demons are not.
Thanks,
Is anyone going to Englishtown Sat.
Bud
I did the primeries up from 70 to 72 and it doesn't like it!
I will change the seconaries and see if that works.
At the speed shop where I got the jets they suggested doing the primaries, I think because they are so far apart 70 & 77. Usually Holley jets are closer than that, but Demons are not.
Thanks,
Is anyone going to Englishtown Sat.
Bud
Pro
Joined: Jun 2000
Posts: 698
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From: Park Ridge IL
Re: Changing jets question? (bud snyder)
I was told on this forum to keep them about 8 to 10 sizes apart.
My carburetor came with 71 and 80 from the Holley and I just changed the primarys to 70 for now. I still need lots of testing to determine what will work best.
Ziggy
My carburetor came with 71 and 80 from the Holley and I just changed the primarys to 70 for now. I still need lots of testing to determine what will work best.
Ziggy
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From: delmont pa
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Re: Changing jets question? (bud snyder)
carbs are jetted for sea level from the factory. you should reduce the AREA of the jet 2% for every 1500 ft above sea level.
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Joined: Dec 1999
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From: Forked River NJ
Re: Changing jets question? (clem zahrobsky)
Bud, My jets are 70 Primary and 80 secondary. If this helps. I am going to Etown on Sat but not in the Vette. It is still on stands. Got the parts today so its making progress
[Modified by Gordonm, 8:04 PM 11/16/2001]
[Modified by Gordonm, 8:04 PM 11/16/2001]
Thread Starter
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From: kennett square,pa,us
Re: Changing jets question? (Gordonm)
Gordon,
I did exactly what you suggested. I eariler changed the primary jets from 70 to 72. The engine stumbled a little off idle. I just changed them back to 70 and the stumble went away. Thank you!
I did at the same time change the secondaries from 78 to 80. I was supposely only slightly lean at WOT, some I can not even feel the results.
I don't know about Englishtown tomorrow, after what happened to you last Sat. it put the fear of GOD in me! Thats an easy 100 miles roll back ride home. I wanted to make Atco Thursday night, but I was still playing with the timing issue. Have fun if I don't see you! What cam does Mike have in that ZZ4 short block?
Thanks again for your help,
Bud
I did exactly what you suggested. I eariler changed the primary jets from 70 to 72. The engine stumbled a little off idle. I just changed them back to 70 and the stumble went away. Thank you!
I did at the same time change the secondaries from 78 to 80. I was supposely only slightly lean at WOT, some I can not even feel the results.
I don't know about Englishtown tomorrow, after what happened to you last Sat. it put the fear of GOD in me! Thats an easy 100 miles roll back ride home. I wanted to make Atco Thursday night, but I was still playing with the timing issue. Have fun if I don't see you! What cam does Mike have in that ZZ4 short block?
Thanks again for your help,
Bud
Race Director
Joined: Dec 1999
Posts: 19,610
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From: Forked River NJ
Re: Changing jets question? (bud snyder)
Bud, I did make Etown today but in the Grand Prix. The cam Mike is running is the stock ZZ4 cam. A hyd. Roller dur at .050 is 208 Intake 221 Exhaust Lift is 474 and 510. Not to wild on duration but good lift. I need to get a roller, lots more power. If I get the rear back together I'd like to try Atco to see what difference the gears make. I won't have it back together till after the Turkey Day break
[Modified by Gordonm, 8:48 PM 11/17/2001]
[Modified by Gordonm, 8:48 PM 11/17/2001]
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Thread Starter
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From: kennett square,pa,us
Re: Changing jets question? (Gordonm)
Gordon,
I passed on E-town as you know. My friend couldn't come along again. It is a long ride by yourself, and I wasn't sure if any C-3 would be there or not. It is hard for me to talk to the C4 & 5 guys, because we have nothing in common. I have a C4, but it is bone stock and it will stay that way in hopes the market may improve for them. I haven't even tagged the car for over 3 years now.
I do plan to get to Atco after Thanksgiving though, maybe we can get together there some Thursday nite. Good luck with the rear!
Bud
I passed on E-town as you know. My friend couldn't come along again. It is a long ride by yourself, and I wasn't sure if any C-3 would be there or not. It is hard for me to talk to the C4 & 5 guys, because we have nothing in common. I have a C4, but it is bone stock and it will stay that way in hopes the market may improve for them. I haven't even tagged the car for over 3 years now.
I do plan to get to Atco after Thanksgiving though, maybe we can get together there some Thursday nite. Good luck with the rear!
Bud
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From: kennett square,pa,us
Re: Changing jets question? (clem zahrobsky)
Clem,
Thanks for the info. I was slightly lean on the dyno, so i now changed the secondary jets from 78 t0 80. That should solve that? If not I think I will just have to live with it as I am now 10 apart.70 & 80.
Bud
Thanks for the info. I was slightly lean on the dyno, so i now changed the secondary jets from 78 t0 80. That should solve that? If not I think I will just have to live with it as I am now 10 apart.70 & 80.
Bud
