BARRETTRACING
Registered: 02/19/12
Posts: 5
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| | 02/19/12 at 07:37 PM | Reply with quote | #1 |
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i have a sv-1 carburator #27503 has a stumble when matted. mixture screws are out 1.5 turns cranks and idles well. i purchased this carburator from Huntsville engines every thing is as it came from pro systems . my engine is a 615 with 12 deg heads, thanks for any help |
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PRO-SYSTEMS
Moderator
Registered: 12/16/11
Posts: 302
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| | 02/19/12 at 08:03 PM | Reply with quote | #2 |
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Hi Barrett Racing,
I would try a .070 squirter hole in it first. Its has the small single .055 hole. Drill them out to single .070 hole
Keep us posted.
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BARRETTRACING
Registered: 02/19/12
Posts: 5
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| | 02/19/12 at 08:58 PM | Reply with quote | #3 |
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the biggest i have is a .0635 seems to be about the same, i will get correct size and try again, seems to be better if i turn out mixture screw 1/2 turn but still stumbles |
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PRO-SYSTEMS
Moderator
Registered: 12/16/11
Posts: 302
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| | 02/19/12 at 09:12 PM | Reply with quote | #4 |
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Don't let the SV1 fool you it will idle MUCH leaner than a normal carb.
Set the four small Idle mixture screws in the 1.5-2.5 full turn range is typical.
Next, turn the idle mixture screws in evenly until it hesitates when you snap the throttle.
Then turn them back out until the hesitation goes away.
If you are at 2.5 turns or more on the mixture screws at this point and its NOT rich at an idle, then we need to go SMALLER on idle air bleed diameter .010-.015 from current (about .040 in your application).
You'll know you got it right, as when you pull it into gear or put a mild load on it to move it will not drop excessively or require a lot of throttle to move.
If it drops excessively or requires a lot of throttle it is too lean, if it requires you to roll and roll it over to clean the plug up to restart it is too rich.
Thanks and keep me posted. |
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BARRETTRACING
Registered: 02/19/12
Posts: 5
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| | 02/20/12 at 08:02 PM | Reply with quote | #5 |
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ok drilled out squirters to.070 and still had stumble, changed idle air bleeds to .040 and had to turn out mixture screw three turns. and stumble is gone. i am getting black smoke at idle like it is to rich |
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jim sciortino
Registered: 12/19/11
Posts: 3
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BARRETTRACING
Registered: 02/19/12
Posts: 5
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jim sciortino
Registered: 12/19/11
Posts: 3
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| | 02/22/12 at 02:12 PM | Reply with quote | #8 |
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Try to take a temp reading with a temp gun on the header tube. See what you get.. |
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PRO-SYSTEMS
Moderator
Registered: 12/16/11
Posts: 302
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| | 02/22/12 at 04:45 PM | Reply with quote | #9 |
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It sounds like it needs the intermediate circuit added to it. That version is a 2 circuit. Send it in and we will update it to the 3 circuit version and freshen it up at no charge.
We are on a 5 day turnaround.
Patrick James
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BARRETTRACING
Registered: 02/19/12
Posts: 5
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| | 02/22/12 at 08:35 PM | Reply with quote | #10 |
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i have changed air bleeds to richen up at idle and still have to turn out idle screws to three turns not to stumble and car is very rich, so i went the other way with the air bleeds to .0635 and plugs are cleaner at idle but still have to turn way out on mixture screws, seems like no matter what i do it still has to be turned out. also just a question about carburetor floats in this carb. as you know i purchased this used with dyno time only and i noticed that float in front of carb is brass float and rear is not? also all air bleeds are marked as .023 but drilled to correct size ? |
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PRO-SYSTEMS
Moderator
Registered: 12/16/11
Posts: 302
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| | 02/22/12 at 10:38 PM | Reply with quote | #11 |
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The rear is a drag float and cant be brass. Always measure bleeds as folks drill them. If the stumble is now gone...go race it..if not send it in for the intermediate. Thanks.
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