tbiga
Junior Member
Posts: 129
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Post by tbiga on May 2, 2010 12:28:07 GMT -7
How many sizes up should I go in the carb? Currently inside carb are #66, the smallest in my kit are #65's. Would sticking #71's be to big of a jump or not enough?
Any advice?
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Post by Richard on May 2, 2010 15:02:08 GMT -7
Get a wideband fuel air meter, and then you'll know.
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Post by ebm86vette on May 2, 2010 17:32:54 GMT -7
At this elevation, usually smaller is better.
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tbiga
Junior Member
Posts: 129
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Post by tbiga on May 2, 2010 18:26:13 GMT -7
Wideband fuel air meter? Is that some electronic gizmo? Smaller is better on fuel milage as well.
I need to stop asking question like everyone know my car.
The car starts cutting out at higher RPMs. It starts at around 4000 to 4500 RMP and never really smooths out once it starts. Many from the boards have suggested larger jets. If I remember right it's a Holley 750 (4160) vacuum secondary, electronic choke.
So I hope I didn't go crazy but I did install some #72 jets. They are easy enough I can go smaller if needed.
Now I have 2 more issues.
1. On one of the fuel bowls there is a screw/nut combo thing on the top (have no idea what it's for or what the official term is) that is leaking gas. When I first put the carb on the car it leaked a little so I just tightened the screw a little and that fixed it but not it's leaking more. It there some O-ring or something simple under there I can change to make it stop? Can it be over tightened and cause issues?
2. Something I've always had is a slight hesitation when opening the throttle. If you crack the throttle open a little to fast (and it not opening all that much) it will rev a few RMP more pause/hesitate/stumble, once it catches up it run perfect until we get to the aforementioned issue with cutting out. Where should I start with trying to solve this problem.
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Post by Crossfire84 on May 2, 2010 19:37:15 GMT -7
Wideband fuel air meter? Is that some electronic gizmo? Smaller is better on fuel milage as well. I need to stop asking question like everyone know my car. The car starts cutting out at higher RPMs. It starts at around 4000 to 4500 RMP and never really smooths out once it starts. Many from the boards have suggested larger jets. If I remember right it's a Holley 750 (4160) vacuum secondary, electronic choke. So I hope I didn't go crazy but I did install some #72 jets. They are easy enough I can go smaller if needed. Now I have 2 more issues. 1. On one of the fuel bowls there is a screw/nut combo thing on the top (have no idea what it's for or what the official term is) that is leaking gas. When I first put the carb on the car it leaked a little so I just tightened the screw a little and that fixed it but not it's leaking more. It there some O-ring or something simple under there I can change to make it stop? Can it be over tightened and cause issues? 2. Something I've always had is a slight hesitation when opening the throttle. If you crack the throttle open a little to fast (and it not opening all that much) it will rev a few RMP more pause/hesitate/stumble, once it catches up it run perfect until we get to the aforementioned issue with cutting out. Where should I start with trying to solve this problem. 1. THAT IS THE ADJUSTMENT FOR RAISING AND LOWERING THE FLOAT LEVEL. THE NUT IS THE ADJUSTER AND THE SCREW LOCKS IT. THE FLOAT IS TO BE ADJUSTED SO THE FUEL LEVEL IS JUST TO THE BOTTOM OD THR SIGH HOLE BEHIND THE LARGE BRASS SCREW IB THE SIDE OF THGE FLOAT BOWL. 2. THE HESITATION INDICATES YOU NEED MORE FUEL FROM THE ACCELERATOR PUMP AS THE THROTTLE IS OPENED. GOOD LUCK, AND... RACE ON!!!
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Post by tom400cfi on May 2, 2010 19:38:35 GMT -7
.5. W/o renting a dyno and/or getting a Wideband O2, the best thing you can do to determine where you need to go w/jetting is this...(and this practice will get you 99% of the way to perfect, if you pay attention to detail): Run the car under the conditions that cause the stumble, for at least a minute. I would use Parley's Canyon for that, personally. With safety in mind, cut it off clean and pull to the side of the road. Pull plugs and look at *Color of porcelain (should be light tan), and *Color change location on the ground electrode (should be at the 90* bend). Combined, those will tell you where you're A/F ratio is at.
1. The screw/nut combo is the float height adjustment. There should be a cork or Blue colored composite gasket under there. you need a new one. You shouldn't need to tighten it more than "just snug".
2. Accelerator pump is what I'd check first on that. Is this symptom worse when it's not FULLY warmed up, bot after tha choke has opened? Say, 5 minutes into a drive?
2.5. If your float level is adjusted too low, it can cause the throttle tip-in hesitation that you described.
EDIT: OOoooooow! Jim beat me to it! lol. ;D
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tbiga
Junior Member
Posts: 129
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Post by tbiga on May 2, 2010 21:29:01 GMT -7
Thanks guys. Really appreciate the help.
I'll do some driving and test the throttle issues more and give you more feed back. But maybe I need a trip to a Dyno sometime soon, anyone going to visit a local dyno anytime in the near future.
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Post by tom400cfi on May 3, 2010 14:47:08 GMT -7
If you can find a dyno operator that wants to make a buck (work), I'm there in a heart beat.
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Post by snowman on May 3, 2010 15:10:21 GMT -7
Not in Salt Lake City.
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Post by ebm86vette on May 3, 2010 23:08:24 GMT -7
Element Racing in Ogden has a dyno that is still in use.
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