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  #1  
Old 09-02-2013, 01:59 AM
iwrock's Avatar
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Tuning carbs....

Are a pain in the rear!

Never done one before, so I am stumbling though getting this Holley 650 tuned!

I know it's not complicated, but I've never done one before, so it's a bit challenging! I got the floats/bowls dialed in, now onto making power. It has great off line power, but once you're off the line (like above 1300rpm), it feels like a 240D!

SirNik gave me a crash course in tuning over the phone, so we will see how it goes tomorrow... Hopefully we can wake this bad boy up, and have some fun!

Thoughts? suggestions?

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  #2  
Old 09-02-2013, 02:09 AM
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Carburetors are of Shaitan. EFI is your friend. What are you working on anyway?
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  #3  
Old 09-02-2013, 05:25 AM
iwrock's Avatar
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We are working on a Nissan S13, with an 85 roller/carb 5.0...
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91 560 SEC AMG - other dogs dd
01 Honda S2000 - dogs dd
07 MB ML320 CDI - dd
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it's automatic.
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  #4  
Old 09-02-2013, 07:46 AM
t walgamuth's Avatar
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What size engine is the carb being used on?

Are your secondary throats opening?
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..I also have a 427 Cobra replica with an aluminum chassis.
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  #5  
Old 09-02-2013, 07:55 AM
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There's a couple types of 650, a 4150 and a 4160. Do you know which this is? At least one company makes replacement jet blocks that have externally removable jets so you don't have to take the whole carb apart to make a change.

This: http://www.summitracing.com/parts/php-15001
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Last edited by KarTek; 09-02-2013 at 08:12 AM.
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  #6  
Old 09-02-2013, 08:41 AM
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Tuning carbs....

http://m.youtube.com/watch?v=6vKlAnKdcB4&desktop_uri=%2Fwatch%3Fv%3D6vKlAnKdcB4

Im thinking the power valve is way off or blown.
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  #7  
Old 09-02-2013, 10:53 AM
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The first thing in tuning a carb is to make sure everything else is good. If anything else is off, you are pissing upwind.
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  #8  
Old 09-02-2013, 11:06 AM
t walgamuth's Avatar
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Quote:
Originally Posted by TwitchKitty View Post
The first thing in tuning a carb is to make sure everything else is good. If anything else is off, you are pissing upwind.
yes, good point.
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.
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  #9  
Old 09-02-2013, 11:43 AM
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Quote:
Originally Posted by Skippy View Post
Carburetors are of Shaitan. EFI is your friend. What are you working on anyway?
There is a reason why I sold the wife's ATV for a newer one that was the same except that it was EFI. Right now, all my toys are EFI. Only the lawn equipment is carb and a couple of 2 strokers. If it was economically feasible, I'd have all 4 strokers at the very least or EFI.

When the carb has a problem, I call someone else to work on it.
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  #10  
Old 09-02-2013, 12:17 PM
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Carbs are not difficult; they just require a systematic approach--like almost anything else. Unless it is new out of the box, assume NOTHING is correct until you have verified it. Don't go changing parts willy-nilly. Proceed in any orderly fashion. Cars and other power equipment have used carbs for well over 110 years. At least with a carb, you can usually see the problem. Its very difficult to trace the electrons moving around inside the chips in the EFI computer.
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  #11  
Old 09-02-2013, 01:02 PM
t walgamuth's Avatar
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Quote:
Originally Posted by MS Fowler View Post
Carbs are not difficult; they just require a systematic approach--like almost anything else. Unless it is new out of the box, assume NOTHING is correct until you have verified it. Don't go changing parts willy-nilly. Proceed in any orderly fashion. Cars and other power equipment have used carbs for well over 110 years. At least with a carb, you can usually see the problem. Its very difficult to trace the electrons moving around inside the chips in the EFI computer.
Agreed....but still sometimes its tough to figure out what's wrong.

The Holley carbs are very similar to Webers. High quality and very adjustable with jets that can be changed without tearing it all apart (though usually changing jets will not solve the problem).
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.
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  #12  
Old 09-02-2013, 01:23 PM
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Quote:
Originally Posted by MS Fowler View Post
Cars and other power equipment have used carbs for well over 110 years. At least with a carb, you can usually see the problem. Its very difficult to trace the electrons moving around inside the chips in the EFI computer.
People have crapped in their pants when they were young too. Doesn't mean that they always should. IMO it is easier to see exactly what is going on when you have a screen shot of what the computer is doing. It is also a lot more precise than say reading plugs when you can see what the O2 sensor is saying. I believe the way to tell if your Jetski carb was "right" was to take it to the middle of the lake, replace the plugs with fresh, start it up, WOT it and read it. Does that tell you idle, mid range? Nope. Just that it was "right" at WOT and therefore MAYBE right at all others. Way too imprecise for me. In my car, I can datalog and see what it is doing. We can also make adjustments to the curve at the right points instead of a "one size fits all" solution. Also checking the carb is way too subjective for my comfort level. I'd much rather have a screen output that shows me as opposed to what looks, sounds or feels ok.
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  #13  
Old 09-02-2013, 01:38 PM
t walgamuth's Avatar
dieselarchitect
 
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Yeah you used to crap your pants too.....and some of us happen to have cars and other devices which have carbs on them so this thread is helpful to all who do.
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.
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  #14  
Old 09-02-2013, 01:43 PM
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Quote:
Originally Posted by t walgamuth View Post
Yeah you used to crap your pants too.....and some of us happen to have cars and other devices which have carbs on them so this thread is helpful to all who do.
Not sure if you still do but I don't anymore. When that day comes where I restart it, probably best to be scrapped then. At this point, you couldn't give me a car or a power toy with a carb unless I could sell it to some sucker who wants it. As I said, I only tolerate it in the lawn equipment because there isn't a finacially feasible choice or it too would be gone like a pair of underwear that someone sharted on.
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01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow
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  #15  
Old 09-02-2013, 03:55 PM
Posting since Jan 2000
 
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Tuning carbs is simple albeit time consuming once you understand the basic subsystems found in all carbs.

Assuming timing advance systems are working correctly, your problem can be a too lean main jet or more likely something to do with the power system. If the carb has a vacuum secondary, that could be your problem, but most 650 hollers have mechanical secondaries.

There is a book, published by HP Books, that has been in print for over 40 years. I think it is called Holley Carburetors. It is an EXCELLENT book for learning the principles of carburetion, and the specifics of Holleys. Regardless of what carb you are messing with, this book will teach you the principles that you need to understand.

The subsystems in a carb interact, so if you don't understand the principles, you will be chasing your tail.

Hope this helps.

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