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Author
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Topic: Help tunning Holley 600
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66 Racer
Journeyman Posts: 77
From: West Covina, California
Registered: Aug 2001
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posted 08-07-2001 10:07 PM
   
Hey,I have a 289 V8 with a holley 600 cfm 4 bbl carb. Im no expert to tunning carbs, well no experience, but i want to learn. My carb needs tunning so I wanted to mess with it, any tips? I used to tune little .12-.15 2 stroke engines with 3 needle carbs so i have some basic knowledge about carbs, i was good with those so im hoping i can transfer some of that knowledge and the "ear" for finding the optimum performance setting. I have only been able to find 3 needles on my carb, im sure there are more on my carb, i found the idle needle which needed to be opened a bit, and then I also found two little screws/needles torwards the front of the carb on each end. Any tips will be greatly appriciated. A general explanation on the effect of rich and lean on these engines would be good too. I worked with .12 engines off radio controlled cars which I believe are the opposite that 4 stroke V8 blocks, since leaner meant more power on them. They also ran about 20% nitro mixtures. Thanks a lot, i enjoyed messing with carbs on those little 2 strokes and want to do the same on my stang! ---Anthony ------------------
Under Construction 66 Coupe 289 V8 - 600cfm Holley - Tri-Y Headers - Flowmaster 2.5 dual exaust - Centerforce clutch
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steve'66
Gearhead Posts: 8754
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 08-07-2001 10:17 PM
Anthony,The needle valves that you are seeing are the idle speed and the idle metering screws. Adjust the two idle mixture screws for max vacumm, and the idle speed srew to about 650 rpm. The real adjustments in a holley are internal.  SteveW
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66 Racer
Journeyman Posts: 77
From: West Covina, California
Registered: Aug 2001
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posted 08-07-2001 11:00 PM
Ok, well, how far do I go, like how many turns from closed on the idle mixture scews. On the idle speed screw i dont have a method of measuring RPMs so a general setting would help, I had to increase the RPMs a bit today to keep it running at idle, but right now its running more RPMs than needed. I need to tune it down a bit, but i think it goes to what you said about the idle mixture screws. About the mixture screws as well, does one have an effect on each element, or does each one control both fuel and air but just on different barrels. One last thing, are there any other needles that can be accesed from the outside of the carb. Also about the internal adjustments, to adjust anything else i would have to actually take the carb apart? By the way what kinds of mixture controls are in there. Thanks ------------------
Under Construction 66 Coupe 289 V8 - 600cfm Holley - Tri-Y Headers - Flowmaster 2.5 dual exaust - Centerforce clutch
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steve'66
Gearhead Posts: 8754
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 08-07-2001 11:41 PM
OK,Start by buying a vac. gauge and a tach. The starting point for the idle screws is 1 1/2 turns out. Adjust each 1/4 turn at a time until you have the max vac at idle. Then lower your idle speed and do it again. The internal "adjustments" control what it does above idle! The jetting and power valves control the real mixture settings. SteveW
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kcode
Gearhead Posts: 2983
From: alvaton,ky,usa Suburb of Bowling Green, M&M #79, MCA #29208
Registered: Jun 99
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posted 08-07-2001 11:47 PM
Externally, without disassembling the carb, you are limited on adjustments. With out any gauges you can set the idle/air mixture. To adjust, there are two small brass colored screws in the front metering block, one on each side. Screw one in lightly until you feel a slight resistence, the motor will probably be stumbling, then back it out 1.5 turns. Do the same on the other side, this is a good starting point. You can also check your float level, on the passenger side there will be a brass screw about 1/2 inch in diameter, if you remove it, you can see in the fuel bowl, the fuel level should be that fuel will just "trickle" out of the sight plug hole. To adjust the fuel level, buy a Holley manual, its alittle difficult to put into words, a picture is worth 1000 words. Good luck Mike
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66 Racer
Journeyman Posts: 77
From: West Covina, California
Registered: Aug 2001
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posted 08-08-2001 05:29 PM
Thanks for this help guys. Im gonna talk to this guy i now to see if he can help me out with the internal adjustments.Thanks againe ------------------
Under Construction 66 Coupe 289 V8 - 600cfm Holley - Tri-Y Headers - Flowmaster 2.5 dual exaust - Centerforce clutch
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