Leaking Holley
Thread Starter
Racer
Joined: Aug 2000
Posts: 349
Likes: 1
From: Hofheim Germany
After disassemled, re-assembled and re-installed my center-carb for the x-th time, there is no chance to adjust correct idle-speed by the idle-micture-screws. With the screws completly in seat (where engine should almost stall) there is a quite satisfying idle-speed. Turning them out will make idle go down! Seems, that engine gets some fuel from another point. All seals are new (the good blue ones) and correct installed. Has anyone an idea, what could be the reason for that?
Desperate regards
Gerrit
Desperate regards
Gerrit
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Educate me on how a Tri-Power works. You have three- two barrel carbs. The center carb does most of the idling chores, correct? The two outside carbs are for extra fuel / power during advance throttle movement, correct?. You keep saying the engine gets some fuel from another source besides the primary center carb. Why wouldn't the outside carbs add fuel at idle?
On a four barrel, the idle mixture screws turned in fully should stall the engine. Unless the secondary's throttle is cracked open ever so slightly. On a Holley 4Brl the secondary's do contribute to the idle system to keep the fuel fresh in the secondary fuel bowl. Having said that, why wouldn't your other two carbs have a idle circuit also? So all six barrels are adding fuel at idle? IDK
On a four barrel, the idle mixture screws turned in fully should stall the engine. Unless the secondary's throttle is cracked open ever so slightly. On a Holley 4Brl the secondary's do contribute to the idle system to keep the fuel fresh in the secondary fuel bowl. Having said that, why wouldn't your other two carbs have a idle circuit also? So all six barrels are adding fuel at idle? IDK
Burning Brakes
Joined: Jul 2016
Posts: 767
Likes: 74
From: Blaine MN
After disassemled, re-assembled and re-installed my center-carb for the x-th time, there is no chance to adjust correct idle-speed by the idle-micture-screws. With the screws completly in seat (where engine should almost stall) there is a quite satisfying idle-speed. Turning them out will make idle go down! Seems, that engine gets some fuel from another point. All seals are new (the good blue ones) and correct installed. Has anyone an idea, what could be the reason for that?
Desperate regards
Gerrit
Desperate regards
Gerrit
It is possible for the idle speed to drop if you open the needles too far, the mixture becomes overly rich. Do you have the correct Carb Base to Manifold gasket installed? The Center Carb location has an area on the Manifold that has a passage for the PCV vacuum source, the passage must be completely covered by Gasket Material. Some of the Gaskets I bought recently didn't cover that area completely and caused me similar issues. If you can, post some pictures of the Throttle Plate to Idle Transfer Slot area. I'd like to see how much of the Transfer Slot is exposed, if it's too much you won't be able to get the idle set right as the Transfer Slot Fuel is not controlled by the needles. A vacuum leak can cause your symptom as you end up using the Transfer Slot Fuel by turning the Idle Speed Screw more open to counter the leak because your leak is below the Thottle Plates and actually lowers the Vac. signal to the Idle Circuit.
Last edited by suprspooky; Oct 5, 2018 at 04:30 PM.
Burning Brakes
Joined: Jul 2016
Posts: 767
Likes: 74
From: Blaine MN
Educate me on how a Tri-Power works. You have three- two barrel carbs. The center carb does most of the idling chores, correct? The two outside carbs are for extra fuel / power during advance throttle movement, correct?. You keep saying the engine gets some fuel from another source besides the primary center carb. Why wouldn't the outside carbs add fuel at idle?
On a four barrel, the idle mixture screws turned in fully should stall the engine. Unless the secondary's throttle is cracked open ever so slightly. On a Holley 4Brl the secondary's do contribute to the idle system to keep the fuel fresh in the secondary fuel bowl. Having said that, why wouldn't your other two carbs have a idle circuit also? So all six barrels are adding fuel at idle? IDK
On a four barrel, the idle mixture screws turned in fully should stall the engine. Unless the secondary's throttle is cracked open ever so slightly. On a Holley 4Brl the secondary's do contribute to the idle system to keep the fuel fresh in the secondary fuel bowl. Having said that, why wouldn't your other two carbs have a idle circuit also? So all six barrels are adding fuel at idle? IDK
Thread Starter
Racer
Joined: Aug 2000
Posts: 349
Likes: 1
From: Hofheim Germany
Thanks once more for your valuable informations!
The gasket under the cc is new and of the correct shape. It covers the transfer-slot as it should. The carb-setup is completely re-installed by now, so I can't make pics (until I take it off for the 1.23458th time).
But I found out two other things:
1. the throttle-plates of the fc did not close completely, caused by a slight unevenness on either the plates or the tube. I've equalized that, so they close completely now.
2. - and that was probably the reason, that somtimes idle was too high - was the linkage from the cc to the secondaries: Not, that the linkage didn't close the secondaries complete, but the screw, what connects the links from the cc to the outers, was not straight in line, but in an angle, that blocks the linkage while in rest-position. Obviously that causes idle to be too high sometimes, because it prevents the throttle-linkage to come to rest-position completely. Now, that I have re-adjustetd the linkage in a way, that gives the "connection-screw" a full free movement, idle seems to be more stable. I have to try out for a few days (and rides), wether the problem ist solved.
Anyway: turning the idle-mixture-screws to their seat will make the idle come down, but nowhere near stalling.
Gerrit
The gasket under the cc is new and of the correct shape. It covers the transfer-slot as it should. The carb-setup is completely re-installed by now, so I can't make pics (until I take it off for the 1.23458th time).
But I found out two other things:
1. the throttle-plates of the fc did not close completely, caused by a slight unevenness on either the plates or the tube. I've equalized that, so they close completely now.
2. - and that was probably the reason, that somtimes idle was too high - was the linkage from the cc to the secondaries: Not, that the linkage didn't close the secondaries complete, but the screw, what connects the links from the cc to the outers, was not straight in line, but in an angle, that blocks the linkage while in rest-position. Obviously that causes idle to be too high sometimes, because it prevents the throttle-linkage to come to rest-position completely. Now, that I have re-adjustetd the linkage in a way, that gives the "connection-screw" a full free movement, idle seems to be more stable. I have to try out for a few days (and rides), wether the problem ist solved.
Anyway: turning the idle-mixture-screws to their seat will make the idle come down, but nowhere near stalling.
Gerrit
Thread Starter
Racer
Joined: Aug 2000
Posts: 349
Likes: 1
From: Hofheim Germany
But if they work - and indeed: most time they do - it is a tremendous feeling, when the secondaries open (especially on the Autobahn). When driving 130+ mph (yes, we can 
) and let Audis disappear in the mirror, I'm proud to have a Tripower!!!! It is a feeling, as if an afterburner fires in. I'm sure "Suprspooky" will agree to that (though he can't drive such fast legaly in the U.S.).
Powerfull regards
Gerrit
) and let Audis disappear in the mirror, I'm proud to have a Tripower!!!! It is a feeling, as if an afterburner fires in. I'm sure "Suprspooky" will agree to that (though he can't drive such fast legaly in the U.S.).Powerfull regards
Gerrit
