Help Messed up Carb
Thread Starter
Drifting
Joined: May 2004
Posts: 1,258
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From: Huntsville Alabama
Help Messed up Carb
Ok so i tried what the holley tech. recommended and what was recommended on here and that is adjusting the Transfer plates on my holley carb. Now the a/f screws when you try to richen or lean the carb make no difference. This carb is driving me nuts i have been fighting off idle hestation for a long time it went away with the biggest pump cam but the car sometimes flooded. The specs listed are what the carb was at from holley but the throttle blades have been adjusted to try and so what the holley tech said and have a .020 transition. I have messed up though.
Can someone walk me through the procedure of adjusting the transfer slots and how do you use a feeler gauge on them to get the .020 that is recommended.
Carb
Holley 750 Vacuum Secondary
pt. no. 0-80508S
Primary jets 72
Secondary metering plate 21
Power Valve 6.5
Acc. Pump 30cc Orange pump cam
Float lever is set to correct to just right at the sight hole
Thanks in advance
Can someone walk me through the procedure of adjusting the transfer slots and how do you use a feeler gauge on them to get the .020 that is recommended.
Carb
Holley 750 Vacuum Secondary
pt. no. 0-80508S
Primary jets 72
Secondary metering plate 21
Power Valve 6.5
Acc. Pump 30cc Orange pump cam
Float lever is set to correct to just right at the sight hole
Thanks in advance
Race Director
Joined: Jan 2000
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From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
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Close throttle plates all the way first....back out screws. Make sure they close all the way and there is no light showing around blades.
Then adjust them open until the transition slots just barely start to uncover. They are the vertical slots in the main body on the outside of throttle bores. You really can't use a feeler gauge unless you have the round wire type. The easist way I can tell you is to adjust where you just barely see the lower edge of slot. Make it where the part showing is a *square*...not a *rectangle* if that makes sense. The slot showing should be about as tall as it is wide.
That should get idle screws back in the game.
JIM
Then adjust them open until the transition slots just barely start to uncover. They are the vertical slots in the main body on the outside of throttle bores. You really can't use a feeler gauge unless you have the round wire type. The easist way I can tell you is to adjust where you just barely see the lower edge of slot. Make it where the part showing is a *square*...not a *rectangle* if that makes sense. The slot showing should be about as tall as it is wide.
That should get idle screws back in the game.
JIM
Thread Starter
Drifting
Joined: May 2004
Posts: 1,258
Likes: 0
From: Huntsville Alabama
ok thanks. another question though I know there is only one screw that opens and closes the secondary plates, but on the primary plates is it just the curb idle screw or do i have to adjust the fast idle screw along with that to get the primary to close back down.
Race Director
Joined: Jan 2000
Posts: 13,022
Likes: 2,265
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
You'll have to have choke linkage in *open* position so the regular idle screw can be adjusted to close blades up. The high idle screw in choke mechanism should be doing nothing through all of this.
BTW- I always remove the sec throttle stop screw and install it from the top side. That way you can play with it without pulling carb off.
JIM
BTW- I always remove the sec throttle stop screw and install it from the top side. That way you can play with it without pulling carb off.
JIM
Thread Starter
Drifting
Joined: May 2004
Posts: 1,258
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From: Huntsville Alabama
cool thanks I got everything adjusted and changed the screw car now idles at 600 and when you put it in drive it does not have a bad rpm change like it had. I sitll have a slight hesitation off idle that i am fight and have been for quite some time. The next question is how do you go about adjusting the pump lever to get the .015 that holley recommends I have it lashed at idle but do not know how to use my feeler gauges to get the .015 at wot.
Thread Starter
Drifting
Joined: May 2004
Posts: 1,258
Likes: 0
From: Huntsville Alabama
ok got the lever speced out correct. Still have my hesitatoin. I think its because of the power valve. I used my vac. gauage and my vaccum is about 10 the needle jumps a little but looks to be right at 10. The specs on my motor are 355 vortec heads rpm airgap intake 9.5:1 comp. The cam is a hydrollic roller 218/228 @ .050 .520 lift its basically the gm hot cam. If i am reading my super tuning and modifying holley book and the holley site correct you are supposed to take the vaccum reading you get and divide by 2 to get the power valve. The pv in there now is a 6.5 so if my vac is at 10 i would need a 5 pv correct? The 10hg vac reading is with the car warm and idling in drive.
