Holley secondary blade adjustment

[cabledog]

Hello. I need to adjust the vacuum secondary throttle blades to allow more air in so I can close down the primaries. How far can I go before engaging transition slot? Is it the same as primaries with the square method? Does the transition slot pull fuel at idle or only when the secondary vacuum is engaged? Sorry if this is a dumb question but I'm still learning. Thanks!

 

[Fran Blacker]

Not sure all Holley carb have an adjust for secondarys but turn carb up side down there could be a small adjustment screw. 3/32 or 1/8" slotted screw. Have them on my 3116 carbs.

 

[cabledog]

Not sure all Holley carb have an adjust for secondarys but turn carb up side down there could be a small adjustment screw. 3/32 or 1/8" slotted screw. Have them on my 3116 carbs.

I adjusted already but it seems like it needs even more air but I just don't know at what point it starts pulling in fuel or if it even will since the secondaries shouldn't be engaging until vacuum condition is met from what I think but I don't know how the transition slots work on the vacuum secondary side so that's why I asked here

 

[cabledog]

Also I do have a very large cam with only 6 inches of vac so I'm having to make outside the box adjustments to get the rich idle down. If I completely seat the mixture screws it doesn't turn the engine off and in fact idles even smoother.

 

[Fran Blacker]

Small hole at top of 1st pic is where mine is. second pic is the bottom of a 3116 carb.

 

[furryfrog]

The idle mixture screws only control fuel out of the office below the throttle plates, fuel will still come out the transfer slots. Sounds like you need to adjust your idle air bleeds and/or idle feed restrictors.You may need to drill some small holes in your throttle plates. I ve never had to tune a carb with 6 inches of vacume personally. Do you have a 4160?

 

[cabledog]

The idle mixture screws only control fuel out of the office below the throttle plates, fuel will still come out the transfer slots. Sounds like you need to adjust your idle air bleeds and/or idle feed restrictors.You may need to drill some small holes in your throttle plates. I ve never had to tune a carb with 6 inches of vacume personally. Do you have a 4160?

Yes it's a 4160. I don't think I can adjust the air bleeds on this one. It's an older 4160 from early 2000s I believe someone once said. I did think about doing the holes the throttle blades. So if I can close the mixture screw all the way and the idle evens out and doesn't die, it's getting too much fuel and I need to lean out the idle with the drilling or opening of the secondary blades right?

 

[cabledog]

The idle mixture screws only control fuel out of the office below the throttle plates, fuel will still come out the transfer slots. Sounds like you need to adjust your idle air bleeds and/or idle feed restrictors.You may need to drill some small holes in your throttle plates. I ve never had to tune a carb with 6 inches of vacume personally. Do you have a 4160?

Also I did increase the main jets from 76 to 80 due to white spark plugs. This wouldn't affect the idle circuit though right? And the way it was setup previously the primary blades were opened so much they were exposing the entire transfer slot and running super rich.

 

[Fran Blacker]

You could experiment with small pieces of wire in IFR's red arrows .020 or so. Bend wire L shaped.

 

[furryfrog]

https://www.hotrod.com/articles/tuning-holley-carb-made-easy

 

[cabledog]

So here is where I am. With throttle plates set correct I idled around 1100 rpm. But I can adjust the curb idle down to 850 and it idles fine. However, it still smells super rich and seating only one needle on the metering block has no effect but if I seat BOTH needles it will begin to stall.

What does that mean? I feel it still needs more air but I'm not an expert.

 

[cabledog]

You could experiment with small pieces of wire in IFR's red arrows .020 or so. Bend wire L shaped.View attachment 714831

I'm going to give this a try. Where can I get the wire that is that size?

 

[Crackedback]

Big cams need LOTS of initial timing...

 

[cabledog]

Big cams need LOTS of initial timing...

I'm at 18 initial 36 total. Do I need more?

 

[BSB67]

Hello. I need to adjust the vacuum secondary throttle blades to allow more air in so I can close down the primaries. How far can I go before engaging transition slot? Is it the same as primaries with the square method? Does the transition slot pull fuel at idle or only when the secondary vacuum is engaged? Sorry if this is a dumb question but I'm still learning. Thanks!

Maybe tell us a little about the motor, the cam, the heads, the intake, and the carb.

 

[62MAX]

So here is where I am. With throttle plates set correct I idled around 1100 rpm. But I can adjust the curb idle down to 850 and it idles fine. However, it still smells super rich and seating only one needle on the metering block has no effect but if I seat BOTH needles it will begin to stall.

What does that mean? I feel it still needs more air but I'm not an expert.

You know it can smell just as bad from being lean !!

 

[Fran Blacker]

I'm going to give this a try. Where can I get the wire that is that size?

I went around my garage with dial vernier calipers found wire. Phone wire door bell wire. The idle feeds on my carbs were huge .058. Race Hemi 3116 carbs, bought an NOS metering block for the carb same thing. Your IFR's could be smaller .039. You could check 12 gauge multi-strand wire or other gauges. Just experiment with different sizes, a Little light grease make it easier to keep them in place. The picture show a more permanent solution but experiment with wire to see if it helps. Set go in top tapped hole.

 

[Crackedback]

If he is turning the idle mix screws all the way in, and it still runs, nothing he does with the IFR is going to help as it's pulling fuel from somewhere other than the idle circuit.

Which camshaft is in the engine. If it's a big one in the 240+ at .050 range, 18 likely isn't enough idle timing.

To me, simple test. get it warmed up and idling, guessing BB, twist the distributor a little bit clockwise. If the engine picked up rpm, it wants the timing. I'll guess an MSD distributor with the black bushing? If so, you may need one of the 10 or 14* bushings I sell.

Get the idle timing correct, then the fuel/carb may come around. Common issue with big cams.

 

[Ratroaster]

"cdog", I'm going to be watching this thread with interest. I too have a rich running BB with 6" of vacuum at idle in gear. Was your's still running rich w/ 80 jets? What power
valve are you running? Thinking of trying a 2.5 PV and smaller jets.
Thanks.

RR