Holley 2818 choke vacuum break adjustment

[Dominic B.]

I am trying to set the vacuum break adjustment on my holley 2818 and not sure about the drill size (gauge) to use in the air horn.

Can someone with a 1965 service manual check and tell me what drill size is used, if it's checked in the top or bottom of the choke plate and where to adjust the intergal choke. I am not sure if the rod gets bent or something else inside the intregal choke.

TIA, Tim Barbieri

[Wayne M.]

Re: Holley 2818 choke vacuum break adjustment

I am trying to set the vacuum break adjustment on my holley 2818 and not sure about the drill size (gauge) to use in the air horn.

Can someone with a 1965 service manual check and tell me what drill size is used, if it's checked in the top or bottom of the choke plate and where to adjust the intergal choke. I am not sure if the rod gets bent or something else inside the intregal choke. ..................

Tim -- I've never done this operation on my 2818's, but here's what the '65 Corvette Shop Manual has to say: Choke Unloader; 0.180 min (3/16" drill). measure opening between choke valve lower edge and the air horn with the drill rod. If necessary to adjust, bend rod at off-set bend.

[Dominic B.]

Re: Holley 2818 choke vacuum break adjustment

Wayne,

What does the manual say about the choke vacuum break setting, that's what I am working on.

Thanks, Tim

[John H.]

Re: Holley 2818 choke vacuum break adjustment

I am trying to set the vacuum break adjustment on my holley 2818 and not sure about the drill size (gauge) to use in the air horn.

Can someone with a 1965 service manual check and tell me what drill size is used, if it's checked in the top or bottom of the choke plate and where to adjust the intergal choke. I am not sure if the rod gets bent or something else inside the intregal choke.

TIA, Tim Barbieri

Tim -

It's a 3/16" drill, and the gap is between the bottom edge of the choke blade and the air horn; it's adjusted by bending the wire choke rod (item #22 in the diagram below) between the choke housing shaft lever and the choke blade shaft.

[Dominic B.]

Re: Holley 2818 choke vacuum break adjustment

Thanks Wayne & John. Worked out great! Can you tell me what the recommended choke coil setting should be?

Tim

[Timothy B.]

Re: Holley 2818 choke vacuum break adjustment

I wanted to visit this adjustment again as I have a few questions.

If I understand correctly there is no vacuum break piston adjustment like the Carter carburetors, the Carters set the vacuum break piston then in another adjustment set the unloader. The Holley 2818 is set by adjusting the unloader setting to approx .180 min. and bending the wire rod as stated above which sets the vacuum break also, is that correct?

Second, if I close the choke and the fast idle sets, there seems to be one higher step on the fast idle cam. I am not sure if that's just the top of the plastic cam or this choke is not setting on the highest step. Can someone help me there because the wire rod is what lifts the plastic fast idle cam and I want to be sure it's setting at the highest idle position with full closed choke before setting rpm. The way this choke is setting there is the fast idle then three steps down with the last step = curb idle.

My next question is to confirm fast idle RPM setting with engine warm at 22-2300rpm (L-79), is this correct? I am not sure if this adjustment is made on the highest step of the cam (which I would have to manually lift) or the next highest step that this choke is setting at as in my second question.

Finally, what's the choke coil setting according to the book? Does the little round loop in the choke coil capture the end of the lever that sticks out or just push against it like the Carter. Seems like it captures it very nice IMO but I want to be sure.

Thanks for all the help, Tim

[Wayne M.]

Re: Holley 2818 choke vacuum break adjustment

..... My next question is to confirm fast idle RPM setting with engine warm at 22-2300rpm (L-79), is this correct? I am not sure if this adjustment is made on the highest step of the cam (which I would have to manually lift) or the next highest step that this choke is setting at as in my second question.

Finally, what's the choke coil setting according to the book? Does the little round loop in the choke coil capture the end of the lever that sticks out or just push against it like the Carter. Seems like it captures it very nice IMO but I want to be sure. ..............

Tim -- you've forced me to look at a '64 2818 I've had on my bench for a few years (pic below) . OK; fast idle spec is 22-2300 rpm (as you've said), with fast idle screw on high step of cam. [from shop manual] "Open throttle slightly and lift fast idle cam up and let throttle close with fast idle screw on high step of cam. Adjust fast idle screw (1/4" open end wrench) to obtain specified engine RPM; then repeat the lifting cam thingy to verify your adjustment". Same procedure for L79 or L76.

Yes, the loop on the end of the bimetallic coil spring slips over the tang that projects from the slot in the circular full gasket. Holley handbook says "to rotate bakelite housing back and forth before tightening retainer -- the choke plate should move as you do so"; (verifies capture of loop). Tighten with choke setting 1 notch to the lean side.

I'll see if I can answer your first paragraph, but it'll take a little more fooling around with what I've got.




X

[Timothy B.]

Re: Holley 2818 choke vacuum break adjustment

Thanks Wayne,

I appreciate all the information you can give me about this choke setting.

This full circular gasket with the slot is not metal like the AFB carburetor it's gasket material, correct? If you can post a picture of this gasket I can check to see if I have one.

[John H.]

Re: Holley 2818 choke vacuum break adjustment

Thanks Wayne,

I appreciate all the information you can give me about this choke setting.

This full circular gasket with the slot is not metal like the AFB carburetor it's gasket material, correct? If you can post a picture of this gasket I can check to see if I have one.

Tim -

See item #4 in the diagram I posted above for the circular gasket. The "clock" setting of the cover (item #3) determines which step of the fast idle cam is engaged when you "set" the choke.

[Wayne M.]

Re: Holley 2818 choke vacuum break adjustment

....This full circular gasket with the slot is not metal like the AFB carburetor it's gasket material, correct? If you can post a picture of this gasket I can check to see if I have one.

Tim -- Here it is; the grey fiber disk (John H.'s item 4) is really stiff. You can also see the top of the piston.

[Timothy B.]

Re: Holley 2818 choke vacuum break adjustment

Thanks again Wayne and John,

Wayne, I have one of those full round gaskets with a slot in some left over carburetor kit parts. Currently there is a round gasket but it's not a full gasket with a slot. I assume the full gasket has something to do with holding heat in for the choke coil.

As asked in my post #6, I just want to be sure when the choke is full closed that the highest step is setting on the fast idle cam. This plastic fast idle cam is lifted by the wire rod so the choke unloader adjustment which is set by rod lengh is important as it controls unloader and fast idle cam position. I seem to have another higher step left on the cam so I need to recheck unloader/rod adjustment.

I appreciate all the help,