Holley Avenger 870 orafice sizes

[rgalajda]

Got a List 80531 850 VS Holley, Build date 3457(2007 ?), on my bench yesterday. Apparently off a 502 Crate engine. Amazing original condition that I bought for $260.
This is a 2 corner idle carb with electric choke. Choke horn is the short version similar to 850 models.

Here are the specs.
Downleg boosters
!.56 venturi
1.75 throttle bore #180 plates
330 pink cam #1 location
.040 squirter
Jets 76 primary 82 secondary

Primary metering block 11981 ( main well has plugs at top, not deep) 2" whistle
Kill bleed .027 at #8 upper dog leg location
IFR .036 lower location #25
Emulsion .027
Emulsion .027
Power Valve 4.5
PVRC .046

Secondary metering block 11697 ( main well has plugs at top, not deep) 2" whistle
no kill bleed
IFR .037 lower location
Emulsion .027
Emulsion .027
Power Valve 3.5
PVRC .059

Main Body
PIAB .072
PHSAB .035

SIAB .027
SHSAB .027

Brass tube in primary venturi for Vacuum Secondaries
.186 check ball with grooved seat below
Pink spring measure 1.9 inches

Weight of carb feels like zinc with chromate finish, not aluminum.
Note that the Holley carb numerical chart venturi and throttle plate specs are incorrect just like the 80870 Holley, which lists these carbs as having a 1 3/8 venturi with 1 11/16 throttle bore
I believe your 80870 was also used on a crate engine.
I will be testing this carb on my BBC 454/500 hp engine in the original configuration shortly. I will report some AFR results.

[Papastoy72]

Just a FYI,
Some of the early 870' carbs used the externally sourced vacuum choke housings for pull-off vs housings using a drilled passage in the carb. Ran into that with the one I have as the passage wasn't drilled. Don't know if this applies to the 531' version.

[1969Camaro]

Is this the vacuum choke you talk about? What is it hooked to

[Papastoy72]

Yes, that's the external vacuum version. You will need to "T" that small nipple into a manifold vacuum source. The vacuum is for the choke pull-off piston in the choke housing.The older Holley website pic's showed that nipple "T-ed" into the manifold vacuum port.

[57 210]

Those pictures are electric choke pictures and that brass port with a screen pulls in air to cool the bimetallic spring that operates the choke. Otherwise the spring will overheat. there is a port on the back of the choke body that uses a gasket to seal a vacuum port in the carb body. Make sure it is open when using the choke and sealed when there is no choke body installed.

[GTO Geoff]

That is much more likely to be a vacuum port, for a number of reasons. If it was for cooling, there would be no need to swage the end of it. It is there for retro-fitted elec hokes on carbs that did not originally have a choke...& need a vac source. Also, the bimetal strip only has current applied for a very short time, no need for cooling.

[57 210]

that choke casting has a hole on the back that meats a vacuum port on the main body. when you take off the manual choke
casting there is a small gasket that seals the two. there is no provision for a vacuum piston to operate the choke, its operated by the bi-metalic spring. There is constant fused 12 volts to the choke housing electric tab on the right side of the housing. It is not interrupted or only on for a short time. The bi-metalic spring heats up and opens the choke and holds it open till it cools off when you turn off the electric feed from the engine run position. If the carb is run with no choke housing that vacuum port on the main body should be plugged.

[tbarb]

I agree with everything 210 say's but if there is no vacuum choke pull off piston inside the electric hot air choke housing where is the choke pull off?

[GTO Geoff]

Sorry, 57 2210, totally wrong.
[1] The choke is not switched off when the ign is turned off after driving the car. The Bimetal strip resets itself to the 'off' position after a fixed period of time, determined by the lean/rich adjustment. If the the bimetal strip current was determined by when the engine is switched off, it could be on for hours if the car is driven for hours.

[2] The choke housing DOES contain a vacuum piston. You can see the piston housing, jutting out bottom right of the choke housing.

[57 210]

tbarb
The metal housing is most likely configured for either electric or other type of operation as determined by the manufacturer. The plastic housing with the two electric tabs has a bi-metalic spring that slowly opens when the engine is turned on. The positive feed
is fused to the run position of the car. The bi-metalic stays activated as long as the engine is in the run position, it is not harmed, just like a ballast resister is not harmed.
The spring has a loop at the end that hooks to a lever that connects to a piston inside the housing. It is connected to the choke lever activator rod. As the spring slowly expands it holds the choke open. The cover can be moved to adjust for different tempeture conditions.