Racing Fuel Systems

Re: Holley Avenger 870 orafice sizes

2023-08-24T14:18:04+01:00

Rgalajda
Thanks for the update, good work.

Statistics: Posted by 57 210 — Thu Aug 24, 2023 2:18 pm

Re: Holley Avenger 870 orafice sizes

2023-08-24T11:26:21+01:00

Statistics: Posted by rgalajda — Thu Aug 24, 2023 11:26 am

Re: Holley Avenger 870 orafice sizes

2023-08-21T13:22:32+01:00

Statistics: Posted by rgalajda — Mon Aug 21, 2023 1:22 pm

Re: Holley Avenger 870 orafice sizes

2023-08-19T16:19:01+01:00

Statistics: Posted by 57 210 — Sat Aug 19, 2023 4:19 pm

Re: Holley Avenger 870 orafice sizes

2023-08-19T11:16:42+01:00

Statistics: Posted by tbarb — Sat Aug 19, 2023 11:16 am

Re: Holley Avenger 870 orafice sizes

2023-08-19T09:19:50+01:00

The vacuum has nothing to do with heat inside the choke hsg. The vac is applied to the piston. If the driver suddenly opens the throttle, with a cold engine & choke blade nearly closed, the engine will stall from lack of air. The sudden loss of vac to the piston allows the attached linkage to open the choke blade, preventing the engine from stalling.

Statistics: Posted by GTO Geoff — Sat Aug 19, 2023 9:19 am

Re: Holley Avenger 870 orafice sizes

2023-08-18T22:51:35+01:00

1969camaro
I would say the vacuum which comes from a small bleed hole, stabilizes the heat buildup inside the cover.

Statistics: Posted by 57 210 — Fri Aug 18, 2023 10:51 pm

Re: Holley Avenger 870 orafice sizes

2023-08-18T20:50:17+01:00

I get how the choke functions, what does the intake vacuum accomplish?

Statistics: Posted by 1969Camaro — Fri Aug 18, 2023 8:50 pm

Re: Holley Avenger 870 orafice sizes

2023-08-18T15:27:59+01:00

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.

Statistics: Posted by 57 210 — Fri Aug 18, 2023 3:27 pm

Re: Holley Avenger 870 orafice sizes

2023-08-18T06:37:18+01:00

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.

Statistics: Posted by GTO Geoff — Fri Aug 18, 2023 6:37 am

Re: Holley Avenger 870 orafice sizes

2023-08-18T00:45:28+01:00

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?

Statistics: Posted by tbarb — Fri Aug 18, 2023 12:45 am

Re: Holley Avenger 870 orafice sizes

2023-08-17T14:27:44+01:00

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.

Statistics: Posted by 57 210 — Thu Aug 17, 2023 2:27 pm

Re: Holley Avenger 870 orafice sizes

2023-08-17T07:03:44+01:00

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.

Statistics: Posted by GTO Geoff — Thu Aug 17, 2023 7:03 am

Re: Holley Avenger 870 orafice sizes

2023-08-16T18:05:47+01:00

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.

Statistics: Posted by 57 210 — Wed Aug 16, 2023 6:05 pm

Re: Holley Avenger 870 orafice sizes

2023-08-14T21:48:53+01:00

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.

Statistics: Posted by Papastoy72 — Mon Aug 14, 2023 9:48 pm