Quadrajet Question

[pontiacgp]

On my 800 cfm quadrajet I have changed the hot air choke to electric because my intake does not have the provisions for the hot air. I would rather use the hot air choke cause I think it's more accurate than the electric. Reading Cliff's book the he suggests to block the air passage to the carb in the choke housing if I am converting it to electric. I was under the impression the carb was set up to use that air and it should not be blocked off. Anyone have any opinions on leaving the hole open or plugging it?

 

[Dayzedandkonfuzed]

I can't give you a for sure answer, but I've got 3 of these carbs in my collection and they're all plugged.

 

[pontiacgp]

I can't give you a for sure answer, but I've got 3 of these carbs in my collection and they're all plugged.

thanks....

 

[techg8]

plug it. The difference would be minor, but it would be there.

 

[pontiacgp]

Thanks....I'll plug it tomorrow cause I have to remove the choke coil anyway. The electric choke coil didn't seem to be operating correctly and thanks to Cliff's book to remind me shifting the hot air coil to the electric coil I need to remove the gasket on the housing for the hot air coil cause the electric coil uses that surface of the housing the ground the coil.....

 

[airboatgreg]

Go with the electric choke. You can block the vacuum passage easily with a lead fishing split shot tapped in the passage. Think about where you feed the 12 volts to power the choke coil though. Some models used a choke relay fed by the alternator and others fed current through the oil pressure switch.

 

[pontiacgp]

Go with the electric choke. You can block the vacuum passage easily with a lead fishing split shot tapped in the passage. Think about where you feed the 12 volts to power the choke coil though. Some models used a choke relay fed by the alternator and others fed current through the oil pressure switch.

I had an electric choke, this "new" carb came with a hot air coil but I don't have the set up on my intake which is too bad so I'm using the electric coil but I forgot to remove the gasket.

 

[Quadrajet Power]

Electric choke should have the vacuum plugged, or it is a vacuum leak. Hot air of course needs it open to pull air through.

If you convert hot air to electric and block the vacuum, it is possible that you will need to add some bypass air for it to idle correctly. Test it for proper idle and go from there.

 

[pontiacgp]

Electric choke should have the vacuum plugged, or it is a vacuum leak. Hot air of course needs it open to pull air through.

If you convert hot air to electric and block the vacuum, it is possible that you will need to add some bypass air for it to idle correctly. Test it for proper idle and go from there.

it's still a "vacuum" leak with the hot air coil installed, the carburetor is set up to use that amount of air so leaving it open should have no effect. because whether the choke is on or off the same amount of air is present. I was surprised to read in Cliff's book the suggestion to plug the hole. I'm going to plug the hole tomorrow and my A/F mixture gauge will let me know if it affects anything

 

[Quadrajet Power]

You are correct, but it is a controlled vacuum leak when connected to hot air coil. Brake booster is a vacuum leak also, but controlled as well. Not the same as leaving it open. All open vacuum ports should be used or plugged.
As I mentioned, you might possibly need to create some additional bypass air if you have a modified engine. Stock will probably be fine without needing additional bypass.