Author Topic: Need help! Replacing my q-jet electric choke coil  (Read 1197 times)

Offline leadlobber7

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Need help! Replacing my q-jet electric choke coil
« on: December 20, 2017, 09:33:42 PM »
1986 Chevrolet k30 454 4x4 th400

I was in the process of marking the choke position on my failed choke coil. And my helper finished taking out the three screws and pulled off the cap, then began messing with the linkage, high idle cam, so on and so forth. Problem is I have my new coil and I don't know where to begin with installing it on the choke housing because I wasn't able to mark housing before it was moved.

If nothing else can somebody send me an attachment of the original Rochester Quadrajet printed instructions on installing and setup of electric choke?

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Offline FlatBlack77

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Re: Need help! Replacing my q-jet electric choke coil
« Reply #1 on: December 20, 2017, 10:29:44 PM »
I used this video and a few others from the same guy
https://www.youtube.com/watch?v=9BCRPsLGMwo
"When you are a hammer, everything looks like a nail"
'77 C/10 - 350/350 mild street motor

Offline bd

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Re: Need help! Replacing my q-jet electric choke coil
« Reply #2 on: December 20, 2017, 10:51:33 PM »
The OEM choke thermostat should be indexed by a notch and tang that fixes it in position making it non-adjustable.  There are two basic designs.  One design uses a small aluminum tang cast directly into the inside rim of the t-stat housing that engages a matching square notch in the outer underside edge of the t-stat cover.  The second design uses a tanged retainer that engages a semi-circular notch on the outer top side edge of the t-stat cover.  In 1986, both electric and hot air choke t-stats were retained by three pop rivets and steel edge retainers instead of screws.  If the choke has been altered to make it adjustable, use the video link posted by FlatBlack.  For choke linkage adjustments, review the 6C1 section of the 1986 Service Manual.
Rich
It's difficult to know just how much you don't know, until you know it....
In other words... if people learn by making mistakes, by now I should know just about everything!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline bd

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Re: Need help! Replacing my q-jet electric choke coil
« Reply #3 on: December 20, 2017, 10:55:15 PM »
BTW - you need to purge your message inbox.  It's full.
Rich
It's difficult to know just how much you don't know, until you know it....
In other words... if people learn by making mistakes, by now I should know just about everything!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline leadlobber7

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Re: Need help! Replacing my q-jet electric choke coil
« Reply #4 on: December 20, 2017, 11:15:39 PM »
BTW - you need to purge your message inbox.  It's full.
thank you sir. It turns out that this carburetor is actually off of an rv 454 engine 80-84 from what I got from the 107 code on the carb body. It does have screws and retainer Clips on the outside of it and it is fully adjustable from the little tick marks on top of the cast aluminum choke body. I watched the video and was successful in getting it installed. But have no four barrel secondaries. Any ideas?

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Offline leadlobber7

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Re: Need help! Replacing my q-jet electric choke coil
« Reply #5 on: December 20, 2017, 11:20:44 PM »
I used this video and a few others from the same guy
https://www.youtube.com/watch?v=9BCRPsLGMwo
hey thanks man that was a big help

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Offline bd

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Re: Need help! Replacing my q-jet electric choke coil
« Reply #6 on: December 21, 2017, 09:18:46 AM »
... have no four barrel secondaries. Any ideas?

Is the choke plate opening all the way?  Make sure the secondary lockout is installed correctly and clearing the secondary throttle shaft pin.
Rich
It's difficult to know just how much you don't know, until you know it....
In other words... if people learn by making mistakes, by now I should know just about everything!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline leadlobber7

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Re: Need help! Replacing my q-jet electric choke coil
« Reply #7 on: December 21, 2017, 09:32:26 AM »
... have no four barrel secondaries. Any ideas?

Is the choke plate opening all the way?  Make sure the secondary lockout is installed correctly and clearing the secondary throttle shaft pin.
It is opening but not 90 degrees, probably 80 degrees after 15 min running high idle @ 1300 rpm. The lockout cam isn't all the way out of the way of the secondary shaft pin

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Offline bd

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Re: Need help! Replacing my q-jet electric choke coil
« Reply #8 on: December 21, 2017, 12:17:17 PM »
The secondary lockout is operated by the choke linkage.  Adjusting the choke for correct operation should restore proper function to the secondaries.

Does your carburetor use an electric or hot air choke?  An electric choke should open fully within about five minutes of engine running.  A hot air choke may take a little longer, dependent on the efficiency of heating and circulation of air through the choke housing and around the choke bimetal spring.


Edit:  A hot air choke is properly adjusted when the choke plate just closes with nominal tension from the bimetal spring at an ambient temperature between 60 - 80 F.
« Last Edit: December 21, 2017, 12:39:20 PM by bd »
Rich
It's difficult to know just how much you don't know, until you know it....
In other words... if people learn by making mistakes, by now I should know just about everything!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline leadlobber7

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Re: Need help! Replacing my q-jet electric choke coil
« Reply #9 on: December 21, 2017, 01:45:49 PM »
The secondary lockout is operated by the choke linkage.  Adjusting the choke for correct operation should restore proper function to the secondaries.

Does your carburetor use an electric or hot air choke?  An electric choke should open fully within about five minutes of engine running.  A hot air choke may take a little longer, dependent on the efficiency of heating and circulation of air through the choke housing and around the choke bimetal spring.


Edit:  A hot air choke is properly adjusted when the choke plate just closes with nominal tension from the bimetal spring at an ambient temperature between 60 - 80 F.
Ok. Maybe i need to lean it out a bit more on the adjustment of the linkage to get the secondaries to function.

It's an Electric choke.

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Offline bd

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Re: Need help! Replacing my q-jet electric choke coil
« Reply #10 on: December 21, 2017, 02:06:58 PM »
Verify that the choke element is receiving I+ (~14.2 volts) with the engine running and that the element is properly grounded through the choke housing to B- before fiddling with the adjustment.  If there is a problem with the supply voltage or ground to the choke element, adjusting the choke to compensate will be a disappointing compromise.  Make sure you didn't install a gasket between the choke element and its housing.
Rich
It's difficult to know just how much you don't know, until you know it....
In other words... if people learn by making mistakes, by now I should know just about everything!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline leadlobber7

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Re: Need help! Replacing my q-jet electric choke coil
« Reply #11 on: December 21, 2017, 02:41:28 PM »
Verify that the choke element is receiving I+ (~14.2 volts) with the engine running and that the element is properly grounded through the choke housing to B- before fiddling with the adjustment.  If there is a problem with the supply voltage or ground to the choke element, adjusting the choke to compensate will be a disappointing compromise.  Make sure you didn't install a gasket between the choke element and its housing.
Ok. Thanks!

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