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Topic: Q-JET

in Forum: C3 Engines


Q-JET

Posted: 4/20/05 7:15am Message 1 of 5
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BINGHAMTON, NY - USA
Joined: 7/19/2003
Posts: 3808
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Well I did it,I pulled the carb off yesterday,dissassembled it ,soaked it in carb cleaner,rinsed it, blew it all out,dried it,reassembled it,with no parts left over I might add,and put it back on the Vette,still needs a little adjustment.it sure is a lot cleaner,the car runs better already,$20.00  for the kit and the carb cleaner,sure beats $300.00 + for a new or rebuilt Q-JET


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Q-JET

Posted: 4/20/05 11:54am Message 2 of 5
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CUYAHOGA FALLS, OH - USA
Joined: 12/2/2003
Posts: 6424
Vette(s): 1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!
Good news.  If you have trouble adjusting it, let me know and I can help.


Q-JET

Posted: 4/20/05 2:20pm Message 3 of 5
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BINGHAMTON, NY - USA
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O.K.,I haven't adjusted it yet,and the mixture screws are open and accessible,no plugs or block off plates in the way,Tell me the adjustment procedure ,oh ZEN MASTER,please


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Q-JET

Posted: 4/20/05 7:01pm Message 4 of 5
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CUYAHOGA FALLS, OH - USA
Joined: 12/2/2003
Posts: 6424
Vette(s): 1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!

Get the engine fully warmed up, and make sure it is not on fast idle.  Set the idle speed.

Now turn the mixture screws out an equal amount.  About 3 turns is a good point.   Connect a vacuum gauge and tach.   Turn both screws in about a 1/4 turn.  Just make sure they are even.  If the engine speeds up, go another 1/4.  If it slows down, turn them back out.

Keep going either direction that both raises rpm and vacuum until it levels off.  If you go to far it will drop again.  Find that peak rpm and vacuum point.  You will find there is a slight "dead spot" where it does not seem to make any difference.  Turn the screws in as far as possible without creating any drop in vac or rpm.  At this point you may find the screws ideal postion are not the same.  A small difference is okay.

Reset the idle, and recheck the mixtures screws if the idle was more than about 50 rpm off.  If the idle is now still okay, the mixture is set.

Open the throttle slightly to set the choke fast idle on the fast idle cam.  Ususally the second step of the cam is specfied, but check the spec for your car.  It will be in the rebuild spec sheet.  Turn the fast idle screw to set the speed.  Slightly open the throttle and release the fast idle.

Go back to my article on Ben's web site and look at the choke adjustments.  The choke coil is just a starting point you may need to tweak.  If the choke opens too fast during cold start up, tighten it about 2 notches on the cover.  If it stays on fast idle too long, loosen it 2 notches.  Then look at the choke pulloff adjustment as well.  If the car runs to rich and wants to load up when first started, set the pulloff to open more,  If it bogs cold on gradual acelleration, close it a bit.

Don't forget to set the secondary air flap spring tension.  This is also highlighted in the article for the procedure.  With there is a adjustment spec in the carb spec you have.  But after that play with it.  Just slightly back off tension a little at a time until the car starts to hesitate or bog on hard acelleration when the secondaries open.  Then tighten it up a tiny amount until the bog quits and response is good.  This will give you the maximum secondary throttle response. No bog, quicker opening.

DRIVE THAT CRITTER!




Q-JET

Posted: 4/21/05 4:07am Message 5 of 5
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BINGHAMTON, NY - USA
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Thanks;KEN


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in Forum: C3 Engines


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