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Unread 07-03-2010, 07:19 AM   #1
Newfie_Jeeper
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305 Chevy with Q-Jet

Hello All,

I've got a 305 chevy, (1984 I think) and SM465 in my YJ. It has the typical Rochester Q jet with E-Choke. I had carb rebuilt, new float and new E Choke and pull off.

Jeep runs great when warm or cold, but inconsistant starts.

I think the choke needs to open quicker.

If I turn on the key, pump the gas once, the engine starts and is smokey and rough for about 30 seconds of revving, then goes to its fast idle and is perfect from there on out.

If I turn the key on, pump the gas once to close the choke, and then wait 1 minute before I start the engine, it will start, go to its fast idle and not smoke.

Do I sound right about the choke setting, and how do I adjust?

Newfie

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Unread 07-03-2010, 04:02 PM   #2
colojeepguy
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Check to see if your choke pull-off is working properly.
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Unread 07-03-2010, 04:17 PM   #3
wushaw
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Black smoke? If so it sounds like it's getting too much fuel from the accelerator pump. Was the carb built to OEM specs, no jets drilled out or anything like that?
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Unread 07-03-2010, 10:13 PM   #4
jessnjon15
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im sorry to say it but a 305 is an atrocious engine, that could be the cause (not trying to bash, just in my dealings/experience its always been that way).

now if you got a 3" stroke crank from eaglerod.com & high comped/cammed it youd have something truly nasty (4.3 V8)
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Unread 07-03-2010, 11:44 PM   #5
jeepdaddy2000
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Quote:
Originally Posted by colojeepguy View Post
Check to see if your choke pull-off is working properly.
My thought as well....
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Unread 07-04-2010, 05:41 AM   #6
colojeepguy
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Quote:
Originally Posted by jessnjon15 View Post
im sorry to say it but a 305 is an atrocious engine, that could be the cause (not trying to bash, just in my dealings/experience its always been that way).

now if you got a 3" stroke crank from eaglerod.com & high comped/cammed it youd have something truly nasty (4.3 V8)
305 isn't the best engine chevy ever built, but it should provide adequate power for a YJ. A different cam & crank won't help the choke to work properly.
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Unread 07-04-2010, 07:25 PM   #7
wushaw
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Quote:
Originally Posted by jessnjon15 View Post
im sorry to say it but a 305 is an atrocious engine, that could be the cause (not trying to bash, just in my dealings/experience its always been that way).

now if you got a 3" stroke crank from eaglerod.com & high comped/cammed it youd have something truly nasty (4.3 V8)
I had one out of a 76 Monza that outlived that car, caught fire in a 67 chevy pu and after replacement of all gaskets & intake went into a 65 chevy pu and was sold a few years later still running great, no tellin how many miles on that motor, didn't burn oil and 155psi across the board on compression.

I do understand your general concensious of a 305 though they got a bad rap in the early 80's with a bunch of bad cams.

I am missing something on why would ya want to turn 305cid into 263cid?
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Unread 07-05-2010, 08:49 AM   #8
Dryseals
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Should be three screws on the choke housing, loosen them enough to turn the choke adjustment. The electronic choke uses a heat strip that warms with time. Easiest way to adjust, remove the air cleaner, do your one minute wait (don't crank the engine) and see where the choke position is. Let it cool down for at least an hour. loosen the three screws, set the choke (engine off) and adjust the choke to where it was after a minute. Tighten the screws.
The choke is bimetalic and will close more in colder weather, it's summer time, you should need a whole lot of choke.
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Unread 07-08-2010, 05:03 AM   #9
Newfie_Jeeper
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I had the carb rebuilt by a GM mechanic in his spare time, using napa kit, float, and e choke. My e choke has 3 rivits, not screws. I could drill them and replace if necessary

The engine does smoke ocassionally, especially when cold, but it doesnt smell like its burning oil, it smells rich.

I have a question about adjustment screws. The drivers side is for idle, and the screw on passenger side beneath the e choke adjusts your fast idle.

Right above the e choke, where pull off is (mine is on front pass side) there is an adustment screw to limit or allow the travel of the pull off when cold. COULD I HAVE THIS SCREW ADJUSTED WRONG? Any Idea on setting?

Thanks in advance,

Newfie
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Unread 07-08-2010, 07:38 AM   #10
colojeepguy
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Wait till your engine is cold. Take the air cleaner off & pump the accelerator linkage 1 time. The choke should slam completely shut. Now have a helper start the engine. The choke pull-off should immediately open the choke about 1/4 inch or so. If it doesn't, the engine will starve for air & run rough & blow black smoke. The pull-off is operated by manifold vacuum-if it doesn't hold vacuum it'll need to be replaced. You can adjust it to where it opens the choke enough to allow the engine to run-some have a screw, some you have to tweak the linkage.
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Unread 07-09-2010, 07:18 AM   #11
Dryseals
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Quote:
Originally Posted by Newfie_Jeeper View Post
I had the carb rebuilt by a GM mechanic in his spare time, using napa kit, float, and e choke. My e choke has 3 rivits, not screws. I could drill them and replace if necessary

The engine does smoke ocassionally, especially when cold, but it doesnt smell like its burning oil, it smells rich.

I have a question about adjustment screws. The drivers side is for idle, and the screw on passenger side beneath the e choke adjusts your fast idle.

Right above the e choke, where pull off is (mine is on front pass side) there is an adustment screw to limit or allow the travel of the pull off when cold. COULD I HAVE THIS SCREW ADJUSTED WRONG? Any Idea on setting?

Thanks in advance,

Newfie
Now we get into particulars. The choke pull offs I've seen are all on the rear passenger side and as soon as the engine starts, it should open the choke. There's a setting for the E choke and when they are adjusted correctly the rivets do not need removing. But like anything else, they can wear our.

Get the numbers off the carb so we can tell what exactly it is and we can move from there.

FYI. Q-jets were built for the car they would be driving, their not a how do you say a generic although they can be made to fit what ever you want. I like using the q-jet with standard chevy engines because the amount of "timed port" vacuum matches the vacuum advance in the distributor by the rear gears and vehicle weight and engine. So depending on your application and if you're running a GM distributor, you can dial in the advancement curve to fit your vehicle. They get a bad rap becuase folks will grab a 750 off a station wagon with a 455 and then drop it in a 350 with a distibutor from a 307. In most cases a weight/spring change in the distributor and the correct advance module with the right jetting/rods in the carb will tune them right in.

I stil love the sound of the back barrels kicking in, nothing like it.
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Unread 07-14-2010, 07:44 AM   #12
Newfie_Jeeper
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Thanks for all the imput! I resolved the issue. I made some adjustments to the screw that limits the travel of the pull off during cold start, and now it is right on! NO smoke on start, turn the key, goes to high idle and away she goes. I doesnt even need to warm up to work well.

Thanks again for the help!

Newfie
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