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Old 01-04-2013, 05:49 PM
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350 small block vortec problems, stalls out

Hello thanks for looking, I recently just built a 82 Chevy small block 350 with 98 vortec heads. The motor fires and runs but think we have a vacuum leak because it won't stay idling long! It fires runs for about 5 sec then putters out! Will continue running if you keep on Throttle. We have installed a mother thumper cam and roller rockers. It has a quadrajet carb and lots of vacuum ports on it. Could someone please send me a diagram or something to tell me what I need for this motor to run reliabley without during out? It's not a street truck its 4x4 strictly toy off road. We have the vacuum advanced hooked up to what we think is the right vacuum to the carb. And the break booster as well. Any help or hints tips would be great thanks! If you need more info I'll do my best to answer them thanks

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Old 01-04-2013, 06:32 PM
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Plug all the line(temporarily)set timing for 35 total at 3k.turn idle screw up to 1400 rpm( w/e it takes to keep running. adjust carb,turn down idle . check all tune up specs and continue down until it idles at 850 ish.
test for vacuum leaks with carb cleaner or other aerosol spray.
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Old 01-04-2013, 06:38 PM
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Ok we will give that a shot any tips on adjusting the quadrajet?
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Old 01-04-2013, 07:15 PM
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Help on 350 small block vortec head build! Please!

If you think you have a vacuum leak, here's how to check. Using a can of starting fluid spray sparingly along the intake where the gaskets are. Spray around base of the carburetor too. If you have a leak the idle will increase. What type of intake do you have? When you installed the intake did you use any sealer on threads? Here is a link to an article to read about setting your timing. http://www.crankshaftcoalition.com/w...EI_distributor
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Old 01-04-2013, 07:21 PM
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I don't thinks it's quiet a leak but I think more I'm either pulling to much vacuum or not enough we aren't sure what goes where off the carb. Vacuume wise. And the intake is an off brand that is made for the 350 with the newer vortec heads and yes we sealed everything with gasket sealer thanks for the thread/ web site
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Old 01-04-2013, 07:51 PM
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You got a working choke?
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Old 01-04-2013, 07:53 PM
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We do not have a working choke!
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Old 01-04-2013, 07:59 PM
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No choke!!
THat's why it dies. It's lean.
Set up a choke or a manual throttle to warm it up.
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Old 01-04-2013, 08:02 PM
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What about re tuning carb to have no choke I mean we can get it to stay running to warm it up. I can hold the pedal at let's say two grand and it will run there constant! But when you let off it will idle for about 5 seconds and it tries to stay idling but eventually dies out. So still leaning towards choke?
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Old 01-04-2013, 08:20 PM
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Quote:
Originally Posted by Ltsulli1 View Post
What about re tuning carb to have no choke I mean we can get it to stay running to warm it up. I can hold the pedal at let's say two grand and it will run there constant! But when you let off it will idle for about 5 seconds and it tries to stay idling but eventually dies out. So still leaning towards choke?
Its not going to be a choke issue, I rarely have a choke on any of my junk, get it started, get it to 1500ish for a minute or 2, should idle down and stay running...and that's in chilly Canada climate and with the heat risers blocked. The mother thmpr is a pain in the ***, ask me how I know....get all the vacuum ports plugged, get your base timing to 24, adjust idle down to 800, and see what it does....but yes, this is after you have plugged everything and confirmed no vacuum leaks....if it runs decent, and stays running, then we can worry about where all your vacuum should be routed. That cam is going to want alot alot of initial...
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Old 01-04-2013, 08:22 PM
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Quote:
Originally Posted by vinniekq2 View Post
Plug all the line(temporarily)set timing for 35 total at 3k.turn idle screw up to 1400 rpm( w/e it takes to keep running. adjust carb,turn down idle . check all tune up specs and continue down until it idles at 850 ish.
test for vacuum leaks with carb cleaner or other aerosol spray.
Didn't even see this Vinnie lol....oops.....
Yep....this will work....
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Old 01-04-2013, 08:30 PM
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Ok I'll give that a shot within the next few days thanks for your help I'll let you know how things go!!!
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Old 01-04-2013, 08:39 PM
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When you say plug all the vacuum ports you do mean everything right? Vacuum advance and vacuum for brake booster? Everything on the carb? Just wanted to clarify thank you
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Old 01-04-2013, 10:14 PM
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When you say plug all the vacuum ports you do mean everything right? Vacuum advance and vacuum for brake booster? Everything on the carb? Just wanted to clarify thank you
Yessir.....
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Old 01-04-2013, 10:41 PM
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350 small block vortec problems, stalls out

I forgot about your vacuum lines. If I remember correctly, the Q-jet has a threaded fitting on the backside of the carburetor. This is where the vacuum line from the brake booster goes. The brake booster should have its own vacuum port, do not tee anything else to it. There should be a 3/8 port on the front of the carburetor for the PCV valve. You should have a vacuum port fitting that screws into the manifold behind the carburetor for your vacuum to modulator valve on the transmission. There will be other vacuum ports on the front for the distributor vacuum advance. Just remember the ports that have vacuum at idle are manifold vacuum and the ports that don't are ported vacuum. I have a picture from a website that might help you. Look at post #7. Good luck. PALEEZE help me hook up my QuadraJET and vaccuum stuff. - THE H.A.M.B.
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