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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: cptmoney on September 19, 2017, 08:25:30 pm

Title: My '84 K10 small block 350 engine races away!
Post by: cptmoney on September 19, 2017, 08:25:30 pm

So I'm trying my best to bring my old '84 K10 back to life after MANY years of sitting... and I'm running into some issues that I need help with.

It's got a 350 V8 with the standard quadrajet 4v carb.  Starts right up, but almost instantly hits high RPMs (seriously - like 2500-3000) and stays right there.  I cannot get her to settle down.

What could that be attributed to?  Vacuum leak is my first thought, but I can't find anything loose or out of place. I must be missing something obvious.

Can anybody steer me in the right direction with this thing?  Where should I even start looking?

Keep in mind she sat for literally 5 years without moving - at all.  That could be related to the problem.

Here's a free pics of the engine bay......

(https://uploads.tapatalk-cdn.com/20170920/7a9f47614f88e85f0dea6fb634283709.jpg)(https://uploads.tapatalk-cdn.com/20170920/49f719f0a04d92fd4744b5802b162567.jpg)(https://uploads.tapatalk-cdn.com/20170920/fa794a6357658b080388a45b53099553.jpg)

Title: Re: My '84 K10 small block 350 engine races away!
Post by: cptmoney on September 19, 2017, 08:27:32 pm

A few more pics...

Anybody see anything obvious?  To at least get me started? (https://uploads.tapatalk-cdn.com/20170920/86dccdf304a7442f4785397d2e569950.jpg)(https://uploads.tapatalk-cdn.com/20170920/5814984d35300a8748117eaffa2a6fe4.jpg)(https://uploads.tapatalk-cdn.com/20170920/f67e2086e79e4c30c8fcf1d972e64c5f.jpg)

Title: Re: My '84 K10 small block 350 engine races away!
Post by: bd on September 19, 2017, 08:43:58 pm

Disconnect the cruise control linkage from the carburetor and recheck for symptoms.  Sometimes the Custom Cruise III throttle link will twist and hang up on the servo, holding the throttle open.  What happens if you force the choke fully open?  Check the cold idle speed adjustment.

Title: Re: My '84 K10 small block 350 engine races away!
Post by: Stewart G Griffin on September 20, 2017, 09:46:14 am

Also, do you have a tach?

2500 rpm, if that's what it's doing, is not necessarily out of normal specs i don't think.

Title: Re: My '84 K10 small block 350 engine races away!
Post by: VileZambonie on September 20, 2017, 11:55:19 am

2500 at idle is way out of spec lol

Title: Re: My '84 K10 small block 350 engine races away!
Post by: bd on September 20, 2017, 12:30:46 pm

Stewart, although it varies significantly from year-to-year, V6's can be as high as 2,200 RPM on the high step of the fast idle cam, whereas V8's typically are ≤1,600 RPM on the high step of the cam.  For any given application, fast idle should be adjusted according to the tune-up specifications for the particular year model of vehicle/engine.

Title: Re: My '84 K10 small block 350 engine races away!
Post by: Stewart G Griffin on September 20, 2017, 03:43:50 pm

Yes, i may have gotten it confused with the v-6's which i think allow for high idle at 2000+

Also i meant HIGH idle, not curb idle.