Toggle sidebar

the engine wants to run after shutting key off...

The 2025 Calendars are HERE! Get yours TODAY!
The 2025 Calendars are HERE. Two different editions, two different sizes, and a digital package!! Starting at $12.97US
rogus

rogus

Master Mechanic
Mar 14, 2020
415
149
43
I recently dropped a new 355 sbc into my 86 Elky. It hasn't seen the road yet and I'm still working on getting everything adjusted. I let the engine run till it warmed up and when I shut it off it tried to continue to run for a few seconds.

It uses an HEI and 670cfm Brawler carb, if that's of any help.

What generally causes this "run on" to occur? Is there a general list of possible fixes?
 
Get an Olds. 🙂 Sorry, had to.

Run on as far as what? Dieseling? Or just running right along like the key was still on? Could be a misadjusted fuel system, ignition timing, or hot spots. Or somethng may not be getting the signal to cut off the primary ignition circuitry right away. How's the start switch adjustment?
 
  • Like
  • Haha
Reactions: 78Delta88, Rktpwrd, melloelky and 1 other person
sorry. not used to calling it dieseling. It's a new switch. Out of the 3 things you listed my guess is that it's a fuel supply problem. I need to adjust the carb still.
 
Poor quality gas, large amounts of ignition advance also contributes to dieseling. Oh, and with all that other junk, if your idle speed is high it can be a contributing factor.
 
Last edited:
  • Like
Reactions: Rktpwrd and rogus
One typical culprit is the primary butterflys are open too far overexposing the idle transfer slots adding additional fuel over the idle feed port also causing an overly rich condition, bad for sparkplugs and the cylinder walls.

When this happens, you have zero control of the idle mixture screws, this happens quite frequently when opening the primaries up to far(as 69hurstolds had mentioned) to acheive the desired idle RPM when using radical camshafts, in that instance, you have to ballance the intake air by opening up the secondaries just a tad so you dont overexpose the primary side.

Whats the total specs on the 355 engine?
 
Last edited:
  • Like
Reactions: Rktpwrd and rogus
Ernest said:
One typical culprit is the primary butterflys are set too high over exposing the idle transfer slots adding additional fuel over the idle feed port.

When this happens, you have zero control of the idle mixture screws, this happens quite frequently when turning the primaries up to far(as 69hurstolds had mentioned) to get a decent idle rpm when using radical camshafts, in that instance, you have to ballance the intake air by opening up the secondaries just a tad so you dont overexpose the primary side.

Whats the total specs on the 355 engine?
Click to expand...
Info is attached. It has a 670cfm Brawler carb, hei distributer, long tube headers...
 

Attachments

  • 001enginespec.jpeg
    001enginespec.jpeg
    53.9 KB · Views: 9
The good thing is that you are running with a GM factory roller block, but modified to run a mechanical fuel pump.

Everything else looks good... but from what i can barely read(sorry), the 212int/230exh camshaft should run comfortably @ 800rpm at idle with 14degree initial timing.

That 670 brawler should handle your engine without any problems, much like my holley 670 street avanger being used on my ZZ4 crate engine, it took me awhile to figure things out, but its running good atm.
 
  • Like
Reactions: rogus
Ernest said:
The good thing is that you are running with a GM factory roller block, but modified to run a mechanical fuel pump.

Everything else looks good... but from what i can barely read(sorry), the 212int/230exh camshaft should run comfortably @ 800rpm at idle with 14degree initial timing.

That 670 brawler should handle your engine without any problems, much like my holley 670 street avanger being used on my ZZ4 crate engine, it took me awhile to figure things out, but it running good atm.
Click to expand...
Thanks. I'm still relatively new at this.
 
Back the idle speed down until it stops.
Then readjust mixture and timing if need be.
 
  • Like
Reactions: rogus
Get it cool enough temperature wise then get it rich enough to idle down to 650 rpm or less if that dosnt fix it
 
You must log in or register to reply here.
The 2025 Calendars are HERE! Get yours TODAY!
The 2025 Calendars are HERE. Two different editions, two different sizes, and a digital package!! Starting at $12.97US

Similar threads

G
1978 Cutlass 305 5.0 Timing
Replies
5
Views
215
Engine / Swaps / Driveability
spongbob
spongbob
scoti
    • Agree
Front/Engine Compartment Aftermarket Wheel Tubs
Replies
9
Views
250
General Discussion
scoti
scoti
Supersport88
1988 Monte Carlo SS 5.3l ls swap engine mounting
Replies
2
Views
163
G-Body LS Swap
Rgpmalibu
Rgpmalibu
Jim H.
BUILD THREAD 350 Olds engine
Replies
4
Views
232
G-Body Build Threads
78Delta88
78Delta88

GBodyForum is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.

Please support GBodyForum Sponsors

Classic Truck Consoles Dixie Restoration Depot UMI Performance

Contact [email protected] for info on becoming a sponsor

Top Bottom