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View Full Version : SBC HEI Cold Starts, then Spits, Sputters, and won't Idle??



monteboy84
10-25-2011, 04:52 AM
Hi guys,

My Monte died about a block from my house last night, it's had an ongoing problem that's kept it stuck in the garage for a month now, and I'm at my wit's end. It starts up and free-revs fine when I start it cold, but once I put it in gear and try driving, it takes maybe 100 feet for it to start spitting, sputtering and carrying on, then it won't rev over 2k RPM's either free-revving or in gear. It gets a sound almost like the plug wires are out of sequence. I thought it was out-running the Carter fuel pump before, and sucking the carb bowls dry, but I had a brand new Holley inline pump and regulator here for it, and it acts the same with them installed.

Specs:
SBC Vortec 5.7 bone stock from 98 GMC
Edelbrock RPM Air-Gap Intake
Crate Demon 650 Vacuum Secondary Elec Choke Carb
78 Chev HEI distributor, original module, pickup coil, and coil, new MSD cap and rotor
New this summer Accel Plug Wires
Holley blue fuel pump and regulator
Factory wiring to distributor, distributor only grounded through block, no external ground wire.

Ideas so far:
Ignition Module - I pulled the module and have it with me to get tested over lunchbreak
Bad coil?
Poor ground through the block -Solution would be to add an external ground wire to the distributor

Any other ideas? It died late at night and is off to the side of the road so I locked it and left it after pulling the module, but I really need to get this fixed today. I'm hoping it's just the module but I really have never had module problems before so I don't know if this is how they act? Any votes for current ideas or other suggestions to try would be greatly appreciated.

Thanks!
Matt

astroracer
10-25-2011, 06:22 AM
Stock fuel tank? Sounds like a fuel delivery problem. Rust in the tank. Have you checked the fuel filter? Blocked pick-up?

monteboy84
10-25-2011, 07:02 AM
It's got fuel, when it's dying and running like crap I can still see fuel in the sights on the fuel bowls.

-matt

ETA: I've also got 2 fuel filters on it, one right before the pump and 1 right after the regulator.

monteboy84
10-25-2011, 10:22 AM
Got the new Ignition Module in and it runs fine now.

Thanks

-matt

sr73bu
10-25-2011, 06:41 PM
Got the new Ignition Module in and it runs fine now.

Thanks

-matt

If you still have problems (i burned so many coils/modules in the past) MSD sells a remote coil dust cover that allows you to run an older style oil filled coil. Most of the issues with HEI's are heat. Everything is under that cap and the coil can get hot and fail (cracked epoxy) or it can get hot causing the module to fail. I recently switched to a remote style coil and it seems to run better... I have a few friends that swear by the conversion both for reliability and performance. Hope this helps. On the flip side of this,, my fathers old chevy truck still runs fine on the original hei... go figure.

-Sean

astroracer
10-26-2011, 02:24 AM
Very good, glad you solved the problem.

monteboy84
10-26-2011, 09:04 AM
Thanks for the heads-up on the external coil adaptor Sean! I hadn't thought of that, it's definitely something I'll look into. I'm planning a swap for a fuel-injected Gen III 5.3, so this motor/trans would get sold, but if I hold off on the swap for another summer I'll definitely go to the external coil. Right now I'm trying to nurse this motor and trans along until I find a buyer and pull them to do the swap :)

Thanks again for your help guys.

-matt

John Wright
10-26-2011, 09:10 AM
I've had modules and coils that did that...glad that you were able to get it.

Keep an eye on your plug wires and plugs...if one isn't firing correctly or a wire grounded to something, you can go through a bunch of those modules before you find the bad wire or plug.

sr73bu
10-27-2011, 06:36 PM
Check my build thread (sig).. I just posted photos from when I switched to the remote coil...


-Sean

monteboy84
10-28-2011, 05:04 AM
Perfect, thanks!

I love your car BTW, very unique choice but you're doing a great job with it!

-matt

David Pozzi
10-28-2011, 08:06 PM
I've had modules and coils that did that...glad that you were able to get it.

Keep an eye on your plug wires and plugs...if one isn't firing correctly or a wire grounded to something, you can go through a bunch of those modules before you find the bad wire or plug.
This is excellent advice, the HEI will pump out a lot of high voltage if a wire goes bad & it can arc down & hit the module.

Chevelle598bb
11-04-2011, 01:57 PM
The condensor unit that the control module connects to in the HEI can also go bad. The harness that connects the module and the condensor can also get corroded and cause too much resistance causing the module to overheat. They can cause symptoms as you described and also burn out a new control module in about 3 hours of driving (I went through 3 modules before I figured out the condensor was bad). They are usually sold with the harness attached to them and are around 8 bucks if you can still find them at the local auto parts store. The Wells ignition part # for the condensor is 1B1001. Autozone use to carry wells but any auto parts store can cross reference it for you. Good luck.