Got my GN back on the road finally, had the engine rebuilt (minus machine work since it was still in stock specs) along with ported/polished 8445's and a roller cam, then had a few headaches with a Hydroboost swap. Got about 500 miles on the car and I've tried a few WOT runs, haven't recorded with PL yet, but it feels like the spark is being blown out at 21#, this is through the mufflers. It has more surge if I open the cut out and the boost goes up to 23#. WB O2 is showing anywhere between 11.5:1 to 12.0:1. No Knock. Plugs are NGK UR5's gapped at a tight .031", same plugs and same gap as I had when the longblock was stock running 28#.
Ported heads more prone to blow out spark?
- Thread starter Roc87
- Start date
Welcome!
By registering with us, you'll be able to discuss, share and private message with other members of our community.
Coil pack & Ign. module have less than 1000 miles on them, thanks to chasing a fouling plug issue last year that lead to the engine rebuild. I do have another one I could try. GNEric who built the engine says he has plugs gapped at .025" on his GN with GN1 heads though
Try that first but I've seen new modules and coil packs not work.
Actually coilpack/ign. module is the OEM off an '86 T, thought my new one was on there. I tightened up the gaps on the plugs from .031 to .027, but haven't driven it yet to see if that made the difference. Have no idea what brand the new coilpack/ign. module is, don't even remember where I bought it, but it was from a vendor, I hope it's Delco. If the tighter plugs didn't do it, I'll swap the mod./coil. Just wanted to do one thing at a time
TT/Ameasap
The White Blur
- Joined
- Jan 31, 2002
- Messages
- 5,374
Yes, more airflow can cause spark blowout. Your flowing the same amount of air as your were at around 26-27 psi if the heads are race ported. I went from .030 to .022 and it went away. Now I have to get boost to where I want it (25-26#) and increase the gap gradually. Kinda like getting the right air pressure in a slick. The TR6 is on my list of things to get....Its just really expensive up front.
I'm gonna wait 'til there's a few thousand miles on the engine before cranking the boost back up, but it feels every bit as strong at 21# as it did at 28#, maybe better
TR6 looks like a great piece, it's on my list as well, especially if I have to close the gap to .022
TR6 looks like a great piece, it's on my list as well, especially if I have to close the gap to .022
turbo nasty
Turbo Dojo / MNTR
- Joined
- Jul 19, 2001
- Messages
- 9,478
Whats your batt volt at WOT?
forcefed3.8's
Buckeye Bullet
- Joined
- May 26, 2002
- Messages
- 3,845
You are too lean, and the extra boost when the exhaust is uncapped it making it leaner. Not that this is your problem, just an observation.
- Joined
- May 28, 2001
- Messages
- 2,523
I run a .025 gap on AC Delco plugs. No problems.
Congrats you are making more power now at a lower boost level don't blow up the motor.....
Congrats you are making more power now at a lower boost level don't blow up the motor.....
Congrats you are making more power now at a lower boost level don't blow up the motor.....
That's my biggest fear and the main reason I never wanted to mess with the stock long block (before it really needed the refresh)
Good idea--Eric; I can bring mine over if you want to try it...
TT/Ameasap
The White Blur
- Joined
- Jan 31, 2002
- Messages
- 5,374
Exactly. Gap them tight and then see if it goes away. If it does, start creeping the gap back up when you achieve max boost pressure.
I still have mine gapped to .022 for a reason.
Tip: Dont bend the ground strap more than a couple times, this weakens the material. Just get new plugs and start where you left off.
forcefed3.8's
Buckeye Bullet
- Joined
- May 26, 2002
- Messages
- 3,845
I never want to be leaner than 11.3. I don't mess with alky too much, but usually keep it around 10.9 to 11.1.
