What Plugs and gap?

[Tims65]

What are the best plugs and gap to run on my 347 stroker?

Engine specs:
347 cubic inch 302 based roller block engine
Dart Pro 1 heads
Edelbrock Air gap manifold
Compression Ratio - 10.25:1
Cam Specs:
- Intake SAE - 281
- Exhaust SAE - 285
- Intake @.050 - 232
- Exhaust @.050 - 236
- Intake Lift - .566
- Exhaust Lift - .571

Flywheel horsepower:
Torq - 434 at 4400
HP - 471.5 at 5800

Thanks,
Tim

 

[Anonymous]

No idea for your engine, but I run Autolite APP45's with a gap of .032"

 

[Kats66Pny]

:stu no clue what would be best for yours... but I have NGK's (http://www.ngksparkplugs.com/products/s ... p?mode=nml) in mine with a gap of 54 I think was recommended and I guess its good enough because it started today. LOL

 

[Sluggo]

What does the head manufacturer recommend?

You may need a longer reach than the factory recommendation.
By application mine calls for an Autolite 45 but the heads are late 80s heads so they take a 14mm thread. An Autolite 25 would be the correct choice but I'm running 23s because I needed a colder plug.

 

[Arto65FB]

What ignition? You can have bigger caps with "big" ignition. For example, DUI recommends 0.5" gaps.

 

[Tims65]

What ignition? You can have bigger caps with "big" ignition. For example, DUI recommends 0.5" gaps.

MSD with an MSD 6AL box.

Tim

 

[Anonymous]

I've played with the gaps up to.040" with no discernible difference.

 

[blackford]

Not to be cute or anything, but what's wrong with the plugs that gave you 471.5 HP?

I've used Autolite Platinums with poor results with open exhaust (cut out like a SOB above 4500). Put good old Autolite 45s gapped at .035 back in and cured the problem. Mind you I have Pertronix and Flame Thrower so your results may vary.