hotter plugs for A series?

[metalmonkey47]

My A15 has an MSD CDI ign box on it, but I'm curious if I should run a hotter plug or open the gap? I'm using the Oem NGK BPR5EGP, but have found the BPR2ES here at work, and I'm trying to decide if the hotter plug would make a difference on the motor. It has a great deal more spark over the Oem ignition.

 

 

 

Input?

[motavated]

that is too hot. I read for every 100 hp, you need something colder. Not hotter.

[flatcat19]

Colder is the way to go.

Then bump up the timing a touch.

[metalmonkey47]

How much colder should I go? I found it makes the most power with the timing retarded. Even a little advance looses power.

[ggzilla]

No to changing the heat range of the plugs -- why do that? It's not related to the type of coil you have, but to the engine tune.

 

Yes to changing the gap -- use MSD's recommendation or try 0.042 inch.

 

After you drive 100 miles, inspect the plugs with a magnifying glass (look at the insulator down inside the plug). If they are fuel-fouled, try a hotter plug. If they are white blistered, try a colder plug.

[justin 620]

I have a rookie question... Why is it bad to run hotter plugs?

[metalmonkey47]

No to changing the heat range of the plugs -- why do that? It's not related to the type of coil you have, but to the engine tune.

 

Yes to changing the gap -- use MSD's recommendation or try 0.042 inch.

 

After you drive 100 miles, inspect the plugs with a magnifying glass (look at the insulator down inside the plug). If they are fuel-fouled, try a hotter plug. If they are white blistered, try a colder plug.

 

Well, i have much more then just an ignition coil on it. I have the MSD CD ignition. http://www.street-fire.com/cdiignition.html

It fires a much larger spark then the factory ignition did. It fires sparks for 20 degrees of crank rotation.

 

My thought was if I've upgraded the rest of the ignition, I might as well look into better plugs as well, since they are very important.

 

 

Gap I'll have to look into, or play with. I've always figured I might need to re-gap them one day.

[ggzilla]

Hotter plugs do not mean better plugs. If they are too hot, you risk pre-detonation, run-on, and blistering the plug insulator.

 

But for sure, change them if they need it.

[metalmonkey47]

Hotter plugs do not mean better plugs. If they are too hot, you risk pre-detonation, run-on, and blistering the plug insulator.

 

But for sure, change them if they need it.

 

Makes sense. I need to take mine out and inspect them.

 

May not do any more then just open up the gap a little though, but I'll replace if necessary.