[HP52TA]

While gathering parts for my 406 rebuild I have picked up an Edelbrock Performer Nitrous kit along the way, which is adjustable from 50 to 100HP max. Edelbrock indicates this kit can be used on a stock engine without internal modifications.

The rings I am installing are Speed Pro Plasma Moly rings (ductile iron top ring) on hyper pistons and based on the Speed Pro's ring gap guide should be gapped as;
Top Ring - "Nitrous Oxide, Street" application of .005 per inch of bore diameter, which works out to 0.021”
Second Ring - "Nitrous Oxide, Street" application of .006 per inch of bore diameter, which works out to 0.025”

As these are the minimum gaps, I was planning to open them up a bit more to;
Top Ring @ 0.024"
Second Ring @ 0.028"

Are these reasonable gaps to be running for this application (Sunday driver with odd run down the strip) or should I be sticking closer to the N/A gaps defined for "Moderate Performance" being Top Ring .004 / Second Ring .005 per inch of bore diameter.

[tomthecomic]

With my experience you should go with the moderate performance gap. I have a book that I will look at later and give you a better answer. I would not even worry about that till 150 and alot of racing. 100 is not that big a deal and with the jets being rich you should be ok. I would run same heat range plug but with non projected tip and take out 2* and make sure you have 6psi fuel with motor on and nitrous fuel on. I would also brake in the motor for a while first.

[F-BIRD'88]

You can be liberal with the ring end gap. You won't give up power.
I would go with .026-.028 on your 400SBC.
When it comes to ring gaps, nitrous and hyper pistons, bigger is better.