I have a L98 with bolt-ons. I have a super-powershot set for about 110hp as it sits. Never even used it (or finished hooking it up.) Scroll down for engine mod list.

Anyways, I am having cylinder head problems so I am going to take them off and do a valvejob and polish the runners. I have a Walbro 255 fuel pump, a MSD Digital 6+ ignition, and access to 104 octane fuel. I also have a nitrous progressive controller and I am going to get Drag Radials for the track.

Is there anything else I really need to do before I up the ante to 150hp for the track? Leave no stone unturned in your thoughts guys. Last thing I need is a screwed up engine.

Engine Mod list
L98 Crate engine
LT4 Standard Cam
Comp Cams 981 springs, LT4 retainers and Pro-Magnum 1.6 Roller Rockers
MSD Digital 6+ ignition
Timing set to 8* advance, MSD will pull 4* when I hit the arming switch
Walbro 255 fuel pump, Fuel pressure set to about 43psi
Headers and exhaust-

 

I'd pull out 2 more degrees on a stock bottom end. That way you don't have to by race gas.
Use non platinum plugs
Gap them at .035-.040
Keep bottle pressure around 1000psi, and you should be good.

BTW - I love that MSD digi 6+. Leavin on the 2 step at 6k is a blast.

 

While you got the heads and valves out, port the exhaust something fierce. The n2o will thank you later. If it's not a daily, then I'd even opt for a 5 angle job.

 

Well, I'd like to change the heads (and forge up the engine) eventually. But I dont have the funds to do so and its cold in florida for a very short time.

 

One step colder on the plugs, sorry, forgot that.

For example, normal is 3933, use a 3932 for spray. (those were just examples, not saying to run that particular plug).

 

If I had the heads off I would do a 30 degree back cut on the intake valve also. And if the motor was stock cut the heads .030.

 

Should I change the exhaust valves to something that can take the added heat?

 

Stock valves will work fine for a short-duration power shot like that.

Make sure that whoever does the valve seats understands you are using nitrous and knows what that means. He should understand that means not to go too thin on the 45* angle that contacts the valve when it is closed. Thin valve seats can help flow, but they don't conduct heat away from the valve very well and they don't last as long on a daily driver. Make sure he keeps that exhaust valve-to-seat contact area at least as wide as stock, not thinner.

 

I'm the one doing the valvejob actually....

 

Keep the 45 on the exhaust seat at least .070" wide.
I'd go ahead and radius the chamber side edge of the exhaust and polish the chamber side.

For the 150 shot or higher I'd run Autolite AR12 (taiper) or AR51 (flat) plugs depending on which style you use in your heads.
Stock heads normally take the AR12.

Polishing the chambers isn't a bad idea while you've got it apart, and go ahead and test fit the plugs you'll be running to make sure the threads don't stick out into the chamber. If they do, then you'll need a special washer to shim the plug back out.