I'm replacing my 346 w/ a LS7 based 427. My current motor makes about 430-440 rwhp and I'm running 42lb injectors. As part of the swap I will be upgrading my stock fuel pump.

Is it ok to run the current tune if I keep it under 3,000 rpm? Then after about 500 miles I would get a dyno tune.

Would it be better to get a base/safe tune from the tuner?

I was thinking of using Mike Norris.

Thanks

 

as long as it was tuned for the 42s you may be okay, but it is best to break the engine in on the dyno.

 

Mike Norris is good from what I have heard, I recently got my car tuned by Jeremy Formato, my buddy asked him this question and he said it would be fine to drive the car keeping the rpm's low over to his place to do the tuning, and then go to the dyno.

Chad

 

do you have a wideband? if not get one and you can do anything you want...the only thing thats going to hurt it is getting lean under power.

 

Well....over-fueling is going to cause problems too to his pretty new engine.

 

I tried to say the 42's are in my current motor and are already tuned.

 

If it will even run

 

Exactly. Regardless of being tuned for the injectors, the computer will think it's a 346. You've added another 80 cid, so it's going to be pretty lean, to say the least.

 

+ why even risk it? Im pretty sure there is a pretty penny wrapped up in that 427. I learned my lesson on driving a car untuned,lean and it costed me a motor

 

So I'd need to install a base tune and then make sure I have a wideband? I thought at low rpm it wouldn't need significantly more fuel than my current 346. Guess I was wrong? Install is in my garage so my options are limited. No I don't want to hurt the motor.

I e-mailed Mike and haven't received a reponse. Guess he doesn't do e-mails.

Thanks for the replies.