View Full Version : Upgrading to 46# injectors. Need Tune?

08-01-2012, 04:33 AM
My build is a 403 Stroker with Heads, cam, manifolds. Lookin for 500 wheel or so.
I will be installing a Walbro 255 Pump and have 46# injectors.

Question: Is it safe to put the injectors in when the new motor goes in? And then drive it to the tuner?
Or would it be better to keep stock injectors for now?

Also, is it safe to drive around with stock injectors and just the pump?
I won't be gassing it over 5k rpm max (for break in), until I can get it tuned?
Would that be bad for the new engine?

Please respond soon!

08-01-2012, 05:08 AM
The new injectors are definitely going to need a tune...

Could you drive on them lightly just to your tuner? Probably but I wouldnt recommend... especially for long distances or any type of high RPMs.

Best thing to do is leave your stock injectors in... and swap the new injectors in before the tune. You can bring an extra Fuel Rail with the injectors already installed ready to go if you want to. All you will need is the fuel line disconnect tool... and maybe some silicone spray to lubricate the injector O-Rings while removing and reinstalling.

When my friend upgraded to the LS2 top end on his 04 GTO... we drove to the tuner with the stock injectors in... and swapped them out quickly with an extra fuel rail like I described above. Works like a charm...

I dont think you will have any issue driving with the stock injectors and the new pump at all...

08-01-2012, 09:03 PM
Listen to poolshark, those injectors will want to pump a lot more fuel with out the tune being changed.

08-02-2012, 12:12 AM
Thanks guys. Now would it be ok though to drive it on stock injectors? Considering that they'd be maxing out?

08-02-2012, 07:44 AM
As long as you don't go WOT they wont be maxing out.

08-04-2012, 03:36 AM
^ Bingo...

08-05-2012, 03:08 AM
I'm in the same boat here. I am at 97% at 6500rpm. I am about to get new injectors, but I won't put them in until the day I go down to get the retune. Listen to kjhallex, keep stockers on until the last minute and then get a retune. Keep the rpm's down to the point that they don't get to 100% duty cycle and there won't be a problem.