Guys,

I just replaced a 323ci (5.3L) with a 408ci(6.7L)....the intake/TB,MAF, and everything else (fuel pump, electrical harness, all accessories) are the same.

What's new are the LT headers, 44lb injectors, bigger cam and CNC'c 243 heads. The 408 fired right up, sounds great and idles perfect.

So my appointment with the dyno-shop isn't for another 2 1/2 weeks....so you know what I'm thinking here....

What could I potentially screw up by taking it for a spin to break in the ring seals?...


Stroker2112
408ci iron block, forged Eagle crank, 4340 rods, Diamond pistons, Torquer2, Cnc'd 243 heads milled .015, true duals w/flowmasters, chromoly rods, dual Golds, 1.7 SS roller rockers, K&N Air, stock intake/TB (next on upgrade list)...

 

Keep the RPMs low & stay out of the throttle and you should be ok. The fuel trims will compensate for the fueling errors. Just make sure you don't get on it as tempting as it may be.

 

SSpdDmon,

What could happen if I got into the throttle....I'd love to break in the ring seals ....I've got 2 1/2 freeking weeks of waiting before the tune!!!...

What if I put the old injectors back in?...would that mitigate any possible problems allowing me to seal the rings?...

 

arent the stock 5.3 injectors like 24lb? and now your up to 44lb? personally i wouldnt drive it like that, but thats me.

 

100% agreed

 

I would not of even started it up with those mods on a 5.3 truck tune.

 

Hell I am surprised it idles and even starts with the stock 5.3 tune