I need to know if my stock 350 chip will be ok to break in my new 383.
It has 24# injectors, pretty much stock TPI, sportsmanII heads, slp headers, 204/214 cam, and a forged bottom end. I dont trust myself to make any prom changes until it is at least broke in. Also what is the differance between 87 and 88 stock proms.

Thanx in advance

 

It should be alright with an adjustable fuel pressure regulator. Bump up the fuel pressure about five pounds. The car may burn a little rich at idle but you need to watch your WOT and make sure it doesn't lean out. The last think you want is detonation.

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Getty up my *** this ain't no damn pony ride!!!!
86 IROC 383tpi
The "bone stock" that rocks!

 

No, the last thing he wants to do is flood it on initial start-up. Wash those cylinder walls with fuel and you'll be re-ringing pretty soon.
And starting high on the FP with 24# injectors on an engine that isn't that much bigger than the stock chip was meant to feed would probably be way too rich. I'd try to start lower on the FP at the least.
If you have the capability though i highly recomend burning a PROM. You don't have to make drastic changes, but i am pretty sure there are a couple simple switches you could set, first you change the injector constant to 24# (or whatever the effective rate is at the pressure you are running, ex. if they are SVO injectors they are 24 @ 39psi not 43) and i beleive their is also a spot for dispolacement that the VE and such tables use to computer actual fuel. So in essence you'd be burning a 'stock' fuel map that would at least be calibrated for your increase in engine and injector size.

So, did i get that right guys...if not, sue me, i haven't even looked at a .bin editor yet. i am a sponge...
...ed

 

95% of break-in will be in closed loop, so your computer will make your mixture perfect. When you do enter PE mode, watch the o2 readings and knock counts to make sure you are no going lean or detonating. I broke in my 383 with a stock chip an 24lb/hr injectors, but in the end it needed lots of adjustments to get it right.

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Dave Zelinka

 

You also mentioned the difference between 97 and 88 PROMS so your running a MAF system that will pretty much self calibrate to the increased airflow of more cubes and adding fuel automatically. Leave the FP where it is for the break-in. In actuality you will probably running a hair rich because of the inj change until the ECM starts reading o2 when it goes closed loop.

 

I agree with lowering the fuel pressure for the initial startup and ensuing open-loop operation. Last thing you need is no oil on newly machined and TIGHT piston/ring to wall clearances... The ECU will enrichen it to proper amount to run in closed loop. I wouldn't drive it in open loop situtaions, though, until broken in and FP back to more normal levels.