Fast355 et al,Disclaimer-I would like to do the following mods WITHOUT a tune.
‘88 LO3 IROC convertible T5.

I know the following combination wouldn’t be completely optimal as far as gas mileage horsepower and torque etc., but, without EBL flash or any kind of tune, would a solid 13 pounds of fuel pressure and a few extra degrees of timing keep the drivability generally acceptable?



Presently have Hooker 2055’s & their full Aerochamber header-back exhaust.



Swap to a used L31,

LT4 cam, springs,

Performer intake,

46mm SPR TBI with adjustable fuel pressure reg to 13 lbs,

TBI-intake adapter plate,

Bump up timing 6? degrees,

L69 dual snorkle air cleaner,

185’F t’stat & fan switch possibly?
Has anyone done mods like this and just driven it without a tune?

Just curious why would you want it to run lean ?

Well, of course I wouldn’t INTENTIONALLY want to run lean.
I had read that a close to stock tune with a mild cam and a maxed out factory fuel pressure regulator(converted to adjustable from the fixed factory style) would be adequate, or at least ok to drive.

Alittle more support if you use a 89-92 ecm . But why guess around with afr
you could put a 28 psi. Or 350 truck injectors and modify a atjp tune for manual transmission.
it will run lean heck tpi guys use a stock 305 calibration in a 350 with 19#hr injectors.
right , No . Will it run yes . Might weigh your tuning options

If you don't want to tune it, put a carburetor on it.

Thanks Tuned Performance. Actually, I just had to replace the TBI fuel pump, it was only delivering 8 lbs to the TBI. How does one modify a atjp tune & what is it? Aldo didn’t know that a newer ECM is better.

ATJP , ANLU both good binary tunes $61 mask. Lots of great information in the diy tuning section.
vortecs don’t like much timing so data logging watching Blm and knock counts and even a wideband to help aid tuning.
but bang for the buck ebl might be better than the 8746 ecm.
or hate to say :cringe: carb

Vortecs need alot more than TBI stock tune runs. I had a Vortec head TPI 350 run pretty darn good on a stock 1995 G20 350 TBI tune with the timing set at 10° BTDC. Ran a little better after some tuning, but it started, ran well cold or hot, had a great idle, had good throttle response and drove great. Was a little rich at WOT but pulled like a freight train even on the TBI tuning. I was actually a little tripped out on how well it ran.

I would be one of the guys you might roll your eyes at.
I don’t know what ATJP , ANLU binary tunes $61 masks are yet.
Block learn modules or knock counts terms somewhat familiar with lol.
Very bottom left of the TBI learning curve, at present. Just want another 45 c.I. & 300 real HP.