2cub49

So I finally wore out the old 350 after hammering on it for 5 years.

I used 30 lb ford injectors with the 350 powerdyne setup and they worked great.

Now we put in a Golen 383 blower engine and an M6 so I decided to go with 48lb Racetronix injectors.

When set at 48lb in LT-1 Edit the car was way too rich.
I ran them at 54lb setting to lean it out and had it dynoed.
The dyno guy said it was a very good a/f ratio 11.9 at WOT
though still a bit rich. 325 rwhp 348 ftlbs torque

So we tried 42lb injectors I bought off the board here and they were way rich at the 42 setting.
The car was backfiring and developed a misfire with flashing SES.
I went to settings 45, 47, 49, 51 and finally 52 and the miss has gone away.
Currently at the 52lb setting things look good on the
wideband LC-1 02 guage and reading the #4 plug which is easy to get to.

I'm doing some logging as well.

The ford 30 lbs ran fine at Ion's 31 lb setting and I was wondering since I only have 4.5 lbs of boost now on the 383 if I could just put the 30's back in.
I think they would be just enough.
I have a Procharger to put in place of the Powerdyne but I'm not going to do that till next year as now I just want to drive the car and it's pretty good with the M6 325 dynoed rwhp after not being driven much for 5 years.

I can save the larger injectors for when I put in the Procharger.

Anyone else have some similar adventures with injectors or advice they could give me.

Thanks in advance

Injuneer

Please don't cross-post the same question on multiple forums.

2cub49

Sorry
I wasn't sure where to put this one as it's a bit of both.
I just noticed there's a box in LT-1 Edit for cylinder displacement
and I was still set on 350 cu in.
I haven't used this software in a while.
I changed it to 383 and set the injector down to 45 from 52 so I'll see how that works tomorrow.

sepno77

I wouldn't sweat him man. That guy is on his rag. Hope you get it figured out.

2cub49

Resetting the cu inches didn't do much so I went back to 52lbs but left the correct cu inch size.
That seems to work well and I may go a pound or 2 leaner.
The wideband jumps around a lot but the low reading has gone to 10.6 when I WOT for a few seconds so I think I have some room still.

I was interested in what others have experienced.

rskrause

Has the mass air table been altered, or is it a non-stock mass air? NHoramlly, it should be pretty close with "correct" injector size. Have you checked the fuel pressure?

Rich

2cub49

The first dyno run showed the fuel pressure dropping off down to 20 psi.
We put in a new holley 255 liter fuel pump.
Second dyno run showed no drop off.
The results with the 48lb injectors was 325 rwhp and 348 rwtque
11.9 a/f at WOT.
Mass airflow is Granatelli.
It all worked fine when it was a 350.
It's the same tune Ion wrote for that and the one we dynoed.
I think I'll put the ford 30's back in and see how that goes.
I have the wideband LC-1 which can log my a/f over time and
gives me a digital display.
The 48's were rich and the 42's are even worse.
Do you think 30's will be enough for a 383 with 4 lbs boost.

rskrause

I think you need to figure out the problem. Do you have the original mass air to swap back in? FP should rise with boost so that the delta (difference) stays at the desired pressure. IOW, if you want a delta of 42psi at idle (with vacuum line to FPR disconnected) you should see 46 at 4lbs of boost. The PCM bases fuel calculations on a constant FP. The FPR compensates for manifold pressure (MAP).

Rich

2cub49

I have a new stock MAF I had bought on Ebay for this project which is going on for 2 years now.
I remember now people said the Granatelli was hard to tune.
Worked fine on my stock 350 with powerdyne.
I forgot about it but since you reminded me I dug it up.
I'll put it in today and see how it goes.

2cub49

The car likes the stock MAF better for drivability.
I'm still running the higher numbers for injector size but it seems to be working for me and the plugs look good.