383 tuning help

[Fast355]

450 HP Hour requires 9.16 Gallons per hour of Gasohol.
Mechanical efficiency of stock motor is 49% with new pistons rings increased compression and roller cam 76-80%

At 6lbs per gallon thats 54.96 PPH

The injectors will provide at stock fuel pressure 336HP no problem.
At 18psi like I recommend they will flow reliably at 74-75PPH

My experience and wideband both disagree with your HP potential of the TBI injectors.

350 with TBI heads, stock TBI cam, 1.6 roller rockers, Edelbrock 3704 intake manifold bored to 2", 454 TBI unit with 350 injectors, doug thorley tri-y headers, dual 2.5" exhaust into a X-pipe in my 1983 G20 van put down right at 200 RWHP and 300 RWTQ. Stock injectors at 14 psi were insufficient over 4,000 rpm to feed the stock long block. They went static, duty cycle above 100% and the engine misfired terribly and fell flat on its face before 5,000 rpm. I swapped to a Marine regulator and injectors from a 405 HP Mercruiser 502. Those are high pressure 61s that deliver 105 lb/hr @ 32 psi. I could turn the engine 5,500 rpm after with no fuel issues. I put a Weiand 177 on the same engine and used a rising rate FMU. At 10 psi boost it took 50 PSI of fuel pressure to feed the engine. I went 13.7 @ 101 mph in a 5,300 lbs G20 van with the Weiand 177 on the stock longblock, 700r4 with stock 1,600 rpm converter, and 3.08 gears turning P295/50R17s.

61# injectors are good for about 72 lb/hr @ 18 psi. I have once flowed one on an injector bench in 4 psi increments from 10 psi through 62 psi. The high pressure injectors will reliable open up to about 70 psi, however above about 50 psi the increased pressure does very little to increase flow.

[C2500]

Sorry for the confusion guys I sent that post on timing with my phone..Any way I set 0* with the spout disconnected..shut it off and reconnected the spout then started and timing is in the 20* mark at idle..

[C2500]

Ed just sent me back my chip with an adjustment and told me that the bored TB I have may be junk. Any way here’s his chip anyone recognize it??88F05DCB-AC87-4152-9A11-7217D769995B.jpg

[lionelhutz]

The i on that memory chip appears to be an Intel mark.

[C2500]

I spoke to Ed and he said to set timing at 0* with spout disconnected.. Can’t help but all this is confusing what some are telling me and what others are saying. I’m sure there are way to do this and all get to where it should be..I need someone to help me figure this out..
Also tuner pro web help never seems to help..lots of unanswered questions there...

[myburb]

There is lots of differing opinions and reasons for them. The initial timing is used only on the start and limp. The initial is added to the computer timing to get the final advance. If you just use the gm 0 degrees the spark table should be useable as it is. It you use some other initial you will have to modify the table to suit that. My two bits would be use 0 degrees and at a later date when you feel you understand it all, experiment as much as you like.

[lionelhutz]

There is a setting in the calibration called spark bias where you set the static advance of the distributor. So, if Ed says to use 0* that is because he knows the tune is set to work with 0* at the distributor. Basically, you just match the advance you set to the setting in the tune.

When you want to adjust the operating timing you don't the distributor or the static timing setting. You adjust the 3-D timing table.

[daveosx]

The calculation for HP to pounds of fuel is universal not a short cut it's just the physics.
1 HP = 2545 BTU’s per hour

Gasoline is 5.92 lbs per gallon
Gasohol is 6.1 Lbs per gallon

Flat head ford is rated at 49% Therodynamic Efficiency and BTU per pound is based on that .
Modern engines run from the factory at @76%.
Theoretical 18000 BTU per pound of gasoline is based on 49% conversion ratio.
Stock 1979 and up engine is @76% or 28000 BTU per pound of gasoline.
Rings valve seats and throttle plate sealing provides 80% on typical modified engine or 29000BTU per pound.
1 LBS of fuel on a modern modified engine should produce 11.4 HP
Parasytic Loses valve springs, piston skirts, oil pump timing chain ETC lower the net power.

pumping 130 Gallons of air and 9.16 Gallons of fuel on that motor will yield 335 HP


C2500s engine build is the Super Chevy magazines Test mule for carboration and the same build is typically 450 HP.
These motors with carb are routinely dynode with 650 and 700 CFM at 450 HP

As far as your results I understand you are commanding the injector to open and close.
Have you put a scope on the injectors them selves while running and confirmed that you are getting the actual commanded on period.
I alter the ignition with CDI after the module and give a solid 5v pp signal to the reference line.
I get @7400 rpm no load at 4ms on 65/68 TBI injectors
I have seen refurb ECM with cheap slow Mosfet installed could be a slew issue rather than injector flow.

In example I had a 1995 Impala/caprice with 1996 LT-4 Corvette, Radically ported iron heads 280cc intake runners, 194/160 with orange ZZX Beehive springs, 1.6 roller rocker crane rev kit lifter springs, .575 intake .560 exhaust 117lsa cam, SPO timing chain on steel gears, Low RPM water pump drive, HyperUtetic Pistons with tungsten Disulfide coated skirts, Rods drilled with piston squirters, copper shim head gaskets final compression ration 10.8 : 1, HMV55HV millings with 5W-50 oil, oil cooler trans cooler, 4L60E with 4.3L convertor, truck low gear spray, Steel drive shaft GM 10bolt 3.73 with Eaton Posi.
TH ignition system was/ is triggered using opti spark pick up CDI box and twin coil MSD coils. Ford 4cylinder ecoboost injectors in sequential mode rather than batch.
Routinely ran at 7500RPM and even peeked it a few times at 8500rpm.
According to iPhone pocket Dyno and Cats Tuner dyno hit 600HP on regular basis.
Never drag raced the car just street racing.
Have driven the car at Taledega at over 180MPH and at Daytona over 160