thewizzard

Folks:

I need a little help here if anyone is willing to provide it. I've read through all the stickies, etc..., and then read them again... and even again. I've got the prominator installed and have gotten my fueling tables to within +/-5 BLMs to 128. This after installing the 28-32psi fuel pressure regulator from a BBC TBI and playing with my BPW until I was able to populate my VE table to a maximum of about 98% in one cell. (Any lower BPW and my VE would be way past 100% - which from what I understand the computer will not use)

So, now comes timing right. This is a rebuilt 350 SBC, with a comp cams 210/220@0.050, .480/.480 lift (Think total duration is 264/274 - its a 264HR-12). It has street/garage ported 193 heads (I know.. .for the cost could have put vortecs on ). "Ultimate TBI Mods" - i.e. removed tbi ridges, and reduced the size of the throttle shafts. Headman headers into single 3 inch exhaust with no cat and a dynomax muffler.

So, the chip that came out was a 1227747 ARJT bin. Because I could not retrieve it from the prom - as I was intalling the prominator and didn't have anything to read it with - I used the ARJT from moates (i think). So using the same timing table (Attached).

My question is this: Where do I go next with the spark table? Is there a better spark table that I can paste in as a starting point given my setup? Or do I just start adding timing? If the latter, do I do it accross the board - say by reducing/increasing the "warm spark bias"?

Any input, suggestion or comments are more than welcome at this point. I'm kinda lost at this point...


Cheers,
Ben

Fast355

iTrader: (2)

I like AKTX (Astro/Safari 4.3) for a good starting point. In my experience it has worked well with mild 350s.

Gotta love the fueling ability you have with the late 454 regulator and small injectors. You BPW should be well under 100. In my experience a BPW of 100 will let you go smooth up to about 5,500 before running into static injectors. When you hit about 6,500 rpm you need less than 70 BPW, my 312 was 65 @ WOT and no vacuum, but around 110 with vacuum to the regulator.

thewizzard

Thanks Fast!!

So other than using the 4.3 spark table as a starting point... I've got a question regarding the BPW. I originally started with a BPW of 96, but soon realized that my VE was ending up well above 100%. My understanding was that the computer would not fuel for anything above 100% and that BPW needed to be increased in order to reduce my VE... which I did and am now at a BPW of 125 (Granted my FP isn't maxed, and haven't gotten a gauge, so my estimate - based on the location of the metal tang - is about 29psi).

Also, any pointers on the process to use when pasting this new table in? In other words... would the process be kind of like this:
1. Start and run until closed loop with a known good program
2. Switch to new program with new spark table
3. Watch everything at idle in the driveway to look for spark counts
4. Go for a light cruise and watch for spark counts
5. Adjust fueling if required
6. repeat 4-5 while increasing the load/RPM

Thanks in advance.

Ben

thewizzard

Ok, so with the 4.3l spark table, and some adjustments since.... well it's got a lot more jam than it did before!!!

But... my question now pertains to part of my last post.

Given that my BPW is now back at 135... and that I now have just gotten my fueling table back to normal and under 100% VE. Is it possible, as Fast states that the BPW should be much lower (I originally calculated it at 96 @ 86lb/hr on the injectors with new flow rate) and that my fuel pressure should simply be increased. In other words, if my VE in the upper portion of the VE table is going above 100% when BPW is lower, does the engine simply want me to bump up the fuel pressure again? This would most certainly make it overly rich again at lower kpa/rpms, but would it potentially keep my VE from going over 100% and forcing me to up my BPW again?

Any help is greatly appreciated.

Cheers,
Ben

thewizzard

Anyone?

Dominic Sorresso

wizzard,

You need to find out if you have enough fuel volume at WOT. If you are near 100% in the lower VE table then its a pretty good bet WOT will show static injectors. Mine is a stock block 350 Xfire running 80# BBC injectors. My BPC is set at 86. WOT DC% is around 70-75%. Its taken some time to get the
idle right since the PW could get down to .8-.9. FP is set to 20# up from the original 10. No sense going thru all the tune for PT only to find out that you don't have enough fuel at WOT. The other option is using a VAFPR if you have an ECM, like EBL, that will accomodate one.