1998 Vortec Timing Table (Black Box Computer) Open / Closed Throttle ONLY!

[pmkls1]

You are sort of comparing apples to oranges Quaff. It sounds like you are running a conventional distributor that isn't computer controlled. I am assuming that you are probably running a typical HEI dizzy. The initial advance is a little different with a computer controlled distributor. But, before even getting into details with the timing there are a couple of other items I'd like to address.

You say that you get 10:1 with a compression gauge when cranking it over and that has me a bit confused. I'm not aware of a compression gauge that will measure compression ratio so I'm curious as to what you meant exactly. Typical flat-tops will average around the 10:1 range with vortec heads, though. But, that isn't really aggressive though as a stock L31 vortec runs 9.4:1 compression. Your cam is also fairly close to the stock L31 cam with a modest increase in lift and duration and very similar LSA and centerlines. It is an excellent cam grind for what you are running, but it isn't very aggressive by any means.

I also have a thought on your starter as well. Are you running an old-school small block starter ? If so you may want to consider a gear reduction starter. The stock vortec engines used a gear reduction starter, but I believe it was mainly for weight savings and compact size. Those starters are a bit pricey and not super special, but a typical aftermarket high torque mini-starter runs a little over $100 and is a good investment. If you only have a slow crank with more initial advance I don't think that the starter is an issue, but I would still be wary of the starter if you are running an old-school one.

[Aksl]

Hi their guys,

I`m new to this forum, and didn`t yet find out my way around it. I wonder if you can help me, or direct me where to make a thread, in order to get some help.

I have a project with my Chevy 5.7 silverado 1990. I`m kind of restorating it, with additional upgrates. So wat i did is, i fully rebuild the engine, sandblasted and painted GM orange, installed KB flat top hypereutectic pistons, and comp cam 08-467-8. And as final i have made a vortec heads conversion, living the vortec manifold and injectors CFSI, installing the PCM Black box, and joining the two wirings together, in cabin is old and underhood is from vortec. So, now, the truck starts and works, but the problem is it gives me 20 degrees oftiming, and misfires. I took the car to a programmer, he unsoldered the chip and soldered an addapter for the chip, so it can be taken off easialy, reprogrammed it, and played with the ignition timer. When he gave me the car back, it had a P1345 stands for timing poins of crank and cam are off, said that have to adjust that and it will work fine. After checking all the marks and setting back the ignition timing (the marks were ok), the fault dissapeared and the engine light whent off. I have contacted him and said that it has to be adjusted through PCM black box, after reading alot of forums and projects, i think i`m right. Couldsomeone help me with this problem, any help is appreciated!!! Thanks in advance.

Ow, and one more thing, i havent yet conected the gear box wires to the PCM, want to do it from dashboard, not directly from the gearbox, but dont know yet to what pins in PCM and what to connect. Haven`t yet found the info. any help would be grate on that topic as well.

Thank you!

[FirstGenThree]

Not certain if I should try to resurrect this thread or add to my own but im interested in and willing to help get these timing tables figured out. I also use EFILive so I can snag a stock tune from the trucks of several friends if need be. I guess I have two main questions to start. First off, the vortec timing table appears to have much more advance than tbi but when I go through all the adders\multipliers I suspect thats not the case. Also do other bins have a PID for actual timing advance while datalogging? I ask because I see no way to log this but i'm running my stock and rather uncommon 6299 ecm with $99. Just fyi im running a vortec headed 385 stroker with 10.2 static compression and a very short duration crower roller cam.

[dave w]

I think upgrading the 16146299 ECM to the 16197427 PCM would be good option. http://www.gearhead-efi.com/Fuel-Inj...Information-0D

The 1227747 TBI ECM has great support, and is almost identically wired like the 16146299.

dave w