350 build with LT1 intake and DIS?

[CamaroDude85]

I was thinking of hopping up the 305 but decided a 350 would be better. Here's what I'm thinking I'm gonna build(slowly but surely as funds allow) to put in the Camaro.

350 OE roller block with hypereutectic pistons, cast steel crank, reworked rods with ARP bolts, Pro Comp 210cc heads, Comp XFI280 cam and of course headers/good exhaust and some 3.73's out back. I wanna top it off with a LT1 intake, run the LT1 oil pump drive and N* DIS. I think this is a good relatively budget build that according to Desktop dyno will put out 460hp at 6k and 445tq at 4.5k.

What I'm wondering is can the 7427 PCM I currently have run this combo? I know it'll run the MPI with the resistor mod but how about the cam and N* DIS? Every thing I've seen about the DIS says you have to change the reference angle and min/max spark but there is no reference angle in the 7427 just the initial spark advance. Is reference angle and initial spark the same/similar? I'd like to keep the 7427 because I'm familiar with it and the .xdf has got to be the nicest well organized one out there.

Just trying to get my ducks in a row with this one, I was going to put a 5.3 lm7 that I had in it till I seen that the cross member needed notching, plus all the other goodies to make it fit and that tuning software is $600+

[RobertISaar]

there's a reference angle, it's just not defined as such.

keep in mind, the northstar DIS will want all 3 sensors functioning, but you can get away with any 2 out of the 3 of the crank sensors and cam sensor.

[CamaroDude85]

Yeah my plan was to run the 2 crank sensors and get a trigger wheel laser cut somewhere. I'm lucky enough that my Dad has a pretty well equipped machine shop so making the bracket for the crank sensors will be a piece of cake. As for the reference angle is that something I need to look through the $0d hack for?

[RobertISaar]

it's possible that it's already in the XDF, just called something different.

it MAY be initial advance, depending on who made the XDF. certain masks have both an initial advance and a reference angle though.

[CamaroDude85]

Alright thanks. I'm gonna dig through the xdf and hack and see what my limited knowledge can come of with lol.

[CamaroDude85]

Ok digging through the different hack's I've came across, couldn't find anything with reference angle, only initial. But in one hack I seen at the top it was for a DIS engine the 2.2l S10 bin BHFM. In it initial advance is set to 66.1, maximum spark advance is at -6.0 and maximum spark retard is -66.1. So I'm gonna assume this is how a $0d bin should be set up to work with DIS. This is got me wanting to do DIS on the little 305 now for something to play with and it'll be one less thing to figure out when I eventually(wife, kids, house kinda take precedence) do the swap to the 350.

[RobertISaar]

with the 60V6 stuff, initial advance is actually initial advance, as in the first spark advance value when the first coil triggering happens.

it would seem a lot of masks do away with that entirely and initial advance should really be labeled "crank sensor BTDC signal offset" or something similar to it...

anyways, 66.1 sounds believable for the 4 cylinder stuff, with the 60V6, it's all 60*. with the northstar, i want to say it's something like 72*? been a while since i've looked into it though.

max spark advance of -6.... sounds kind of odd.
max retard of -66.... also sounds kind of odd.

i think those values got swapped, 66* BTDC for max advance and 6* BTDC for max retard sound a lot more realistic, if not a bit extreme.

[CamaroDude85]

It sounds totally backwards to me too but I found this http://www.thirdgen.org/techboard/di...y-dizzy-5.html and it seems that they found that max retard of -54.84, max advance -6.33 and setting initial timing to 65. They were running initial at 75 but found it to run 10 advanced from what it should of been so switched to 65. This was all on a 7730 BTW. I think the ECM does some of that politician fuzzy math to get everything to work right, it doesn't make a bit of sense to me as to how the negative values work.

Anyways here in the next couple months I'm gonna give it ago with the 305 and if I can get it to work I'm gonna do a write-up of how it was done in case anyone else wants to go this route. I remember seeing in I think Car Craft where they gained 20hp by using eficonnection's 24x setup on a LT1. They explained it better than me, but something about the single coil not being to charge quickly enough. It would misfire every so often at higher rpm's and you wouldn't be able to notice the misfire.

[RobertISaar]

well, the actual "initial advance" value you come up with will depend almost entirely on the trigger wheel/crank sensors bracket you come up with. i think that's why they had trouble in the other thread, it wasn't setup to emulate exactly where it would have been on a N*, so it came out odd.

perhaps the min/max advance is mask dependant... with the 93-95 3100/3.4 flash PCM, i have max SA at 60.35* BTDC and min SA is -30* BTDC (so 30* ATDC).

then again, they could have been dealing with SA compared to reference pulse as well, which can throw in some more interesting math.

[JeepsAndGuns]

We talked about the northstar DIS for a while. Its still something I want to do. My biggest hurdle is the trigger wheel and a mount for the crank sensors. I have already sourced two comeplete northstar DIS icm/coilpack assemblies and 4 crank sensors from the local pull a part. I just need the trigger wheel and a mount for the sensors made for my engine.

[CamaroDude85]

Been pricing a few places online and it looks to be about $150 to get a trigger wheel cut out on a laser cutter or water jet. Once I get a hold the module and coil packs I'm gonna see if locally it could be done cheaper cause that's kinda pricey for maybe $15 worth of steel but I guess them machines don't pay for them selfs. As for the bracket I don't see it being to bad I know the one I come up with isn't going to be pretty by any means but it'll get the job done.

[RobertISaar]

as long as the sensor to sensor angle is maintained, i don't see an issue that can't be overcome with programming.

[gregs78cam]

Get me a good description of what is required for the trigger wheel, and I will get it modeled up in SolidWorks and see what I can get done. We have a 1KW laser at work that will do 1/4" and I also work part time for a guy with a plasma table that can cut 1/2" with ease.

EDIT: Something like this? Let me know if you need it a specific size, want lightening holes, or whatever.

[JeepsAndGuns]

http://lukeskaff.com/?page_id=380

Thats the site I got all my original info from, as well as the idea of doing it in the first place. Down at the bottom he has info on making the wheel, and also has a autocad file of the wheel. I would need a large center hold cut out on mine to fit over the balancer hub. I would have to remove my crank pulley and measure it.

[EagleMark]

You had the right idea and blew it off because of cost? Need to figure the cost of what your doing first to have something to compare to. Couple years ago I rebuilt an IH 345 engine, nothing special, just done right, .020 over bore with aftermarket Isky cam that cost less then stock and a balanced rotating assembly and it was $3000.ish for parts and machine work, we did all dissassembly and re-assembly. It was my sons second engine rebuild I taught him.

Then call around (or use a freinds shop name for better price) to some junk yards for a low mile LS engine and trans with harness and PCM. You'll be in way cheaper and have a better motor/tran with no rebuild needed.
http://www.lsxtv.com/tech-stories/en...ags-to-riches/