Since I'm converting to Holley MPFI instead of TBI but wish to use a 730 ecm, is there any way I could I use the newer style ignition from a gen 1 vortec truck? It has a crank sensor and cam sensor. External coil and external module.
How hard would it be to adapt to this style of ignition?
Since I don't have my TPI harness yet. I could start with a truck harness and modify it for the older ecm if necessary.
Or would I be better off to stick with the small cap 87-95 style distibutor?

 

that sounds like a huge waste of time for no gains

 

Putting anything but nitrous or a blower on your 305 sounds like a huge waste of time for no (real) gains-IMO.

More accurate timing is the gain it accomplishes and since I'm building a motor that'll run me around 5 grand and then spraying a 200-250 shot, that's pretty important.

Does anyone else know anything about it?

 

The Vortec parts can be made to fit, and they are excellent pieces for hotrodding a V8, but the physical interface with that 730 ECM may be pretty complicated.

If you plan to run the $8D mask for the 730 ECM, you mainly have the problem of where to get a spark signal during cranking - $8D has no provision for this, it's handled in the HEI module.

There is also a general size limitatiion on the timing chain you can fit behind the Vortec crank wheel. See the pix below:



Unless you can write your own code patch for the $8D ECM, you are probably stuck with the original-style distrib for a start-up pulse. The $8D mask has no use for a cam signal anyway.

If you get beyond that, the Vortec ignition module & coil are excellent pieces for a modified engine - they are designed to throw more spark energy than the stock HEI parts (as I understand them). Good luck.

 

Also

 

Last:

 

Doc,
Thanks for the reply. The block is a 99 model 350 and I have a Rollmaster Billet double roller timing set that I plan on using. I'm gonna go dig it up to compare it to yours to see if it's got more room for the trigger wheel.

As for the 730 ECM interface...that's not a definate.
I don't have one yet or a harness so I can go several ways.
Would a Syclone/Typhoon ECM work better? Or can you think of any other ECM's that would be a better choice?
What about the 96-99 truck PCM? I know it's OBDII, but would it give any advantages to my setup? The vortec injection was multi port with a throttle body as is my Holley MPFI system. I would probably have to re-terminate some connectors for TPS or IAC but that's no biggie. Could that be a better route?

 

wow, i try to help by giving an honest opinion that is supported by another memebers proof of the work involved, and you get offended and try to insult me

 

Guy: word your reply better. You made no reference to anyones attempts or specific results at this. You wrote what appeared to be an opinion. Sorry if I pegged you wrong, but recognize that your reply lacked any valid info.

Now....back to the topic.
Anybody have any other suggestions on this?

 

drain

I'm not sure that choosing a different ECM will help much. The 730 ECM is thoroughly hacked, and really easy to work with. But none of the P4 masks I've seen support an internal cranking pulse (Sy/Ty won't help - it uses a distrib too AFAIK).

Newer GM ECMs that natively support a crank trigger signal aren't very well hacked yet, as far as I've seen.

I imagine a Vortec PCM could be made to work at some price, but I don't know how difficult the conversion would be. OBD2 adds a lot of complexity to the whole project so I've stayed away from them. You might check with this guy about using the truck PCM stand-alone - he's very capable: http://westers_garage.eidnet.org/Index2.htm


Using the Vortec distrib is no big advantage unless you need the cam signal - it's the same construction as a regular SB distrib, except with a 1X Hall signal in place of the 8X reluctor.

The real benefits to the Vortec are in the crank signal & the stronger coil/module.

A crank trigger improves spark accuracy, as I learned when I installed mine But the interface wound up more complex than I wanted - I use the HEI module to trigger a heavier, add-on inductive box on mine. It's been working fine for over 6 months, and I like it a lot, but it is sort of a kludge.

If I wanted to take the trouble, I would swap the HEI module for a National Semiconductor 1815 chip, and use that to drive an LT4/Vortec module. That would clean things up some. But right now I'm planning to go in a different direction for the next phase:

My next project will be to see if I can adapt a Northstar DIS to the small-block, so I can get rid of the distrib entirely. I think multi-coils would be a REAL improvement to the system...

have fun