Is there an actual difference between a Memcal from a 305 vs a memcal from a 350 or ar they identical and its just the program thats different? I'm assuming it is the latter for any given year..

If it's the same year with same ECM's then the memcal is the same, the PROM will be different for 305's and 350's and 305/5-speeds will be different from 305/auto's.

The memcal assembly contains both the functions of the PROM and the CALPAK. Like the PROM, it contains the calibrations needed for a specific vehicle. It also is the fuel back up control for the computer should it become damaged or faulty.
To allow one type of computer to be used for many different vehicles, a device called a Programable Read Only Memory (PROM) unit is used. The PROM is located inside the computer and has system calibration information based upon the vehicle's axle ratio, engine, transmission, weight, and other specific configurations of the vehicle.
If the computer is equipped with a CALPAK chip, it will be located next to the PROM and must be transferred along with the PROM

in other words the memcal and prom are the same unless the ecm has a calpak then the prom is seperate

Thanks guys - the reason I asked is when I look at TPIParts.net for replacement chips, it says you need a Memcal from the original motor (of the same displacement) - I'm guessing now b/c thats b/c they dont change the cylinder size constant or the fuel and spark tables in the PROM as opposed to the "limp home" type function.

Next question is, can I install a Corvette MAP/TPI bin on a PROM and install it on my 305 MAP/TPI Memcal? I am building a Aluminium headed 350 with a T56 and figured that the Vette bin file would be a pretty good starting point... If so, can you give me any pointers on finding that vette bin i am looking for? I have looked at heaps of places that list endless bin files but none of them have trustworthy desriptions and most are just "a bunch of letters.bin"

Maybe i will post that Q in the DIY Prom forum...

Thanks again!

The Corvette PROM has oil temp sensors in it, and you will get a SES light if the computer doesnt see those inputs. I found that out the hard way.

I'm now using a modified AXXD, which is a 305 5-speed G92 chip.

I'm guessing it is too much work to add oil temp sensors then?

I asked the Corvette guys, because I wanted to add an oil temp sensor myself, and they said yes its more work than its worth.

Hmm.. I wonder how TPIParts.net gets around that then? The mention on their website that they can start with a Corvette bin file but they dont mention the CEL b/c of Oil Temp sensors...

Is it an electrical or mechanical challenge do you know?

Yes, if you do a custom chip you can turn off the flags in the Constant Table so it will not check for the oil temp sensor.

Well now you are confusing me even further.. If you can simply turn them off, why did you revert to a modified 305 bin instead of sticking with the Corvette bin?

At the time I was using the Corvette bin, I didnt have the capability to do my own custom chips. Once we realized the problem with the oil temp sensor setting the SES light, the guy doing my chips changed programs.

I had switched from a 305 5-speed with 19lb injectors to a 350 5-speed with 22lbs injectors and Corvette heads, so we thought starting with the Corvette chip would be better. As it turns out, the 305 5-speed chip worked just fine with the Corvette fuel and spark tables copied into it.

So when you say "chip" you mean you used the actual PROM/Memcal from a Corvette? And it was this PROM that had the oil temp sensor stuff in it.. So switching back to the original 305 5 speed PROM overcame that problem.

So the next question is, whats the differences between a 305/Auto PROM and a 305/5 speed PROM? Is it all programable from within the bin file?

What I want to know for sure is, if i use my original 305/Auto PROM and install a Corvette 350/6 Speed bin file, will it effectivley make my 305/Auto PROM seem like a Vette 350/6 Speed?

OR do i need to install a 305/5 Speed bin file onto the same 305/Auto Prom and copy in the Vette fuel and spark tables? This seems more logical to me given what you have said.

Thanks for the help by the way! Just trying to learn all this stuff

When I say chip I mean the programming coded in the PROM, in this case. I guess I should use the term bin file? And the PROM is the part of the memcal that holds the black rectangular pieces on the top. And the memcal is the whole thing that plugs into the ECM.

Its my understanding there are parts of the bin file that we dont quite understand yet. So I would start with the bin file that has the right transmission and modify it to your specs. Yes you can erase your existing chip/PROM with ultraviolet light and reprogram it using a chip burner. You cannot reprogram changes to the existing chip/PROM until you erase it first and burn your new program onto it. You could use either the 305 5-speed f-body bin file, or the Corvette 6-speed bin file, with the oil temp SES check turned off.

So if one were doing a MAF to SD setup and has a 91-92 730 ecm, and needed a memcal as well, but didnt want to spend 300 bucks for a new GM 350 memcal, could one use the 305 TPI memcal ?

Since guys use 350 computers for 383's and 400+ inch motors anyway, why does the memcal matter? Shouldnt a TPI 305 memcal work just as good as a 350 memcal?

Thats pretty much what I was trying to figure out. Having read and re-read the replys in this thread many times, I am going with the understanding that the Memcals are pretty much the same but the programming in the PROM is different (as you would expect). I also expect that you should be fine using a 305 Memcal but will need to adjust the several perameters in the bin to alter it sufficiently enough to support a 350 motor - Displacement, Injector size, fuel & spark tables etc etc..

ricco, can you answer my thread about no fuel pump, injector pulse. i beleive you know the answer.

See thats my thing, I burn my own chips and the motor in question isnt even in the same ball park as the stock L98 or LB9. I was going to use $59 on a twin turbo 400 using 730 ecm. I was under the impression you need a memcal for the chip/prom thing to work and it has to be a 350 memcal for some reason.

Then i thought well my motor isnt a 350 nor is it the same style block so why would it matter?

Since the prom/chip is gonna be completely custom for my application, any memcal should be ok? Or are there still some changes to make in the bin file that only applies to the memcal side of things?

You're at exactly the same place as I am at :-) Although my build doesnt sound as radical as yours.

I'm guessing that if anything, it is just the "limp home" mode that would be different but "limp home" for a 305 can't be that different from "limp home" for a 350 etc.

Kevin, could you chime in? Are you using a 305 or 350 memcal with your custom PROM program?

305 or 350 does not matter. What matters is that its a V8 TPI memcal.

Got yah! i think i'm gonna try a 305 memcal then for TPI. You may have saved me 300 bucks