1987 with a 350 and 200R4 w/ lock up tc. am using the 305 computer controlled carb w/ modifications and the stock distributer. am using the 350 knock sensor and spark module for the ZZ4 engine. computer and prom are from 87 monte SS. tried the prom for ZZ4 and it will not work.

any suggestions on a prom suitable for a 350?

thanks
bart

My truck came from the factory with a 305 and 200C tranny. I swapped the 305 for a 350 and the 200C for a 350C. Am using the same ECM and prom with no problem.

What happened to the original ECM and its prom? Why are you not using that combination? If you still have it, reinstall it to see if you like the results. Also, the prom usually does not go bad. I have replaced many ECM's on several GM cars over the years and have never seen but one prom go bad. It was in an Oldsmobile and got wet from a bad leak around the windshield.

You can go to the dealer or find an auto parts store that specializes in GM products and tell them what you need. They can look up the prom you need and sell you a new one for about $40.00. However, I would buy a used ECM for the vehicle. Lots of units out there for sale that already have the prom. I bought two recently. One off this forum and one off EBAY. The EBAY unit was complete with prom and sold for $4.00!

Or, I will make you a deal on one of the spares I have. One is from an 86 Elcamino with 305 and automatic transmission. The other is from and 87 Caprice with 305 and auto tranny. I have not compared the two, but I'll bet they are identical. If interested, pm me or email me at walford1@bellsouth.net

I put a 350 crate motor in my ride and was going to use the computer controlled carb/distributor. I got the 350 knock sensor and spark control module too. I read an article in Super Chevy that said I would need a new chip because of the vacumn characteristics of the cam in the Vortec crate motor. I ended up installing a new carb/distributor and threw the computer away. I've still got the prom I had programmed by Hypertech. I'm going to list it in the Parts for Sale Section. Look for it there if you think you can use it.

My prom died years ago (before I bought it) It doesn't do a thing anyway. You can get controllers for the lock up converters by themselves. Just ditch the computer and change the distributer. voila no problems.