questions re: mpi on 258/4.0 head
I have decided that mpi is the way to go for the j10. I had been planning to go with gm tbi, but I am worried about the totally different character of the 4.0 head on the 258,(comp. ratio, flow rates of head) and I don't want to have to have a custom eprom burned for this. If the engine was in a cj, I'd be more willing to confer with people about having a custom chip burned, but where it is in an fsj, I run with way more load on the engine and wouldn't really trust a curve designed for a cj.
I feel safer with the idea of MPI, mostly because i know I can eliminate ping with larger injectors. I could also use the extra horses out of the 1 and 6 cans.
One thing that has been bothering me though, is the operating temp of the engine. The 4.0 head article says to use plugs of one range colder than stock, and a 180* tstat. 4.0 MPI goes closed loop @ 195* though, correct? What I am thinking is to find a switch that closes at 180* instead of 195*. I'd rather have the engine run at 195*, but obviously can't if it will cause detonation.
My questions are:
1. does the 180* switch idea seem feasible?
2. would using larger injectors (such as mustang 24 lb/hr injectors as opposed to stock which I believe are 19 lb/hr) eliminate the question of operating temperature vs.detonation by richening the fuel mixture?