Originally Posted By: oiler
Hi, I have a 1983 250 in a GMC truck. I want to keep it a inline 6.
I was going to spend about $2000 on the engine until I spotted this thread:

https://www.inliners.org/ubbthreads/ubbthreads.php?ubb=showflat&Number=24366&fpart=1

Now I think spending any money on performance improvements on the 250 is not cost effective.
The 4200 makes more HP stock and gets better gas mileage.

@ efi-diy Do you think your 4200 made more HP than stock with a locked exhaust cam? \:\)


I most likely lost power with the locked VVT, currently MS-EFI can't control the VVT so right now I'm stuck unless I shell out for a high end ECU. If I was staying with a stock engine there is no reason not to use the stock GM electronics.

51 GMC 4.2 turbo
Can't solved today's problems using the same technology/thinking that created them