I did this changeover two years ago in my 91 5.0Simple Me said:Hi all, I am considering an engine swap in my 91 Brougham. It has the stock 305 in it now, but with bad rings, plenty of blow by, and kinda doggy performance to begin with, I am thinking I want something more. I was thinking of a GM Goodwrench crate 350, but I need to know if anyone has done this before. I will be going from TBI to carbureted, and I am not even sure if the bell housings will match up correctly. I am hoping that someone can tell me what I am getting into, I don't have to worry about labor if I decide to go through with it, so all the cost will be in parts, machining, etc....
I bought a GM 350 crate motor and have put 35,000 miles on the new engine. I don't know why you would want to go from a TBI to a carb.
The bellhousing will match up. Go with the GM crate motor, it has a 3yr. 50,000 mile warranty. Don't rebuild buy new it's cheaper than rebuilding.
I ran Valvoline 10w30 for the first 5,000 miles and then switched to Mobil 1 10w30 after that.