Does anybody know what

kind of compression I will most likely end up with if I put a Renix 4.0 head on an '85 258 block. I have a rebuilt 258 that I can use, but I am concerned of the possibility of "ping". I already know that most of the serp. belt stuff willl not fit, since some of the mounting bosses are not on the block, so that is not an issue at this point. Thanks in advance, Ren

Compression will be about the same. I ran the block off my 84 4.2 on the wife's 89 using the original head and Renix. As you noted, you will be missing the boss on the right side to attach the alternator bracket. I ran it for two years before putting in a 4.0...

Note...I swaped out the engine due to excessive oil consumption. The original engine overheated and froze. I had the head rebuilt and used a spare block that had about 5K miles on it. I pulled the engine apart to see what the problem was....head was dumping the oil in through the valve guides...I guess the machinest didn't do a very good job for me....

Rather than fix the head, I just put in a 4.2. I figure I can sell the block someday....it has less the 20K miles on it now......and there is nothing wrong with it.

Thanks for the reply. It is nice to know that this thing will run on "poor-people" gas. I checked the head/block match-up this evening, and unfortunately, I have to mod. the head where the water jacket wants to expose itself. I guess the next trip is to the machine shop. I already plan on using the valve-train parts from the 258 head, including pushrods, so that should take care of those issues. I will post again on this thread when I get the head back, and install the motor with bigger injectors and an adjustable MAP sensor to help run the injectors. 'til then, Ren