I am trying to finish rebuilding my 351M engine and since this has been a lengthy process while waiting on aftermarket parts I have forgotten how several parts go back on the block. I have a threaded hole on the left side of the timing chain cover plate above the water pump. Does the temp sensing unit go here? The other threaded hole is just to the right of where the fuel pump goes into the block. I don't remember taking anything off from here when I sent the block out to get reworked. I am thinking that a threaded plug goes here since I don't have any other sensing units laying around and the oil pressure sending unit threads into the top of the block behind the base of the intake manifold. Am I right in assuming that a plug goes there? I also would like to know where I can find a service manual that goes into better detail as to what goes where on the 78 Bronco as my chilton and haynes manuals are not much for showing all parts and bolts. I appreciate any help as I want to enjoy driving my Bronco again.

 

Your right. Both of the holes get plugged. The oil sending unit goes on the top rear of the block. And water temp sending unit should thread into the water pump. The two holes are just extra locations for sending units. Why I don't know. You could probably use the front hole for water temp if running an electric water pump if anybody made one for anything besides Chevy engines.

 

It goes in the hole you thought it did. On the right side front of the engine by the timing cover. I've had many of these engines and thats where it goes. I would think a plug goes in the one by the fuel pump as I recall nothing being there. A plug goes in the top of the water pump unless you have a heat operated ported vacuum switch that goes there.

 

I concure. front plug is for temp sender, water neck holes are for sensors for carb vaccume controls. the one by the fuel pump does get plugged it is an oil passage. I just got done with my rompen,stompen 400 build, hope yours runs as good as mine (i used the 98 sep Hot rod build).
Im not sure if i got there numbers, but it aint no dog anymore.

PS I used one of the water neck holes for mech gauges. water pump hole gets pluged

 

Travis, the reason I mentioned the hole in the top of the water pump could take a thermal vacuum switch is because my 82 heavy duty F-250 4x4 with a 400 (factory set-up) uses this hole for just such a thing, it was the first 400 I had ever seen to do so, but both ports were being used on the water neck with thermal vacuum switchs also so thats probably why.

 

I want to thank those that answered my previous questions on my engine rebuild. I want to replace my 78 Bronco's doors which have areas where it has rusted through.Will the doors from 1980 or later pickup or bronco swap out? Also will the removable top from a 1980 or later bronco work on my 78? I am having a hard time finding a 78 /79 top in the local salvage yards.

 

I am not sure about the removable top, but the doors will not fit. The use different hinges and have different body lines. If you are looking at Ford replacement parts I would reccomend going to a dealer and see if they can get you the parts. I found this cheaper, yes I said cheaper than paying the markup of the catolog and shipping. I'm sure some one on the board knows about the tops. All I am sure that the 80-96 tops are the same.