Good evening all! I've gotten myself an 81 F100 Stepside that has a 2bbl Holley and an Offy DP intake. I need to fab up a heat plate for the intake but I have not a clue on how to do it. From what I have seen, it is essentially a plate bolted to the bottom of the intake with two ports for the coolant flow, but where does the coolant go? Are there ports in the intake that the coolant flows thru, or does it just go in that small indention at the bottom of the intake? Any help from the expert would be greatly appreciated.

Thanks
Papa

 

The coolant just fills that small void you see. It comes in one fitting and exits the other, and goes on its way to the heater.

I used to make them guys here, but gave that up. There are two ways to make one. Either you or a shop can assemble it by welding, or by drilling/tapping. If it is to be welded then visit a steel supplier and get some 1/4" plate, ten inches of 1/2" or 3/8" steel tubing, two 90* elbows, and two 5/8" hose bibs, bought from Napa.

Use the gasket that is supposed to sandwich between the oem intake and exhaust manifold and trace the outside perimeter and holes onto the plate. Cut plate and drill the holes. You'll also need to mark and drill two 3/8" holes somewhere on the plate, keeping this set of holes a minimum of one inch from the edge. Now weld the 90* elbow over the last two holes with the end not welded facing the side of the plate with only one mounting hole. Weld a 5" tube to the elbow, and the hose bib to the tube.

Or, you make it using 3/8" or 1/2" galvanized pipe, tap the plate holes and screw the thing together.

Oh yeah, use the previously mentioned gasket and trace it once more onto gasket material and make a gasket. Apply it with very thin layer of silicone on either side. Tighten evenly and slowly, gradually.

Here is a photo of a welded plate. If you use 3/8" pipe, the hoses fit right on the ends without the hose bibs, and that will save you $13.



Below is a shot of a manifold made welding a 3/8" galvanized elbow to a plate. You can see there are no hose bibs needed with the 3/8" nipple. I just cut off the threaded ends. Also, angle the tube a bit as in the photo. It makes putting on the hoses easier. With the long tubes they clear the headers and the heat better.



Let me also say that if you're going to use galvanized pipe, you need to grind off the galvanized coating before welding. AND! Fumes created by welding on galvanized metal can Kill you or poison you. Take precautions! Kevin.