Another thing I noticed about...
Another thing I noticed about the new crate engine were the partially threaded holes in each of the engine’s aluminum cylinder heads (arrows). A call to the Ford Racing tech line informed me that these were for use with what they call “thermactor tubes”. These tubes are used on vehicles fitted with emissions provisions but in off-road or pre-emissions usage they can be blocked using a plug set available through Ford Racing. I didn’t want to take the time to order the real plugs so I quickly fashioned some out of a quartet of 5/8-11x1-inch bolts.
Bright and early that next Saturday morning I headed back out to the garage to hopefully finish up what I’d originally thought was to be an easy engine swap (though, if only I’d had the foresight to read the engine installation instructions beforehand I would have saved myself a bunch of work and a lot of heartache). After replacing the flexplate and reinstalling the transmission I went ahead and installed the assembly into the Model A for the second time.
The Ford Racing M-6007-X302 is a long-block assembly; no intake, carb, or distributor (as well as the aforementioned pulleys, water pump, and flywheel/flexplate). Once the assembly had been reinstalled, my next step was to install an intake manifold and carb. The Ford installation instructions do give you a Ford Racing part number for intake gaskets, and though you’d think I’d have learned my lessons with my previous incorrect assumptions, I went ahead and used a set of Fel-Pro gaskets I’d purchased ahead of the engine swap. Everything seemed to be going along just fine. I installed the new intake and torqued it down in the correct sequence and to the correct specs, bolted up my new Summit Racing 600-cfm four-barrel carb, and dropped the nearly new distributor in place. Then I installed a fresh oil filter, fresh oil, and finished filling the C4 with fluid. I also hooked up the radiator hoses, belts, fuel line, and attached the throttle linkage.
Among the parts I thought...
Among the parts I thought I’d use on the new engine was the 289’s flexplate. I removed and mounted it to the X302 with a set of fresh flywheel bolts and lock washers and then mated the new trans to the engine. From there I moved to the front and began to swap the front crank pulley as well—that’s when I found that the old pulleys wouldn’t fit the new X302 anyway. This problem resulted in a bit more investigation and thankfully I learned another important difference between early and late Ford small-blocks. Later engines use a 50-in/oz balancer and flexplate combo not a 28-in/oz setup as used prior to 1981. Come to find out, if I’d been able and did use the older flexplate and balancer/pulley assembly I would have severely damaged the X302. So, the time I saved by making my own plugs for the heads was used to order up the correct flexplate and to find the matching pulleys needed.
I had just finished double-checking the timing and marking the distributor location so I could pull it and prime the engine before start up when I noticed that the aluminum heads each had a large, partially threaded hole bored front-to-back—what now? This time I had the presence of mind to dial up the Ford Racing parts tech line before going any further. I got through pretty quickly and asked the tech guy what the heck those holes were for. Well, come to find out, the holes are there to accommodate what they call “thermactor tubes”. These tubes are emissions related and normally bridge the holes from side-to-side (one on the front of the heads and one on the rear of the heads). These are not needed on non-emissions vehicles and can be plugged with a plug set sold by Ford Racing. Well, not wanting to stop the install and hold off to the following weekend for a second time, I measured the holes and found they were 5/8-inch diameter with an 11-thread pitch. I jumped in the car once again and hit my local hardware store and picked up four 5/8-11x1-inch bolts to use as plugs. I got back to the garage and cut the hex heads off the bolts and using my die grinder cut slits into the bolts so they could be installed flush to the heads using a screwdriver. Thinking I’d passed the last of my hurdles, I dabbed the newly fabricated plugs with a bit of antiseize compound and sealed all four holes—now I should be ready to fire that baby up.