When I first bought the car I had decoded the VIN or warranty number enough to realize that the 2 barrel carburetor and intake manifold were not original. I was having problems with the carb so I decided to replace it with an Edlebrock 600 cfm 4 barrel and aluminum intake manifold. This definitely improved the performance. I really didn't think more about the engine itself. It ran well when I had parked it. So lately when I decided to rebuild the Mustang I originally had thought I would leave the engine as is. But after looking under the hood it looked terrible and I knew that I would at least like to rebuild the carburetor.

I had bought a rebuilt 1975 C4 transmission for $100. I was planning on just swapping the transmissions but uncertainty was holding me back. I felt that I should check the replacement transmission just to make sure everything was good inside the case.

I removed the engine without any difficulty but the transmission was a bit harder. I ended up spilling quite a bit of transmission fluid all over the garage floor which was extremely frustrating as I tried to maneuver the transmission off the jack. The car was not high enough to simply pull the transmission jack out with the transmission on top like it is supposed to be.  I didn't worry too much about spilling the fluid. Next time I will buy those fluid stoppers to prevent the mess. I also need to figure a way to jack the car up higher without a lift.

I researched the engine block, cylinder head and transmission part numbers. But first I should relate to you what I found when I disassembled the engine. When I took the heads off I noticed that the front two cylinders had leaks. The left one had oil and sludge while the right one had water and calcium/rust crud. The other cylinders appeared normal. I am not sure how the water leaked in but it is a good bet that the right head is cracked. As for the left head it was plane that the oil had leaked through the exhaust valve guide. You could see where the valve had cut into the piston slightly and the valve seat was cut through. I have not disassembled either head at this point to further investigate. My initial conclusion is that they will have to be replaced. The head with cut valve seat may be salvageable if the actual casting has not been damaged. I also noticed a large hole in the valley pan of the block as it rises to the circular opening for the distributor. It is clear that a piece had been broken out. How this happen is hard to figure. The hole was in the wall of the distributor shaft cavity and shouldn't have an effect on the performance of the engine. It could be rounded out and a screen epoxied in it to prevent any large bits of metal from draining into the oil pan. This is a good practice for the other oil return holes at any rate. Nothing else appears to be a problem. I did noticed that the engine had been rebuilt before since it was sporting 0.30 over sized pistons which means it was bored out at some point. This led me to wonder if the engine was original or a replacement. I also wasn't sure if I should swap the short block with a rebuilt short block I found offered at a engine builder in Glendale not to far from here. My main concern was if this was the original engine for this car keeping it with the car could potentially look better on paper. I was already disappointed that it was no longer a 289 cubic inch being that is was bored 0.30 inches over the stock 4.00 inch cylinder diameter. It will need to be bored out to 0.40 inches based on the current condition of the cylinder walls. Yes reboring does increase cubic inches which increases power but I was hoping, perhaps naively, that it was steal a 289 cubic inch engine as they are very hard to find. Most of them are bored out 0.30 or 0.40 inches. The decision now to rebuild this short block or replace it with one already built lay with whether or not this was the original engine.

The first problem I ran into was that the engine tag was missing although the part numbers were still in place. After a fruitless search through my Mustang Restoration Guide and the service manuals I found a web site that helped decode the part numbers.http://www.classicmustang.com/decoding_part_numbers.htm
Apparently since Ford had a tendency of mixing parts from available bins there is not a clear cut method to determining the actual installed parts for any given vehicle. Assumptions and educated guesses have to be made. The numbers I decoded signify the block was intended for a 1966 Ford Galaxie whereas the heads where intended for 1966 Ford Fairlane. The date codes were either on the same day or within three days of each other. It is safe to say that the heads and block match although from different Fords. So next I decode the transmission numbers. These came back to indicate parts from 1966 Galaxie, 1964 Galaxie and a 1966 Falcon were assembled together. Based on this the years make sense but the compelling evidence that the engine and transmission were not original to this car was that fact that it had a factory 2 valve manifold when I bought it where there should have been a 4 valve. It doesn't make a whole lot of sense to go out of your way to find a 2 valve cast iron manifold for a bored out 289 rebuilt engine. Since none of the numbers came up with a Mustang code and the assembly date for the car was February 15, 1965 whereas the dates for the engine were January 25 or 28, 1966 it stands to reason that the engine and transmission were not original. This is of course is based on the information gleaned from the website I found and may not be 100 percent accurate since I have not found any Ford literature to back it up. This doesn't mean it isn't 100 percent accurate just that I do not have any way to verify the information.

The result of all this investigation allows me to feel that I don't need to worry about keeping the engine.