It took me forever to identify the motor since it originally came out with a 360. After measuring the stroke I found out it is a 390, and the manifold and carb are off a 1966 high performance motor with the large thermostat. I measured the stroke to be right at 3 and 7/8ths inches but I am sure there is can be some slight error there. Clearly not a 360, most likely a 390. The thing runs like a scalded ape. Fast, I mean real fast. After some more work underneath the truck I will be painting it jet Black, or perhaps metallic blue.

ONe question for those that may know. I changed the plugs, wires, cap, rotor, etc, and it seems like the truck is now idling a little rougher than it did before. Kinda like a bigger cam would make it idle. When looking at the manual for the spark plug gap I found different gaps for older and newer 390s. I dont know if I have a 60s or 70s 390. Do you think that could be the problem? Also changed the thermostat and now the truck will not get quite up to operating temp (within the lines on the instrument panel). Do you think this could cause the rough idle as well, as the choke probably is not opening up all the way. What do you think anybody? Any help would be much appreciated. The spark plug gap has me a little concerned.

 

Nice looking truck.

 

Awesome truck. Why not paint it back green? I love that color. Don't see many vehicles that color.

 

Im still considering it. My wife loves the color it is. Probably easier to go back with the green because of the interior and other aspects. I just like the black or blue on the trucks. Dont guess I have seen any new green paint jobs in this color to give me pause.

 

I say stay with the original color! Looks good, still got that cool old school look, and you don't see that color anymore!!

Black, or blue, there are millions of them out there.

Nice looking truck you go there too!!

 

Does the factory air work? Did that Holley carb come stock on dents (I'm asking because I saw one at the junkyard with the same carb). Oh yeah, nice bible.

 

For the plug gap I would go with the stock setting for '75 390. If it idles a little rough try opening the gap up a couple of thousandths and see if that helps.
The type of ignition you're running is a big factor in how wide the gap needs to be. The higher the secondary voltage, the wider the gap can be set without misfire.
Also, if you're concerned about the choke not opening fully. Get the engine up to operating temp. then remove the air filter cover and see if it is in fact open all the way.
Also, check the ignition timing. I know you're not sure what the engine actually came out of but again, I would start with the stock spec. for your truck and go from there.

 

The choke was working fine, temp in the correct range on the gauge before I changed the thermostat and now it will not get to proper temp. I know I need to change the thermostat to a higher temp, and that will open the choke up all the way. I just did not know if that is what is causing the different idle.

As for the question earlier on the carb and manifold, they are off a 1966 motor. Look at the casting number on the picture under the carb and it reads C6AE for 1966. I broke the thermostat housing and the was told the thermostat and housing I have are off a high perfomance motor. The heads are off a 1972, and block is a 72 as well. Numberdummy posted that it was possible the block was a 62 but most likely 72. Thats what worries me about the different spark gaps because some 390s differed there, and that could be the problem. When I give it gas though it runs perfectly, its just the idle. It does not die, or even act like it will, its just alot rougher than it was before I tuned it up.

I was told the air conditioner works well when I bought the truck, but I havent had it long enough to see warm weather yet, or turned it on this winter.

 

This may be a douchebag question, but how did you get to the plugs near the rear of the engine? I wasn't able to get to 3,4, and 8.

 

did u just buy this truck? from nj or pa?

 

The back plugs were pretty hard, but once I figured out how to approach it, it wasnt to bad. You need a swivel, and at least two long extensions to get you out past the heater core, blower compartments. Put the 13/16 socket on with your hand, a very small extension, (you may or may not need it). Put the swivel into the the 13/16 socket(it may help to have the swivel already in the socket when you put it on the spark plug), and then the two long extensions straight out past the box and running parallel with the motor. It may help to use deep creep or some kind of spray to help break it loose. You will use the extension on the other side (drivers side as well, but just one long one and needs to run right up and almost into the master cylinder if I remember correctly.

I bought the truck about 3 months ago in Ok.

 

Nice lookin truck you got there. I would go back with the green as well. Its nice to see original Ford factory colors since you don't see any colors like that these days.
My 73 is tu-tone green and I love it, makes it stick out. Some hate it but I don't care, lol.

 

very nice looking truck you got there...the body looks to be in really good shape...is the body as nice in person then pics?

 

Nice looking truck. It looks to be mostly unmolested, so it should be a great start to a project. I'm with the others, stick with the "grandma's refrigerator" green. It fots the truk so well, and every nice dentside you see is almost always black, blue, or red.

 

Sounds like everyone is all for the original color!