My son just purchased a 72 F-250 for next to nutin. anyway engine had a weak cylindar so we tore it down over the weekend and discovered that a wrist pin keeper had come loose and wore a grove so deep in the wall that i was really surprised that the water jacket was still in tact. anyway it's salvage. i have a 300 6-cyl. in storage , will this bolt up to the c-6 thats in the 72? the 300 is out of a 66. sorry to say i dont know at this point exactly what type of c-6 it is. i have done this conversion to a four speed and had bell housing problems so am curious what will need to be done if anything. Dutch

 

A 390 C6 will not bolt to a Small block pattern 300.

You can reuse the engine perches and transmission mount.

The C6 for A FE is engine specific. 352, 360, 390, 406, 410, 427, 428.

The 300 shares the 302W pattern.

For a 300 obtain a C4 as the C6 robs a lot of energy form the engine verses the C4.

Garbz

 

A C5 would be a better option if you can find one. They are a stronger version of the C4, specifically how, I don't know. I believe they can be ID'ed by having the dipstick attached to the pan, otherwise they look like a C4.

 

1965/77 F100/250 / 240/300 I-6 / C4 transmission

1978/79 F100/250 / 300 I-6 / C4 or C6 transmission.

1965/79 F350 / 240/300 I-6 / MX Cruiseomatic

 

Did the swap, didn't have much trouble finding a tranny, actually went to a transmission shop, gave him my old C6, he had an FMX there, he rebuilt it for a few bucks with a shift kit and a good torque converter and warrentied it. So maybe check your local tranny shop and see,,,,
You will need to move the engine perches forward, and I don't recall, but I think the tranny crossmember also moved forward.
And while the engine and tranny are out, get some Natures Orange from Home Depot, and spray ALL OVER in the engine compartment, then go to a car wash and clean it, and then paint it with a nice black, and you will be amazed how nice it looks and how much easier it is to work on.

 

Good idea on the tranny swap,will look into that.this truck is filthy, both valve covers had been tightened down to tight and leaked like a seive. needless to say it has a 1/4 inch of grease on every paart under the motor andframe. makes my skin crawl just lookin at it. all of my trucks i can work on anywhere on the truck and not get greasy. it definately will be cleaned before it's put back in the shop again. we have a product here thats called orange tuff, prolly the same stuff you mentioned also use a lot of superclean. wal-mart and K-mart carry that. works well also. I have my own pressure washer so nothing ever gets dirty if it's cleaned after a spill. Dutch

 

BY th way, thanks Garbz2 and Numberdummy for the info. will save a lot of legwork on the search. Dutch

 

I realize this thread is several years old, but during my searches this was as close as I could find.

I understand that a 390 and a 300 will not bolt up to the same C6 would this also be true for the T18 manual transmission?

In other words, could a current truck with the 390/T18 combination be swapped to a 300/T18 using the existing transmission? Or would there be other modifications that would need to be made (other than adjusting the engine mounts). I was looking at a curent truck, but was informed that the 390 was getting very "tired" and have always wanted a truck with the 300. Truck will mostly be used to drive back and forth to work (20 mile round trip) and dump runs but would also need to pull an occasional travel trailer (2 times a year). I no longer drive fast so slowing on the hills doesn't bother me these days, just looking for increased milage, driveability and cool factor for having someting different.

Your input / wisdom is always appreciated.

 

With a manual transmission you can likely swap out the bellhousing for one that went between a 300 and a T18. The same bellhousing that works on a FE won't bolt straight up to a 300 as they are a different pattern.


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