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View Full Version : 1970 390 & c6 into a 58 bird


tiltbed
09-22-2017, 01:23 AM
ok,i know it`s been done before but my question is what motor mounts must i use on the 1970 390? it seems like the C6 might be hitting the floor hump. would there be enough room to use the oem 59 mounts? if not what year flat mounts would i have to go with?thanks,Sid....oh and i have a 59 t bird removed the 352 and cruise o matic. nothing wrong with them ...but bigger is better? no? lol

simplyconnected
09-22-2017, 03:13 AM
Truthfully, if I had a 3-speed C-O-M that fit your 390, why not use it? You're going from one three-speed to another.

The later 390s added an 'extra' motor mount but they are backward compatible.

A word of caution... Ford put 390s in everything including Mustangs. That means it came in a variety of trans mountings. That's why I say, if your C-O-M fits, hey why not use it because all the hookup will fit as well. - Dave

tiltbed
09-22-2017, 12:17 PM
yes the com is good but i have already done extensive work to the C6,plus it and the 390 were free. Just trying to figure out what other members had used in way of motor mounts for this instalation. year, "C" or flat mounts ect. It is better in my mind to buy the right thing first. Plus the C6 is suppose to be an improvement seeing that it came out of a 1970 F250.

sidewalkman
09-22-2017, 12:32 PM
I respect Daves opinions and knowledge, but if youre putting any kind of power in front of a COM transmission you are begging for the tail shaft to blow off. That's the weak link. A C6 is a far beefier trans, so do it!

jopizz
09-22-2017, 12:33 PM
The 390 and 352 blocks are the same. You should use the stock 1959 motor mount.

John

simplyconnected
09-22-2017, 08:26 PM
...if youre putting any kind of power in front of a COM transmission you are begging for the tail shaft to blow off...I wonder if all the owners of Bulldozers that came with C-O-M transmissions are aware of this.

I am not trying to dissuade anyone from using a C-6 because it IS a beefier trans BUT ...as with most things in life, this improvement comes with an added cost and this isn't a racing application. The C-6 requires more HP to run than the C-O-M, making it less efficient. Efficiency isn't talked about very much but it is important.

430 MEL Bulldozers came out in '58 for the T-Bird, producing the highest torque of any Ford engine of the time. They were married with C-O-M transmissions over many car lines very successfully. I don't hear complaints about their tail shafts. (Just say'n.)

Unless you're pulling stumps or racing, many 'factory' transmissions worked just fine before 1966 came along.

If this 390 is a truck engine (TE, not FE), I would get rid of the heads that came with small, truck, intake valves. This is where Edelbrock offers a very attractive aluminum alternative that is 'gasohol ready'. - Dave

pbf777
09-23-2017, 01:11 PM
Please note that the terminology: "Cruise-O-Matic", describes several different transmission units in the Ford production line.:confused:
Although often similar in design, each unit was engineered for it's unique application.

For example, I believe the 352 FE engine of this period generally received the "MX" version or "medium size" units of the C.O.M. transmission; but, the 430 MEL's received the "Lincoln Multi-Drive" or sometimes referred to as "Lincoln" or "Large-Case" units , only titled as the C.O.M. in T-Bird applications as they are Fords not Lincolns.

Generally, I believe the noted failure of these C.O.M.s was/is the development of cracks in the rear bulkhead of the cast iron gear case. This lead(s) to loss of hydraulic pressure and function failure. The practice of abruptly shifting from the drive position to reverse or vis-a-versa, particularly with the wheels in motion (poor driving technique) is generally attributed to the cause of this failure. This failure seems to be less prevalent in the "Large-Case" units. I don't know if this actually results in the tailshaft flying off, but that event does happen for a number of other reasons, and not unique to C.O.M.s.

Scott.

tiltbed
09-23-2017, 04:10 PM
i thanks all for their replies,but i think it`s getting off topic. my orignal question was:::: do i use the oem "C" mounts or go with the flatter (lowering engine aprox 1 1/2") this would allow the C6 to ride below the tunnel. I believe the ford truck had the flatter mounts. And yes the 390 would have sufficent power to turn the C6. (fresh rebuild,cam,headers,HEI GM ingnition ect.) thanks again to all...need mount year,part# or what ever. hope to be a one time deal.

Woobie
09-23-2017, 05:55 PM
...but bigger is better? no? lol

If the 390 is an F250 390...your looking at about a 250hp rating and around 8.5 compression

bigger than the 352 though !!

If not mistaken, Mr. Jopizz answered your question on motor mounts

Cheers

RustyNCa
09-25-2017, 12:36 PM
yes the com is good but i have already done extensive work to the C6,plus it and the 390 were free. Just trying to figure out what other members had used in way of motor mounts for this instalation. year, "C" or flat mounts ect. It is better in my mind to buy the right thing first. Plus the C6 is suppose to be an improvement seeing that it came out of a 1970 F250.

I think the issue with the lower mount would be the steering linkage? I was noticing yesterday while under my 58, that now has a 390/C6 combo in it, that the center links are rubbing the oil pan.

I don't remember anymore what motor mounts I used back when I swapped in the 390.