I’m looking at swapping my 302 in my 68 XR7 and put a Blue Print 347 in it. The engine swap I believe is pretty easy, but I wonder about the parts behind the motor! C-4 tranny! Can it handle added hp.? Rear end? Drive line?? If anyone has some advice, I’d sure like to hear what you can help with!! I want to do it right the first time!
Following; will be interested to see what the “experienced” crowd offers. If the 347 is over 400 hp (guessing 415ish) you might wish for at least a C6 behind it - the rear would depend on whether you’re running 8”, or 9”. You would probably prefer the 9” with the stroker. Only a deduced opinion on my part. Oh, and driveshaft (?driveline) will likely need swapping as appropriate for tranny change.
If have to change transmission, put something wit an over drive in it
The C4 can handle the HP it just needs to be gone through by Broader Performance first. Worn out it won’t survive long. I would be more worried about the rear end. An 8” is good for around 250 HP after that it is going to fail.
My c-4 is fresh. Tranny is an 8 inch. I’ve been told the 8 can be upgraded. be nice not to have to put a 9 but will do if needed. c-6 or t-5??
yes 415 hp.
How are you going to drive it? Most street driven cars are really never highly stressed.
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Reading that the c-4 can handle 650 and 450 ft lbs and 8 inch rear end 375-400 and up to 500 with mods.
yes, every once in a while, stomp it but no racing! rolling starts at a light maybe on a straight highway. I’m pretty nice to my baby! old enough to know what not a good idea like when I was a teen.
I think you need to swap the 8 inch for either a late model Mustang / Capri / Explorer rear or a 9 inch. The 8 inch just won’t cut it. The C4 being freshly rebuilt is not the same as having Broader rebuild it.
I find that hard to believe of a “stock” C4. Of course you could always find out and replace later…..
Thats is why I asking for input. The internet said with mods. I’m leaning to a 9 inch, have the c4 built up and drive line upgraded. I’m not racing. just have a want for the 347! Don’t really need it to be honest but when I get it in my mind, I can’t stop. The idea of this was to find out others that have and what they did! I’ve been a tech for years and know hp equal the torque that breaks things. be nice to keep the 8 inch and it probably would work until one day!!! what tranny?? for speed??? who out there has done this! and what did you do?
I don’t know but, if you don’t have traction you should be fine? Wait for drag radials until after beefed trans and 9” Will RPM destroy stock C4 or 8” More of a question than a statement.
My car was a 289 4V, 4 speed, totally worn out. It now has the same motor you described, Tremec 5 spd, new 9” 3.73 posi rear end, and a new drive shaft. It has a lot of suspension mods, 4 whl discs, and is meant to handle as well as it goes. I’m hoping for a test fire of the engine the second week in October.
So, the answer is: no real world experience, yet. Likely very little until spring arrives in Wisconsin next April.
Good luck
Ron
Keep in touch! Is you tranny an auto or clutch! Very curious!!
There are a lot of Cougars running around with 351 W dropped in to replace the 302. Almost all of them run the original C4 and 8” rear. Including my son’s car. It has a couple of performance improvements, performance intake manifold and headers. The C4 was rebuilt with some slight upgrades to the clutch packs. It isn’t drag raced but it chirps the tires pretty often going into second gear and occasionally lights up the tires when you punch it on a slow roll. With maybe 10,000 miles on it nothing has failed.
We have an AOD and it will probably get a 3.50 set of rear gears in the 8”. Maybe then it will be more stressed.
That doesn’t mean you can’t build it to what ever level you want. No one ever said this hobby was based on logic. Just that you may not have to do it
It has a modern driveline hydraulically operated clutch.
Best
Ron
Have a guy local that put a built 351 in his and he had his c-4 modified with a shit kit. Still has 8 inch but has an Eaton true track possi he plans to put in. 355 ratio! Not sure what I have but I like that it cruises 75 on the freeway without winding up! I plan to talk with Don at west coast cougar tomorrow. If anyone knows he will! Thanks for all the replies!! Love my cougar
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Nobody is questioning it can’t be “built” to do it - the real question is what can it handle in stock form.
yes I agree!