1966 Mustang Transmission decision

MDeezie66 · 09-29-2009

Hi every one, Im brand new to writing in furums so here i go. I have a 1966 Mustang with a inline 6 engine and 4 speed manual, im in the process of getting a 347 stoker motor to replace that, the engine is estimated to making around 450HP and 400ft lbs torque. Question is what transmission would you use if u had this setup? Im leaning towards changing it to a automatic but any suggestions would be helpful. Thanks

PaulS · 09-29-2009

A well prepared C4 would handle the power without a problem but so would a Ford top-loader four speed.
You can order a C4 built for 500HP from Jay at Broader Performance ( Broader Performance Home Page ) for about $800 and a 4 speed from David Kee for a lot more. It just depends on what you like in a transmission. The C4 will give you manual or auto control over 1st and 2nd gears so you can shift it when you want or let it do the shifting when you feel lazy.

I prefer the C4 because it is less costly and the maintenance is lower (service every 20000 miles) than replacing the clutch in the 4 speed. (I go through clutches quickly as I do a lot of shifting and live in Seattle - the city built on seven hills). If the ground is level and you never get tired of shifting gears and you can go the $2000 for the Top-loader then it is a great choice. If you sometimes like to have the transmission do the shifting and like the lower price then the C4 is a great choice.
It really is up to what you want / need to make you happy.

MDeezie66 · 09-30-2009

Thanks for the site Paul. Im more happy going with the c4 mainly with the price, but do u think it will hold up with the power? Even if i get a little throttle happy?

im looking at the site and it shows a few different type of c4's with upgrades, is it worth the upgrades you think? or should i just go with the basic model?

PaulS · 10-02-2009

That C4 from Jay will handle your power even if you were to make it a full time drag car! Just run a big cooler.

MDeezie66 · 10-08-2009

so i talked to a transmission guy today, he is telling me if i go with the c4 and my setup, my rpm will be around 3100 on the freeway. Im thinking thats a bit too high if i ever wanna leave town. will 3000 rpm on the freeway hurt my engine?

PaulS · 10-08-2009

The only way your RPM will change from what it is now is if you use different rear end gears. Typical for the 66 would be about 2800 at 60mph.
If you put in 3.5 - 3.75 gears the RPM will likely be around 3000-3500 and your engine will be fine at that RPM - biggest complaint is the noise it makes, it tends to get on people's nerves.
I always liked the sound of an engine running at the peak torque RPM. Some think its bad - but the engine is designed to run at twice that speed so what can it hurt?

mustang402 · 10-09-2009

I just had to chime in here and say, Good info Paul couldn't have stated it better!

mustang402 · 10-09-2009

Don't know what happened

MDeezie66 · 10-09-2009

Quote:

Originally Posted by PaulS

The only way your RPM will change from what it is now is if you use different rear end gears. Typical for the 66 would be about 2800 at 60mph.
If you put in 3.5 - 3.75 gears the RPM will likely be around 3000-3500 and your engine will be fine at that RPM - biggest complaint is the noise it makes, it tends to get on people's nerves.
I always liked the sound of an engine running at the peak torque RPM. Some think its bad - but the engine is designed to run at twice that speed so what can it hurt?

Thanks again Paul

, he kinda got me worried when he said it will stress the motor out alot, he also said it would be loud but i dont mind the noise. Thats what hot rodding is about!