Hello everyone! Just joined and glad to be able to ask questions to those who enjoy mopar!
I'm in the starting stages of building a 1946 dodge WC pickup into a street rod. It has already been started by someone many years ago but has sat for over 17 yrs now, and now I would like to take a shot to make a nice rod/show ride.
It now has a volare' front end and a locked up (1969 on the block)318, 904 trans and 8 -3/4 rear with 276 gears.
I believe I would like to replace the 904 with a 727 trans, and re-gear or replace the axle with 3.73. Will most likely have 17"or 20" wheels, which depends on my final ride height.
My question is, do I rebuild the 318, or replace with a 360. Looking for someplace around 300+ hp. This is not to be a race car, but would like to have enough ponies to lay down some serious tracks and have fun with this build. Thanks in advance for the replies!

 

Welcome!

While 300+ hp is doable with both motors, I'd go with a 360. Make sure that you pick up a LA if you want to go with a 727 or stay with the 904.

If you want to go with a magnum, I'd look for 2wd truck then(92 and later). The nice thing about going this route is that you'd have everything you need to keep the MPFI, you'll have OD and the Magnum 360 motors are capable of making the HP that you are looking for just be reconfiguring the computer (Dodge de-tuned them quiet a bit). If you want more, throw on an aftermarket MPFI intake (mopar makes them), good flowing air intake, and a full exhaust from a pair of shorty headers back and you could easily produce 400+ hp.

I'd leave the 8.75 rear axle as they are a good axle to have and I'd regear it to ~3.55. This will allow you to cruise down the highway without keeping your RPMS up so high and still allow you to get up and go when wanted/needed.

 

i would diffidently replace the 904 with a 727 or a 46re overdrive trany for the od/lu.
i have wasted 3 904's over the years with 300+ hp 318
if you go with the 46re od trany you'll have even better high way rpm's
and if you go with taller rim's a higher gear would be better 3.55-3.91
the later is what i run in my vehicle with od and at 65 i turn 2200rpm without the lock up in-gauged...

 

Absolute nonsense. There are plenty of guys running lots of HP through a 904. In fact, some claim the 904 is safer as it has less rotating weight.

However, being practical may provide you with a transmission. That is, I would go with a 360. They are plentiful, and much easier to get useable "street HP" than a 318. So what you are looking for is a 360 AND transmission. The 360 must have a "weighted" torque converter which is part of the engine balance package, IE balancer and TQ weights. Your other choice would be either a 904/ 727 out of a 318 with a neutral balance converter, and you can buy weighted, aftermarket flex plates to make up the difference.

The other glitch will be the oil pan. 273/318/340 pans will not fit a 360 LA, so if your installation needs a front sump pan, and you get an engine out of a pu/ van, you'll have to buy a different pan.

The engine mounting ears are different on the driver side between 318/ 360 but in most cases you can either use a spacer/ washers on one bolt.

 

If you want / need the overdrive you need the 46RH. The 46RE is electric and requires pcm control. Ive never seen it run with a carb. Im sure someone has figured it out. I just haven't seen it so cant help with that. The RH is a 4 pin that you can rig to a toggle to for the OD.

For a nice street rod build you could grab a early magnum 360 and the RH trans.

Add an intake, carb and distributer. Add an electric fuel pump and keep the entire serpentine belt set up. You can have hoses made and keep the steering pump too. Run an E fan that fits and your in business.

Keep the truck cam as it is the same cam in the 300 HP crate motor. If you want more power cam it accordingly.

 

iv'e been running a 89-90 46re for a few month's now in my 86 5th ave M body and for years in a work van that was original 727
the results are great. no computer necessary
as far as the 904 i've never ran a race built on my 318 broke several internal part's between three of them maybe if i put large dollars into a race built one would probably never had a problem but for stock tranies the 727 hold's up better pound for pound on the back of my motor, and now it's a 46re w/LU.
so far it's holding up fine

as far as purchasing a 360 with trany i agree with you it's the most cost effective way.

 

gentleman,
Thank you all for the great info. You certainly gave me a lot to think about. Although I've decided to go with the 360 engine, the trans and axle ratio is still in the making. With all the info you guys gave me, like I mentioned, gives me a lot to think about. I donnt expect this project to be done soon, but when it is or even along the way, will keep you up to date. Thanks to all again!
Mike

 

Your welcome keep us posted..
Post picture's

 

Hi guys, I'm back. Update, got a 360 magnum and ready to rebuild, no trans yet but working a guy to sell. Found a member for the 8 3/4 w/3.55 so following all your suggestions. One problem, I would love to keep the MPFI but MSD only has the kits for the bowties and nothing for the mopar. Besides the obvious of stripping a harness from a junk yard, is there some aftermarket kit to keep the MPFI for the magnum? Would love the MSD Atomic if they made one. Anything like that?

 

Since you have no tranny an easy solution exists.

Get a wrecked 360 truck van or durango from the boneyard. Take the pcm, harness, (rebuild the trans), intake, injectors etc.... And go.

You can use the truck power block, all the o2 sensors, serpentine belt setup etc..

Ive done this with this year and several other manufacturers. Usually reselling stuff from the wrecked truck more than covers the cost.