mopar small block or 4.7?

[onebigmj]

I was going to put a 4.7 stroker together for my comanche but I started thinking about putting a nice 318 in it. I looked at the cost and the 318 will be a good bit cheaper than the 4.7 and nothing beats the sound of a V8.

What do you guys think?

[tjbliley]

Have you been spying on me and Mjeff87. We just had this conversation about 2 hours ago or so. It is a good idea but there are alot of things to look at when you do a V8 swap. Most important is the unibody structure and the strength of the mounting system in the MJ. I am sure there are those who have done it with out issue butthe engineering of the unibody just was not designed to handle the torque and power. The drivetrain mounting system was also not made to handle it. trying to contain the torque with folded sheetmetal just has to been investigated alot further.

[onebigmj]

Correct me if I'm wrong but aren't there alot of xj's and mj's running around with chevy 350s in them without any problems?

[DrThunder]

i plan to do a v-8 swap sometime this year whether it's a 350 or a 360. seriously though if you're going to spend all that time doing a swap do it with the dodge 360, it is far superior to the 318 especially in an offroading situation where low rpm power is desired. as for the frame not holding up, unless you're going to go substantially more powerful than a 4.0 like in the 300 horse and up range i wouldn't worry about it.

[onebigmj]

I have a 360 out of a dodge motorhome with 56k on it and was considering freshing it up and droping it in but my truck will be driven on the street alot and I'm considering fuelmileage. Would there be a big difference between a 360 and a 318 in mileage?

[mjeff87]

:brows: :brows: :brows:

 

Too funny, like Jerry said, we were just discussing this earlier today.

 

Lots to consider aside from just getting a SB (Chebby, Dodge, whatever) to fit. You'll need to brace the crap out of the engine cradle (and run rubber mounts as well), reinforce the tranny mount, figure out the exhaust in particular the driverside manifold/header to clearance both the steering and front DS, refab the front clip to accept a radiator capable of keeping the engine cool, and lots of other stuff.

 

That said, I'm seriously contemplating a 340 at this point :brows:

 

Jeff

[BLHTAZ]

I had considered a 360 swap at one time and even had the donor vehicle ('84 Grand Wagoneer) purchased and sitting in my yard, but after much research, it was just not worth the effort when you can buy a stroker for around $2000 - $2400 and just drop it in and have 300 HP just hook right up. No wiring worries, no exhaust worries, nothing but just swap it out ;) .

 

I sold the Grand and am now just awaiting the time to get the stroker done.

[possum]

I run a 350 chevy and did not have to brace the engine gradle. And I run solid motor mounts too. Haven't seen any body / frame fatigue yet. It ain't pretty but it works-

[mjeff87]

and the stock 2.8 radiator, too :eek: ? How hot does it run (and what kind of pusher fan is that)?

 

You wouldn't happen to have a shot of the driverside/header area, would you?

 

thx!

 

Jeff

[possum]

It runs around 195-210 but I have got it up to 230 when I was stuck before. The fan is a Spal fan. It sucks a few amps but it moves some big air. This is the best shot of the driver's side I have right now.

[Confedneck]

a 4.7 is gonna build more power than a stock 318 or 360 anyways, what were the latest 318s? 235hp?

[mjeff87]

possum, thanks for the pics. I might hit you backchannel with a couple other questions if you don't mind.

 

I'm assuming you're running a TH350 or 400 tranny behind that?

 

Jeff

[TNT]

:brows: :brows: :brows:

 

Too funny, like Jerry said, we were just discussing this earlier today.

 

Lots to consider aside from just getting a SB (Chebby, Dodge, whatever) to fit. You'll need to brace the crap out of the engine cradle (and run rubber mounts as well), reinforce the tranny mount, figure out the exhaust in particular the driverside manifold/header to clearance both the steering and front DS, refab the front clip to accept a radiator capable of keeping the engine cool, and lots of other stuff.

 

That said, I'm seriously contemplating a 340 at this point :brows:

 

Jeff

 

If you don't grab that 340 let me know. Hopefully it's a 68-71 engine with the forged crank. I would build it to about 400hp and run it on a custom fuel injection set-up that I would tune. It would be a good 7000rpm engine that will make a fulltime 4wd MJ a evo killer. :brows:

[possum]

Any questions you have I will try to answer. And yes I am running a 3 speed TH350 longtail.