318/904 Keep or Replace?

NBC-Steve · Apr 15, 2020

I have a 72 Satellite with a 318 and a 904 transmission. The engine has 75K miles and I did a mini rebuild to get a little more HP that helped. The tranny has a leak so I replaced the shift lever seal and that helped but it didn't fix all my leaks.

I want more HP so I can have some real fun, I'm getting tired of the leaky tranny so I am thinking of replacing the 318/904 with a 360 long block and put a good cam in it with flat pistons and a new (Rebuilt) 727 with a shift kit. Reason for a 360 is that they are affordable and I just brought all kinds of nice goodies for the 318 that I would like to reuse on the 360.

So here's my questions,
1. Does Chrysler "Numbers Match" like GM?
2. Am I committing a Mopar sin by swapping out?
3. How difficult is it to do that swap 318 to 360? (I already know that I'll have to replace the driveline.) I don't want to mess with the K frame too much. I'll do a 400 or 440 if its just as much work. (I'll just have to save up more $$$)

Ultimately my build will be a resto-mod, it will be mostly original with a few modern upgrades and in show quality plus show the kids in Honda's how its done old school.

Any suggestions are welcome.

66 Sat · Apr 15, 2020

It's up to you on the engine, you may be able to get a bit more out of the 318 depending on what you've already done, but I wouldn't base my decision on a leaking 904 with the assumption the 727 will be leak free, as they are a very similar design. It may be just a case of changing a few more seals or the transmission oil pan gasket.

Cranky · Apr 15, 2020

Yes, the numbers on the engine and trans should correspond to the numbers on the car and iirc, the K frame was the same as the older B body cars and those allowed a big block to fit on them with the correct engine brackets. I think the 73 B cars got a different suspension setup and the K's were changed too and sitting a big block on them was more of a pain. 318's do respond well to mods like any brand of small block but like all others, the weight of the car is the main problem. And be aware that there are some pretty fast Hunduhs out there

Jerry Hall · Apr 15, 2020

Beautiful car. A 318 car is not usually one that most people are concerned with keeping matching numbers. If yours is matching numbers, I would consider a performance rebuild of the 904 and a stroker kit for the 318. Until a good friend of mine did this, I was not especially a fan of the small blocks. My friend stroked a 340 to a 408 cu. in. with fuel injection. His was a 727 but he fully rebuilt it with performance in mind. I still have some faster stuff than him but he's now above stock Hemi performance and I have to dig a little deeper in my bag of tricks to keep up. Again your car looks great and keeping the small block will be less expensive due to the things you can reuse and retain.

dvw · Apr 15, 2020

No need for a 727. 904 will hold up fine to 500hp without anything special. Plus it can be fitted with a 2.74/1.54 gear set (replacing 2.45/1.45) for less than $200. A 360 is the ticket since almost everything still works. To install a 360 you'll need a 360 balance flexplate and modify the left motor mount bracket. Car pan if the donor came from a truck.
Everything else fits. Or you could stroke the 318 to 390" (4.0" crank .030" over bore). You would need better heads to take advantage. I just built a 360 Magnum with this trans combo. 3.23 rear axle. Former 2.45 3.23=7.91 2.74 x 3.23=8.85 Acts like a 3.61 axle in 1st 3.61 x 2.45=8.84.
See post here, easy 400hp on 87 octane
https://www.forbbodiesonly.com/moparforum/threads/garage-360-build-how-i-do-it.187572/
Doug

JimCoronette · Apr 15, 2020

Looks like the backup/reverse switch is leaking.
Jack up the back of the car and change it.
Look for next leak, repeat as necessary.

As for horsepower; Is there ever enough?
you have 250, you want 500
you have 500, you want 1000
you have 1000, you want 1500
Where does it end?

Personally, I would build the existing 318 with a stroker kit (390cu in) 340 heads and exhaust manifolds.
With the small block you can use your existing AC stuff.
Build the 904 so you don't have to replace the driveshaft.
Now when you dust mustang GTs, you can say, "It's just a 318"
A 318 auto 72 Satty isn't really a ultra rare high dollar car, so it's a good restomod candidate.

Darter6 · Apr 15, 2020

I agree with dvw. The 904 is a keeper. The biggest question is "How much you wanna spend ? " Or better yet, how much do you have to spend ? That is the question.
Every above post is a good answer. I had a guy call me recently and said he wanted to build a Slant 6 supercharged to put in a 74 D 100 pick-up.I told him that $6000 will just get him started .His reply was "Money is no object".

Darter6 · Apr 15, 2020

Good looking clean car by the way ! :thumbsup:

NBC-Steve · Apr 15, 2020

Excellent suggestions from everyone, that's why I love this forum. I have never done a Stroker kit so what's involved with installing one? (I've only done create engines)

aeon280 · Apr 15, 2020

NBC-Steve said:
Excellent suggestions from everyone, that's why I love this forum. I have never done a Stroker kit so what's involved with installing one? (I've only done create engines)

If you want it done right then I would suggest tearing down your current block to just a bare block. Take the block and mains to a machine shop and let them determine what you need to order. Bore size, bearing size etc... Unless you have owned the car from brand new or already pulled it apart its hard to know if its been bored out before, or if the crank has been turned down. Once that is determined order an unbalanced stroker kit and have the same machine shop balance it and install the crank and pistons. You can have them also assemble the top end or do it yourself if you have the tools and knowledge.

Darter6 · Apr 16, 2020

I have a friend that did the 318/390 stroker and installed it in a B body station wagon. The power out put is un-believe-able !

toolmanmike · Apr 16, 2020

Yep, a 390 stroker will pull like a freight train.

rumblefish360 · Apr 16, 2020

IMO, the best way to do a stroker starts with giving the block to the machinist and asking the first and most important question of how thick the cylinder walls are and how far does the cylinders have to be bored? Once that is known, you can proceed with the purchase of a stroker kit.

FWIW, I’d just about never use a stock exhaust or intake manifold a stroker. Now if it works as a build in the spirt of a FAST engine... that’s different. Maybe one for me down the road just because I like to screw around.

It do realize you are giving away A LOT of HP with there use. So if you want to teach the Honda kids a lesson, just remember the HP to weight game. There engines are super tiny and weigh nothing, just like the there car does. Your moving twice the length and weight they are.

dvw · Apr 16, 2020

Crate strokers available right here and other spots as well. If you haven't built an engine there is a learning curve. The stroker is no tougher if you use a kit for the rotating assy from a well known supplier. They will take the guess work out of the equation. Don't discount using a 360 or 360 Magnum either. My wife's iron headed 360 LA runs easy 12s on 87 octane in street trim.
https://www.forbbodiesonly.com/mopa...-cam-stroker-engine-pre-release-offer.177644/
Doug

plymouthman72 · Apr 16, 2020

NBC-Steve said:
Excellent suggestions from everyone, that's why I love this forum. I have never done a Stroker kit so what's involved with installing one? (I've only done create engines)

I would definitely do what Aeon said and strip it down to a bare block and have the block cleaned, checked and honed as needed (well worth the money for any block you choose).

I am not sure how much experience you have assembling engines (I don't have a ton of experience myself so take this for what it's worth) but building a stroker is not much different than rebuilding a normal engine. You are really just changing out the crank to get a longer stroke. However the longer the stroke, the more issues you can run into with rotating clearance. I am not sure about max stroke lengths on 318's but my 340 had to have the block "notched" to clear the H rods when I stroked it out to a 416 (4" crank stroke). I am not sure if factory rods would have that issue though. Other than that, assembling the short block is just following the required assembly steps and make sure to measure all of your clearances. Also make sure to check your rings to see if they are file to fit vs standard sizes or you will not have enough ring gap. Ask me how I know....

The top end is where it gets fun and much more difficult. If you don't already know how to degree a cam or properly measure push rod lengths, you will definitely want to learn. I also went with a roller cam and lifters on my set up and had a ton of issues with push rod geometry and clearance issues because the 340 is not meant for those kinds of parts so I would recommend a flat tappet set up if your trying to stay in a budget.

It sounds hard but if you have the desire too, you should definitely try it. I made mistakes my first time through but man did I learn a lot of valuable knowledge from my mistakes and I sure as heck know what to do next time.

If you are going to spend the money on a stroker kit though, I would recommend finding a 360 and doing it to that. you will make very good power stroking out your 318 but it will be the same cost to do as a 360 and 360's are easy to find. For the cost of finding a 360 make even more power.

Hopefully this helps from a novice member.

JedIEG · Apr 17, 2020

I'm in a similar situation, engine, transmission and car. You may want to consider a full 360/a518 set up out of a 95-back Ram for more power and an extra gear. The core setup would be sub $500 at your local pick-a-part and then you can rebuild that to your liking and still drive the car. It's only about $100 for the controls to make that trans work and under $500 for a nice performance rebuild kit , but you need go be able to fabricate a new cross member and cut the transmission case to get it to fit our cars.

oldkimmer · Apr 17, 2020

I would ask Johnymac. He hangs out on FABO. He works for Blue Print Engines. They build many crate engines. They have an excellent warranty. Kim

rumblefish360 · Apr 18, 2020

Good idea Kim. This should get his attention....

@Johnny Mac , please read above.

Johnny Mac · Apr 20, 2020

NBC-Steve said:
Excellent suggestions from everyone, that's why I love this forum. I have never done a Stroker kit so what's involved with installing one? (I've only done create engines)

Hey there,

Thanks to the other members for calling me out! Yes I have some great 408 offerings. both and iron head, and aluminum head version. I also sell a matched trans with converter if interested.

Glad to chat on the phone, or Pm, whatever works.

Here are some links to check out. I can do an engine/trans/converter compete combo for about $8000. I also have longblock 408's from 5K

Hope to hear from ya.

https://blueprintengines.com/collections/chrysler-crate-engines

https://blueprintengines.com/collec...stall-converter-bpp727?variant=12466762580034

NBC-Steve · May 26, 2020

I'm really liking the Blue Print Engines and I will probably go with that plan. The current situation with COVID-19 has slowed my progress a bit but I'm still hoping that I will launch this awesome project this summer. I can't wait to put that 408 in the "Banana".

Next question is I would like to use my existing 904 transmission but have it rebuilt by a local shop. Would the 904 work with the 408 Stroker and what gearing should I consider?

In the meantime I brought a new Snap-On tool box and got several goodies from my dealer and one of them is these cool fender covers to replace my 25 year old fender cover. (Yeah that's where the engine money went too.)

318/904 Keep or Replace?

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