Hi, I'm really new to the four wheeling world. I've had my cj-7 for about 4 years now, I've put dana 44's out of a scoutt under it and recently bought 4:56 gears and ARB air lockers and put 35 inch toyo mud terrains on it. Well, anyways the stock 258 ways just rebuilt but, I want something with more hp. Can anyone help me with what motor and tranny combo I should go with. I really a chevy motor and tranny with a dana 300 trans case. But I have no idea on what chevy motor or tranns.

GM - SM465/420 w/ NP205

http://www.novak-adapt.com for adapters to D300.

The SBC is a very popular swap. There are kits out there that make the conversion pretty much painless...except for your checking account. Do a google search useing "SBC, chevy 350 swap pirate 4x4" or something similiar and you will see what i mean.
Even easier, would be to find a AMC V8 and swap that in. The only things you would need to change would be frame mount brackets, crossing the fuel line over, and building exhaust.
304's and 360's can be had pretty cheap, and occasionally you run into a 401 that's affordable. All are easy swaps into a 6cyl equiped CJ as they all share the same bellhouseing boltpattern and clutch components.

What are using this rig for? Why do you want more HP? Dig more & bigger holes in the trail? Not raggin on ya.
Looks like you lost some what you gained with the lower gears (4.56:1) with the taller tires (35's).... now want more HP to make up the difference, right?
What tranny do you have? Want to keep it? or replace with?
The SBC is a great upgrade but big bucks. If you go this way look for a GM truck tranny (sm-420 is a very good choice).
The AMC V-8 would be less $$$$$ and much less work, Radiator even fits. Then look for a T-18 tranny. This combo will keep your driveline length from getting too short.
What about the smogs laws in your state? Any problems there?
For the Dana 300, if you can find a Scout 1980 Dana 300 you can skip the adapters (if your replacing a Dana 20)
The 4:1 kit for a Dana 300 or the 3.15:1 kit for a Dana 20 might be all you need to gain back that Humph!

More HP from your 258:
What are you running for a carb now? MC 2100 or 2150 swap helps a bunch.
Consider full injection yet? Several ways to go but all Big bucks again!
The 4.0 head conversion on a 258 is supposed to be great..... 20 to 40 more hp depending who you believe.
What do you have for an ignition system? HEI, MSD system or ???? Upgraded ingition can really make a difference.
The 1990-96 4.0 full injection.

good luck

I had the same issue with my cj 7. I swapped in larger tires and 4.11's but I just felt like it didn't go the way I wanted it to. I had just rebuilt the engine and put in a t 5 tranny but it just wouldn't go any faster than 50-55 on the freeway in 5th gear and the engine just sounded like it needed another gear.

I went with a SBC 5.7, 700r4 tranny and a np 208. when I got everything in there i found out my rear drive shaft was going to end up being about 9 inches. So I did some searching and found out I could use the 700r4 to np208 adapter to install a dana 300 transcase by changing the input gear.... JB conversions has the gear for 175 I think, I trimmed the output shaft on the tranny about 3/8 and installed the dana 300... it even clocks the transcase a few degrees up.. I was stoked with this change until I found out the drive shaft wouldn't work due to clearance issues with the clocking of the tc and the 700r4 being in the way... so there was a need for a "thin" drive shaft... and I looked around and just this weekend I solved that issue... used a dana 30 axle shaft combined with a dana 30 yoke.... I'll post picks of that booty fab sometime tomorrow.... the hardest part of getting this hybrid drive shaft to work was finding a conversion u joint that would work... and about a half hour with a spicer catalog at autozone fixed that realy quick....

After all the mess I went thru to get the conversion to a 5.7, all the headaches and problems that came up I would still do it all over again... especially since now I know how to fix the little things that pop up with a conversion....

5.0 with an AOD use whatever case you like after that the AOD has a lower first and secont than the C6 and if built right can handle some seroius abuse.

I agree with most above but caution you not to get overly attached to the dana 300, it's a good case but is part of what will drive your conversion cost up. I'd recommend getting an entire gm drivetrain. 5.7/sm420/np205 if you want manual or 5.7/th350 or 700r4/np205 or np241. Buying a combo usually will save you some bucks.

Thanks, you guys think that a all GM drivetrain will be better that piecing together a motor and trans with a dana 300. Also is the sm 465 a good tranny to go with a TBI 350 or with any other chevy motor.:

The 465 is an absolute monster. Bulletproof, compound low gearing, and heavy as all hell. You almost cant break em.

You need to sit down and weight the costs however, depending on what settup you absolutely have to have. A SBC conversion is going to be some money tied up, even if you use the whole drivetrain. You will need a cheby radiator, hi-$ engine conversion mounts, exhaust, driveline lengthening/shortening, and a host of other things.
An AMC V8 conversion however, will run you the cost of the motor, stock mounts, exhaust. If you upgrade to a T18, add another big chunk for the adapter.....but you wont have to mess with drivelines, tranny crossmember (minor grinding), and the other headaches of dealing with a hybrid settup.

When i did my 401 swap, i was into it for about $450 before exhaust work. That was the cost of the motor, frame mounts, and flywheel. I found a good deal. I already had a T18a, so i know the feeling of being raped for an expensive adapter....cost more then my engine swap.

But, that money will go elsewhere if you do a SBC swap. It will be one of those things where you start to weigh the cost, amount of labor you want to put into it, and see what kind of deals pop up.

The amount of work needed to do the swap is not that big of a worry as much as the cost is. You know how those college budgets are. So a AMC 360 and a T-18 combo will be a good canadite for my jeep. I don't 4wheel everyday, my rig is a daily driver. I just want more get up and go then the 258 I-6 has.

I agree with most above but caution you not to get overly attached to the dana 300, it's a good case but is part of what will drive your conversion cost up. I'd recommend getting an entire gm drivetrain. 5.7/sm420/np205 if you want manual or 5.7/th350 or 700r4/np205 or np241. Buying a combo usually will save you some bucks.

Are the NP205 or 241 shorter than the 208 that forced overtime bolted up to the 700r4? Are the 205 and 241 passenger side drop? What about the low range ratios?

Do you guys have smog testing up in Corning? If so, find something that will smog easily to avoid bi-annual headaches.
Travis..

Are the NP205 or 241 shorter than the 208 that forced overtime bolted up to the 700r4? Are the 205 and 241 passenger side drop? What about the low range ratios?

So I got off my ass and did a little googling. Looks like 205 mated to SM465 would be easiest and strong combo. I should have explained that I'm looking to do a little research for a friend before he purchases a 76 cj7 that has no powertrain. With the passenger side drop and fact that he want fuel injected v8 I think he should go for a 350tbi and bolt it to an sm465 and np205. Probably wise to get tranny t-case combo as 1 from boneyard or wherever else. Looks like he'll lose about 6" of rear driveshaft length if he does this. Should be no problem for the cj7 considering I chopped 6" off my cj5 rear driveshaft and it's been working great.

Anyone know the year cutoff for the np205 with the fixed rear yokes? Also, did the 205's come with double cardan/cv style front driveshaft? That would be handy if he is shortening his rear driveshaft to put on the backside.

I skimmed over this thread and i didnt see anyone talk about a different intake and carb. I also have an 85 cj7 with 36' iroks and 4:56 gears, with the 258 and the factory 4 speed manual trans. I had the same power problems and put the offenhauser 4 barrel intake with a holley 390 cfm 4 barrel carb and put a msd coil on the ignition and opened the plug gaps to .045. It really brought that motor to life. Just another way to go if you are just looking for enough power to turn 35's.

Jeepraider06-

All of the above suggestions are good. My only question is what are your long term thoughts for this jeep? If fixing it the way you want it and driving it until you go to the Great Jeep Jamboree in the Sky, do it any way you want. If you might need/want to sell it at some time in the not too distant future you may want to keep your Jeep, Jeep. I find that CJs with too many non "Jeep" parts (ie: the drive train) tend to, but not always, sell for less. Now don't flame me for that statement, as there are exceptions but one mans dream is not necessarily another's and the less cobbled together with non Jeep (or Scout) parts a CJ is the better. Just my opinion.