258 to 305 swap

[oldenburgd]

Im sure this is a sin in the jeep world but my brother bought a 79 Silver Ann CJ5 ....with a blown motor. Ive never seen a crank chewed up so bad with so many cylinders crack. My question is, if I bought him a sbc 305, what needs to be done to bolt it to the t 18 Transmission thats in it. I know this question has been asked before but i cant find one with this Transmission .

 

[Kane]

You will need the adapter from Novak and also an older GM bellhousing. You will then need a new chevy clutch but the pressure plate has to be for a Ford or Jeep due to the 1 1/16 diameter input shaft. This is how mine is set up. Then of course you will need the rest of the conversion parts such as motor mounts, exhaust, and a new radiator that has the outlets and inlet on the opposite side.

 

[oldenburgd]

so it's not going to be a "weekend" job. Alright, to reword your parts list, I need the novak conversion $300, stock gm clutch assembly (auto zone), but buy a ford/jeep plate that has 1 1/16 shaft. Is there any specific year to pick or just the shaft size. Will the original plate work? As far as the motor mounts, are they a fab issue or is it just easier to dump the $AMC 150 for the novak ones? What is the deal with the exhaust?

 

[jeepy]

There is a better way to mate it to that Transmission . And Novak can even help you with that. You don't use any adapters. With a CJ5 , anything you can do to keep the driveline shorter is better for your rear driveshaft angle. (This of course is really only a concern if you off-road and lift your jeep. If it just a steet vehicle, just get the adapter.)

There are a couple of different ways to go about it depending on your budget and skills. The main idea is to not use an adapter between the chev bellhousing and the jeep Transmission . Instead you install into your Transmission (which requires some workbench time) a Ford T-18 input shaft that just so happens to be the correct length for the chev bellhousing. TaDaa, No adapter.

Input shaft can be bought from Novak or sourced from a junkyard. I would go the junkyard route because it is probably cheaper, and you might be able to use a spare part from it someday.

Bellhousing: Has to be modified to fit the tranny. If you get a regular aluminum Chevy one, you have to weld in some extra aluminum, and drill/tap a hole. Easier way is to buy a chevy steel blowproof racing housing from Jegs or somewhere and all you have to do is drill a hole (no welding).

Front Bearing retainer: is the part bolted to the front of the T-18 that the throw-out bearing slides on. You can possibly modify the one you have to work, or you can buy one from Novak. Unless you are good at fabwork, buy it from Novak.

Clutch Pressure plate: Buy a new GM truck one to fit the manual Transmission flywheel that is hopefully attached to the back of the new motor.

Clutch disc: Use the ford truck one. It is ok if it is a little smaller than the GM pressure plate.

Other things to consider: If you go this route. measure from the front of the tranny to see how far back the motor would sit with the shorter chevy bellhousing. If it sits too far back, then you can move everything forward to fix it and have an even longer rear driveshaft. You will also benefit hill climbing with more weight towards the front of your jeep for climbing traction. Of course this would invove changing driveshaft lengths which is topic for another conversation.

Radiator: You would have to modify the radiator by moving one of the hose inlets to the other side. Do it yourself, or pay a radiator shop $50.00 to do it. The radiator probably should cool it ok, but you may have to add a shroud to it. Some people get away with stock radiators, others do not.

One more thought: Why screw around with a 305. Get a 350 for the same $ and effort.

One more last, last thought: I might have the adapter you are looking for laying in my garage, if you go that route.

Great winter project for you!

 

[oldenburgd]

Thanks for the detail. The big factor is the budget/time, isnt it always? I live 4 hours away from where the jeep is, so using my time and my brothers money. I found another adapter and it looks to be more inclusive then the one from novak. Chevy To Jeep Conversion Aluminum Bellhousing by Advance Adapters and Other Jeep Parts and Jeep Accessories by 4 Wheel Drive Hardware-RH2 What do you think? What is the adapter and how much would you want for it? I need to get him a Christmas present to get him going in the right direction. Although I am hesitant because I just found out that he had scrapped three motors in the last month. 1 was the original motor, one was a double hump 305 that I gave him a year ago, and the other was a parts motor for the original. all totaling up to 70$ from the scrap yard. I'd really like to give him an <-BAD WORD-> whooping for Christmas

 

[oldenburgd]

Found a motor on craigslist. 78-79 70kmiles on it, needs a carb rebuild. Wuddya think?

 

[jeepy]

The adapter you linked to at Novak does not say it is for a T-18 .

I would have to look for the adapter this weekend. And I would have to know how long your T-18 input shaft length is to tell you if it would fit or not (There were many different lengths). You also would still need a replacement bearing retainer from Novak to keep the oil in the tranny because you would be moving your retainer to the front of the adapter.

Just make sure that any engine you buy, you can hear run. It at least needs to run on all cylinders, not smoke, and not knock.

edit: Now that I think about it, That adapter was cracked. I did weld it back together and use it for a few years, but I don't think it would be appropriate to sell it.

 

[priceg]

Found a motor on craigslist. 78-79 70kmiles on it, needs a carb rebuild. Wuddya think?

Consider a 350 instead of a 305, simply because the money is the same.

 

[oldenburgd]

AMC's are harder to come by in my parts of the world. So if anybody is near Iowa..like a state away. I dont mind driving if its a good running motor

 

[79cj7bogger]

i would just find another AMC 258 i6 / 4.2l i'd rather run that than do a chevy swap even if time and money wasnt an issue

 

[1986cj7]

i would just find another AMC 258 i6 / 4.2l i'd rather run that than do a chevy swap even if time and money wasnt an issue

In my opinion you would be money and time ahead if you just get another AMC 258 i6 / 4.2l by the time you put money into adapters and changing motor mounts and all, it would probably cost more to use a different motor.

 

[poppatello]

Another thing to consider with staying with the AMC 258 i6 / 4.2l . If you do any wheeling with other jeeps if you have a normal jeep engine most likely AMC 258 i6 / 4.2l for the most part and have a trail break down, chances are another jeeper has the part you need on his rig. I found that out twice on my first two outtings. I was running an AMC 4 banger but some AMC 258 i6 / 4.2l parts will work which got me going. If they didn't have it many live near by and had all kinds of items to rebuild a standard jeep from scratch (jeep axles, driveline, ect.). If you start swapping out odds and ends it will be most likely your buddies may not have the spare parts you need so you'll have to rely on the parts store or your personal stash so if your a few miles from home you'll be s.o.o.l on the trails...