2.8 to 3.4 jeep ?

[creekscout]

I have a 86 comanche with a bad 2.8 motor that I plan to replace with a 3.4 that I have located from a camaro. I want to know what I need to do to swap in the 3.4 with an edelbrock intake and carb. I know I have to install an electric fuel pump, I am removing all emissions crap so I don't have that stuff in the way. Does the 3.4 have a hole to install the distributor into and use just as it worked in the 2.8. Can I still use the 3.4 oilpan, the truck is 2 wheel drive by the way.I know I have to change water pumps and all other front end accessories, but are there other things I need to know. I am unsure about the flexplate working, the truck is an automatic torqueflight.Will the exhaust manifolds still fit. Will there be electrical changes? That's all I can think of now but I know I am forgetting some things.Thanks for any and all help.

[Mad Max]

Since I have done this swap here is what it takes: EVRYTHING interchanges. The distributor drops right in, the edelbrock intake bolts right on. Make sure you use the Jeep oil pan. There are a few extra sensors for the Camaro - crank trigger sensor and cam angle sensor. I pulled them and used small freeze plugs to block the holes. The motor mounts even bolt right up. You will be amazed at the power difference between the weezer 2.8 and the 3.4.
It would really help to install a large exhaust - like 2 1/2 inch diameter. BTW, the Camaro exhaust manifolds have larger diameter outlets. I think the Camaro Y pipe might even fit in the Jeep - its pretty large piped and closely follows the engine profile. It also goes to a 2 1/2 inch Cat. You may find aftermarket large Jeep exhausts that will bolt right up. There is one minor problem - the Edelbrock intake is pretty tall, and finding an airfilter to fit is tricky. I used a cheap open element recessed base (Jegs and Summit) with a skinny air filter element. It still crushed the hood insulation, but it worked. Don't let all of that Camaro injection stuff fool you, once stripped off the engine, the 2.8 and 3.4 look identical. You also want to run a Holley 390 CFM carby. Don't use a 600, it won't run well. You may be able to use a 450 CFM, the 390 works better and still gives decent fuel mileage. Oh, look again, I'm pretty sure that your Jeep has a GM auto tranny - the flex bolts right up.
I also did this same swap in my current '91 S10. Stock with the cheesy T body injection, a 3 inch exhaust (Jegs) an open element air filter, 3.42 open rear and 5 speed, it went 16.3 at the track in the 1/4.
It is a super swap and really easy.

[creekscout]

Thanks for the reply, I hope it is as easy as you say. The edelbrock intake came today, it has the two barrel top adapter. I was hoping the camaro oil pan would work since the truck is only 2wd, but no big deal, which oil pump must I use then? Thanks again because I know I will have more questions.

[Mad Max]

It's not the oil pump, its the pick up. Use the jeep oil pick up tube. Basically what you are doing is using the 3.4 long block and bolting on all of the jeep components. I don't remember which 2 bbl carb the Edelbrock uses, the small carb adapter won't give you as much power. It all depends on your priorities. If you have swapped a motor in the past, this won't be too tough.
It is basically a straight forward swap. I can answer any questions you have.
Do you have the 2.8 oil pan? If not, the Camaro might work. I ran into problems on my S10 swap, I used the Jeep 2.8 pan on the Cherokee (same as Comanchee) swap.

[geoffinbc]

You will have to swap pans unless you are sure there are no cross members in the way. If you do swap pans and they have different sump depths then you will need a new pickup. The old 2.8L pickup is only 5/8" while the 3.4L pickup is 3/4" new ones can be purchased through Melling. You may want to consider a new pump while you are at it. And when you set the depth of the pickup it is a wise idea to tack it in place.

[creekscout]

Yes, I do have the 2.8 jeep oil pan as I have not pulled the motor out yet. I have heard of freeze plugs rusting out, should I consider replacing them. The front cover that I have heard needs to be changed as well as the waterpump is that the timing cover. I am very sure that it has a 904 torqueflight in it. That's all for now.

[neo71665]

Personally I change the freeze plugs on every engine I pull out. They are cheap enough and its easy enough while its out to justify the few dollars saved now not doing it. Trust me there is nothing more of a bigger PITA than having to pull a engine you just put in a few months ago to replace a leaking freeze plug.

Pretty sure its like the s-series swap and you use you have to use the front cover and accessories that were on the original engine to make it a bolt in.

[creekscout]

I hope to have the motor out of the jeep by this weekend, but until then I already have more questions. I plan on going to a flea market at the dragstrip this saturday looking for some parts to pick up for the 3.4 motor, and I could use fome help on waht to look for. First off I have an edelbrock intake with the 2bbl top, and I was wondering what carbs will work for this, the stock 2.8 is a rochester with electric adj., so I don't think I will use that. I might add that this is just going to be a daily driver but I do live in the mountains so I would like as much power as possible. Also for ignition any coil or distributor advice. I am also wondering the best route to take for gaskets, I will be replacing the oil pan, intake, waterpump, front cover, freezeplugs, rear main seal, valvecovers, carb,distributor, so my question is will I be better off buying a whole overhaul gasket kit to make it simpler and cheaper. That's it for now. Thanks again for any info.

[geoffinbc]

Yes buy an upper and lower gasket kit from Felpro. Use any 390 CFM carb you prefer. If your switching carbs you need a mechanical/vacuum advance distributor from an 82-84 S-10

[blowns10]

Get a fel pro overhaul kit. You can get a better carburetor from weber carburetors or the holley carb works. You can get a coil from MSD ignition and they've got some more parts you can view on their website. Late.

[zoideraserb]

you could get a 4bbl adapter as well.. there is alot more potential with a small 4bbl then with a 2bbl carb.. Or if you wanted to muss with the wiring the best fuel system to use would be the efi from the camaro. you have a non electric trans so you could just hook up the TV cable to the throttle body. Might be worth the extra wiring to have the reliability of the efi/dis system. Might lose a couple gauges unless you use the jeep sending units though.

[creekscout]

OK I have the engine out now and I still have a lot of questions. The distributor has a vacuum canister on it and has only wires coming off of it, so is this the same distributor like the 82-82 s10 that I have been searching for. Also I am wondering if edelbrock valve covers for a 2.8 will fit on the 3.4, I want to get rid of that long filler neck. I have been reading the recent threads about the similar engine swap in the S10 and am wondering about using the newer front cover like that thread mentions. Is anyone familiar with the 2.8 jeep oilpan and how it compares to the other two. Does anyone know the part no. for that front cover? I had planned on replacing the freeze plugs on the 3.4 and now I see why it is important since I pulled the 2.8 and found the freeze plug in the back of the block leaking. Should I consider changing valve seals? Where do I purchase the recommended LIM gaskets? That's all for now. Thanks again

[geoffinbc]

Yes it is the same as an S-10. The motor is essentially an S-10 engine. Yes you can use the Edelbrock covers, Fiero aluminum covers or stock S-10 covers without the filler neck. Your Jeep oil pan should be the same as an S-10 oil pan. There are only 2 kinds the 2wd pans or 4wd pan. Go to a junkyard and visually compare yours to the S-10 ones and get the new style pan for a 1 piece pan seal. You will need an 86 front cover to keep your stock belts with the new pan or grab an 87 or later setup with all the brackets and get your truck setup with serpentine belts. Replace ALL the freeze plugs and buy a Fel Pro upper and lower gasket kit so you get everything you need for the engine. You should change the valve seals but you need to check the valve stem clearance or the new seals wont last long.

[86FieroSEv6]

I recommend brass core plugs for a long life trouble free build.

[creekscout]

I just reread my latest post and I see that I omitted the word two in the distributor information where I said that mine has a vacuum canister and two wires coming out of it. Is this the right distributor to use for a non emission setup engine with either a varajet 2se or a holley 390cfm 4 bbl, I haven't decided which way to go as I now have an edelbrock base with both a 2bbl and 4 bbl top. Napa has fel pro gaskets but they do not list them as upper and lower gasket sets. Also for one of the gaskets they said they had to know if it was a U or T code engine, where do I find that info. I am going to take the oil pan off tomorrow and try to compare it to the camaro pan to see if I can get by with the camaro pan.