Announcement Announcement Module
No announcement yet.
304 Rebuild Page Title Module
Move Remove Collapse
Conversation Detail Module
  • Filter
  • Time
  • Show
Clear All
new posts

  • 304 Rebuild

    Is there an inexpensive rebuild kit for a '76 304. I don't want to spend a ton of money on this engine... but it seems like a good engine and I just want to maybe go through it and just "refresh" it. I don't wnat to "upgrade" it at all... I am fine with stock performance.

    If possible I want to avoid any machine shop. I just want to pull the engine, go through it and replace stuff. The main problems are low oil pressure (about 25 psi under power), oil leaks around oil pan even after changing rear main seal and oil pan gasket, and some top end chatter (sounds like valve train issues).

    Is this even reasonable to consider? Or do I need to get the cyclinders bored and such?

    How much is this gonna cost me?

  • #2
    Start with some good diagnostics
    1) Comprestion Test
    2) Leak Down test if you can
    3) What do the plugs look like
    I redid the top end of my 78 304 and had good luck with it.


    • #3
      Originally posted by jeffm3434
      Is this even reasonable to consider? Or do I need to get the cyclinders bored and such?

      How much is this gonna cost me?

      Depends how much actual wear is on the cylinder walls, what the valve seats look like, bearings, etc and a slew of other things that qre only conveniently checked by a machine shop.

      You may or may not get away with just "bolting stuff on", but at the very least you aren't going to get away with it without tearing the motor apart.

      I had mine done with no special nod towards a "performance" rebuild and dropped $1,700.00 on it. I did nothing but drop it off and pick it up but still, it would have been cheaper to do your average bow-tie. If I had it to do over again I would not have bothered with the 304. It's performance increase over the 258 is questionable, and the rebuild expense was a third more. If you want to stick with AMC V8 I'd look for a 360 or 390 to build.

      Personally, I'm getting ready to dump the 304 and install a 5.0 HO in mine. It's got 45K on the clock and even buying a slushbox and xfer case adapter I'm not much over the cost of the reubild of the 304. Should have done this in the first place.


      • #4
        i second tgreening. i rebuilt a 304 a couple years ago. with under 5K miles on it i just finished swapping it for a SBC 350. if your losing oil pressure the most likely culprit is the mains. if you're going to pull the engine you might as well pull the crank and have it turned or polished. the block will probably need bored more than honed. the ridge on the top will determine that. i dumped a ton of money in my 304...i should say i wasted a ton of money on it.


        • #5
          Ditto, wasted money and time on the 304 could have had the sbc in and running a long time ago. This time doing it right, 350 with th350.


          • #6
            A AMC 304 is as bad as a 305 SBC, they both are like pizzin in the wind. The first go around they run forever but are gutless. I wouldn't waste time and money on either. If you are going AMC get a 360 (at a minimum) and SBC get a 350 (at a minimum) of course 401 and 400 are prefered lol but arn't cheap.
            There are tons of waggys out there with good engines, I have gotten several 360's out of them and ran them as I purchased them for years. If you really wqant to rebuild a engine (thats the prefered method) get a 360 and stick the money into it. Expect to spend 1300-1800 to do it right. Get the bottom end balanced and fix the oiling issues, you'll be golden.


            • #7
              AMC 304 vs. SBC

              Went thru the same thoughts you did and I went with an AMC 360. If you go thru 4Wheel Drive and Novak catalogs you can get a good estimate on what it would cost for SBC conversion. I wanted to do mine in one weekend without very lot of fabrication - would have been $800.00 plus, not counting a good SBC.

              Jeep transmission to SBC engine adapter
              Motor mounts - bolt or weld on
              Radiator - to get hose on proper side without pinching, not really required unless you have problems.
              SBC Conversion headers - if used. Apparently can't use standard Chev Headers.

              Could have been more parts required but I quit at $800.00! Sure that with good fabrication skills and a friend that has done it before you can do it for a lot less.

              A good running AMC 360 for a few hundred - the $800.00 went a long ways to make my ride nicer.

              Good luck whichever way you go!


              • #8
                As far a cheap kits go, check these guys out:


                They do have a nearly complete kit for the 304 for 558.80. No valves or valvesprings, but most everything else is included. There are also upgrades available like Felpro gaskets instead of Victor, moly rings, RV cam etc. The whole shabang comes to 762.13 + S&H


                • #9
                  BUmP =]

                  my oil PSI is pushing about 75-80 on startup and 40 during opperation, 20-25psi at idle after its been run a pretty good while.

                  numbers sound alright to me, but i figured id ask

                  the valves on both banks are chattering, i think its cyl. no.'s 5/7/6/8 by ear at idle.

                  could be all of them.

                  doesnt do it when its at cold startup, once things get warmed up its terrible.

                  an engine swap is a last resort... i need to keep this motor. i dont have the time or money to dump into a 360 nor a place to do it even if i did.

                  i was thinking new heads and a set of new headers while i was at it. but i cant seem to be certain on which heads will be best for the money..

                  if im gonna come out worse keeping the motor with new heads then i guess its engine swap time. but again.. last resort pls ;p

                  thanks ahead of time



                  • #10
                    I had my 304 built with new pistons, cam lifters, valves, crank and the heads ported and polished for about 1175. These motors are not cheap to build, but if it is supposed to go there you run into a lot less headaches. I went the conversion route before on another CJ with a 4.3 it ended up costing me a whole lot more than I thought it would. It was still right under 1k, but I spent more time chasing ghosts than it was worth.


                    • #11
                      I have rebuilt four of my 304's. Well, really one TOH and three full. The wuestion is whether you want to do it right, or do it quick and easy. Quick and easy will last you about a year. Doing it right will last you much longer, but will cost you more. These guys are right about the 304 not being a stellar performer. I used to swear by it, and even get mad if someone bad mouthed that engine. But if you have some miles on it, it will need to be pulled out, torn apart, heads sent out, cylinders bored, then carefully put back together. Then you have to wait to get all the parts for the rebuild after it comes back from the machine shop. You will want to upgrade to 360 AMC valves (I say AMC cause I found out DC 360 valves will NOT work!), measure for your new bore, then do you get larger rings or oversized pistons? There is a shop in Fayetteville that carries many of the parts you need. Rocket Auto. I found a machine shop in Fay also, and one of the guys that works their races AMC, so he knows those engines very well.

                      I looked at doing the 350 convertion, but it seemed like a it was a bit over my head. Plus, I've never heard anything bad about the 360. Weird, cause it is just a 304 with a bigger bore (basically). So I went with a 360, and I am VERY happy with it.

                      But back to your question really. 304's chatter. They have oil pressure issues. You can just freshen it up a little with some new gaskets and a new oil pump. If you can wait 80 days or so, I'll be home!

                      Okay, I'll still be in bed then, better make it 84 days.


                      • #12
                        wow that would be awsome! =D

                        yea 4 days of sleeping is a requirement, not a statistic =]

                        cant believe your coming back so soon man. and yea i dont like to talk down about the 304, its been a really good motor. i cant believe your offering to help, thats so awsome! someone whos done it before haha, i saw your jeep pics, they are sexy =]

                        i wouldnt mind refreshing it, i believe it has over 185,000 on it. my dad used it as a daily driver back in his high school days.

                        and as for performance, it doesnt need to be a total performance package. just something done right the first time so it can still be dependable.


                        • #13
                          I think I have all the required tools still. I'm a hand tool guy, I haven't upgraded to the impact tools yet. I think that would really send my wife over the edge. Besides, I don't have room for the tools I have now!

                          So you let me know!


                          • #14
                            So what happened?

                            Rebuilt my 304 in June ofr 2005. It's no racing motor but I think it's great for a CJ5. So what happened?