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cam swap

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 81sb, Oct 25, 2002.

  1. 81sb

    81sb Registered Member

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    How hard is it to replace the cam and lifters in a 81 305. I know it is going to be time consuming with all the dissassembly required. I am pretty mechanical but have not torn that much of my mill apart before.

    Thanks
    81sb /forums/images/graemlins/k5.gif
     
  2. trouble1

    trouble1 1/2 ton status

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    Do a search on "cams" and "camshafts" there are a couple of great writeups on them. I ordered my cam today...never tried anything of the sort, but feeling pretty confident between the pages I printed out on here, the chiltons manual and the knowledge that if I get into any trouble I can get on here and someone will have the answer. Actually, I'll probably have this under the hood with me and I'll be logged on to it while I am replacing. As far as the cam to get...There are many ppl on here that can steer you right if I havent already irritated them for the week on camshafts. There is a goo bit of it in my post asking for preformance guys. I cant wait to take it out Saturday after I'm done to see how it does!!! /forums/images/graemlins/laugh.gif /forums/images/graemlins/k5.gif
     
  3. xnoahx

    xnoahx 1/2 ton status

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    The cam and lifters swap is relatively "easy." Its just like you said, lots involved in it. to do it you have to remove your distributor, intake manifold, valve covers, pushrods, water pump, harmonic balancer, timing chain cover, timing chain and gear set, and of course the old cam and lifters.

    Heres how I did it, goin from memory
    Started off by getting the engine in the #1 firing postion. There are a couple of ways to do this, you can take off your distributor cap and bump the engine till it rests on the #1 firing postion or you can remove your drivers side valve cover and bump it over untill both the intake and exhaust valves are closed(springs are not compressed.) you can double check both ways by looking at the timing mark on your harmonic balancer. oth ways are also easier to do if you remove your spark plugs becuase there is no compression on the engine and it turns freely. Once you get the engine at TDC you can get to dissasembly,

    I started by removing all the lines to the carb and intake minifold like the fuel line and radiator hoses(make sure to make a note of where everything goes because you will have to reconnect everything.) Now its time to start pulling parts. Heres the order I did it in: distributor(make not of the postion of the rotor with a mark on the housing), alernator(just to have some more room), intake manifold, valve covers, water pump, harmonic balancer, timing chain cover, lower timing gear(I replaced it, it doesnt need to come off if you are reusing it.) With all this out of the way, I then loosened the rocker arms until I could rotate them out of the way to remove my pushrods, Its a good idea to label where each one came from becasue you want to put them back in their original location. After I got the pushrods out I was able to pull out the old lifters. Now you can pull your old cam out with the large upper timing gear attached. It should slide right out, just try to back it straight out.

    Now you are ready to install your new cam and lifters. Coat the whole cam with assembly lube. You cant have too much of this on there, lay it on and be sure that you have the cam well covered on all the lobes and journals. Now you can slide it right in, I bolted my timing gear on it when i was putting it in just to have a handle. Again be sure to keep it straight and take it slow. With it in you can install your new lifters, replace your push rods, and readjust your rocker arms. The procedure for doing that should be in your service manual, if you dont have one, ask on here, someone will tell you. Next put your timing chain on and re-install your timing cover with a new gasket. now you can put your harmonic balacer back on. There are tools available that are made just for this and it is recomended that you have one on hand to do it, If not you can just use a block of wood and a BIG hammer(WARNING: this way is not recomended by ANYONE, it can cause problems with your engine, but I did it with no problems and so have countless others.) Use the tool if at all possible. Now with all new gaskets you can reinstall your valve covers, intake manifold, and water pump. hook your alternator back up of you removed it and put your distributor back in so the rotor is pointing where it was when you removed it(use the mark you made when you removed it.) Reconnect any vaccum/fuel/coolant/misc lines that you disconnected and refill your coolant. That should do it, hopefully it will start up and run like a champ when all is said and done.

    Now, some areas that may give you trouble. The harmonic balancer, it is on there very good but you can go to autozone and use their loan-a-tool service and get a puller or you can buy one for about $15. Also, since you are going to be getting access to it, you might want to get a new timing chain and gear set if they are stock. You can pick up a roller chain and gear set from summit racing for about $30. You just have to line up the match marks on the gears, real easy to do. Also, the lower timing gear is pressed on pretty well also, I used a 3-jaw puller to remove mine, another tool you can get on loan from auto-zone. Other than that, If you have all the parts, tools, and replacement gaskets you can finish the job in a day.
     
  4. Sandman

    Sandman 3/4 ton status Author

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    Here is an article that I wrote for this site and it is posted in the Bloody Knuckle. See, you need to get a membership! /forums/images/graemlins/grin.gif

    Cam Swap
     

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