I just purchased an 89 Iroc that has a flat cam, thats causing an engine knock. I want to replace the cam before school starts 8/12/02 so fast answers would be great. I need to know exactly what the process for swapping the cam is, and i need suggestions on cams, and what to look for in a cam. It will be going into a bone stock 89 350 TPI.

Thanks in advance

 

What makes you believe the cam is causing the engine knock? Did you pull a valve cover, or the intake to verify the lifter isn't moving? A collapsed lifter or bent pushrod could cause a knock too. I've never seen a roller cam go flat, but I guess if the lifter bought the farm and fell apart, it could wipe it out pretty quick. To answer your question, a simple cam swap can turn into a major project if you don't prepare ahead. First off, you'll need the cam, and if it got ruined by the lifters, look at a set of those too. The nice thing about the roller cam in your 89 is that you can re-use the lifters on a new cam as long as they are in good shape, which is something you couldn't do on a flat tappet cam. You should replace the timing set as well. You'll need gaskets for the intake, valve covers, timing chain, distributor, and waterpump. You'll have to disconnect the fuel lines to the rails in order to get the intake off, so you'll need some new viton O rings not just any old rubber ones. It would also be a good idea to replace the seal in the timing cover while it's apart. You'll also need some loctite, and some gasket sealer. I prefer the black high temp RTV because it's sensor safe, and works on EVERYTHING. Also some new coolant and oil and filter for after the swap is done to make sure no coolant got into the oil.

The special tools you'll need are a harmonic balancer puller, (DO NOT USE A GEAR PULLER ON IT, it will ruin the balancer) a harmonic balancer installation tool, a gear puller for the crank gear, A torque wrench, and maybe some flare nut wrenches for the fuel lines if they are stubborn, but you can get away with regular wrenches. You're going to need a Chilton book for the torque specs and sequences too.

Start by draining the coolant, removing the fan, radiator, hoses, belt, waterpump and balancer. Remove any brackets that attach to the accesory brackets and intake. remove the plenum, runners, distributor, intake, and valve covers. You will have to remove some of the smog equipment to get the valve covers off. You will have to loosen the oil pan to drop the front of it a little to get the timing cover off. loosen the rockers and remove the pushrods. remove the spider and take the lifters out. Try to keep the pushrods and lifters in the order you take them out, because they all have worn to each other and should stay together. egg cartons are good for the lifters, and a box with 16 holes punched in it is good for the pushrods. Once the timing cover is off, remove the timing gears/chain. Remove the cam retaining bracket. You can have a friend hold the AC condenser out of the way while you remove the cam, that way you won't lose the charge in the system. Be careful, those fins can be sharp. I'm sure I've forgotten something here, but everything should be obvious when you dig in. I believe you can do the removal without removing tha accesory brackets and components, but I'm not 100%. I'll cover installation in the next reply.

 

The one thing I need to stress is keep everything clean. You don't want dirt getting in the engine, so keep that in mind as you work. I should have mentioned that before disassembly. An air hose or a shop vac can really help. To assemble everything, you'll be working in reverse. Take a lot of caution when removing and installing the cam as to avoid scarring the cam bearings. It doesn't take much to damage them, and you aren't going to be able to replace the bearings with the engine in the car. A bolt threaded into the end of the cam will act as a handle and give you a little more leverage. Install the new cam, retainer, using loctite on the bolts and torqued to spec, and timing set, (aligning the dots if you're not picky, degreeing the cam if you are, which is another topic.) With the dots aligned, this puts the engine at TDC for number one cylinder. You'll need the balancer installation tool and a short piece of pipe to install the crank gear. Don't hammer it on or you'll ruin the thrust surface on the main bearing.

Install the seal in the timing cover, use some black RTV to hold the gasket in place (I usually coat both sides of the gaskets with a thin coat of the black RTV) and install the cover and re-tighten the oil pan. It has a one piece rubber gasket that should be reuseable. Install the balancer, it should have the timing mark at the TDC mark. Next is the waterpump, again using black RTV on both sides of the gaskets. Install the lifters, spider, again using loctite, and pushrods. Rotate the pushrods on #1 as you tighten the rocker nut. When you feel resistance turning it, and have no play in it, tighten it another 1/4, to 1/2 turn, Repeat for each cylinder with the piston at TDC for each. after you have them all ajusted, go back and set #1 at TDC. Now you can install the intake, following the proper torque sequence, and distributor, with the rotor pointing at #1 terminal. You may have to use a long screwdriver to align the oil pump drive shaft to the dist. gear. Keep in mind as the dist. goes in and seats, the helical gears on it and the cam will make the rotor turn somewhat, so you'll have to overshoot some when doing this. It's something that is self explanitory as you do it. Now you can finish reinstalling everything else. once it's together and you refill the radiator, have someone start the car as you turn the dist. to get it running, then set it close with a timing light. once it warms up, providing there are no leaks, set the timing to 6* and check your idle speed and TPS voltage to make sure that it's set right. there ya go.

I hope it's just your cam, but usually a knock is caused by a rod bearing. As far as cams go, you can get a used LT1 cam from the boards, or ebay for between 25-50 bucks and they are a nice upgrade for a stock motor. Best part is they are real cheap. it's close in duration, but has a little more lift than the L98. The only thing that it needs to fit is the dowel pin has to be ground down a little. No big deal. Just take your time and it goes pretty well.

 

well, the car has an exhaust leak in the passenger manifold, and thats the side that the noise is coming from its more of a click tha "knock" I took it to a checy dealership where my friend is a mechanic, and he listened to it (wanted it checked before i bought it) sid that he thought it was either a lifter or a flat cam, but it was hard to tell with the exhaust leak. Is there any easy way to tell if its the lifter?

Thanks ZZsmpch for all the in depth post's they are great

 

an exhaust leak will sound like a click too. To see if it's the exhaust, unplug the injectors one at a time on that side and see if the clicking stops. with one of them off, that cylinder won't be firing. It could be that.

 

ok i had a neigbor come over (he's a mechanic at the local gm place) he unplugged the injectors one at a time down that side, and on the #5 the clicking got really faint when he unhooked the injector, so he said that it could either be a lifter, or the rod bearing. He said that the easiest way to find out would be to pull the valve cover, then take a rag and push on the rocker for the #5 cylinder, he said if the clicking stopped, then it was the lifter but if the click got worse then it was a rod bearing. Is this the correct way to test?

 

You can check the lifter that way, but first make sure it's ajusted right. Put #5 on TDC and turn the pushrod and see if it has resistance, if not then it could be either out of ajustment or the lifter collapsed. The valve trane won't have an affect on a rod bearing. The rod bearing would be loudest when the engine is cold, or under heavy load/throttle. It sounds to me like an exhaust leak, so I'd try the cheap stuff first. I don't know about the L98, but my L03 didn't have exhaust gaskets, but rather was relying on the surfaces being flat to seal. A lot of engines are like that. Try new exhaust gaskets, and checking your rocker ajustment before going any further. I once had a bad wrist pin in a 390 ford FE big block that turned out to be an exhaust leak. wish I knew that before I yanked the mill out.

 

okay this may sound dumb, but how do you set #5 at TDC I know your thinking how was i going to swap cams if i cant even get the cylinder to TDC, but if i have to do a cam swap my neighbor the mechanic will be there guiding me through it. Any way how do you get #5 to TDC, and what do you mean by turn the pushrod? do you mean twist it areound in a circular motion? And can i buy exhaust gaskets to fit that motor?

Thanks again:hail:

P.S. the pic in the sig is the new car!

 

To get #5 to tdc, you can remove the sparkplug and either the valve cover (more accurate) or the dist. cap. when the cylinder is at top dead center, both valves are closed and the rotor will be pointing to that post on the distributor with the piston at the top of the bore. Just a quick 4 stroke review, you have an intake stroke, where the intake valve is open, and the piston is drawing the fuel into the cylinder, then you have the compression stroke, where the piston moves up the bore and compresses the gas. In order for that to happen, the valves need to be closed at tdc on the compression stroke, the plug ignites the A/F mix, and forces the piston back down the cylinder, and the crank's recriprocal motion brings the piston back up the bore while the exhaust valve is open, exhausting the spent gas. So, you have intake, compression, combustion, and exhaust, comprising the 4 stroke cycle. Looking at it, you can see that TDC has both valves closed, rotor pointing to that cylinder's plug wire terminal, and the lifters sitting on the base circle of the cam. With the lifters at this point, you can "roll" the pushrod between your fingertips to feel for the resistance. The way to ajust them is to loosen the rocker nut(with the piston at TDC), and then tighten it back down while feeling for the drag on the pushrod. Once you feel it, then turn the rocker nut another 1/4 to 1/2 turn. Be consistant and do them all the same. Sorry for the long winded and remedial explination, but I'm not too good at explaining things. You should be able to get the gaskets at any auto parts store. That's one of the nice things about the small block chevy. Good luck.

 

okay I went out this morning, put it to TDC on the #5 and tried to spin the pushrod around, it wouldnt mave unless a lot of force was applied, so i started it up, and tried pushing on the rockers for #5 i pushed on one and then the other and the sound didnt change at all, the clicking didnt stop (meaning its not the lifter) and the clcik didnt get any worse (so i assume its not the rod bearing). I called my friend the mechanic and he said that its possible thats its just an exhaust leak, but that he thinks its the rod bearing just starting to go bad, and that s why the clicking doesnt really get any worse when you push on it. I pinpointed the leak just barely its right by the very back cylinder on the passenger side (the one closest to the firewall) could this be why the noise doesnt change much when the injectores are unplugged, because the exhaust is passing the leak constantly anyway?

Oh ya thanks again

 

I really don't think it's a rod bearing. They don't click, they knock. You can hear a rod bearing by putting the handle of a long screwdriver against your head, behind your ear and putting the tip of the driver on the block and moving it around to locate it. It really just sounds like you have an exhaust leak to me. I hope so anyway. You can get a mechanic's stethoscope from sears for like $20, and it'll be a handy tool to keep in the box for the future too. Let me know how you make out.

 

okay went and bought a set of exhaust gaskets, put them on, got rid of the leak, but you can still hear a click, so i called the mechanic again! and he said theres definatly wrong and that i shouldnt drive the car till he comes over tomorrow after work, that way I dont screw anything up. like doing

 

hey, the mechanic just left and he said that its both the lifter, and the rod bearing, so i am going to try and get my hands on 2 new lifters in the next day or so, and get rid of that click, then we can be sertain that the rod bearing is clicking. If we end up having to treplace the rod bearing thats okay, because i need a new oil pan too, i crawled under there yesterday when i was changing the exhaust gaskets, and the oil pan thats on it, is pretty hammered by rocks and what not.

Thanks again for all the help ZZsmpch


P.S. If you have any suggestion PLEASE post them

 

Hmm, I wonder if that dented pan is pushed in enough for the crank to be tapping it? Might be worth feeling it with the engine running. I'm glad to hear the cam is OK. I got a set of lifters from cz28.com's board for 35 bucks. They were out of an LT1, but they are the same. I'm not 100% cretain, but I think I saw ZZ4 take-off oil pans somewhere cheap. I'll take a look and see if I can find it and post a reply. L8R

 

do i have to remove the head to change out the lifters? because in my hayes camaro book it shows that they can be pulled out without removing the heads

 

You'll just have to remove the intake, and loosen the rocker nut enough to get the pushrod out.

 

okay it looks like that since i need to replace a rod bearing i might as well replace all of them, so i was thinking wouldnt it be better just to pull the engine, and have it out of the car, i mean wouldnt that be the easiest way to work on it? What things should i replace, this engine only needs to last a year, because in a year i am going to take the engine building class @ the local state college. SO what do i need to replace? heres what i was thinking so far:

Rod bearings
Lifters (whole set)
oil pan
cam, and timing chain set (maybe)

 

It would be a good idea to do the Main and Cam bearings also. Probably the oil pump too

 

okay,
ZZsmpch, if i go with the LT1 cam, what needs to be ground down? and how much? do i just take it to a machine shop and tell them what to do?

looks as if i am going to run the car as-is until my first weekend break from school, then we are going to pull the engine put in all new:

rod bearing
oil pan
oil pump
lifters
cam (probly an LT1)
timing set
maybe valve springs

if i do these mods, will it be worth the time/ cost to keep the car running for another year?

 

It kinda depends on the condition of the engine/car. If it's in generally sound condition with good cylinders, then It would definitely be worth it. If it's smoking and rusty, well.... A lot of folks put down swapping in an LT1 cam, because it's close in duration to the L98, and is a factory cam. It's definitely worth swapping in to a stock engine for a few more horses if you're looking for a cheap upgrade. There's a dowel pin on the end of the cam that goes through the timing gear. It will hit the timing cover because it's a little too long. I just took it over to my bench grinder and ground it down until it was the same as my stock cam's pin.

One more piece I'd advise you to change is the oil pump drive shaft. It's cheap insurance. Usually when an oil pump stops working, it's a broken drive. Did you look into rebuild kits from PAW and Summit?

 

The dowel pin on the L98 cam sticks out roughly .300"
The dowel pin on the LT1 cam sticks out roughly .600"
I tapped mine in as far as it would go,then ground the rest off with a bench grinder to reach the desired length..
I've heard some guys say that they were able to tap the pin in far enough to reach .300", but mine wouldnt go that far...

 

ya, i got to thinking about it, and it may be cheaper to get a rebuild kit, and just do it all at once, thanks for the advice guys!


oh btw the engine is in great shape, it only has 79,000 miles on it, but it sat from 97-now with a dead fuel pump, so I think thats why the bearing went bad so quick