blueking Posted August 18, 2008 Share Posted August 18, 2008 i have a hotter cam for my 280zx im interested in swaping out only the cam no rockers springs, ect.. i do not want to take out my motor to adjust the timing.on a chevy motor its possible to just pull out the cam and not have to ajust the timing if you just keep everything at the possition it came out and have the lobe exactly at 12 when you take it out and put it back in. i dont have experience with the l28 so i want to know its the same situation or should i just take it to a tune shop and have them do it? Quote Link to comment Share on other sites More sharing options...
turbobluestreak Posted August 18, 2008 Share Posted August 18, 2008 yes you can do the swap in the car, I removed the rockers and unhooked the timing and then removed the cam keeping the cam towers in place. You'll need to make the timing tool to hold the chain in place, in my experence I needed to unhook the transmission crossmember to tilt the motor back so the cam would clear the core support. tbs Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 18, 2008 Share Posted August 18, 2008 It's easier in my opinion to pull the cam towers. But then you have to drain the coolant and hope the headgasket holds. I've done it twice and never had a problem even though people will tell you that it can't be done. Quote Link to comment Share on other sites More sharing options...
blueking Posted August 18, 2008 Author Share Posted August 18, 2008 im sorry im just learning about engines the cam towers are the metal bands over the cam i am not mistaken right? the ones that loop over the bearing? and by coolant you mean antifreeze correct? if so i need to flush the rad anyways so itll be a good time. thanks both of yall Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 18, 2008 Share Posted August 18, 2008 im sorry im just learning about engines the cam towers are the metal bands over the cam i am not mistaken right? the ones that loop over the bearing?and by coolant you mean antifreeze correct? if so i need to flush the rad anyways so itll be a good time. thanks both of yall Yes and yes. Quote Link to comment Share on other sites More sharing options...
David K Posted August 18, 2008 Share Posted August 18, 2008 From someone who has done this several times, please please make sure the cam tower bolts line up and thread properly before wrench/torque them down. The valve springs are going to be pushing up on sections of the cam, so make sure you line it all up correctly and apply even torque by tightening in steps. I completely toasted a couple of threads on the very first head i did a cam on. I thought i learned by my mistakes, but ended up stripping a hole on the second try. That was years ago, but it does happen. EDIT: also make sure you mark and replace the cam towers where you got them from on the head. Make sure you put the bolts back in the same holes you took them out of. Basically keep everything where you got it. Ive put a head together from a bag of parts i got from a friend. I ended up having to take it to a machinist to have him determine where the cam towers went. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 19, 2008 Share Posted August 19, 2008 From someone who has done this several times, please please make sure the cam tower bolts line up and thread properly before wrench/torque them down. The valve springs are going to be pushing up on sections of the cam, so make sure you line it all up correctly and apply even torque by tightening in steps. I completely toasted a couple of threads on the very first head i did a cam on. I thought i learned by my mistakes, but ended up stripping a hole on the second try. That was years ago, but it does happen. I'm struggling to figure out how this happened. You put the rockers on AFTER you installed the cam towers, of course. So you should be able to tighten the cam towers down, spin the cam and make sure everything is aligned correctly, then put the timing chain on, and then lastly stick the rockers on. Maybe you did it a different way??? EDIT: also make sure you mark and replace the cam towers where you got them from on the head. Make sure you put the bolts back in the same holes you took them out of. Basically keep everything where you got it. Ive put a head together from a bag of parts i got from a friend. I ended up having to take it to a machinist to have him determine where the cam towers went. Marking the towers is a good practice. I'm not sure the bolts need to go back in the same holes though. Quote Link to comment Share on other sites More sharing options...
blueking Posted August 19, 2008 Author Share Posted August 19, 2008 so let me get this straight in some steps 1 drain anti freeze 2 remove valve cover 3 remove valve cover gasket 4 mark cam towers 5 put the sprocket thing in the 12 o'clock position **which should be done first between 6 and 7!!! 6 take off cam towers 7 remove rockers 8 take off cam 9 put new cam on towers 10 replace cam towers in the proper (origanal) spots 11 rotate the cam to make sure it is properly seated 12 place rockers back on 13 align cam to 12 o'clock position 14 replace chain being care full not to rotate it 15 make sure everything is tightened 16 clean off all old gasket off or surfaces 17 align new gasket and bolt valve cover back into place 18 flush radiator (considering its empty) 19 replace fill rad with antifreeze and water mixture then she should be good to start up right? also just for good measure should i mark 12 o'clock position of the cam to the crank at the bottom where all the belts meet? for insurance? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 19, 2008 Share Posted August 19, 2008 #12 should be between #14 and #15. You need to bolt the cam towers down and then rotate the engine so that a cam lobe is up, then you loosen the valve adjuster all the way down and force the rocker on. Once you have them all on then you can adjust the valves cold. You might want to consider that the cam may require different thickness lash pads, and that to get the full benefit of the cam you'd really need to degree it (look in the stickies for this forum for more on that). But if you just wanted to slap it on, then I think you have all the main steps in your list that I can think of off the top of my head. Quote Link to comment Share on other sites More sharing options...
blueking Posted August 19, 2008 Author Share Posted August 19, 2008 so what is "adjusting the valves" Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 19, 2008 Share Posted August 19, 2008 The L engine has no hydraulic lifters, the valve lash is manually adjusted. You need to get a manual if you're not familiar with valve adjustments, and you should also look up "timing chain tensioner" here and elsewhere on the web before you start. Quote Link to comment Share on other sites More sharing options...
blueking Posted August 19, 2008 Author Share Posted August 19, 2008 i have how to modify you sohc, the factory zx book, and a haynes book but as an explanation a valve adjustment is adjusting the mount a valve is moved into the cylinder or what this is starting to sound like a pain in the ass how much do you think it would be to get an ase or mod shop to do this, more then 100? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 19, 2008 Share Posted August 19, 2008 i have how to modify you sohc, the factory zx book, and a haynes book but as an explanation a valve adjustment is adjusting the mount a valve is moved into the cylinder or what this is starting to sound like a pain in the ass how much do you think it would be to get an ase or mod shop to do this, more then 100? You move the adjusters which are on the passenger side of the head up or down. This raises or lowers the ball pivot on one end of the rocker, which in turn raises the contact area of the rocker arm closer to the camshaft. I'm sure your FSM and the haynes has the info on how to adjust the valves. To do it perfectly will take some time and effort. To slap it in there won't be nearly as bad, but the one thing that is fairly crucial is that you get the wipe pattern right. If it is wrong you'll waste the cam and the rockers. Quote Link to comment Share on other sites More sharing options...
blueking Posted August 19, 2008 Author Share Posted August 19, 2008 hmmm sounds like something ill need to see in order to do.... im going to consult my schools shop teacher about this and see if i can watch him do this, i have a feeling im going to ♥♥♥♥ this up badly haha , what do you think the price would be to have it done by someone that knows what there doing? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 19, 2008 Share Posted August 19, 2008 No idea. You could call around. I suggest you find a shop that is familiar with old Z's because if they go by the hour and don't know what they're doing it could get expensive. Quote Link to comment Share on other sites More sharing options...
woldson Posted August 19, 2008 Share Posted August 19, 2008 The frist cam job I did, I did not let the car cool to ambient tempature!!!! I mean it was coolish to the touch but not enough. So when I pulled the towers the head warped a little and then guess what?!!!. Wait for over night just to save you a major hardach. Quote Link to comment Share on other sites More sharing options...
blueking Posted August 19, 2008 Author Share Posted August 19, 2008 ok so i referred to my manuals and adjusting the pattern on the lash should be pretty easy (in theory) so how exactly does a rocker need to be placed back on? i read a forum and it said to use a screwdriver and that made me shiver at the thought of accidentally scratching the new cam also on resale how much do you think a used zx cam would go for if i decide i never want to go back to stock quick thought the stock 16 on a zx should propell the car to 0-60 in over 8 seconds i think but when i went for a spin last night i got a "spoken count" of 7.5 im going to investigate this further and see i counted acurately anybody have a good idea of how long it should take me to get from 60- 85? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 19, 2008 Share Posted August 19, 2008 ok so i referred to my manuals and adjusting the pattern on the lash should be pretty easy (in theory)so how exactly does a rocker need to be placed back on? i read a forum and it said to use a screwdriver and that made me shiver at the thought of accidentally scratching the new cam The screwdriver goes underneath the rocker, so not too much chance of damaging the cam. I used a long 3/8" extension once, so if you prefer at least that wouldn't have any sharp edges. I pried on the casting plugs down in the bottom of the head. I don't know any of the other answers you were looking for, except to say that a stock cam should basically be a giveaway. They're a dime a dozen. Quote Link to comment Share on other sites More sharing options...
scoutman75 Posted August 20, 2008 Share Posted August 20, 2008 It's easier in my opinion to pull the cam towers. But then you have to drain the coolant and hope the headgasket holds. I've done it twice and never had a problem even though people will tell you that it can't be done. i do that quit often due to diff cams for diff. tracks and never had a problembut we also use arp studs to hold down the head Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted August 20, 2008 Share Posted August 20, 2008 I hope the cam you are putting in doesn't require heavier springs... You may want to post the manufacturer and specs of the cam so the experts here can verify that you won't have a problem... Generally speaking, if lift is ~.450 or less stock springs are ok... I'm pretty sure that you will need thicker lash caps, because the base circle diameter is probably smaller... Quote Link to comment Share on other sites More sharing options...
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