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gday, just thought id make a post on how to change cams and timing chains on an alloytec as i just recently did them myself, and dosent seem to be much, if not any info on cams for alloytecs, theres a reason for that ahaha.
just thought id say too, this is very pretty complicated job for someone whos never seen a dohc setup before, or in my case never gone past taking a intake/exhaust manifold off, but once you take the time too learn about how this engine works, and get your hands dirty, its not all that difficult.
so when starting out, disconnect the battery negative, and start stripping the engine, take off the intake manifold, airbox, all the front accessories, get the wiring looms out the way, take the lower manifold out, and rocker covers.
for the middle manifold, there was a push lock fuel line connected, and your supposed to have a special tool to retract 4 metal tabs, i just used a very small screwdriver, and pushed them all in, bit tricky but got it done.
for the harmonic balancer, i used an impact wrench, and that got the bolt out, and just a 170mm pulley to get it off. can be a c*nt to get off some cars though, it is possible.
also left the radiator in, just removed all the hoses going to it.
and for the bit i spend the most time on, getting the ac compressor off, i think this was mainly hard as i had no space where i was, but i spent an hour or so trying to figure out which bolts take it out. so firts you want to remove the powersteering pump, and its bracket, 3 bolts hold the bracket on. then for the compressor, there are 3 long bolts that hold the actual compressor on, and 4 bolts for the bracket, all have to be removed as there is a bolt for the timing cover behind the bracket.
that was really the only hard things for the outside of the engine.
once the timing cover and rocker covers are off, there are two ways you can go about removing and installing the timing chains, using 1 stage, or 2 stages of timing. i only found out that using only 1 stage is a proper way of doing it, and even gm themselves did it that way. i did it in 2 stages though. both work fine.
im not gonna explain how to do it, as theres heaps of videos and threads on how to do it, but i found this to be the best video on explain it:
once all the chains, tensioners and guides are off, you can start of the cams. one thing i did is when the chains were still on, is just cracked the vvt sprocket bolt loose, so i dont shift it when the chains are off.
start by removing the cam caps, there are marked, just take photos though, dont want to mix them up. do one at a time too, there is one big cam cap the the front of the engine that sits over both cams, pretty sure its used to make sure the cams sit in the exact position. once there removed, the cam will lift out. pull the vvt sprocket off, and put it on the new cam. if your using the aftermarket mace cams, it will say on them, RE, RI, LE, LI. obviously right exhaust, left intake etc. hence why you do one cam at a time. right also being the right bank, so the left of the engine, its confusing i know ahaha.
there is also a indent in the cams for the sprocket to line up to aswell, so no worries fitting that, once thats done place the cam in, make sure it cam out the same way it went back in, because it will fit in there different ways, so again, photos. and put the cam caps back on, and tighten to 10nm. pretty sure i tightened from the inner cam cap to outwards too. and repeat that 4 times and your sweet, put the chains and tensioners n what not back on, and everything should line up perfectly.
also check your marks, alot. like 5 times ahaha. dont want to go back there again. spin the engine a couple times make sure it feels sweet. then put it back together, also i recommend organizing your bolts or taking photos of them, and not just chuck them all in 1 box, because most of them look the exact same with small differences, so you go to put it back together and theres 100 bolts that look the same. and also take your time too, use single hex sockets, aswell. and threads strip very easy aswell. i stripped 2 threads out, lucky they werent important, but just keep that in mind.
now if everything is right, it should turn on, and have a very lumpy idle, i noticed the car shook a fair bit on a cold start, once it warmed up though, it ran not too bad, but didnt sound to lumpy either, i drove it for a week before tuning it too, got a running lean code 7 days after putting the cams in too. my advice if your gonna drive it, dont flog it. it drives pretty good but will be too lean. just baby it.
i ended up going from 155kw to 176kw with cams and cpr6. feels alot quicker. the guy who tuned it has never tuned an alloytec and was mucking around with it. which is why im assuming it didnt make as much power as i hoped.
now was it worth it, yes, in my case. was a very good learning experice, got the parts cheap as chips, same with the tune, and my car goes womp womp womp womp now ahaha. but for someone whos buying the cams brand new and paying someone to do it, with the cost starting around 2500, probably not. if you can find someone who can confidently tune them, might be a different story.
if i can do this job, someone who has never done more then spark plugs and intake manifolds on an engine, i reckon most people can. i will note im also an apprentice mechanic, i work on diffs, so i am a bit mechanically minded. but if you do lots of research, it wont be too hard.
also i didnt use any special tools, like timing retainer, cam tools, as the ones i bought were if your leaving your engine in stage 2 timing, and flywheel holder, in my opinion there not needed, unless just doing cams, timing retainer is usefull.
heres some photos that may help people too,
and a video too, sounds mint as:
you can see the discoloration on that right bank though, looks like 2 different engines. only done 150ks too.
anyway, hope this helps someone, or answers any questions people had about cams.
just thought id say too, this is very pretty complicated job for someone whos never seen a dohc setup before, or in my case never gone past taking a intake/exhaust manifold off, but once you take the time too learn about how this engine works, and get your hands dirty, its not all that difficult.
so when starting out, disconnect the battery negative, and start stripping the engine, take off the intake manifold, airbox, all the front accessories, get the wiring looms out the way, take the lower manifold out, and rocker covers.
for the middle manifold, there was a push lock fuel line connected, and your supposed to have a special tool to retract 4 metal tabs, i just used a very small screwdriver, and pushed them all in, bit tricky but got it done.
for the harmonic balancer, i used an impact wrench, and that got the bolt out, and just a 170mm pulley to get it off. can be a c*nt to get off some cars though, it is possible.
also left the radiator in, just removed all the hoses going to it.
and for the bit i spend the most time on, getting the ac compressor off, i think this was mainly hard as i had no space where i was, but i spent an hour or so trying to figure out which bolts take it out. so firts you want to remove the powersteering pump, and its bracket, 3 bolts hold the bracket on. then for the compressor, there are 3 long bolts that hold the actual compressor on, and 4 bolts for the bracket, all have to be removed as there is a bolt for the timing cover behind the bracket.
that was really the only hard things for the outside of the engine.
once the timing cover and rocker covers are off, there are two ways you can go about removing and installing the timing chains, using 1 stage, or 2 stages of timing. i only found out that using only 1 stage is a proper way of doing it, and even gm themselves did it that way. i did it in 2 stages though. both work fine.
im not gonna explain how to do it, as theres heaps of videos and threads on how to do it, but i found this to be the best video on explain it:
once all the chains, tensioners and guides are off, you can start of the cams. one thing i did is when the chains were still on, is just cracked the vvt sprocket bolt loose, so i dont shift it when the chains are off.
start by removing the cam caps, there are marked, just take photos though, dont want to mix them up. do one at a time too, there is one big cam cap the the front of the engine that sits over both cams, pretty sure its used to make sure the cams sit in the exact position. once there removed, the cam will lift out. pull the vvt sprocket off, and put it on the new cam. if your using the aftermarket mace cams, it will say on them, RE, RI, LE, LI. obviously right exhaust, left intake etc. hence why you do one cam at a time. right also being the right bank, so the left of the engine, its confusing i know ahaha.
there is also a indent in the cams for the sprocket to line up to aswell, so no worries fitting that, once thats done place the cam in, make sure it cam out the same way it went back in, because it will fit in there different ways, so again, photos. and put the cam caps back on, and tighten to 10nm. pretty sure i tightened from the inner cam cap to outwards too. and repeat that 4 times and your sweet, put the chains and tensioners n what not back on, and everything should line up perfectly.
also check your marks, alot. like 5 times ahaha. dont want to go back there again. spin the engine a couple times make sure it feels sweet. then put it back together, also i recommend organizing your bolts or taking photos of them, and not just chuck them all in 1 box, because most of them look the exact same with small differences, so you go to put it back together and theres 100 bolts that look the same. and also take your time too, use single hex sockets, aswell. and threads strip very easy aswell. i stripped 2 threads out, lucky they werent important, but just keep that in mind.
now if everything is right, it should turn on, and have a very lumpy idle, i noticed the car shook a fair bit on a cold start, once it warmed up though, it ran not too bad, but didnt sound to lumpy either, i drove it for a week before tuning it too, got a running lean code 7 days after putting the cams in too. my advice if your gonna drive it, dont flog it. it drives pretty good but will be too lean. just baby it.
i ended up going from 155kw to 176kw with cams and cpr6. feels alot quicker. the guy who tuned it has never tuned an alloytec and was mucking around with it. which is why im assuming it didnt make as much power as i hoped.
now was it worth it, yes, in my case. was a very good learning experice, got the parts cheap as chips, same with the tune, and my car goes womp womp womp womp now ahaha. but for someone whos buying the cams brand new and paying someone to do it, with the cost starting around 2500, probably not. if you can find someone who can confidently tune them, might be a different story.
if i can do this job, someone who has never done more then spark plugs and intake manifolds on an engine, i reckon most people can. i will note im also an apprentice mechanic, i work on diffs, so i am a bit mechanically minded. but if you do lots of research, it wont be too hard.
also i didnt use any special tools, like timing retainer, cam tools, as the ones i bought were if your leaving your engine in stage 2 timing, and flywheel holder, in my opinion there not needed, unless just doing cams, timing retainer is usefull.
heres some photos that may help people too,
and a video too, sounds mint as:
you can see the discoloration on that right bank though, looks like 2 different engines. only done 150ks too.
anyway, hope this helps someone, or answers any questions people had about cams.
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