Cam removal without a complete tear down?

[93_jdm_fd]

I finally got a valve shim kit and will be setting my valve clearances tomorrow so I can properly run on 6 cylinders, not like 4 1/2 maybe 5 cylinders. Anyway I know I have line up the crank and cams to TDC but can I just zip tie the belt to the cam gears and unbolt them from the cams, slide them back on when I'm done with setting the clearances?

I just don't have time to pull the crank pulley off and break the crank pulley bolt free. I have to do this outside with hand tools.

[nimblestix]

I think in order to release the tensioner you need to remove the cover and to do that you need to remove the harmonic balancer. Once all that is done you can take the can gears off and remove all the cam caps.

Don't quote me 100%

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[hp44incgtr]

my advice if you never got yo hand dirty doing stuff like that and worry about F**k sh** up you best let an friend or somebody else do it thats just my 2cent you might have the situation completely under control..

[nimblestix]

Get the gtr service manual online and reference it. You can't go wrong if you follow all the steps required. Bag any hardware and label the bags so you know exactly what bolts are what.

But as said above if you aren't comfortable with this type of work then its not advised to attempt. Seek help

Good luck if you do try! Its a gratifying feeling to complete a repair/DIY job

Brent.

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[caliber676]

The tensioner needs to come off which means the lower timing cover must be removed. Even if you could leave the crank on there is a high chance the belt will skip a few teeth with it disassembled. I would do it the right way and save your self hassle in the future

[Black BNR32]

the lower timing belt cover comes off without taking off the harmonic balancer, but you sorta need to wrestle with it.

take some white out and make some marks on the cam gears and belts, before you remove the belt. then line up the marks when re-assembling. do the same for the belt and crank gear (don't need to remove the balancer to do this). that way, all 3 parts must line up correctly when you re-assemble.

technically, you don't need to bring all 3 parts to TDC before removal. you just NEED to maintain the same relationship relative to each other when you re-assemble.

follow the manual for measuring techniques so you get accurate measurements.

[93_jdm_fd]

I have no problem doing it myself, my problem is I don't want to wait until next week to get the valve clearance set. I have the shims now and want to get this done asap. I've done this before on many other single and dual over head cam engines by a few zip ties on the cam pulley(s) and removing bolts that hold cam pulley onto the cam shaft. Replace the cam and bolt the pulley back onto the cam shaft.

I just wanted to know if anyone else has removed the cams this way before I do it on this engine this way and down a car until next week until I get into the shop and can use air tools.

[Black BNR32]

seems like there's not enough belt slack to slide the cam gears back on with the belt zip tied to them. but yeah, just make sure the belt goes back in the same location on the crank gear.

[nimblestix]

This is the type of job that's worth waiting to do right.

However if you are an eager beaver and must do it now then I believe the answer you are looking for is yes. Just make sure everything is lined back up or your screwed bottom line.

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[93_jdm_fd]

wow just replied to my post and have 3 new replies!! Anyway I bought my gtr without an engine because it seems that most people have bought one and within a short period of time the engine pops.

I found a blown one and completely rebuilt it myself and doing pretty much every mod that will allow me to not crack the oil pump. The only thing I didn't do was the head. I had the head sent out and got the machine shop to check the head and install new valve seals. They set the valve clearance or at least I thought they did. They called and I gave them the specs, 0.48mm for intake 0.38mm for exhaust.

Anyway I installed my 86.5mm wiseco pistons, acl bearings, polished crank with proper crank collar, etc, etc. All back together and running somewhat ok. That was over 6 months and 7000kms ago. Ever since I got it running I've been chasing a lumpy idle. I have pretty much gone over everything, still no luck. Decided to check valve clearance myself and found all the intake clearances at 0.35-0.40mm(tight) and the best is 4 of the 12 exhaust valves I can't even fit a 0.05mm feeler gauge in!! I should have done it myself!! So all my headache over this lumpy idle and sluggish low end is from the exhaust valves being way to tight. Both the exhaust valves on cylinder 5 or probably open, I can't get a piece of paper under the lobe and bucket!


Anyway big novel going here but that's some of my history of buying my first gtr. I've owned a gts and many rx7's. I just wanted to cheat it a bit and I might try it my way. Worst case is the belt comes of crank gear and it will have to come apart anyway. I'll line it up TDC and try it, I'll know right away if the belt feels slack, I'll know it slipped. I just can't wait until next week cause the car is being loaded into a trailer and being shipped back to Edmonton. I want it fixed now before I get there and have no place to work on it.

[93_jdm_fd]

I did get the cam gears off without pulling everything else off as to do the timing belt. Lined everything up to TDC, zip tied the cam gears and remove them from the cams. It's not right easy but made it so that I could do it outside with hand tools in about 3 hours total. On my 1 hour lunch break the exhaust cam was off and ready for the proper shims. After work I did the intake side, rotated the crank shaft a few times to check my marks(dead on) and put everything back together.

So all my frustration with this engine was just tight valves. Well extremely tight exhaust valves. Fired it up and it idles super smooth and the 6 months or so since the rebuild is the first time I have ever heard it run smooth. So if anyone out there has a sluggish low end, kinda rough idle and is not a misfire check your valve clearances!

It is super easy to do, remove the valve covers, crankshaft and cams at TDC compression stroke(both intake and exhaust #1 cam lobes will be pointing away from each other and not be touching the bucket), intake spec is 0.45mm(cold) +/-0.03 and the exhaust is 0.35mm(cold) +/-0.03mm. At TDC compression check all the cam lobes that are not touching the spring bucket(3 cylinders intake and 3 cylinders exhaust), rotate crankshaft 360 and check the rest of the cam lobes that are clear of the valve buckets.

If the valves are to tight like mine the valves will not seal properly and could even burn the valves out, and 0.03mm out from spec is not much. So if your not pretty much dead on with your valve clearances it will cause valves to be open or valves to be loose which cause noise, would rather have the noise then quiet, quiet on this engine means danger.

[Black BNR32]

What were your existing clearances?

[93_jdm_fd]

The average on the intake side was 35mm, should be 45mm. So a little tight. The exhaust side had #2 cylinder with one valve at 0mm, both valves on 5 were 0mm and one on cylinder 6 was 0mm. Pretty decent machine shop!! I didn't check them because they called me for the specs from the manual I have. So I thought it should be good to drop onto the block and reinstall everything.

I bought the engine blown so I never heard it running before so that made the diagnosing difficult. Anyway it runs perfect now and even starts and does not stall on cold starts first thing in the morning.

I have read many post on many gtr's that will start up, sputter and then stall only on cold starts. Most replies are saying this is a normal thing, it's not, maybe just tight valves? Everyday since I had this running it would start and stall, then fire right up. I started it this morning since I adjusted the valves and it fired right up, idle was steady and slowly came down to spec, now that's normal.

[Dragon Humper]

It all depends on how tight the tensioner was set. Most performance shops in Japan leave them a little loose. Most factory type mechanics and DIYers make it too tight. How? By following the shop manual to the letter. Thing is, no-one ever seems to be able to hold on to the tensioner well enough while torquing the bolt and it tightens just a little more (making it too tight). If the tensioner was set right, you should be able do do exactly what you just did.



Jon.

[93_jdm_fd]

Yeah when I did set them almost exact, after torquing down the cam caps some were a little tight. So I set those a little loose and re-torqued the caps again and now all were just slightly less drag on the feeler gauges. I would say my intake are about 48mm and the exhaust at 38mm.

I just love that I can start the car cold and it fires right up and idles perfect!! No stall or shaking.