Cam change without loosening timing belt?

[forcefed86]

Searched around for this and I'm turning up nothing.

I had heard/read at some point that if you are running cams with the factory gears you can zip tie off the timing belt snuggly and change each cam without loosening the timing belt and goting through all the trouble of re-tensioning and lining it back up? Is there a writeup of this somewhere? Anyone done it? Problems?

I'm actually wanting to drop the factory cams back in at this point. Not worried about valve clearances etc...

Thanks

 

[JusMX141]

Done it numerous times- cams can be swapped in as little as 20 minutes with an air ratchet. You need the long threaded tensioner tool, but that's all.

Set the engine to TDC, thread the tensioner tool in to fully-collapse the tensioner. I zip-tie the belt to the gear in two places on each gear....then you can remove the large center bolt from one cam at a time, set the gear off of the locating pin on the cam, and then you're free to remove the cam caps. Reinstall in a reverse order and it will go together like butter. DON'T remove both cam gears at the same time or the belt will fall off the crank pulley and you'll lose your valve timing and be forced to pull the entire cover to reset it.

If you do it this way without bleeding the lifters on your own, you must wait for the lifters to bleed themselves off or you'll bend valves!

From the VFAQ, which everyone should read before posting questions:
http://www.vfaq.com/mods/wayback/4g63cams.html

 

[jrohner]

(I guess I can delete what I put here since Justin wrote exactly what I do)
I also use bungie cords to hold the t-belt tight so it doesn't slip on the crank (I had that happen once and had to waste the time of lining that back up).

I made a tensioner tool by grinding a little bit of thread off the end of a long bolt (otherwise it will mushroom a bit when tightened). I first used threaded rod, but it wasn't hard enough and was shot after 1-2 uses.

 

[4g63t]

What they said.! I have seen it done a few times. Even at the shootout I have seen people do it in their race trailers with zip ties and ratchet strapping the gears to the top of the trailer to pull the head off quick without re-timing it.

 

[forcefed86]

Done it numerous times- cams can be swapped in as little as 20 minutes with an air ratchet. You need the long threaded tensioner tool, but that's all.

Set the engine to TDC, thread the tensioner tool in to fully-collapse the tensioner. I zip-tie the belt to the gear in two places on each gear....then you can remove the large center bolt from one cam at a time, set the gear off of the locating pin on the cam, and then you're free to remove the cam caps. Reinstall in a reverse order and it will go together like butter.

If you do it this way without bleeding the lifters on your own, you must wait for the lifters to bleed themselves off or you'll bend valves!

Thanks!

How long does one usually have to wait for the lifters to bleed themselves down? Do you just let the car sit over night before the job? Or do you just manually deflate them when you swap in the new cam?

 

[JusMX141]

I'll let it sit overnight, rotating the engine 1/2 turn by hand every time I walk past it or think about it....say every 15 minutes or so after I've completed the job.

If you leave the valve cover off you can tell when they're bled, but it's better to be safe than sorry if you have the cover on.

 

[Alky_dsm]

There is a video on YouTube of someone replacing cams on an evo 8 without pulling the timing belt off

 

[XiKeiyaZI]

Jus hit it on the head. I've done that method twice in the past. The first time I made a mistake and allowed the timing belt to slip from the crank. The second time I got it down perfectly and was done with it in no time. It was a little nerve racking but once it was done I could appreciate it. The thing is, though, unless you just absolutely hate doing the timing (Removing the 10mm bolts on the water pump pulley is always a pain for me) then the time difference between just redoing the timing and doing it this method should show little to no time difference.

 

[Alky_dsm]

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[Lou98GSX]

i have done it many times . you need the long threaded rod that screws in the right side of the motor . there is a rubber plug there that you remove and thread the rod in so that the timing belt tensioner doesn't extend itself . you have to mark the timing belt to cam sprockets and zip tie the belt . when you are ready to remove the cam make sure you don't let the timing belt get to much slack or it could jump a tooth .you can do one cam at a time.

 

[PieEyedPiper]

Done it numerous times- cams can be swapped in as little as 20 minutes with an air ratchet. You need the long threaded tensioner tool, but that's all.

Set the engine to TDC, thread the tensioner tool in to fully-collapse the tensioner. I zip-tie the belt to the gear in two places on each gear....then you can remove the large center bolt from one cam at a time, set the gear off of the locating pin on the cam, and then you're free to remove the cam caps. Reinstall in a reverse order and it will go together like butter.

If you do it this way without bleeding the lifters on your own, you must wait for the lifters to bleed themselves off or you'll bend valves!

Nifty!

Though I did notice a trend. Some who have used this method ended up re-doing the belt anyhow. And I bet you're right about the air ratchet, using a big bar to break the gears free could maybe have you skipping teeth or something - But I'll gladly take that chance seeing as I'd have chosen to just do it the "hard way" anyways. Good stuff!

 

[phunny]

Done it numerous times- cams can be swapped in as little as 20 minutes with an air ratchet. You need the long threaded tensioner tool, but that's all.

Set the engine to TDC, thread the tensioner tool in to fully-collapse the tensioner. I zip-tie the belt to the gear in two places on each gear....then you can remove the large center bolt from one cam at a time, set the gear off of the locating pin on the cam, and then you're free to remove the cam caps. Reinstall in a reverse order and it will go together like butter.

If you do it this way without bleeding the lifters on your own, you must wait for the lifters to bleed themselves off or you'll bend valves!

I've done this exact same thing twice, always worked perfect.

 

[19Eclipse90]

Just a write-up for what others have mentioned. It has been around for a while: Installing Cams into a 4G63

 

[JusMX141]

Nifty!

Though I did notice a trend. Some who have used this method ended up re-doing the belt anyhow. And I bet you're right about the air ratchet, using a big bar to break the gears free could maybe have you skipping teeth or something - But I'll gladly take that chance seeing as I'd have chosen to just do it the "hard way" anyways. Good stuff!

I always break the cam pulley bolts loose using a breaker bar while holding the cam with a large wrench on the hex portion under the valve cover. I don't trust using an impact gun because of the shock on the valve train, and my air ratchet just doesn't have the ass to break these bolts loose. The air ratchet was simply to make short work of the many cam cap bolts.

The key with not needing to re-time the car is don't let the gear with the belt zip-tied to it fall into the cover enough that it may slip on the crank, but I always make sure to re-line all of the marks after it's fully assembled and the engine has been rotated a few times to verify that everything is kosher before jumping in and hitting the key.

 

[mitsurage]

Back in the day when Kevin Jewer had an evo he used to use this method multiple times a night at the track trying out different cam combinations. Truly is the easiest and fastest way. I have done it as well but I manually bleed the lifters each time unlike others have mentioned, solely for making the job faster.

 

[streetillEagle]

When I was shown this cam swap method years ago I couldn't believe how easy it was. I was paranoid the first time I tried it myself. Now I have the Jay Racing timing gear alignment tool and it made changing cams even easier. The gears stay perfectly spaced and tension holds the whole time. I still use zip ties on the t-belt though.

 

[miguelmcv]

I don't use zip ties to do it, instead I mark the gears and belt, then I use only one gear to pull the belt, I keep the gear pulled by an elastic rope attached to the hood, this way there is no way the belt can be jumped, this way you can do whatever you want with out worrying about the belt.

Here is a pic that I add to give an Idea to the OP at that thread (post #9).

http://www.dsmtuners.com/forums/420a-bolt-tech/438146-changing-cams-without-having-retime.html

It has 2 elastics, one on each gear, But just did it for reference which I was not working on the car.

I just mark both gears with the belt, remove one gear and leave the other one attached to the elastic, after you remove and install the cams, just put the gears back on it's respective marks and you are set.

I have done this so many times as well, when I first start, I always put them on TDC to make sure everything is good and obviously, turn the engine by hand to assure the valves not hitting, Now that I have done it so many times, I don't use TDC, I just mark them and at the end, I just turn the engine by hand to check for valve clearance.
I don't recommend not to put them on TDC, I do it my self because I have done it so many many times and know very well the process, But for a first time I recommend to put it on TDC, and as Justin said, Give a time to the lifters to bleed.