changeing cams...without disturbing timing belt

noobee · Postby **noobee** » Sat May 19, 2012 12:49 am

any special tricks?was going to cable tie belt in position on pulleys.anything else?retain tensioner somehow?
Mick

Postby **NitroDann** » Sat May 19, 2012 1:08 am

Yeah you have to CAREFULLY cabletie the belt to the cam gears, and find a way to keep tension on the crank pulley gear against the belt so it doesnt move, it can be done by yourself but it sucks, honestly, just cabletie the can gears in place, and retime the crank gear.

Dann

noobee · Postby **noobee** » Sat May 19, 2012 1:45 am

thought you would be awake still.i'm working all night,thought id do it when I wake up tomorrow arvo.
was hoping not to pull the front off the motor.but if i screw it up i've got a belt kit and pump here too.
when doing datsun l16,18,20 engines you could saw up a piece of hardwood into a certain shape to hold everything in place.no special trick like that?
Mick

Postby **NitroDann** » Sat May 19, 2012 3:15 am

I bet you could saw a trapezium shape and do something similar, but if you cabletie the cam gears on you dont need to pull it all apart, you take off the cam cover, and the top timing cover to get the gears off, which you have to do to swap the cams. From there you swap the cams and then you put the cam gears back on by prying them onto the cams. dont put the bolts in.

Check the timing, you can see how many teeth out you are at the crank, so you take the cam gears off the cams and pull the belt a few teeth up one side and re pry the cam gears on. Etc.

Takes a few tries but better than pulling it all apart.

Dann

hks_kansei · Postby **hks_kansei** » Sat May 19, 2012 8:35 am

How about marking the belt and all pulleys with a bit of paint?

Just a little line so when you reassemble you simply match up the dots.

StanTheMan · Postby **StanTheMan** » Sat May 19, 2012 11:30 am

you are going to the trouble of changeing the cams but you don't want to touch the sprockets or Timing belt?

There are instructions on Miata net. they are almost idiot proof. You line up the sprockes. The sprockets have markers, you count the teeth o the belt. is it 19 or 21? cant recall right now pretty sure its 21 though :oops:

count them before yoyu unbolt the sprockets
I tell you getting the timing right is the easy bit. Just take your time with it & tripple check before you close it. I'd agree, Its annoying as ƒü¢k to have to open her up again because of the wrong timing.

StanTheMan · Postby **StanTheMan** » Sat May 19, 2012 11:32 am

or pay Nitro Dann a 6pack of his choice to line it up for you.

spikes · Postby **spikes** » Sat May 19, 2012 11:54 am

When Dann and I did Brian's car, we had to pull the cam gears to remove the waterneck for a coolant reroute. It took three people, two to keep tension on the cam gears whilst the third did the work. It can be done, you can probably jerry rig something up with ropes that keeps tension on the belt against the crank gear but personally, it would be way easier just to zip tie the cam gears and mark its position and them just re-timing it against the crank gear.

Postby **NitroDann** » Sat May 19, 2012 11:55 am

Mick is perfectly capable of doing it, He just doesnt want to have to take the V belts and timing covers off.

Dann

StanTheMan · Postby **StanTheMan** » Sat May 19, 2012 1:20 pm

sounds like more trouble that redoing the belts to me. but then I've never attemted to do it that way.

Postby **NitroDann** » Sat May 19, 2012 1:33 pm

All you are doing is tieing the belt to the cam gears, so you retime the crank gear from the mark on the lower timing cover.

Saves 2.3rds of the pulleys.

Dann

manga_blue · Postby **manga_blue** » Sat May 19, 2012 2:29 pm

If you follow Mazda's instructions then you have to take off the lower belt covers to see the timing mark on the toothed pulley. This is the hardest and slowest part of the job and it's a total waste of time. As Dann said, leave the lower covers on and just use TDC for #1 on the timing cover and set the sprockets as per normal.

I've tried it with and without cable ties on the sprockets. It's a 50-50 call on whether it's worth the effort because it's so easy to slip a tooth on the belt on the lower pulley while you're trying to move the sprockets about with the ties on them.

noobee · Postby **noobee** » Sat May 19, 2012 5:18 pm

1 hour into it and have exhaust cam in with a new seal.I dont think i have lost position yet.just having a tea break before I try the other side.

had these cams sitting round for months,been itching to try them but want to drive tomorrow so didnt want to pull the whole front of motor off just yet.will have to do belts soon and front main seal,etc.they have been sitting in shed for 6 months.want to do aircon delete and coolant reroute at same time.
Mick