Disassembly Done ... Time To Rebuild 3.0

[mikedsilva]

cool.. I am at a similar stage in my build to you.. my cams from John are due back today / tomorrow.

[Flat6pac]

Circlip are are far easier to install without the bottom row of head studs in place until you have the bank loaded
Bruce

[arbita1]

I wish this was real progress but it's just the temporary assembly to test the piston to valve clearance. On hold now. Need to get the chain housings cleaned before I install them.




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[arbita1]

How crazy do I have to go with the sprocket alignment if I'm only assembling to check piston to valve clearance.


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[jdbunda]

I am no expert, but I think this depends on the build. If you are switching to high compression pistons and an aggressive cam, it is pretty important to get it dialed in close, and preferably at the high end of the spec range. Less critical if you have OEM parts, or are re-assembling what was already a working motor configuration. After all the work of rebuilding, you don't want to lose it when a simple extra base gasket would have done the trick.

[Trackrash]

Originally Posted by arbita1

How crazy do I have to go with the sprocket alignment if I'm only assembling to check piston to valve clearance.


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Don't worry about it for your measurement, since you will do the sprocket alignment during your final assembly. For your measurement 3 or 4 spacers should work fine.

[arbita1]

Originally Posted by Trackrash

Don't worry about it for your measurement, since you will do the sprocket alignment during your final assembly. For your measurement 3 or 4 spacers should work fine.

Thanks. I did a quick check without torquing the sprocket bolts. I seemed to be within spec on one side and very close on the other. I figured this was good enough to do the piston clearance check. Like you said. I'll dial it in better during final assembly.

[arbita1]

Started working on cam timing. This is kind of practice because it's only to do the piston to valve clearance check. How do I know if I'm at TDC for no.1 or no.4 when I'm on z1?

[mikedsilva]

At z1, set valve clearance on cyl 1 rocker to 0.1mm... rotate crank 360, then set 0.1mm clearance on cyl 4 rocker.
At least that's what I did....

[Trackrash]

Originally Posted by arbita1

Started working on cam timing. This is kind of practice because it's only to do the piston to valve clearance check. How do I know if I'm at TDC for no.1 or no.4 when I'm on z1?

When you start, as long as both cams have the punch mark or 930 at the top when the crank is at Z1 you are at ignition on #1. Remember the cams turn at one half the rotation of the crank and in the opposite direction.

Let us know how your measurement works out. I am at that exact stage on my motor.

[boyt911sc]

Originally Posted by Trackrash

When you start, as long as both cams have the punch mark or 930 at the top when the crank is at Z1 you are at ignition on #1. Remember the cams turn at one half the rotation of the crank and in the opposite direction.

Let us know how your measurement works out. I am at that exact stage on my motor.

+1 to above suggestion. And to make it more convenient, install the ignition distributor with the rotor pointing to the scribed marker (1 o'clock orientation). So you could always refer to the position of the rotor when you do your cam timing. If you follow this procedure, you will avoid having 180° off timing problem.

Tony

[arbita1]

Had another go at it but still not working out. I am shooting for 1.8-2.0mm. I have D.C.-15 cams and that is the recommended setting. I tried setting at 1.9mm but after doing the 720 dog rotation it ends up at 1.7. To get to 1.9 again the z1 mark goes slightly past the case line. What am I doing wrong? Is my chain not tight enough? Here's my set up.



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[Trackrash]

Adjust one hole and try again. The measurement you get after rotating is the one that counts.

[mikedsilva]

You might find there is enough "slop" with the pin installed, that you can rotate the sprocket fore or aft, before tightening the large nut.
At least that's what I found...

[arbita1]

Taking it apart and will reset the cams to dots up and start over.

When timing is set should the dots be pointing up at cyl 1 tdc?


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[Trackrash]

Originally Posted by arbita1

Taking it apart and will reset the cams to dots up and start over.

When timing is set should the dots be pointing up at cyl 1 tdc?


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Yes, when #1 is at firing position. Remember the crank turns two times, 720 deg, for every one revolution of the cams.

[Flat6pac]

If you set the crank Z1 then turn it back about 30-40 degrees you can spin the cams without hitting valves on Pistons
Bruce

[arbita1]

Ok. I think I got the left side done. The right side is now giving me trouble. Somehow both rockers are tight at TDC for cyl no. 4

[arbita1]

I possibly had adjusted the rocker for no.4 at cyl 1 TDC. I'm not sure but I think I have it sorted out now. I have both cams pretty close at 1.9mm. Next is the valve to piston clearance check.

Can I do the method where I set the valve in and rotate the engine. Or do I have to do it in increments and check like the books says?

Here's everything set ready to check.



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[Trackrash]

Do the incremental. If you adjust the valve in and it hits the piston, you may bend the valve.

You can look in the spark plug hole and watch the exhaust valve and piston. Stop where they are closest and then adjust the valve in to check the clearance.

I marked my cam sprockets to keep track when I adjusted my cam timing.