1979 SC Chewed a Valve - Total Rebuild

[OsoMoore]

Is this basically what we're doing? I feel like I must be missing something, because if this would mean we don't care what the depth gauge values are, just that we find the peak.

I'd like to know what is actually happening, not just the list of directions to do the timing.

[stownsen914]

That's basically what's happening. One minor clarification is that when you set cam timing at TDC overlap, the cam is at the "measured lift" spec for your cam (e.g. 1.1-1.4 mm for an SC or 3.2 Carrera), not full lift. I realize you probably already knew this.

If you want to visualize what's happening as you do your cam timing, it can help to have a degree wheel. Even just a printed one taped to your pulley can help visualize.

[OsoMoore]

Originally Posted by stownsen914

That's basically what's happening. One minor clarification is that when you set cam timing at TDC overlap, the cam is at the "measured lift" spec for your cam (e.g. 1.1-1.4 mm for an SC or 3.2 Carrera), not full lift. I realize you probably already knew this.

If you want to visualize what's happening as you do your cam timing, it can help to have a degree wheel. Even just a printed one taped to your pulley can help visualize.

So if you're doing "measured lift" and not full lift, couldn't you be at either the rising edge or the falling edge, and not know which? I guess if you are rotating clockwise you can verify if you are rising or falling by first finding the peak, and then either watching for your desired lift before or after the peak.

[stownsen914]

If you are not careful, then yes that could happen. The usual timing procedure has you start with crankshaft at TDC, and camshafts on both sides with the dot or "930" mark pointed vertically (or with the keyway pointed up, in case the other marks are not there). This has you starting in the ballpark, and then you turn one revolution of the crank to get to TDC overlap on #1 do the small correction to get to the measured lift spec. If you follow that procedure, you won't be far enough off to have the issue you mentioned above.

[OsoMoore]

Ah, so you end up doing this?

EDIT: Typos in my image below.
2.d Unlock crankshaft from camshaft, leaving camshaft at measured lift.
2.e Rotate crankshaft back to TDC.



And I need to check Wayne's book or something to get that desired lift value for my engine.

[stownsen914]

Edit - realized you have the early style camshafts with the big 46 mm nut.

The basic idea is the same to do the cam timing for the early and late cam timing procedures, but the details are slightly different. With the early style camshaft, you have the option of turning the cam with a wrench. With the later bolt style, this is trickier.

The early procedure basically has you turn to TDC like in your 2) c. and then do the correction by unlocking and turning the camshaft.
In the later procedure, since you can't turn the camshaft easily, the procedure do 2) c. by turning to the valve measured lift spec and then unlocking and turning the crank to TDC.

Your summary seems like it might be mixing the two a little but it looks more like the late procedure. Wayne's book covers both. Have a look and you'll get the idea.

[Flat6pac]

Check the Stomski Racing video on setting cam timing. So much easier than guessing.
Bruce

[OsoMoore]

Originally Posted by Flat6pac

Check the Stomski Racing video on setting cam timing. So much easier than guessing.
Bruce

Wow, their tools are so slick! I've got some nice stuff borrowed from the local shop for the weekend, but not this newest stuff.

[PeteKz]

Originally Posted by OsoMoore

Got five replacement rockers from another Pelican. I'll plan to send the set out for refurb later. But these should be fine for finishing the rebuild. Ice comes in November and I can pull them out then.

As I recall, I can get them out without too much trouble just by removing the valve covers.

It sounds like you intend to put the engine back in and drive your car for a few more weeks.

Yes, you can remove and replace the rockers with the engine in the car. I have done that and it was a major PITA (to install RSR o-rings on the shafts). I strongly advise that you install rebuilt rocker arms now and save yourself that trouble and cussing. Just buy a set from Henry or another vendor on an exchange basis.

[OsoMoore]

Some good points on doing rockers now, seriously considering sending them out this week while I finish other stuff. I can always put them back in last before I push the engine back in.

Finished cam timing today with the borrowed tools. I'm still using the old slightly damaged locking pin, so I didn't torque one side down. The new pin comes Tuesday. But that doesn't stop me from finishing the timing itself.

All the stud stuff is sorted out, just need to oil-bathe my new tensioners and put them in place of the rigged stuff for setting timing, sometime tomorrow.

Aren't these things just so beautiful?