No Valve Lash

[ME 109]

Back wheel for me too, but I have an RS.
The rear wheel method is oh so easy to do, for me anyway.

[hudson]

Suggestions above about testing the rods taken - that is one thing I haven't tried.

Here is the frustrated update:

The side is TDC. I removed everything and reinstalled this time using the helpful brooks ream guide. All is well with the installation UNTIL it is time to mate the cylinder with the case surface. As suggested, with sliding on the head, use the rocker arm nuts (without rockers) to draw in the cylinder evently until it surfaces mate and the pushrod tube seals are installed. Technically, no need to torque the nuts, basically works once they are fairly snug - then I unbolt. When I do, the surfaces separate about 2-3mm gap , yet the the tube seals look fully installed. Inserting the pushrods down the tubes, they easily lay in the followers inside the "insert holes" that the rod end goes into (when pulling back out, you can feel a little resistance, which means they are seated in the cam followers). The rod length poking out seems about right and even and they spin freely.

Despite the mating surface gap explained above, I now install the rockers. When sliding on, their are only a few bolt threads showing. I am able to get the rocker nuts barely on, but once I start torquing all the bolts, everything is drawn in. I torque in gradual settings until about 25 ft lbs for 6 bolts (includes 6 & 12 o'clock nuts). The surface mating gap between cylinder and case is closed now.

BUT now everything is extremely tight! No spin on the rods. The rod adjusting screws are all the way backed out and the rocker arms do not move back and forth freely, needs some force.

One thing I also noticed are the position of the valve springs against the rocker arms.

Clearly does not look normal, yet the valves are seated. The springs are new and have the blue markings on them. Are there different springs? But this still would not prevent the rockers from installing properly.

Only thing I can think of is something keep the cylinder mating surface from separating?

Remember this has rebored cylinders and 2nd oversized pistion/rings just done.

1970 R75/5.

Thoughts? Pics following...

[hudson]

Push rod tubes fully inserted? Position of rods?

Push Tubes.JPG (27.98 KiB) Viewed 1548 times

Push Tubes.JPG (27.98 KiB) Viewed 1548 times

[hudson]

Position of Springs - exhuast. It seems to be rubbing on the rocker arm when arm is pulled back?

[hudson]

input springs. Not quite making contact, but close.

[melville]

On /5 and /6 you need to hold the rockers and shaft where you want them when done to keep the rockers from rubbing the springs and the pushrods from rubbing the tubes. Also to set the axial play on the rocker itself.

I can't help but think that you're on the wrong TDC. Check with both valve covers off. One will be correct and you'll have valve clearance and can spin the pushrods. The other will be on overlap and both pushrods won't spin.

On overlap there's not very much lift, so it's hard to eyeball the pushrods and say, "Hey, that's the side that's on overlap!"

[hudson]

The valve covers are always off while doing this. I usually have no trouble finding TDC. But just for the heck of it, with everything installed (except rockers) and tightened just on a snug setting, I spun the rear wheel at each TDC mark and makes no difference. I will try again in case I am going insane. FYI, I have not messed with any of the bottom end - just doing a top end job - so all of that is unaffected.

I even watched the cylinder resealing video from Boxer2valve on youtube. I am doing the same exact thing! I know this is an operator error though... I have done top end installs prior with no problem, that is what is making me crazy.

Trying again tonight: I am going to install the cylinder and head just snugly so as I rotate the flywheel, the piston doesn't push the cylinder forward, install the rods and rotate the engine again at each stop and see if the followers are actually pushing the rods in and out. I've installed & removed everything so much that I can't remember if I did this already. If they aren't it seems it would have to do with sticking followers, correct? With the head on, the rods are even, I would think this would indicate TDC, otherwise either rod would be out further since its pushing out the valve. I always make sure the followers are lubed and I push them all the way back before installing the cylinder. I also use a magnet to draw them out and seem to be come out fine and then push them in with my finger. Could the seals be interfering somehow?

BTW, is it normal that the cylinder keeps popping out after I draw it in and the pushrod tubes are seated? In that Boxer2valve video it does, but it draws in nicely when he starts tightening the nuts with the rockers on it.

I think too that the springs get cocked because there is binding somewhere - when I tighten, the rockers seem to pull a little to the side probably due to this binding and being under strain.

I need my crazy pills...

[jagarra]

Do you happen to have the old pistons? If you do measure between the wrist pin and the top of the old piston and compare to the one you are installing.

[hudson]

Never thought of that before. I bought these pistons/rings with Boxer2valve when they rebored for me. I wouldn't think this would be the case, but at this point who knows...

But if at TDC, and the piston surface nearly comes to the edge of the top of the cylinder opening, and travels no further, would this matter? Not disproving, just thinking aloud. I guess it wouldn't hurt to measure - it's just a pain in the !#$ to reinstall the piston/rings.

[gspd]

Hudson-
TDC, top dead center, is when the pistons are at the top of their stroke.
BOTH pistons reach TDC at the same time.
This will correspond to the OT mark on the flywheel appearing in the inspection hole, assuming that your flywheel is correctly installed.
From this TDC position, if you rock the crankshaft a few degrees forward and back, you will notice that the pushrods on one cylinder move; The exhaust valve closes as the intake valve opens. This is what is called being 'on the overlap'

The pushrods on the other 'non-overlapping' cylinder don't move at all at this point. That is the side of the engine you assemble first.

One full crank rotation will now put the assembled cylinder 'on the overlap' and you can then assemble the other side.

When adjusting the valves, there is no need to use the OT mark as a reference.
If one side is on the overlap (valves rocking when you turn the engine slightly forward and backwards), it is safe to adjust your valve clearances on the other side.

There is really no need to use feeler gauges for setting valve clearances. Just tighten the adjuster until you can't spin the pushrod with your thumb and forefinger, then back off 1/6 turn (one flat of the hex bolt) for the intakes (this will give you .16mm clearance) and just slightly more than 1/6 turn on the exhausts for .20mm clearance