warlord

How much cranking does it take to ruin a new not broken in hydraulic flat tappet cam?
Been trying to start kitt today after doing a cam swap and nothing. I now think the valve lash might be too tight. But before I realised that, I couldn't understand why. So checked stuff then tried it again. So overall an excessive amount and the instructions with the cam said it needs to be started very quick, which is why I primed the oil and carb. If it helps its a stock L69 cam and I have a high torque mini starter. i really am dreading having to change it as I may have killed it.
Thank you.

AlkyIROC

If you put prelube grease on the lobes and lifters I highly doubt there's any damage to the camshaft.

If in doubt about the valves lash, back them all off and reset them. There's different ways to do it but when the lifter is on the base circle of the cam, you tighten the rocker just enough to take away any looseness. That should be zero lash. From a pushrod that you can rattle around to just tight enough that the movement is gone. DO NOT overtighten! Providing it is now at zero lash, tighten the rocker nut 1/2 turn and go to the next rocker. There are different ways to get each lifter on the base circle. You can adjust half the rockers at TDC #1 and the other half at TDC #6.

When the lifter bleeds down, the pushrod will feel loose again but this is normal. That 1/2 turn from zero lash puts the proper preload inside the hydraulic lifter. Once the engine is running, the lifter will pump up the the loosness in the pushrod will be gone.

If you did already overtighten the rockers, first thing I would check is to see if any of the pushrods are bent. With a dial gauge, you can also check to see if the lobe lift is to spec. The chances that a lifter is damaged is possible but I doubt it. To see if a valve got bent, you need to remove all the rockers and using a compression tester, put compressed air into each cylinder to see if any comes out the intake or exhaust.

Since you can't start it after a cam swap I'd do two things. Recheck the valve lash and recheck the timing. With the #1 spark plug removed, bump the engine over until you determine #1 is at TDC. Bar the engine over by hand to line up the timing mark. Remove the distributor cap to make sure the rotor is pointing at the #1 plug wire.

warlord

I used some lucas assembly lube, which is green.
It's a relief to know that I probably haven't damaged the cam. Thank you for putting my mind at ease on that one.

I used the shop manual method of TDC at 1 then do half etc..
I tried to detect zero lash by spinning the push rod. They were easy to turn, so tightened till is stopped spinning. But if I gripped harder it still spun, so tightened again. Which I now realise was my mistake. So, i'm pretty sure that I have too much lash.

I will re do them and check for bent rods etc. I'll use the wiggle up and down method this time I think.

AlkyIROC

Yes. When you first spun them as you tightened up the rockers, you stop tightening the rocker just as it makes light contact with the pushrod. You will still be able to spin the pushrod but it won't have any side to side or up and down movement. That's zero lash. From there, you tighten it 1/2 turn to set the lifter preload and move on to the next rocker. 1/2 turn is roughly 0.030" of preload. 0.015 to 0.045 is acceptable but a light preload may make the rockers tick when running. After the preload has been set and the lifter bleeds down, the pushrod will spin again and feel loose. Like I already said. This is normal and you do not tighten them again.

warlord

I readjusted them today, counted the turns doing no. 6 intake. It was 2 turns too tight. I'm sure I've done it correctly this time. No push rods were bent, so I presume the lifters are undamaged too.
I'll be starting it tomorrow or Tuesday, so fingers crossed.

warlord

Success, started straight up. many thanks for the advice.

It did smoke a bit for the first few mins, I guess that was the fuel dumped into the exhaust with all that cranking on slightly open valves the other day. Also, when I put the new summit exhaust on, it had some oily residue inside. it only did it when cold, went away after a few mins. FOr the remainder of the break in, nothing.
I guess that's just cause of the above or having it appart?

AlkyIROC

With the rockers adjusted too tight, there's a possibility that the valves seals got damaged.

warlord

Tried it this morning, nothing. No smoke at all. So it was just the crap in the exhaust.
Couldn't be happier, I didn't bugger it up and don't have to take it apart again. YAY!

Now to make some brake lines and get some welding done and it's driving time
Thanks Again