Can't adjust valves L18 engine and rocker rolled keeper

[Sealik]

1/4" rope....

 

 

Yes, you can also pressurize the cylinder...I used a leak down tester.

Place cam lobe (turn engine) in desired position for spring compressor (valves closed)...lock crank bolt in place with socket/ratchet or the engine will start spinning over. Air compressor should cycle back on if cylinder pressure drops.....

 

 

If the cylinder is at TDC....valves at 10 and 2....the piston should stay put without locking the crank bolt.

But....to utilize the spring compressor 'properly' (working around the lobe) the valves might not be at 10 and 2

[Sealik]

When you use the 'rope method' the valves/lobes are basically stuck at the 10 and 2 position....that said....the valve with the cam lobe at 10 is easier to work on.

Using cylinder pressure either cam lobe can placed at the 10ish + - position......it helps when the lobe is out of the way for taller (after market) springs/positioning keepers...etc

[ggzilla]

When use the rope method you can put the valves at TDC for the cylinder. Both all the way up. Depends on how you do it. Just put a very little rope in and then turn the cylinder.

[datzenmike]

That there's a possibility that the valve will fall in if I mess with the spring or try to pry the rocker arm in place as indicated earlier.

 

The valve will only drop in the cylinder if you were able to remove the keepers. If you are prying down on the spring to remove the rocker and the lash pad, nothing is going to happen.

[ggzilla]

That's true. There's almost no possibility of dropping the valve if you compress the spring but do not remove the keeper. Especially if you turn the engine so distributor is pointing to that cylinder (TDC for that valve), even if you don't use rope.

 

Didn't you say one of the keeper halves was already missing? Better to be safe than sorry - use the rope.

[datzenmike]

This is becoming more difficult than necessary. I've never heard of a keeper falling out by rubber hammer or 8K RPMs. The spring exerts sufficient upward force to keep them in even if the valves float. 

 

Maybe post a picture of the valve in question and what you are trying to accomplish.

[racerx]

The keeper is still there. It did not come off but the rocker is riding on one side of the keeper or retainer.

[datzenmike]

Slip a long screwdriver or bar under the camshaft and up onto the flat retainer just above the spring and pry down on it. When low enough, slip the rocker back into position on the top of it. Maybe have someone place the rocker while you hold the valve down. Don't forget that there is a small lash pad between the rocker and the valve stem top. Just look at one of the other valves and you'll see what I mean.

 

This is an easy fix.

[racerx]

Thanks for all of the tech. help.  I will try these steps as mentioned.  This never happened to me so, of course, I'll be cautious and will ask a lot of questions.

[Sealik]

Thanks for all of the tech. help.  I will try these steps as mentioned.  This never happened to me so, of course, I'll be cautious and will ask a lot of questions.

 

 

Post some pics

[racerx]

cell phone is messed up right now. Sorry no pics.

[racerx]

Was able to insert the rocker back to keeper and checked valved clearance but no clearance.  Readjusted the 14 mm nut and went clock wise till it stopped and still no clearance.  I've even tried .0025 feeler gauge and no clearance, 008 should be able to slide through for intake ( cold adjustment). Any ideas what is causing it to not able to have clearance.

 

I also rotated the cam so that both valves #4 were closed, then shot compressed into cylinder to check for leakage and no leakage. Also did compression check on #4 and it's about 160.  Other cylinders compression had similar readings.

[DanielC]

Remember what I said at the beginning of the thread about a sunken valve seat?  You have one.

Time for a valve job.  Sorry.

 

DO NOT REMOVE THE CAM CHAIN UNTIL YOU BLOCK THE CHAIN TENSIONER!

Here is a picture of the front of the engine without the front cover on.

The black shoe pushing against the chain is spring loaded.  If you let the chain go slack, it pops out of the block it is mounted in, and you have to remove the front cover too.

[wayno]

Was able to insert the rocker back to keeper and checked valved clearance but no clearance.  Readjusted the 14 mm nut and went clock wise till it stopped and still no clearance.  I've even tried .0025 feeler gauge and no clearance, 008 should be able to slide through for intake ( cold adjustment). Any ideas what is causing it to not able to have clearance.

 

I also rotated the cam so that both valves #4 were closed, then shot compressed into cylinder to check for leakage and no leakage. Also did compression check on #4 and it's about 160.  Other cylinders compression had similar readings.

 

I realize that you likely know this, but you have to hold the lower big nut(17mm I beleave) with a wrench while turning the 14mm nut down to make clearance.

If you have done that, and the 14mm bottoms out in the big nut, and you cannot see anymore threads on the 14mm nut, there is a temporary fix, but it involves grinding down parts to make more clearance, I beleave that you cut the lower big nut in half, and then that will give you more room to go down, not sure if you have to cut the 14mm nut shorter also, which is actually not just a nut, but you need to make sure there is no more adjustment left before you start cutting things.

I have never done is temporary modification before, I am not sure if I described the mod the proper way, you will need to check everything before doing it, perhaps a smaller nut can be used/bought instead of cutting the big one.

 

One of the reasons that valves start to sink into the head is because of brass seats, and how far your foot is in the pedal, I have a work truck that hauls heavy loads and a trailer, so my foot is in the pedal a lot, my new rebuilt head brass seats sunk into the head in less than a year, when you rebuild the head, use hardened seats, no brass.

[racerx]

thanks....oh well..is it possible to drive it around for awhile?  Do you guys recommend any good Datsun mechanics in South Bay Area.?

[datzenmike]

Wayno, I might add that the ball stud the rocker rides on may need a few threads ground off the bottom so it can screw deeper into the head.

[wayno]

Here is a nut with adjustment left.

Here is one with no adjustment left.

If you were able to buy a half nut, then that might get you by a little while.

If no half nuts are available, then the nut you have would need to be cut.

[ggzilla]

If you drive it with 0 valve clearance it will burn the valve. New valve is only about $10 and can be lapped in. But if you have to replace the seat, that's a machining job and also requires the valve seat to be ground. Use the stock stellite seats that were fitted to later Datsuns.

 

Easier to swap on another good used head.

[racerx]

This sucks..miss driving my 510, driving around with a civic...i have to find an L18 head or get mine worked on..then my wife's suv window motor is goin out..thx for all the help..racerx

[1971tantruck]

I have a 1971 datsun truck l16 I got the same problem sounds like time for a valve job`

[datzenmike]

New seats properly installed should do the trick. The L16's 210 head is probably one of the most common heads out there and pretty much throw away priced. Might be an option to just find another.