L24 Rebuild -Again!

[madkaw]

We are all learning some valuable lessons here, so I don't mind the posts.

The local guy to me is actually the better choice. He can't do anything fancy like replace valve seats, but he does seem to know how to do a valve job okay. Word on the street, which I wish I knew earlier, is that my problem is I am dealing with a kid with nice equipment. He doesn't know how to run a business and I think he has a pride issue.

These Datsun motors require a little more work and someone that wants to deal with the geometry needs of a solid lifter cam.

Next head will be a Rebello cam kit complete with proper lash pads and the experience of a Datsun engine builder. So done with my current 'builder'

He did say that the head will be mine tomorrow. He bragged about fussing over the minor details of cleaning the head up. All I wanted was to have it DONE!

I don't even want to think about the invoice. I might be telling him to sell on ebay

Edited June 24, 2015 by madkaw

[madkaw]

So I stop by the machine shop because he wants me to check the wipe patterns. He nailed it on the cam side , but the lash pad doesn't show a wipe all the way across the pad. Sorry no pics since I was on the way to work.

I had him swap out lash pads from another valve that swiped good and no difference. We swapped out the rocker , then swapped out the retainer; none seem to alter the wipe pattern. It seems that the rocker is applying more pressure to one side of the lash pad , though you can see a faint line all the way across. All this was done with a light test spring if that makes a difference.

The problem valves are the intakes that we just got. So if it's not the rocker, lash pad, or retainer, what could be off? I think he did just barely skim the top of the valves. Curiously enough it seems I am right back where I started with uneven wear on the lash pad surface . I've been searching everywhere but the conversations always pertain to centering the cam side

Edited June 30, 2015 by madkaw

[Zed Head]

If the tops of the valves aren't ground square you should be able to rotate the valve and the wear pattern will follow the rotation, from side to side anyway.  The valves can (do, I think) rotate during usage so that would be a problem if it was the case.  You'd want to replace the valve or regrind the tip.

 

The other possibility is that the valve guides aren't square to the came anymore.  An off-center reaming could do that I suppose.  A new valve guide should fix it. 

 

These are just guesses based on my limited knowledge of how these parts fit.  Rotate the valve and see what you get.  It should tell you something.

[madkaw]

Just got off the phone with the machinist and I need to correct the last post. The new Nissan valves went in fine and the wipe patterns look good on both ends of the rocker. I guess i didn't notice but it was the exhaust side we were messing with when I was in there. After I left he did the intakes and they all came out great. There are 2 exhaust valves where the lash pad(valve side) are not wiping all the way across the pad at 100%.  Since we swapped as many parts as possible( rocker, lash pad, retainer), the problem must lie in the guide itself being slightly off, or maybe a cam lobe issue. I mentioned that it was curious that all the intakes came out great considering that he had to enlarge or ream the guides to make that work, since the Nissan valves have a larger stem diameter than the SS valves that were in there previously . So did this secondary ream take out any minor deflection that was in the guide? I think yes. 

 I told him to put it together and let's roll, I'm running out of time to put this engine together.    

[siteunseen]

Are you going to use the oil slinger on your's?  I lost mine when I was rebuilding my 2.8 and forgot all about it until it was too late, front cover was sealed up tight.  I can't decide whether or not to use one this time.  

 

Thanks for an opinion, I tend to worry too much over little stuff like that.

Cliff

[madkaw]

I hear you about the little stuff. Probably put everything I took off back on.

And speaking about put everything back on, the engine is going back together now. Picked up the head yesterday at 9am and had the head on by lunch time. Everything went pretty smoothly until I started the process of degreeing the cam. My piston stop actually snapped off in the bore. I was able to get the pieces out, but I had to make another one. I had found TDC with the head off, but I think my degree wheel moved so I had to verify TDC again- PITA.

THEN I HAD TO GO TO WORK:(

[madkaw]

Well my luck continues. Tried to degree my cam today and the numbers are pretty far off. I guess I will have to call Isky in the morning. I've double checked everything . The marks all line up but my opening and closing times are off a good 30 degrees. Probably find out I'm doing something wrong, but I'm doing this just like I did my Schneider cam and the numbers came in.

Not looking good for Zcon.

[Zed Head]

Does Isky imply that the factory notch and groove are still relevant or do they say that one of their cams must be degree'd using a wheel?  A regrind could have a different centerline.  Just curious which marks you're talking about.  You're not really degreeing your cam just confirming that the alignment marks are correct.  Which, apparently, are not.

[Zed Head]

Got curious and answered my own question.  You do seem to have an issue.  From the Isky Cams page.

 

http://www.iskycams.com/cam-degreeing.html

 

IS CAM DEGREEING NECESSARY? Because Iskenderian Cams are manufactured with such high precision you can install them on the stock timing marks without any further checking; however, for those who wish to learn how to properly check and verify valve timing, we recommend the following procedure. - See more at: http://www.iskycams.com/cam-degreeing.html#sthash.ETH1vHN9.dpuf

[Chickenman]

^ The above described procedure cannot be used on OHC engines such as the Datsun. It is a method used for OHV engines using bucket TAPPETS and pushrods and where you can setup a Dial indicator that is directly in line with the tappet to measure lift.

 

It is impossible to use that procedure on OHC engines because the Camshaft gets in the way and dial indicator can not be aligned correctly.

 

Racer Brown has one method for degreeing Datsun cams in " How to Modify Datsun Engines and Chassis ". It involves reading setting up the Dial Indicator directly on the Valve retainer. This changes the check number lift and timing figures from a tappet measurement, so the correct checking lift and timing numbers at the VALVE must be obtained from the original Camshaft manufacturer.

 

Steve: Isky may have an alternate method for degreeing their OHC grinds, but you must obtain the exact figures from Isky and use their exact checking method. I highly doubt that Isky has made an error in machining... but isht can happen.

 

Edit: Did Isky not include a Timing card and Datsun specific directions on how to properly degree the Datsun cam?

Edited July 6, 2015 by Chickenman

[Chickenman]

Here is a link to the FULL Racer Brown article on Datsun Camshafts. It is probably the best article ever written on the L-Series valve-train.

 

Regarding degreeing of cams. Thoroughly read Chapter 12:  " Checking Valve Timing and Valve to Piston Clearance" .

 

http://www.datsport.com/racer-brown.html

Edited July 6, 2015 by Chickenman

[madkaw]

I have read that Racer Brown article MANY times. It is a great piece of work.

I will take a pic of my set up, and it worked for my Schneider cam. I have an extension so the dial indicator is in line with valve . It sits right on the retainer. Waiting for Ron to get in west coast time and I will be calling him.

Doubt it's been machined wrong and more likely I have screwed up. Like I said, I've done this before, but just enough to be dangerous.