Tony D Posted December 9, 2012 Share Posted December 9, 2012 Amen, bro! The use of an arbor is just common sense! It's how it was done in production, for sure! The "Flat Head" thing is akin to a Chev V8 getting shaved then not milling the intake manifold... The shops don't realise OHC means something on he top side of that warped bottom is turning in bearings with less than 0.003" clearance... I mean, if the BOTTOM is warped, exactly how does it work that the TOP would NOT be? Hahaha I know someone who milled his warped head (0.019" warp!!!) and used the logic "I'm milling for closed chamber anyway o 0.020" isn't a problem!" I warned him... Quick and cheap milling job with the head on parallel blocks to clear the towers (!)... Cam wasn't turning so they knocked he towers around a bit... It turned. Ran it at the track... BROKE THE CAM INTO THREE PIECES!!! "FLAT MEANS FLAT"! You would think that is pretty straightforward, eh? Quote Link to comment Share on other sites More sharing options...
Ben's Z Posted December 9, 2012 Author Share Posted December 9, 2012 All good information. I think the next step is to dissemble completely and check both the top and bottom of head again for straightness. Seeing as it got worse when I torqued the head to the block leaves me to believe this head just isn't there yet, and certainly not there on the top. I was out in the garage again last night and the cam does spin much easier with #3 tower out. My Stanley level could be wrong but if I can get .008 feeler between the level and where the #3 tower mates, we problem. Quote Link to comment Share on other sites More sharing options...
Tony D Posted December 9, 2012 Share Posted December 9, 2012 (edited) That should have been step one 22 posts ago... If you think 0.008" head warpage is "acceptable" you really need to go back to the FSM and read (between the lines)! Why does a 0.003" feeler come to mind, and not a 0.008"? Japanese translations leave a bit to be desired... If you have 0.004" warpage on the head... And 0.004" on the block, you're good to go right? Because 0.008" isn't reached? Hmmmmmmmm... Second hint from the FSM: if your cam tower bore to journal clearance is X, and you have distance Y between towers, how much warpage Z --between two towers is allowable before one of the cam towers binds? Easier than that: if your clearance is X, and your warpage Z = X do you think your journal may touch the cam tower or not allow oil on that part of the tower? What do you suppose will happen when this runs (even if it "turns freely")? Edited December 9, 2012 by Tony D Quote Link to comment Share on other sites More sharing options...
Ben's Z Posted December 9, 2012 Author Share Posted December 9, 2012 That should have been step one 22 posts ago... If you think 0.008" head warpage is "acceptable" you really need to go back to the FSM and read (between the lines)! Why does a 0.003" feeler come to mind, and not a 0.008"? Japanese translations leave a bit to be desired... If you have 0.004" warpage on the head... And 0.004" on the block, you're good to go right? Because 0.008" isn't reached? Hmmmmmmmm... Second hint from the FSM: if your cam tower bore to journal clearance is X, and you have distance Y between towers, how much warpage Z --between two towers is allowable before one of the cam towers binds? Easier than that: if your clearance is X, and your warpage Z = X do you think your journal may touch the cam tower or not allow oil on that part of the tower? What do you suppose will happen when this runs (even if it "turns freely")? I never said it was acceptable. I am looking for errors from the first machine shop. This is my first ever experience with an engine rebuild and a machine shop. I don't run the Penske race shop for my job. I hope to begin the process of rectifying this issue tomorrow with a new shop. From what Peter at PMC is saying, if the head is straight (highly doubtful) not all shops possess the equipment to align bore these heads. I also want to clear the air that I did not actively seek out the cheapest machine shop. I asked around from guys I know. I am in the automotive aftermarket and work for a parts manufacturer and deal with parts distributors and professional shops on a daily basis. I was recommended this first shop by more than one individual. I think the errors are not limited to one thing. Inexperience with seeing these engine, and a lot of sloppiness on their part. I mean they lost one of my cylinder head alignment dowels and bushing inserts for the lash adjusters. They corrected the wrong exhaust valves, but they should have put the right ones in to begin with. Do these guys probably do a good job with BBC and SBC, probably, with OHC L6 Datsuns? Isn't looking too good. On to the next shop. Quote Link to comment Share on other sites More sharing options...
srgunz Posted December 9, 2012 Share Posted December 9, 2012 Very informative. I never knew they had a way to 'straighten' a head first and then mill it true. Quote Link to comment Share on other sites More sharing options...
Tony D Posted December 10, 2012 Share Posted December 10, 2012 NOBODY CAN "ALIGN BORE" THE BEARING SADDLES! You keep refereeing that as some sort of option, as explained before its not! Pete at PMC simply stated what everybody else said, and also confirmed how most production shops do this. It's NOT L-Specific... It's a basic "Marks Machinery" book solution to this type of assembly. If this was to go to an industrial machine shop...the checks they old do using non-dedicated jigs and equipment would stagger your mind. Each non-spec item would then be addressed line-time on the bill. You're doing a lot of checking without a CLUE what you're looking for, which I see all the time. People have told you adnauseam the head must be FLAT AND STRAIGHT... That's top and bottom. From what you say above your topside is warped some 0.010" after they milled the bottom. ANY machine shop should know at this point you must take off the top what you cut off the bottom if the height and cut specs exceed a given point. Pursuant to a topside flatness check revealing the actual warpage. Are you in ANY of the local Z-Clubs? Houston has a buttload of helpful Z-Clubs and an EXTENSIVE list of GOOD L-SAVVY machine shops. It boggles my mind that wasn't your FIRST stop for recommendations when looking for Datsun Headwork. If this shop was suggested by local Z-Club people I would be shocked! I hope this is not the case! Quote Link to comment Share on other sites More sharing options...
Tony D Posted December 10, 2012 Share Posted December 10, 2012 Very informative. I never knew they had a way to 'straighten' a head first and then millit true. Process covered extensively in the "How to Modify" book. Quote Link to comment Share on other sites More sharing options...
PMC raceengines Posted December 10, 2012 Share Posted December 10, 2012 Yep lol its how i started on my path i read that book 50 times ... The truth is if the head is straight top and bottom and not twisted ... yes not twisted then the cam will turn 9/out of 10 times as it should, some times the cam towers need some love. Quote Link to comment Share on other sites More sharing options...
Ben's Z Posted December 10, 2012 Author Share Posted December 10, 2012 Sorry I misread Peter's statement about the "bar going through the towers" and thought boring. I took the head to another shop. I said I don't want it back until the top and the bottom of the head are straight. Gave them the cam and towers to check for binding. With all the frustration it is pretty cool learning the intricacies of engines. Knowing these engines were designed (or any engines for that matter) before the advent of computer aid. Hats off to the pioneers. I have not shared any pictures of my work with my car with anyone. I am freshening up the engine bay too. Here are some before and after pictures of the engine bay. Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 10, 2012 Share Posted December 10, 2012 I said I don't want it back until the top and the bottom of the head are straight. Gave them the cam and towers to check for binding. I hope that you said "parallel" also. Based on your experiences to-date, it could be important. Quote Link to comment Share on other sites More sharing options...
Ben's Z Posted December 14, 2012 Author Share Posted December 14, 2012 (edited) Ok. Took back to second machine shop and they took .012 off of the top. They did say it was uneven. I get the head home and set on top of the block, alignment dowels in and ARP head studs in the block. This cam is still not spinning like it should. I set the towers on with the bolts finger tight and put the cam in, tapped and torqued in different and multiple sequences. I have the suspicion now that the head is bent like a banana with the center exhaust ports being the inside apex. Like this looking from the sprocket "(" I believe this because when I was getting ready to put the cam in to the last tower it simply does not slide home and is offset from the tower hole. I walked around the back of the motor and looked at the back of the cam as it was about to enter the tower and it is clear as day that the cam is not going in on center. I tried my other cams and it is the same case. All of the cams go in my old head and towers bolted to my old block like butter. My question is why would my head fit down on the alignment dowels if it has this curve to it? I believe now I have over $300 bucks in a large alumnum paper weight. I even tried an extra rear tower I had, it was worse. I also tried retorquing the head to the block and took it up to 60 ft lbs. Unlike before it never got tighter to turn the cam as the torque load increased, no better no worse. Ok I just thought about this again and then went out and checked my thoughts. The head is actually curved in the middle with inside apex being the center exhaust ports. I once again put my Stanley level across the intake surface on the head and indeed their is a gap at the center exhaust ports. Edited December 14, 2012 by Ben's Z Quote Link to comment Share on other sites More sharing options...
Ben's Z Posted December 14, 2012 Author Share Posted December 14, 2012 .012 feeler on the center exhaust ports, it fits. Accuracy of Stanley level? Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 14, 2012 Share Posted December 14, 2012 (edited) Flip the level over and measure again. Do the same on the bottom of the head. Make sure the head is of even temperature throughout, cold on one side hot on the other will give some bend although I have no idea how much. There are much better tools out there for those measurements and many people here who know how to use them. I'm just throwing some basics out. You don't trust the shop? Didn't they tell you how "straight" the head was, or how much they cut? Didn't they have the cam towers to measure from since that was the ulitmate goal? This story gets weirder and weirder. Edit- actually, considering the whole thread, the real issue/question seems to be how much it would have cost to have it bored (line- to align, or align-, whatever your preference) and whether or not you could find a shop that knows how to bore aluminum camshaft bearing brackets (towers), (as opposed to steel crankshaft bearing journals). It seems easy in principle, so why didn't any of the "machine" shops you've been to suggest it. Seriously, if you took the head in to a shop and said "my camshaft is binding, how do I fix it", it seems like a shop with some experience would have measured camshaft run-out, then suggested a fix. It's odd that you haven't found a shop that can just look at the head and its parts and offer a fix, even if it's expensive. How can this be so hard? Edited December 14, 2012 by NewZed Quote Link to comment Share on other sites More sharing options...
Tony D Posted December 14, 2012 Share Posted December 14, 2012 This story reveals minimum checks done at EVERY STEP. The "Blinder's on System of Checking"---go until you find the first thing, then rush to fix it. A dimensional check on a bare head takes five minutes with a feeler gauge, straightedge, and height checking device like a surface plate mounted height gauge or vernier calliper. That they are fixing one thing at a time is par for the course for a production shop being told what to do, or being quick to push stuff out and bill for it. Again, Houston-San Antonio-Dallas ALL have GREAT Z-Car Clubs, with hundreds of active members who can tell you where to go for COMPETENT machine work on the Nissan OHC head... Pleas avail yourself of this LIVE resource and find a shop that knows what they are doing. This is turning not the classic pay me now or pay me later scenario... Quote Link to comment Share on other sites More sharing options...
Xnke Posted December 14, 2012 Share Posted December 14, 2012 He's saying the top of the head is now flat...and the bottom of the head is now flat...but the head is bent as if someone has put the front end of the head on one table, the back end of the head on the other table, and used a press to push against the center of the intake/exhaust manifold mating face. I have never seen an L head warped that way, but I guess it could happen. (I just went out and measured all of mine, all are straight along the manifold face, two are warped 0.004" and 0.009", five of them are fine.) Quote Link to comment Share on other sites More sharing options...
PMC raceengines Posted December 14, 2012 Share Posted December 14, 2012 like i said not twisted .... no point just planing both sides it has to be fixted before you start removing ally 3 steps make it straght with heat or a press, i like the heat option then when its straght plane the head face then the cam side to make it spot on .. i have seen many heads that are not right , and any good shop can fix it , the cam towers should never need to be worked over , only when there damaged do they need work , this case its the head ... your shop has no idear what there doing Quote Link to comment Share on other sites More sharing options...
Ben's Z Posted December 14, 2012 Author Share Posted December 14, 2012 He's saying the top of the head is now flat...and the bottom of the head is now flat...but the head is bent as if someone has put the front end of the head on one table, the back end of the head on the other table, and used a press to push against the center of the intake/exhaust manifold mating face. I have never seen an L head warped that way, but I guess it could happen. (I just went out and measured all of mine, all are straight along the manifold face, two are warped 0.004" and 0.009", five of them are fine.) This Quote Link to comment Share on other sites More sharing options...
Gollum Posted December 14, 2012 Share Posted December 14, 2012 (edited) I believe now I have over $300 bucks in a large alumnum paper weight. My suggestion? You have two options: 1. Take another $300 and to go anther shop that is actually recommended by a Zclub local to you. Have the head fixed RIGHT, and if they're a good shop they'll tell you if it's already fubar because of the milling before being straightened. 2. Take another $300 and go buy a decent $100 head out there. Buy $200 worth of basic tools needed to do your own head. And now that you can actually check PROPERLY, by YOURSELF weather or not the head is twisted, if you get a bad head you can just sell it and find another. And once you DO find a head in good shape you can just do all your own cleanup and basic port work YOURSELF. I like option number 2 because though it's the long road it makes you more valuable as a car hobbyist overall. Go to a hot rod show and ask around to find out how many guys actually do their own head work, and you'll find the numbers aren't that many, and that's with simple OHV engines! I find that 9 times out of 10 when I'm looking at a car that really impresses me the owner starts saying things like "we started with xxx, and then we xxxx" and I ask "who's we?" and I get an answer similar to, "I had a buddy with a shop helping me"... aka... they PAID for someone else who either HAS the skills, or HAS the time. The best solution to not be a bad consumer, is to actually be a producer, as that's the best education as to how it works. This is a simple principle. If you don't want to be a victim of McDonalds and their fatty food, go work for a restaurant and receive your own education as to how running a restaurant actually works, and then you'll have a new understanding of how McDonalds works and why. If you don't want to be a victim of big banks that take your money through fees and penalties, go become an investor/money manager and get an understanding of how the game is played. It's easy to become a victim when you simply don't know any better. I've found myself paying double what I should have for something, and looking back the only fault is my own. I can't blame the other party, because I personally can't blame someone else for my lack of understanding. That'd be like blaming my teacher for a poor grade. It doesn't work that way. If I put in the time and effort, there should be a worthwhile product at the end of the day. So I say build your own damn head and just be done with it. (and I say that in the most "I love you man" across the internet as possible) Edited December 14, 2012 by Gollum Quote Link to comment Share on other sites More sharing options...
Ben's Z Posted December 14, 2012 Author Share Posted December 14, 2012 I contacted some Houston z club folks via Facebook today and I called the shop a few of them recommended. I told the guy on the phone my problem and he said he cannot correct a head that is distorted in this manner Quote Link to comment Share on other sites More sharing options...
PMC raceengines Posted December 14, 2012 Share Posted December 14, 2012 Its commen to fix heads that are twisted and bent , i find it hard to beleve that shops there are so in the dark , this is normal engine reco work , ,,, saying that if the skill level is so bad in your area just get a new head and start over by your self , a straght edge and some hand tools and your away just like all the engine men in your area by the sound of it Quote Link to comment Share on other sites More sharing options...
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