Datsun#1 Posted July 16, 2015 Share Posted July 16, 2015 Hey,I got a used l28 and I was going to re set the cam timing because the PO had it all mucked up. The cam dow was in the 5 o'clock position at TDC. Not good! He didnt know what he was doing.my issue now is I cant turn the camshaft enough to get the dowl in the 12 o clock position..is there any way I can rotate the camshaft safly without removing the valve springs??? Could I just lossen the lash a lot? Thanks! Quote Link to comment Share on other sites More sharing options...
NewZed Posted July 16, 2015 Share Posted July 16, 2015 He said he's trying to move the cam shaft. Should move pretty easily with a wrench or big pliers on one of the knobs (the rough part of the casting) on the shaft itself. Why he's looking at the dowel position with the crank at zero timing (#1 at TDC) is a question though. Should be looking at the notch and groove. Quote Link to comment Share on other sites More sharing options...
Datsun#1 Posted July 17, 2015 Author Share Posted July 17, 2015 The cam will not rotate freely.it will move about 10 degrees both ways.I need to put the cam dowl in the #1 hole...the guy originally had the shinny link on the #1 mark with the cam dowl in the #3 hole.the chain is basically brand new.no strech so id like to correct the issue Quote Link to comment Share on other sites More sharing options...
Datsun#1 Posted July 17, 2015 Author Share Posted July 17, 2015 I think the springs are why the cam wont turn all the way around Quote Link to comment Share on other sites More sharing options...
TimZ Posted July 17, 2015 Share Posted July 17, 2015 (edited) I think the springs are why the cam wont turn all the way around Okay I'll bite. Why are you trying to rotate the cam more than 10 degrees? It sounds as though you have the timing chain off the cam sprocket, correct? If so, then the cam rotation stop is likely due to one or more of the valves hitting the pistons. You know, like in that other thread you were posting in... Edited July 17, 2015 by TimZ Quote Link to comment Share on other sites More sharing options...
NewZed Posted July 17, 2015 Share Posted July 17, 2015 (edited) The cam will not rotate freely.it will move about 10 degrees both ways.I need to put the cam dowl in the #1 hole...the guy originally had the shinny link on the #1 mark with the cam dowl in the #3 hole.the chain is basically brand new.no strech so id like to correct the issue Define freely. The shiny mark only matters during the first installation. Once the engine turns it will only line up occasionally. The notch and groove are what you use on a complete engine that has been turned. Seems like you're not really sure how things work, be careful. Read the Engine Mechanical chapter to learn about the notch and groove. Study the valve train parts to see how the parts work together. The springs close the valves and the cam lobes open them, against spring pressure. So of course the springs will resist. But there are also springs trying to close valves that are already open. It's a wash. If you can only move the cam shaft +/- 10 degrees, something's more wrong than cam timing. But you shouldn't need to move it that far anyway to switch holes on the cam sprocket. You're going to bend a valve if the head is installed. Did the engine rotate before you decided the cam sprocket needed moving? Edit - just realized, considering all, that odds are high the problem is bent valves. Might be too late for cam timing adjustment. Edited July 17, 2015 by NewZed Quote Link to comment Share on other sites More sharing options...
Datsun#1 Posted July 17, 2015 Author Share Posted July 17, 2015 Engine ran.ill pull the head and check the valves this weekend.then ill reply back.thanks guys.I do understand cam timing as I have built 3 l6 engines.I just never had the issue of the cam not rotating.ill do some investigating Quote Link to comment Share on other sites More sharing options...
Datsun#1 Posted July 17, 2015 Author Share Posted July 17, 2015 My biggest problem was buying an engine from someone with hardly any l6 experience Quote Link to comment Share on other sites More sharing options...
NewZed Posted July 17, 2015 Share Posted July 17, 2015 I do understand cam timing as I have built 3 l6 engines. So what is the relation of the notch to the groove then? If the engine runs why would you pull the head? The logic train has no tracks... Quote Link to comment Share on other sites More sharing options...
Datsun#1 Posted July 18, 2015 Author Share Posted July 18, 2015 The guy installed the cam wayyyyy retarded and the dang thing has no power below 5k.the cam isnt vary radical.he says its 274dur/480lift. This cam should be pulling way before 5k.so I pulled the valve cover,blocked the chain,then looked at the notch,the shinny link was on the #1 mark.pulled the cam sprocket (all at TDC) and the cam dowl was in position 3.WRONG...so I was going to put the dowl in position 1 and hope that would fix the problem. I turned the cam slowly and it stops either direction.so im gonna pull the head tonight and see if I bent a valve.if not,im going to turn the cam with the head off to position the dowl in the 12 o clock position.then re install the head after a clay test of course. Quote Link to comment Share on other sites More sharing options...
Datsun#1 Posted July 18, 2015 Author Share Posted July 18, 2015 The timing chain is new.he replaced it before the purchase.I just dont think he knew what he was doing Quote Link to comment Share on other sites More sharing options...
Datsun#1 Posted July 18, 2015 Author Share Posted July 18, 2015 And @Timz, The other thread I commented in was about my other z.not this current engine.I have 2 zeds my friend Quote Link to comment Share on other sites More sharing options...
djwarner Posted July 18, 2015 Share Posted July 18, 2015 If you are going to the vintage car show at The Villages today, look me up. I'll have a Gray Series I with blue interior. I recently overhauled my engine and have photos. Quote Link to comment Share on other sites More sharing options...
NewZed Posted July 18, 2015 Share Posted July 18, 2015 The guy installed the cam wayyyyy retarded and the dang thing has no power below 5k.the cam isnt vary radical.he says its 274dur/480lift. This cam should be pulling way before 5k.so I pulled the valve cover,blocked the chain,then looked at the notch,the shinny link was on the #1 mark.pulled the cam sprocket (all at TDC) and the cam dowl was in position 3.WRONG...so I was going to put the dowl in position 1 and hope that would fix the problem. I turned the cam slowly and it stops either direction.so im gonna pull the head tonight and see if I bent a valve.if not,im going to turn the cam with the head off to position the dowl in the 12 o clock position.then re install the head after a clay test of course. So this is an aftermarket cam. You should set it up the way the manufacturer recommends. Although most cam shops use the stock factory marks. So the notch and groove are still relevant. Also, your thinking seems to be backward. Advancing cam timing moves the power curve to lower RPM. You said that you should have more power at low RPM, "no power below 5k". So you're going the wrong way to get more low end. Nissan set the holes up so that each higher number advances cam timing to make up for chain stretch. You're already maxed out to get more low end. If the head was off the engine, you could put a wrench on the sprocket bolt and spin the cam pretty easily, with all valves and springs installed. You're probably just being too careful. BUT, you're still missing the point about the holes only being 4 crankshaft degrees apart. That's only 2 camshaft degrees. You already have 10 degrees of movement. Why are you trying to rotate it farther? You should stop what you're trying to do and study up. You're wasting your time. Quote Link to comment Share on other sites More sharing options...
Datsun#1 Posted July 18, 2015 Author Share Posted July 18, 2015 Well,I know the number 3 hole is full advance.but what would it be if the cam Is in the number 3 hole but the chain link is in the #1 position? Shouldn't the link be on the #3 mark aswell? IF the idea was to have the cam in the #3 hole for full advance or make up of chain strech? The reason im confused is why would you install the chain in the #1 position but have the dowl in the #3? Quote Link to comment Share on other sites More sharing options...
NewZed Posted July 18, 2015 Share Posted July 18, 2015 All that matters is the relation of the camshaft to the crankshaft with the straight side (driver's side) of the chain straight and tight. The chain links just end up where ever once things start rotating. The bright links are just a convenience for chain installation. The effect of cam timing on power is well-documented all over the internet. What's probably going on is that the guy you bought the engine from moved the sprocket to #3 to get more low end. You probably have a race cam that will never work well at low RPM. Or there's something else not right and you're just focused on the wrong thing. What's your ignition timing set at and what's the advance curve of the distributor? Is it working right? Carbs or EFI? Cam timing doesn't seem like the source of the problem. http://www.compcams.com/Pages/413/cam-timing-lobe-separation-angle.aspx Quote Link to comment Share on other sites More sharing options...
Datsun#1 Posted July 18, 2015 Author Share Posted July 18, 2015 Ignition timing is set,19initial and 36full Quote Link to comment Share on other sites More sharing options...
Datsun#1 Posted July 18, 2015 Author Share Posted July 18, 2015 Dual su carbs.cleaned and tuned Quote Link to comment Share on other sites More sharing options...
madkaw Posted July 18, 2015 Share Posted July 18, 2015 Disregard the shiny links unless you have the timing cover off to count pins. You might just have to pull the timing cover and start over. Why pull the head unless no compression. Quote Link to comment Share on other sites More sharing options...
TimZ Posted July 19, 2015 Share Posted July 19, 2015 (edited) And @Timz, The other thread I commented in was about my other z.not this current engine.I have 2 zeds my friend Oh, I see. So this engine is immune to valves hitting pistons if you rotate the cam with the timing chain disconnected? Awesome. So here's what appears to have happened - you made an incorrect assumption about the purpose of the shiny link and assumed that the link was in the wrong place when it probably wasn't. Now you've removed the chain from the sprocket, messed with the cam timing and may or may not be able to get back to where you started. Can you still put it back like it was before you pulled the sprocket? If you can, then do. Then you will want to rotate the engine by hand (DO NOT USE THE STARTER) multiple times until the shiny link eventually comes up on #3. Now if you want to return the sprocket to the #1 dowel hole you can do so, and you will find that the #1 tooth lines up with the shiny link without moving the cam much, if at all. This will only require a very small turn to the cam at most. If the engine hangs up at any point while you are trying to rotate it, then you've borked the cam timing and you need to stop. As madkaw mentioned, your best bet will then be to remove the timing cover and retime everything per the FSM. Removing the head won't help with this. If you are able to get the timing back to the #1 hole and it rotates without hanging up, then you should run a simple compression check to see if you have issues with bent valves. Even better would be a leakdown test, but the compression test will give you an indication as to whether you need to look further. Edited July 19, 2015 by TimZ Quote Link to comment Share on other sites More sharing options...
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