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| 1981 Stanza SSS http://www.ozdat.com.au/forum/viewtopic.php?t=33671 |
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| Author: | Clubber [ Fri Aug 07, 2015 1:44 pm ] |
| Post subject: | Re: 1981 Stanza SSS |
Hey Baz Hey do you adjust the chain tension?? I thought about that, but I couldn't see any way to adjust it... It's got a new spring/tensioner on it and everything. I hope I don't have to adjust it, I've got the rocker cover and everything on, with the engine just about ready to go back in... :/ Yes, the adjusters are rather high as I have fitted a reground 180B cam, so the base circle is considerably smaller than it used to be... Tolerances are set to 10" on the inlets and 12" on the exhaust though, so I think it's alright (fingers crossed)... Yeah, rocker wipe has been checked and is fine. I have checked piston to valve clearance and, well - lets just say that everything is alright so long as the cam stays in correct time with the crankshaft and the timing chain doesn't decide to take a walk... |
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| Author: | Clubber [ Sun Aug 09, 2015 10:53 am ] |
| Post subject: | Re: 1981 Stanza SSS |
Progress.... Pardon the pun, but I reckon this exhaust looks hot as... ![[ img ]](http://i1068.photobucket.com/albums/u442/Clubber997/DSCN4478_zpsmoqjuuwu.jpg) And this is how the engine currently looks. Just waiting on an engine crane from next door and she'll be right to go in (when I can convince Dad to let me out long enough from my "studying" - who needs a HSC anyway...  )![[ img ]](http://i1068.photobucket.com/albums/u442/Clubber997/DSCN4482_zpsewf0yy6q.jpg) ![[ img ]](http://i1068.photobucket.com/albums/u442/Clubber997/DSCN4484_zpswluqeknk.jpg) ![[ img ]](http://i1068.photobucket.com/albums/u442/Clubber997/DSCN4485_zpsxliq8nzk.jpg) ![[ img ]](http://i1068.photobucket.com/albums/u442/Clubber997/DSCN4487_zpsp8xqdjcs.jpg)
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| Author: | unfamilia [ Sun Aug 09, 2015 3:07 pm ] |
| Post subject: | Re: 1981 Stanza SSS |
Personally I'd leave the carbs and exhaust off. I'd even take the oil pressure switch out as I have snapped one off before. Hope timing stays spot on. |
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| Author: | Clubber [ Sun Aug 09, 2015 4:04 pm ] |
| Post subject: | Re: 1981 Stanza SSS |
Yeah, that was just for the pictures if I'm honest - they were only done up hand tight. Besides, I wanted to see it all together outside of the car, just for fun... I had a good think about that timing chain tensioner - and someone correct me if I'm wrong - but I can't see any way to adjust it. The bolt holes and housing are both non adjustable and fixed. The chain guide is fully back (and Baz mentioned the tensioner specifically, so unless he misspoke and was being very unclear?). And I can't see anyway to adjust where the tensioner sits without removing a link or two from the chain - but I also can't see anything wrong with where it's sitting now. It's tensioning the chain, like it should (it's got a spring in there, and is also further pressurised by oil). I can't see any possibility of the tensioner over-extending, and I can't see how the timing will retard unless there is too much slack on the chain and it skips a tooth. On top of that, the several workshop manuals I have (Nissan, Gregory's, etc) all show the tensioner extended that much. I also have turned the engine over quite a few times, and the cam timing has not changed. Crank and cam sprocket chain wrap seems alright to me, and I can't see anything wrong with where the chain is sitting now. I'm not trying to be a smartass or know-it-all, and I'm sorry if I've come across that way, but I'm just trying to explain my logic so you guys know what I'm thinking.... |
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| Author: | Baz [ Sun Aug 09, 2015 11:27 pm ] |
| Post subject: | Re: 1981 Stanza SSS |
You have spent considerable money on your engine & done it wrong. answer these questions if you can. 1. What thickness lash pads did you use to get the rocker wipe correct? 2. what is the piston to valve clearance? 3. Did you do a search on this forum before building the engine. 4. Did you read this? http://www.datsport.com/racer-brown.html 5. why did you machine the head to get more compression instead of using the right pistons? Understand this... I am trying to help you as I have done for many others over many years. I have built more L series than most people alive. I have just about had it with people not listening to good advise. My time is worth money & I have supported this forum since day one. Just because I like to help. Read it. I have never seen rockers on the angle of your engine that would not run off the cam & destroy it. Nor will your engine last if you leave the tensioner loose. You should search this forum for the info you need to fix up your engine before you spend money doing it again. I will tell you this..... amongst other thing.... as engines rpms rise the centrifugal force of the chain will over come the pressure of the tensioner causing the chain to rise up on the cam sprocket. This retards the valve timing..... causing the exhaust valve to close later. The piston is always chasing the exhaust valve.... so if sufficient valve to piston clearance was not allowed for disaster follows. You also missed reading NADs questions about 5 posts down on how to correct a loose timing chain. I would suggest you read it... |
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| Author: | Clubber [ Mon Aug 10, 2015 2:49 pm ] |
| Post subject: | Re: 1981 Stanza SSS |
Hey Baz, 1. I do not know. I sent the rockers off to Tighe Engineering in Brisbane to get refurbished, and I *assumed* they would've told me if something was wrong, seeing as they also supplied the cam and knew what I was doing. (I assume the pads on top of the rockers are the lashpads?) 2. I cannot recall the exact measurement as it was done a while ago, but I dropped measured how far down the valves dropped with the piston at TDC and measured somewhere around 250-300". Is this what you mean? 3. No, when I started this engine I did not even have internet access at home, let alone knowledge of this site. Just me and my old man and some old books. 4. Nope... 5. The head needed machining anyway as it was left with a machine shop for many years and was unfortunately neglected. It needed 2mm shaved off to get the surface in reasonable condition. Also, at the time, I was not aware flat top pistons could be purchased (I had a hard enough time chasing down NOS 30" oversize pistons). And mate, I understand that you are trying to help and I really, really appreciate it. I am grateful for any and all help I can get off you, as this is my first "good" engine that I've built, and my first L series, and I've heard that you're a very knowledgeable bloke. I'm sorry if I've come across wrong but I'm not trying to ignore you or be a smartass or whatever, I'm just trying to learn and make sure that I correctly understand what you're telling me (and explain my thinking/logic so you can tell me if/where I've gone wrong - if that makes sense?). Rest assured, I am listening intently and taking on board everything you're telling me. So, from what you're telling me, I need to adjust chain tension/where the tensioner sits against the housing? Would I best go about this by shimming the cam towers or drilling/tapping holes as you said in Nad's post, or some other way? And are you saying that I need thicker lash pads to get the rockers lower? Where do I get them from and how do I install them? Again, thanks heaps for your time and knowledge, I am really appreciative of it! I am very, very sorry if I have come across wrong, I mean no disrespect to you at all, I just did not understand what you were saying and was trying to figure out where the gaps were in my understanding... |
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| Author: | Nad015 [ Mon Aug 10, 2015 4:00 pm ] |
| Post subject: | Re: 1981 Stanza SSS |
Wow, yes mate you need to make absolutely sure you set up the wipe on the rockers correctly at the very minimum. Do not attempt to start the engine before this is set. If it's in correct you will immediately destroy the cam and the rockers. You, the engine/head builder needs to do this, tighe cams could suggest lash pads to get you in the ball park but every head even every lash pad could be different, and you need to check this. |
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| Author: | Clubber [ Mon Aug 10, 2015 5:11 pm ] |
| Post subject: | Re: 1981 Stanza SSS |
It becomes increasingly apparent to me that what I think a wipe test is may not be correct... How, exactly, do you perform this test and what am I looking for/adjusting? And as a sidenote, by lashpads do you mean the part that goes between the rocker and valve stem, or the part in the rocker that the cam lobe acts on? And thanks for all your help fellas! As you may be able to tell, I'm kinda new to this... |
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| Author: | Clubber [ Mon Aug 10, 2015 7:35 pm ] |
| Post subject: | Re: 1981 Stanza SSS |
Ok, so to check valve to piston clearance, rather than pull the head off, get a new gasket etc etc (I'm meant to be doing this for a school project, which is due 20/08/2015), I decided to save some time and buy a inspection camera (needed one anyway). I'll let the pictures do the explaining... Thanks for speaking up Baz, there is a bees D!ck clearance there if that, and I shudder to think what would've happened if I even tried to crank it over!!!  ![[ img ]](http://i1068.photobucket.com/albums/u442/Clubber997/Screenshot_2015-08-10-17-42-56_zpsimmypdgs.png) ![[ img ]](http://i1068.photobucket.com/albums/u442/Clubber997/Screenshot_2015-08-10-17-42-00_zpsox6z2vb0.png) At this point, I'm thinking the easiest way to solve my piston/valve clearance problem is to get another cam made with about 100" less lift (equating to 150" less lift at the valve, I believe?). Thoughts? Will I still need oversize rocker guides (that's the part that needs changing, isn't it? Not the actual pad on the rocker?), and if so will I need a range of them in order to find which fits best? Also, to solve the timing tensioner problem, I'm thinking redrill and tap the holes for the tensioner in the block, as was suggested in Nad's earlier thread, as I do not want to risk taking the cam towers off again (it was extremely difficult to get the cam turning freely after reinstalling them...). Am I onto the right track now? Thanks in advance! |
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| Author: | Nad015 [ Mon Aug 10, 2015 8:57 pm ] |
| Post subject: | Re: 1981 Stanza SSS |
Cool camera, Probably hard to tell if you have sufficient clearance but. I think around 1.5mm(not exactly sure on this measurement) clearance is minimum. But it won't be with your piston at tdc. Exhaust will be closest a bit before tdc intake closest a bit after tdc. Usually you would check your piston to valve clearance on pre assembly. Using plasticine on the piston top setting the cam timing, valve clearances then turning the engine over carefully then measuring the valve mark in the plasticine, and then because you have a adjustable cam gear you would retard and advance the cam and check the clearance is good with the different cam timing in case you change cam timing during tuning so you know the piston to valve clearance is ok. What is the specs of the cam you got? And did you set it up with a degree wheel? |
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| Author: | Nad015 [ Mon Aug 10, 2015 9:00 pm ] |
| Post subject: | Re: 1981 Stanza SSS |
Also so you did do a rocker pad wipe test? There's plenty of threads with this in it, if you haven't done the test |
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| Author: | unfamilia [ Tue Aug 11, 2015 12:18 am ] |
| Post subject: | Re: 1981 Stanza SSS |
Get another head gasket and check it properly. Cheaper then getting another cam made. $20 from repo maybe |
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| Author: | Baz [ Tue Aug 11, 2015 12:42 am ] |
| Post subject: | Re: 1981 Stanza SSS |
Please read the racer brown link I posted. That will explain all you need. It is a MUST if you are modding datsuns. Its a fun read as well. RB had a great sense of humour. Once you read through it you will be able to understand the complexity in such a simple engine. |
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| Author: | SR20Datsun [ Tue Aug 11, 2015 10:22 am ] | ||
| Post subject: | Re: 1981 Stanza SSS | ||
And thanks for all your help fellas! As you may be able to tell, I'm kinda new to this...
Nothing wrong with that. Keep asking those questions.
...(I'm meant to be doing this for a school project, which is due 20/08/2015)...
On a slightly different path, why don't you change your school project around a little. If you know you can't make the deadline for getting the engine in and running, perhaps make that part of the project stating why you couldn't get it finished and what you would do differently.Projects never go 100% to plan and sometimes the deviation takes more time. Planning for the unknowns is something that all of us struggle with. My suggestion (if you want to go in this direction) is to perform a risk analysis: Rank all of the things that you know about from Low, Medium High with the colour green, orange and red. The reds (or High risk) are the ones that you are worried about. Such as putting in the wrong Cam which will cause interference with the valves to pistons. Work on the highest risk issues first. Forming the conclusion that you require more time and coming up with an estimate is Project Management 101. Perhaps something to investigate? |
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| Author: | green200b [ Tue Aug 11, 2015 11:10 am ] | |
| Post subject: | Re: 1981 Stanza SSS | |
On a slightly different path, why don't you change your school project around a little. If you know you can't make the deadline for getting the engine in and running, perhaps make that part of the project stating why you couldn't get it finished and what you would do differently.
Excellent advice. I did my green 200B up as a school project and was supposed to have it roadworthied at the end. I didn't due to various setbacks but I was able to explain this and what still needed to be done. My teacher knew nothing about cars but I made her think I did and got an A+ (one of the last ones I got at school :p).Projects never go 100% to plan and sometimes the deviation takes more time. Planning for the unknowns is something that all of us struggle with. My suggestion (if you want to go in this direction) is to perform a risk analysis: Rank all of the things that you know about from Low, Medium High with the colour green, orange and red. The reds (or High risk) are the ones that you are worried about. Such as putting in the wrong Cam which will cause interference with the valves to pistons. Work on the highest risk issues first. Don't stress too much, you have to learn somewhere and I can certainly relate to doing up a car whilst at school. The advantage you have over me is that you know about Ozdat! Also if you do get stuck I can highly recommend just calling Baz at Datsport, he will be more than happy to help you out over the phone as he has done to me and probably everyone else on here! |
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