Well, I finally got my gear back from the machinist, so am just about ready to jump in the deep end and attempt to bolt all back together. Before I begin and do anything stupid I've got a couple of questions for the engine guru's out there. 1) A mate suggested I give the block a clean with detergent and water before I start, to ensure all the microscopic bits of metal from the machining are gone. Does anyone see any problem with this? 2) What bolts should not be re-used, I am getting new Head bolts, the rods came with new bolts. Anything else? Crank brace bolts? Keeping in mind I'm not after massive power. 3) How do I determine the correct piston ring gap? Max boost to begin with will only be 12ish psi until I can get a tune, then maybe push it to 15psi. As I'm only using rebuilt stock turbo's its not likely I'll be pushing it much past that. That's about all I can think of for now, would appreciate any input.
Did they remove all the welsh plugs and oil gallery plugs aswell as the oil restrictors. You should get the whole block acid dipped or whatever they call it in the big parts wash bin to remove and old grease oil and other nasties in there. Once fully cleaned fit all new welsh and oil gallery plugs. Pay a builder to put all the pistons in and gap everything etc and balance the whole short block assembly. I would use the ARP head/main stud kit all new gaskets from the OEM kit new oil pump and full 100k kit. I just ordered most of this stuff from Coz this morning plus things like engine slingers new dipstick and tube, VCT solenoids, TPS, fuel injector lower insulators etc. There is a heap of stuff and greatly depends on your budget as to how much you want to do.
Thanks for the feedback Jason. I removed all the welsh plugs myself before I took the block in. Yeah it's been through the parts cleaner thing and the whole rotating assembly has been balanced. I'm not going to pay a builder to put it together because I want to do it myself. I've got everything I need to put the short block together, new gaskets, bearings etc. just wanted to get some info before I started.
Hang on you must mean the crank balanced by itself either static or rotational or a mixture of both is better. I am getting mine checked once fully assembled also will have pulley, crank sprocket etc all attached and make sure that everything is fully balanced etc as a short block. I think they call it blueprinting or something in old school terminology. You have bigger balls than me mate I will leave the rotating assembly to the pros but will do the rest of the bolting back on stuff like heads, manifolds etc
If you have new pistons and/or rods you should really get it balanced. Unless they are exactly the same weight and have the same CG as the old stuff (never gonna happen)
Like I said already (well sort of) the crank has been balanced with the pistons, rods, flywheel and clutch, harmonic balancer and sprocket to the extend they have taken weight off parts of the flywheel and balancer so it all matches perfectly. I'm not trying to cut corners here, I believe I've done everything properly, how are you supposed to balance the rotating assembly once it's all put together in the block? And what benifit would it give? The main question I need answered is how do I determin the correct gap for the piston rings? I remember when Wizard was building his engine he mentioned correct ring gap will vary depending on what sort of boost you're running. I was just wondering how I was supposed to determine this. As to assembling the rotating assembly myself. Well, I've got a mate who has experience building engines that's gonna help me out, so I'm pretty confident we can get it right.
Taz, you are dead right.The rotating mass ( flywheel,crank,harmonic balancer)is dynamically balanced,the bits that go up (rods, pistons)and down are statically balanced. Check and read EVERYTHING in the Service Manual,and use it as your Bible for the re-build ( re ring gap check)
If you're not running big boost or going to be revving much higher than stock everything should be fine. As for blueprinting, there is much much more to get right than just having everything in balance but only go there if you want to get it as close to 'perfect' as you can! If you're going to be using a heavy clutch, I would suggest getting the inner end of the crank machined so that when all of the pressure is placed onto the crank, no bearings will starve from oil for that split second (if you are working with an experienced builder, he should know what part of the crank I am referring to) although I don't know anyone else that really bothers with it. If you wash the block, ensure you dry it with a compressor or something so that you don't get any surface rust (as it's a PITA to clean off later)
Would a triple plate OS Giken be considered heavy? My left leg certainly thinks it is. Thanks for the the tips guys, I'm looking forward to getting going with this.
Also the gaps in the rings should be 120° away from each other. In other words don't line up the gaps in the rings.
Really? I was just reading an article that said not to file them on an angle, that they should be square. So rule of thumb is .004 inches per inch of bore. But that is for a non turbo engine isn't it? How will boost effect this?
Hi is talking about gap location relative to the other rings. Make sure the gaps are not directly over the gap of the lower ring if that makes sense the gaps should be located at 120 degree intervals around the circumference of the piston. Also a triple plate clutch dont do it its not needed. The slotcar uses a heavy single and puts out 400+ rwkw. I use a custom hybrid single 5 puck with high clamp load and its awesome. Save you cash for some other mods. I have also heard they can damage zed gearboxes but have no first hand evidence as such.
Oh, oops, ha ha, yeah I get it. Yeah it says in the service manual how they should be lined up. The triple plat clutch was on the car when I bought it. I know it's complete over kill but I'm not buying a new one at this stage. My gear box still seems to shift pretty smooth.
Good luck With the rebuild Tazzy. You will have fun and gain a lot of satisfaction from doing it your self. Any questions ask away. Ring gaps will be fine for stock turbos, only if your running big power and boost do you need to gap them more. the top compression ring more so than the other as it cops the most heat and expands the most. my rebuild. http://www.aus300zx.com/forum/showthread.php?t=255459&highlight=rebuild
Thanks Wizard So the gap set by Wiseco should be OK, and it's just a matter of checking them to make sure they're right?
