JCan Posted June 3, 2013 Share Posted June 3, 2013 Leon. Are you going to adjust the valve to cam lash yourself or have the machine shop do it? If you have the machine shop do it, that means you have your custom cam? Im really excited to learn what you did and how it works! On another topic, I believe you are using tripple webbers right? Are you going to use the stock fuel rail? if so, pay close attention to the return line. I learned (from steve at ztherapy) that the return outlet tends to get clogged (the tube diameter is reduced at the output to set pressure in stock cars). I believe that having gas continuously flowing from the gas tank to the carbs and back helps keep the gasoline cool and helps eliminate vapor locking. Lastly, I am very interested in learning what head gasket you end up using and what you expect your head to piston gap is. Good luck! Jim Quote Link to comment Share on other sites More sharing options...
Leon Posted June 3, 2013 Author Share Posted June 3, 2013 (edited) Thanks Jim! I'll be assembling the head myself, so no custom cam yet. If I run into an issue of a custom grind being way too expensive, I'll have to settle for Isky's Stage 3 as I think it'll be close to what I'm looking for. Either way, I'd like to experiment with a custom grind at some point, even if it doesn't happen this time. I'm still working on my cam sizing spreadsheet. Still need to figure out minimum lift and overlap numbers... The triple Webers on my orange car use the stock fuel rail, with the feed coming in at the front carb, daisy-chained to the rear, and back into the fuel rail. I plugged the return almost 2 years ago when chasing a fueling issue (turned out to be the filter) and never unplugged it, although I probably should. I've not had vapor locking issues though, even in 100deg+ heat at Long Beach last year. On this Z, I'm doing away with the stock rail altogether and will be using AN lines, with a return. Good thoughts on the head gasket and piston-to-head clearance, I'll report when I find out. Edited June 3, 2013 by Leon Quote Link to comment Share on other sites More sharing options...
Leon Posted June 3, 2013 Author Share Posted June 3, 2013 Current to-do/buy list: - Regrind rockers (I know Delta Cams does it for a good price) - sourcing 2mm/0.080" cam tower shims (considering making these myself or buying from Derek) - sourcing longer valves (Rockauto or SI) - low profile valve stem seals (FEL-PRO SS72686, thanks for the tip Leo!) - figuring out my cam and springs, lash pads may need replacement (Isky) - Head gasket (unsure...) - Manifold studs and gasket (MSA/Rockauto/local) - Valve spring shims (not yet found) Quote Link to comment Share on other sites More sharing options...
JCan Posted June 3, 2013 Share Posted June 3, 2013 Leon. Stage 3 cam?!!!!@!@ WOW! Will you have to notch the pistons to accomodate the valves with this 0.490 lift cam? it has a 72 degree valve overlap but should provide excellent torque out through 7kRPM right? meaning that you should be able to race through 8krpm?! Now my question. You have balanced the crank, pistons, flywheel, pressure plate. Are you going to lighten the flywheel/clutch assy? What pulley will you put on the front of the motor? If you look at the stock pulley you will notice that it is drilled (I believe to balance the motor used in initial production). I left mine alone, do you plan to balance this pulley with the crank? It is something I overlooked when I balanced my motor. In my build, I did not use valve spring shims, but purchased new springs from isky. I believe all you have to do is tell him that you have increased the resting spring distance 2mm and he can either tell you that the spring is okay by itself of change out either the inner or outer spring. Note: I used the springs as provided and found no issues (though I have only run the car for 300 miles). I have two felpro head gaskets that I purchased new and used to measure piston to head clearance so therefore they have been torqued down once but have not been run in the car for any length of time. I am happy to mail them to you if you want to use them for piston to head measurements. I also have valve springs (inner outer) spring caps and lash caps from the p90 head i used if you need them. Fun stuff! Quote Link to comment Share on other sites More sharing options...
Leon Posted June 3, 2013 Author Share Posted June 3, 2013 (edited) Fun stuff indeed! It should spin freely past 7k RPM but retain decent mid-range grunt. I wish I could race through 8k RPM but I don't think the pistons would like that very much. I'll be using a 10lb Tilton flywheel but undecided on clutch so far. I have a brand new stock clutch that I can use but unsure of how much stress it will take. Great info on the springs, thanks! I was going to do just that, talk to Isky and see what they think. I think I'll end up being OK without any spring spacers, it was just a note I wanted in there so I keep it in mind.I'll take you up on that generous offer! I'll take the head gaskets. Just let me know how much and where to send monies to cover postage. Edited June 3, 2013 by Leon Quote Link to comment Share on other sites More sharing options...
Leon Posted June 6, 2013 Author Share Posted June 6, 2013 Strike a few things off the list... - Regrind rockers (shipping off to Delta in next couple of days) - sourcing 2mm/0.080" cam tower shims (considering making these myself or buying from Derek) - sourcing longer valves (SI has great prices) - low profile valve stem seals (FEL-PRO SS72686 bought on ebay) - figuring out my cam and springs, lash pads may need replacement (Isky) - Head gasket (will probably get Fel-Pro) - Manifold studs (MSA) - Manifold gasket (Rockauto) - Valve spring shims (TBD) In the meantime, Jim sent me some head gaskets to use for piston-to-head and valve clearance checks (thanks again Jim!). Also, the machinist called yesterday to inform me that the crank needs turning, as the journals have rust on them. I'm now on the lookout for a stock L28 crank in good shape (posted a WTB ad here). I've got some local guys on the lookout as well. If I can't find one soon, I'll have to get mine turned and balanced. We'll see what happens... Quote Link to comment Share on other sites More sharing options...
Leon Posted June 7, 2013 Author Share Posted June 7, 2013 (edited) Already got a possible source for a crank thanks to the local network (thanks Leo and Kyle!). The parts are beginning to trickle in... Edited July 6, 2014 by Leon Quote Link to comment Share on other sites More sharing options...
Leon Posted June 8, 2013 Author Share Posted June 8, 2013 (edited) A few more knick-knacks... Edited July 6, 2014 by Leon Quote Link to comment Share on other sites More sharing options...
Gollum Posted June 8, 2013 Share Posted June 8, 2013 Keep us updated on how the valve stem install goes. Even braap says he tends to rip them from time to time. Quote Link to comment Share on other sites More sharing options...
Leon Posted June 8, 2013 Author Share Posted June 8, 2013 Keep us updated on how the valve stem install goes. Even braap says he tends to rip them from time to time. Will do. I did read his thread on how he installs them so I'll be extra careful (don't forget those valve stem condoms!). Quote Link to comment Share on other sites More sharing options...
Leon Posted June 8, 2013 Author Share Posted June 8, 2013 Oh, and those head gaskets came in too. Thanks again Jim, I owe you one! Quote Link to comment Share on other sites More sharing options...
madkaw Posted June 8, 2013 Share Posted June 8, 2013 What are you shooting for as far as head to piston clearance? Quote Link to comment Share on other sites More sharing options...
Leon Posted June 8, 2013 Author Share Posted June 8, 2013 What are you shooting for as far as head to piston clearance? I don't have a specific number in mind, but as close as I can get away with. I'd be happy with .025-.030". Quote Link to comment Share on other sites More sharing options...
Leon Posted June 10, 2013 Author Share Posted June 10, 2013 (edited) Got a polished and balanced crank yesterday (thanks to stravi757)! It'll go into the shop for a quick re-polish (specs of surface rust on some journals) and probably check the balance just to be sure. Edited July 6, 2014 by Leon Quote Link to comment Share on other sites More sharing options...
Leon Posted June 13, 2013 Author Share Posted June 13, 2013 (edited) Quick update from machinist: P90 chambers are 44cc. Now I don't know how accurately he cc'd them, but I was expecting closer to 46cc. Thus, my compression ratio will be just about 10:1 depending on compressed head gasket thickness. This is a bit more than I was anticipating but I think it'll be alright given the nice chambers of the P90 plus the hotter cam. He's shooting to have the machine work and balancing done by early next week. Edited June 13, 2013 by Leon Quote Link to comment Share on other sites More sharing options...
madkaw Posted June 14, 2013 Share Posted June 14, 2013 Surely a machinist would make an accurate measurement I think you would be okay with 10-1 with a hot cam, but you are in CA I would shoot for 25-30 squish regardless of CR Quote Link to comment Share on other sites More sharing options...
Leon Posted June 14, 2013 Author Share Posted June 14, 2013 Surely a machinist would make an accurate measurement I think you would be okay with 10-1 with a hot cam, but you are in CA I would shoot for 25-30 squish regardless of CR The uncertainty is about the valves not being installed. Maybe he temporarily installed them with the old springs and hardware? I'll clarify his procedure when I pick up the engine, and I can always double-check myself once I've lapped the valves and installed new hardware. I should be fine at 10:1 as long as I do a good job on the tune and minimize cylinder-to-cylinder variations. That will remain to be seen. Quote Link to comment Share on other sites More sharing options...
Gollum Posted June 15, 2013 Share Posted June 15, 2013 It's a 260Z. Not a huge concern being in CA unless he gets pulled over and for some random reason the cop decides he needs to go to a ref to check on part legality. As far as overall build principle. 10:1 is perfect imo if you're willing to tune it right. I plan to run MUCH higher on that on my build eventually but will also be unconventional in many ways. Right cam and the right tune and you'll be just fine. Quote Link to comment Share on other sites More sharing options...
JCan Posted June 15, 2013 Share Posted June 15, 2013 According to my calculations, on my motor, 46cc equates to 9.78 compression ratio and 42cc equates to 10.13. I guess we do not know how much the head was decked prior to milling (I worried about this issue during milling with my head). I agree that you should re-measure the cylinder chambers prior to engine assembly. I am beginning to like copper gaskets more and more. They come in your choice of thickness (.022,.032,.040,.043,.054,.063,.070, .086, .093, and .125 inches), they do not compress, and it allows you to build your motor exactly as you want it (noting that you can increase/decrease the gasket thickness slightly if you are shooting for a specific compression ratio. I purchase mine at Gasket works copper@headgasket.com for $135! Building motors is just fun! Quote Link to comment Share on other sites More sharing options...
Leon Posted June 15, 2013 Author Share Posted June 15, 2013 I measured the head with some vernier calipers before I took it in and the head seemed to be stock thickness (~108mm). It was in great shape and didn't look like it had been messed with. I plan to remeasure chamber volume just to be sure. I'll also measure head thickness to see how much was taken off. A copper gasket sounds nice but the $135 might be hard to swallow right now! I still need to decide on fuel line routing and order AN lines and fittings which will be a pretty big expense. I'll keep the copper gaskets in mind, Jim. Couple more things to cross off the list: - Regrind rockers (shipped to Delta last week) - sourcing 2mm/0.080" cam tower shims (ordered .080" 7075 shim stock yesterday ) - sourcing longer valves (SI has great prices) - low profile valve stem seals (FEL-PRO SS72686 bought on ebay) - figuring out my cam and springs, lash pads may need replacement (made cam sizing spreadsheet, still need to call Isky...) - Head gasket (will probably get Fel-Pro, maybe copper?) - Manifold studs (MSA) - Manifold gasket (turns out I have spares) - Valve spring shims (TBD) I'll also be going through boxes of parts this weekend and trying to inventory what I actually have. Quote Link to comment Share on other sites More sharing options...
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