BobbyBreeze Posted August 7, 2017 Share Posted August 7, 2017 On 8/4/2017 at 14:18, RUNAMUCK said: Here's a question on a flat Tappet engine, if you fit a fully hektik race cam, they say to break the cam in on stock valve springs/only run the outers if you have nice new doubles. On like a Datsun A series, it's not a hard job to swap them after the cam is broken in. But how about on an Ohc motor like say a CA18, or an RFB (de/det obviously) if you fit monster cams, you're obviously gonna Rev the clacker off it. Requiring uprated valve springs. How do engines such as this go? It's pretty much a head off job to swap the valve springs on one of those motors. @BobbyBreeze? Just have to run them in on the high rate springs. Its not really an issue if you follow a good break in procedure. Flat tappets seem to like to wipe themselves on pushrod motors a lot more than OHC. My guess is it has more to do with how they generally use lobe taper to ensure lifter rotation - incorrect lifter bore angle/clearance, lobe taper, lifter radius or cam end float can easily stick a lifter. DOHC use a flat lobe offset off the bucket centreline to rotate them, quite a bit less to go wrong. 3 Quote Link to comment Share on other sites More sharing options...
Steelies Posted August 7, 2017 Share Posted August 7, 2017 On 8/4/2017 at 18:09, NickJ said: We get pretty much that cnc bent by autobend, always comes out pretty good. Grinding plastic and high tollerance? not something heard often, that has me interested to hear more about need to rotate a plastic rod inside a tube with science happening in the gap between the two, so the gap needs to be pretty uniform. had some rods ground overseas to required spec but would rather get them done local. Quote Link to comment Share on other sites More sharing options...
NickJ Posted August 8, 2017 Share Posted August 8, 2017 12 hours ago, Steelies said: need to rotate a plastic rod inside a tube with science happening in the gap between the two, so the gap needs to be pretty uniform. had some rods ground overseas to required spec but would rather get them done local. Sounds just like some of the silly stuff we get involved with, but centerless grinding is not a station we have, I was interested as the dimensional effects from temperature can be quite extreme in plastics that I assumed they would overpower the benefits of grinding? Quote Link to comment Share on other sites More sharing options...
Steelies Posted August 8, 2017 Share Posted August 8, 2017 yeah good point. the main thing for us is a constant gap, rather than the gap size. the whole machine is alloy/glass/ceramic/PEEK and is a nightmare to keep stable so temp issues are further down the list. of course the first thing the users do is temp cycle them well out of spec haha. found someone here who can supply PEEK rod to H9 at 16mm but the stuff we got done elsewhere was to a quarter of that, so they win and we send stacks of short rods across the globe for grinding, joy! Quote Link to comment Share on other sites More sharing options...
PINTO Posted August 8, 2017 Share Posted August 8, 2017 Hai Spam. Looking for old school roof rack rubber feet, for they old chevette's 40th burfday, anyone know who sells them in NZL? SLURP SLURP Quote Link to comment Share on other sites More sharing options...
tortron Posted August 8, 2017 Share Posted August 8, 2017 Try www.comac.co.nz 2 Quote Link to comment Share on other sites More sharing options...
Steelies Posted August 8, 2017 Share Posted August 8, 2017 Rubber Bits Petone, maninga. 1 Quote Link to comment Share on other sites More sharing options...
PINTO Posted August 8, 2017 Share Posted August 8, 2017 Cheers team, Nick found me some on Basics site also http://www.basisnz.co.nz/Products/Hardware/CUP-(296-133B) Quote Link to comment Share on other sites More sharing options...
PINTO Posted August 8, 2017 Share Posted August 8, 2017 18 minutes ago, tortron said: Try www.comac.co.nz Flip they have some well priced stuff! thanks again 1 Quote Link to comment Share on other sites More sharing options...
PINTO Posted August 9, 2017 Share Posted August 9, 2017 On the same topic these clamps / turn buckles have been nicely done http://www.trademe.co.nz/motors/car-parts-accessories/roof-racks-bull-bars/auction-1389381230.htm 1 Quote Link to comment Share on other sites More sharing options...
datlow Posted August 9, 2017 Share Posted August 9, 2017 On 4 August 2017 at 17:30, RUNAMUCK said: How many kms has it done? I recently acquired a vq. And I have no desire whatsoever to lay a spanner on it. 235k, seems to be the early vqs that suffer heard a few 350zs needing valve seals the maximas suffer supposedly from the cats being too close to the engine and the bits of magic inside them flakes of gets swirled around and back into the engine and fucks the bore also have no interest in finding out which one it is so just feed it the good (cheapest) oil and will continue to drive till it dies 1 Quote Link to comment Share on other sites More sharing options...
RUNAMUCK Posted August 9, 2017 Share Posted August 9, 2017 They go hard for what they are to be sure. 1 Quote Link to comment Share on other sites More sharing options...
NickJ Posted August 9, 2017 Share Posted August 9, 2017 11 hours ago, Steelies said: yeah good point. the main thing for us is a constant gap, rather than the gap size. the whole machine is alloy/glass/ceramic/PEEK and is a nightmare to keep stable so temp issues are further down the list. of course the first thing the users do is temp cycle them well out of spec haha. found someone here who can supply PEEK rod to H9 at 16mm but the stuff we got done elsewhere was to a quarter of that, so they win and we send stacks of short rods across the globe for grinding, joy! Ahh, PEEK eh, I'll have a chat to our machinists if they can think of anyone who would get involved. On a side note I was cryo testing conventional plastics earlier in the year and the amount samples bent out of shape was very amusing, not to mention the contraction! Wish I had some PEEK to throw in at the time, its not meant to move much at all. Quote Link to comment Share on other sites More sharing options...
Steelies Posted August 9, 2017 Share Posted August 9, 2017 chur! 165 mm lengths. using peek for it's low NMR signal spec'ing these parts at 20-70ish degrees if possible. in a previous version 70 was where the peek grew enough to explode some other parts, haha. would be interested to know how much a turned/ground natural peek rod bows with temp changes, and whether it can be relieved in some way. might have a play myself. Quote Link to comment Share on other sites More sharing options...
Steelies Posted August 10, 2017 Share Posted August 10, 2017 it was an end plug in a glass tube, sized to max out at 70deg. shit went ping! pretty limited in materials because of this nmr jazz. https://en.wikipedia.org/wiki/Nuclear_magnetic_resonance 1 Quote Link to comment Share on other sites More sharing options...
HighLUX Posted August 10, 2017 Share Posted August 10, 2017 I have no idea what your upto but it sounds like interesting witchcraft 4 Quote Link to comment Share on other sites More sharing options...
Transom Posted August 10, 2017 Share Posted August 10, 2017 I just read that NMR wiki page and now I have even less idea what they are on about ... 2 Quote Link to comment Share on other sites More sharing options...
Popular Post Steelies Posted August 10, 2017 Popular Post Share Posted August 10, 2017 i dont know what they do with the stuff either, hence link instead of explanation. here's something far more interesting. 13 Quote Link to comment Share on other sites More sharing options...
Yowzer Posted August 10, 2017 Share Posted August 10, 2017 Is that powered from the axle? Quote Link to comment Share on other sites More sharing options...
NickJ Posted August 10, 2017 Share Posted August 10, 2017 Give it a hoon, can anneal thermoplastics, results can be interesting/frustrating, starting from rod it might pay to machine the skin off first and then make the part from the core. 11 hours ago, nzed said: PCTFE is great in the cryogenic temps. PEEK isnt great - it has no low temp goodness, it's designed more for higher temp, its hardness is probably what would assist it in lower temps though? I've only seen it while designing other parts, has a low CTE which is why I remembered it but I haven't done much else. 1 Quote Link to comment Share on other sites More sharing options...
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