JohnH
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Posts posted by JohnH
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I believe the piston crown material starts around the bottom ring landing on the fire ring of the stock flat tops. I'm just going by memory as its been over a year. Should be easy enough to measure with a piston in hand.
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Depends on how much piston valve clearance you need. I have cut 1.5mm eyebrows into the stock l28 flat tops that was required for a 530 lift cam & a highly shaved N42 using a 1mm head gasket. Without the eyebrow reliefs I was getting slight valve marking on the piston crowns. I used the old hotrodders method. I brought the piston to be relieved up to TDC, taped off completely around the piston (oil & water ports also), JB welded 80 grit heavy pad backed sandpaper to an intake & exhaust valve, lubed the stem portion of the valves & popped them into the head, sat the head on the block, used depth stops on the valves for the required 1.5mm, attached an electric drill to valve stem top & created valve reliefs, lifted head off, vacuum up piston shavings & repeat. This is of course sans cam, cam towers & valve springs on the head. Engine is currently running & have had no problems in this regard. There are plenty of similar method valve relief cutters out there for US domestic V8's but I could not find any in a L28 size. I would say perhaps 2mm would be pushing it for valve pockets on stock flat tops.
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Stahl and Nissan Motorsports make headers with primaries that are 1 3/4" diameter. The collectors I can't comment on. In the exhaust section of this website is a thread talking about Stahl not making the headers anymore though you can buy the tubes and weld them I think.
Or you can go with a header from Japan, there are a variety that have large diameter primaries, and the majority of them are very expensive. Anywhere from $800-2500 US.
The biggest is not always the bestest
Stahl Headers is going out of business. They no longer make an assembled header. There may have a header kit left in their inventory sell off.
Nissan Motorsports no longer makes a race header (among most other parts) for the L-series engine.
For a decent size race header you will have to look to the Japanese aftermarket $1000 - $2500 this side of the Pacific (Kameari, Fujitsubo, Trust) or have one custom fabricated.
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You DIVIDE by rocker ratio. Do some measurements. For example, set clearance at cam to 0.010 for intake per stock spec. Measure at valve is 0.007.
According to Racer Brown you have that calculation wrong.
"Any material removed from the base circle radius of the cam lobes (1/2 the base circle diameter) must be replaced at the valve stems as a function of rocker arm ratio. The stock cam base circle diameter is 1.300 inches 0 a base circle radius of 0.650-inch. Now assume that the base circle diameter of the new cam is 1.200 inches (0.600-inch base circle radius), 0.050 inches smaller on the radius than stock. The book gives the stock rocker arm ration as 1.5 to 1, but I have found that 1.48 to 1 is a more reliable number, although we may be quibbling. Multiply the 0.050-inch difference in base circle radius by the rocker arm ratio --say 1.5 to 1, and you come up with a number 0.075-inch. This is the amount the calve lash pad must be increased in thickness over and above the stock lash pad thickness for the rocker arm geometry to come out someplace close to stock, assuming nothing else has been changed."
datsport.com/racer-brown.html
see Rocker Arm Geometry
I think you should do some measurements on your heads & all the other peoples heads you have "helped" with your "calculations".
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Wow, that BC is tiny. Hope you got lots of head, manif and high CR for that cam. Schneider has 220's. I used SS feeler gage stock and cut little squares to fit under the lash pads. Lets see, calc lash pad thickness:
Pad = (stock BC - cam BC) / 2 / rocker ratio + stock lash pad = ((1.3 - 1.056) / 2 / 1.5 ) + .117 = .198
Something's wrong. Is your head a P90? NewZed may be on to something re valves being trimmed too much to equalize. I NEVER trim my stem tips, cuz of loss of tip hardness.
If you can, remove springs and measure inner pocket height (inner spring perch to stem tip without shims. Should be 1.610 - 1.625 on new N42. Outer pocket will be .050 more. Of course depends on if new valves, new seats or how much grinder pocketed valves into head. Normally, exh valve pocket taller by .020. Did you use any cam tower shims?
My base circle is 1.25I, 1.23E and I am using 160/140 pads
My SS-56-SS-54-112 RB cam used 200I/175E pads
Nope. Brand new valves for N42 head. Head has been shaved & ported & will be fueled by triple 45's
My calculations. Rounded off to nearest 10th inch
(1/2 base circle diameter of stock cam - 1/2 base circle diameter of reground cam) x rocker arm ratio + stock lash pad thickness = new lash pad thickness or X
(.5 x 1.30 - .5 x 1.056) x 1.48 + .120 = X
(.650 - .528) x 1.48 +.120 = X
.122 x 1.48 + .120 = X
.180 + .120 = .300
Verified by visual wipe pattern inspection on rocker arms at random exhaust & intake springs.
The .300 lash pad is not out of the ordinary for this .530 lift re-grind when considering the recomended lash pad from Isky for the fresh billet new cam is .260 ". Hence where I got the .260 " lash pads. What is out of the ordinary are companies that expound on being Datsun Z specialist's can't keep a relatively inexpensive & common part on the shelves. The amount of common parts that are no longer availble or becoming rarer is enough to question the viability of keeping an L series engine in the Z.
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This is from Mike of MSA.
"At this time all of the lash pads are out of stock. I spoke to my buyer yesterday and he is thinking that Nissan is going to discontinue the lash pads in all sizes. It has been getting more difficult to get them from Nissan. We are currently looking to see if there is a manufacture that will and can make them for us.
Mike"
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Base circle measures 1.056". Ramps look fairly steep too. Maybe too steep. The retainers are .230" deep measured from the top of the retainer to the top of the valve stem & were used with .260" lash pads. With the .260" lash pads & .040" cut worth of feeler gage underneath the lash pad sits about 3/4 in the retainer.
dapiper What did you use to shim your pads? As Xnke mentions Rockwell hardness is a concern of mine. I can get "blue steel" tempered shim stock in .042. sheets but would have to cut shims to shape. I have also been combing the internet for valve shims used on other vehicles & motorcycles but have not found a compatible diameter or thickness yet.
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Is it a safe & reliable to shim the lash pads for normal engine use. I have a Nissan billet 530 lift regrind that I checked the rocker wipe pattern on & requires a .300 lash pad. I'm having difficulty finding .300 lash pads. MSA does not have them at the moment, Brian at Z Car customs is on vacation, Courtesy does not have them, Nissan does not have them & I'm waiting back to hear from others. I have .260 lash pads & Isky retainers so I would only shim them under the pad .040. Any thoughts on this or anyone know where I can get a set of .300 L6 lash pads.
Thanks
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Thanks guys. I do have a Nismo multi hole cam sprocket somewhere around but I think I might go with a Tomei or Kameari slide adjustable sprocket & degree the cam in sans cam tower shims.
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Pardon my ignorance, but wouldn't you install the cam with zero timing advance? The big advantage of the Kameari part is to take up the extra slack created when shaving the head. With the cam dialed into zero advance and the crank at TDC, the relative location of links on the timing chain are irrelevant because the chain will maintaing the relative position of the cam and the crank.
Am I wrong?
The Kameari twin gear tensioner can be adjusted for chain slack. However that chain slack is only on the slack side of the chain path (passenger side of engine). The drive side or constant tensioned side if you like is always a fixed distance from the crankshaft timing chain drive to the cam sprocket. If you use the stock cam sprocket in its # 1 position & don't shim the cam towers after the head is milled the cam timing will be retarded by the amount milled as the distance between the cam center line & the crankshaft center line has now been shortened. This is of course when timing from TDC from the shiny chain marks (42 links between cam mark & crankshaft gear mark) which begs the question if one can advance the cam by one tooth on the cam sprocket & how much is that in degrees as oppose to the 4 degrees advance of the #2 cam sprocket position.
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Let me put it a different way "How much cam retard does milling a head 80 thou cause while using a perfectly good timing chain?"
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I have be searching around trying to find some definate answers. I'm replacing a head on a F54 flat top N/A setup. The N42 head that I'm putting on has been milled 80 thou. I have a Kameari twin gear chain tensioner with a relatively new chain (under 5K). If I do not run the shims under the cam towers can I advance the cam sprocket to the second position so the cam timing would be correct. Would the stock cam sprocket 2nd position be enough or too much advance or would an adjustable cam spocket like Tomei help. The Kameari tensioner will take up the dreaded slack in the chain so I'm not worried about that. Its the cam timing I'm concerned with if I do not shim the towers.
I found a couple of threads which have vague references.
This one but the orginal question was ignored & not responded directly to.
and this one which has a vague reference
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Would you like some panel bond to play with John?
I might take you up on that next IMSA style Z I do.
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I don't trust chemical adhesives with differing types of materials. I would pop rivet the parts on then blend the seams into the existing body work. Old school but its tried & true.
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"Lol this again.
To say the least, the little cone nozzle thing was actually just a baffle to quiet the car down since apparently they drive them around a little too. For the cranks, mill 6mm off the back flywheel flange (don't mill where the pilot bearing goes... please) and then drill and tap the flywheel bolt threads deeper. I would also put 2 more dowels so you have a total of 3 on the back. The front of the crank snout is modified to use 1 big key instead of 3 small keys. I believe this keeps them from walloping out. You can see in the picture of the crank they show it. At first I was like what the hell are they trying to show and then I read more about it. I'm not sure how they go about putting one huge key in the crank though... Is it just a steel piece that they tap in?"
After reviewing this thread again to see if there was anything new added, I was doing a search on the net for Japan based S30 products. I came across this link that says it all regarding "exhaust nozzels".
http://www.rhdjapan.com/nissan/s30-fairlady-z/silencers-ecvs
As stated in this thread either in obvious print or between the lines, the 400hp n/a power Japan biulders are making is based on a stroker with good $$$$ head work, matching cam & induction system. No secret - except for the finesse craftsman details. There is absolutely no reason anyone outside of Japan cannot replicate this without some $$$$, patience & R&D on their own. The Brad Frissele race car is reported to produce 400HP & that is on GTU engine specs.
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No Comment....
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Nice work. I have Brians Gnose installed with the extra aftermarket JDM lower chin air damn on my Z. Just a curious question - what are you going to do about fuel filling as I have noticed no fill port in the posted pictures.
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A rear diffuser must work in conjunction with front end & mid section areo mods. Basically a flat plane of narrow road to vehicle under surface height must be created in front of the diffuser which will channel air from the front of the vehicle to the end of the diffuser. Its this venturi effect that cause a low pressure point that enables downforce.
for your reading & viewing pleasure.
http://www.racecar-engineering.com/articles/f1/316271/diffusers-explained.html
.46 minute on the youtube video
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Try Z Car Customs http://www.zccjdm.com/
Brian has custom copper gaskets as well as Kameari steel gaskets.
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John,
Do you know why it failed? Were you using the special bolt/washer with the BHJ damper of the stock crank bolt?
I believe mine failed due to the inherent rockwell difference between the crankshaft & the dampner hub materials. Having removed & installed the dampner a few times loosened the press fit of the hub. NO mention of a special bolt/washer combination was made in the information/installation materials from BHJ on this specific dampner.
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I would not buy a BHJ dampner ever again. At least the ones with the aluminum hub. I have had one fail due to the aluminum hub. Completely wrecked the crankshaft keyway. Aluminum hub on a steel crank = fail. I'm not the only one on this board who has had this happen. I'm currently using the SFI spec, single V, steel hub dampner from Powerforce Professional Products with the special bolt/washer sold at MSA for half the price.
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Thanks everyone, I figured I had it tensioned too tight. From what I could discern from the instructions Kameari calls for a regular inspection of the locking plate bolts every 3000 km. The TI Baby locking plate adjuster arm is just extra insurance the tension stays constant if the Kameari plate does come loose. I would not call the TI Baby useless as you would have to figure a market necesity for an independent manufacturer to design & sell this specific specialty product in Japan.
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I can't translate the instructions. How much tension should be applied to the tensioned side (left) of the chain assembly. I have around 1/8 play right now. Just wondering how loose or how tight the chain should be. I also have the TI Baby adjuster lock on it as well which I used to tension the chain before locking down the plate bolts.
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No TimZ I did not use the Nissan comp stepped washer. Regular dampner washer.
Bryan not a very encouraging response back from BHJ. What I read from Chris's reply is that essentialy people who bought these when they first came out were test mules. A part essentially designed for a race application that cannot be taken on or off on a regular basis on engine that may go through a few builds a year is just poor design. I don't think weight was a factor over the dampner not coming apart at high RPM's when compared to stock dampners. So another $225 plus shipping & duty to get this fixed. NO THANK YOU BHJ. I will take my money & my word of mouth to another company that actually engineers a dampner that does not fail because you have taken the dampner off the engine to do some work.
Side mirrors that don't suck
in Miscellaneous Tech
Posted
This is a real pet peave of mine. I'm still in the process of looking for decent door mirrors, I had the MSA racing style mirrors & they were just plain crap. They were loose, cheaply made & one retaining mechanism on a plastic base failed. I next bought the Vitaloni California mirrors from MSA (currently on the car). They are also crap. Poor visibilty & I cannot get the retaining screw tight enough on the arm for them to stay put so they end up sagging at speed. Contemplating JB welding them in place. I was also looking into the Pegasus GT mirrors & ebay open wheel racing style ones (similar to one posted in this thread) but that arm/mirror style appears to be flimsy based on a screw set & ball socket joint & sometimes 2 pivot sockets a mirror. Although those high quality motorcycle mirrors thedarkie posted look interesting I think what is needed is a solid body mirror enclosure where the mirror lense itself is the only part that moves. I remember really liking the door mirrors on the 280ZX I had. I have one spare right side that I'm going to test fit next. I also heard the first gen RX7 has decent door mirrors for an S30.