Xnke Posted April 12, 2009 Author Share Posted April 12, 2009 Ok, so I installed and set up the cam this evening, just one chamber with stock valve, valve springs, valve seal, and retainer/keeper. I used a stock lash pad because it was on hand. Delta Camshaft grind # 280/480 Measured valve lift: 0.447" Duration at 0.050: 233* (pretty close to the 234* they claim, I'll call it good.) LSA: 108* With the stock springs, I had 0.049" clearance between coils, so the springs are not coil bound. This is a plus. On the other hand, the misrepresentation kinda upsets me, but I guess I can get over it. I can always get another cam later, I will be using the Ford Fel-pro seals and since I have a new set of stock valve springs that I forgot completely about, (I found them in unopened Nissan boxes in the driver's side tool box/hidden compartment) I will use those for now. I don't plan to really be hammering on the car on the street, but I do plan to take it to the track for some test 'n tune sessions after it's broken in. If I go with a higher cam later, I'll swap the springs out for the Schneiders. Hopefully I'll find this cam agreeable. Zmanco, do you have your notes on the rest of your head setup? Assuming stock components, flat top pistons in 0.030 oversize, and a stock headgasket, this puts you at 9.2:1 compression. You say you still had ping at 4-5KRPM, and had to pull timing to get rid of it. If I run my head as is, no shave, I'll end up at 8.8:1 static compression ratio. (valve unshrouding produced a 46.6cc chamber) I wonder how much timing I'll have to pull to get it to run correctly? 10*? Less? More? Who knows. I'll just put it together and find out, I guess. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted April 12, 2009 Share Posted April 12, 2009 I had my CR calculated at 10.2:1. Setup was stock N42 head except for port matching and mild shave (.001 IIRC) to clean up, Delta cam, 0.030 over flat tops and Felpro gasket. On this and other forums I've seen a wide range of experiences with people running high compression and these open chamber heads. I wouldn't say my experience is typical: I've seen some very competent people run similar setups with full advance and not have detonation problems. There's clearly some other factor at work that I don't understand. But from what I've read, at 8.8:1 CR you shouldn't have any detonation issues, at least not from too high CR. Quote Link to comment Share on other sites More sharing options...
Pyro Posted April 12, 2009 Share Posted April 12, 2009 you are going to need thicker lash pad with that cam! I would guess 0.200". courtesy nissan sells them for 3.00/each. However, 0.160" is the thickest you can put in stock retainers. High performance retainer's typically had deeper retainer holes for thicker lash pads. If the lash pad is too thin the valve train will sound like a diesel and may eat the cam lobes if the wipe pattern goes off the rocker arm pad. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted April 12, 2009 Share Posted April 12, 2009 FWIW, on my head 0.180" lash pads resulted in a good wipe pattern. Pyro, I hadn't heard that .160" was the max for the stock retainers. I guess I've been lucky! Quote Link to comment Share on other sites More sharing options...
Xnke Posted April 12, 2009 Author Share Posted April 12, 2009 I had a perfectly fine wipe pattern with the stock 0.120" lash pad, but it was cheated to the lifter side. Still had about .7mm to go before the cam ran off the rocker. I turned up a 0.050" spacer to fit in the dish in the bottom of the stock lash pad, giving me a 0.170" lash pad, and had a perfectly centered wipe pattern for all the intake valves, I would need a 0.175" pad for the exhausts as they are currently. Since the head is getting the valve guides replaced, the seats need to be recut anyway, so all the lash pad measurements I make now will be subject to change, and hopefully my machinist will get the intakes and exhausts equal. (currently, all the intakes are the same, and all the exhausts are the same, but the intake is not the same as the exhaust.) Pending the response from Delta cams, I will probably run the cam anyway. If I need more, I'll get a cam ground to a true .480"/284*. Quote Link to comment Share on other sites More sharing options...
Pyro Posted April 13, 2009 Share Posted April 13, 2009 Even with an acceptable wipe pattern (at the edge of the pivot ball side), there will be a lot of clearance between the lash pad and the rocker arm even after the valve are set at a tight 0.008". The extra clearance at the lash pad makes the valve train sound like a diesel. If you want a quiet valve train then you need to set the wipe pattern closer to the valve side, and that takes thick lash pads and after market retainers. 0.160" max spec is in the "how to modify Datsun L series engines". stock lash pad retainer wells are shallow compared to aftermarket retainer wells. Quote Link to comment Share on other sites More sharing options...
Xnke Posted April 13, 2009 Author Share Posted April 13, 2009 Also noted in "How To Modify", ford valve keepers will also allow for thicker lash pads, as well as increasing retainer to stem seal clearance by a small amount. Quote Link to comment Share on other sites More sharing options...
Whittie Posted April 13, 2009 Share Posted April 13, 2009 Yep, NZ and Aust use RON, and the US uses SON or something I think. the ON stand for Octane Number, but the bit at the front means different things. NZ 91 equates to a US 88 I think (from what I have read in an AA article about taking your car travelling on a carnet du passage) so their 87 octane is still slightly under NZ base fuel octane. We have 91, 95 and 98 here in NZ. Bang on the money there Kiwi, AUS (and one would assume, NZ) uses RON and the US use MON and RON By definition: The octane number is the resistance of a fuel to pinging compared to iso-octane (100 octane). RON: Research Octane Number - Test Engine at full throttle and low engine speed (i.e, low speed driving around town) MON: Motor Octane Number - Test engine at high RPM (ie, racing) In AUS the spec is on RON alone. In the US the quoted 'octane' number is (MON + RON)/2 so it is the average of the two values. Typically MON is significantly lower than RON (from memory 5-10 points). Therefore, a 93 Octane american fuel is equivalent to a 98 octane australian fuel, or very close. Quote Link to comment Share on other sites More sharing options...
Xnke Posted April 13, 2009 Author Share Posted April 13, 2009 Ok, so I talked to Scott at Delta Cam today, and they had no idea that the cam was that oversold. I sent him my data, and he ran it against his data and a fresh cam grind, and agreed wholeheartedly that the cam they have been grinding for 25 years as a .480" lift cam really could only even theoretically achieve 0.450" lift! After years of hearing nothing but great reports about this cam, this is the first time he's actually personally run the numbers to figure out the lift figures. He's going to set up the fresh regrind on the measuring machine, and make out a new cam card to go with the cam. I should be receiving it shortly, via email. I'll post it up here for all others to see, as I'm sure there are more than just the two of us running this cam. Also, he offered to grind a new cam to the true 480 lift and 280 duration for me in the future, when I have the engine running, for my personal evaluation of the new cam profile. I explained that the engine would not be running for several months, and he said that would not be an issue, just call up when the time came and we'd get the details worked out. For now, I'll be running stock springs, and will have the Schneider springs and retainers ready when I go to the dyno with this cam and the as-yet-undelivered true "480/280" grind. I'll post before and after graphs, making sure to make minimum changes to other factors (fueling, timing, ect.) Quote Link to comment Share on other sites More sharing options...
Zmanco Posted April 14, 2009 Share Posted April 14, 2009 Thanks Xnke, I guess I could have/should have followed through with them, but I was glad to not have to replace the valve springs so didn't go any further. I will be very curious to see how much difference greater lift (with all else mostly equal) makes. Quote Link to comment Share on other sites More sharing options...
Pyro Posted April 14, 2009 Share Posted April 14, 2009 It is good to know what the lift and duration are. However on a L series datsun engine, the lift at the valve depends on the location of the wipe pattern, as this effects the ratio of the rocker arm. The amount of lash also effects the lift by a small amount. Furthermore, 280 degree cam compared to a 276 degrees cam will not be noticeable. Quote Link to comment Share on other sites More sharing options...
itsA280Ithink Posted April 22, 2009 Share Posted April 22, 2009 I actually built a hydrogen system to boost the octane levels in my friends combustion chamber. On a 383 stroker, he's running about a 13:1 and was tired of always using race fuel. i was playing with hydrogen sysems for a while and found out the MPG increase wasnt so great, but the octane boost and reduced carbon was worth it Quote Link to comment Share on other sites More sharing options...
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