DeusEx Posted August 12, 2004 Share Posted August 12, 2004 Hey Guys Just a quick question, i am getting my cam from a N42 reground for my :P90 and i was wondering if anyone had any expierence with a reground cam in a similar set up, ie, im after the duration, timing details. What i want and what i have *the cam must be daily drivable (not overly agressive) *has to idle and start easily *Triple 45mm Webbers *Ported and Polished P90 *L28 with Flatops Any suggestions or details from people with a similar setup would be welcome Quote Link to comment Share on other sites More sharing options...
DeusEx Posted August 13, 2004 Author Share Posted August 13, 2004 Ok i put my cam in and was recommeneded the following grind Intake: opens @ 26 degrees BTDC (before top dead center) closes @ 66 " ABDC (after bottom dead center) add 180 " total 272 degrees duration Exhaust: opens @ 66 degrees BBDC (before bottom dead center) closes @ 26 " ATDC (after top dead center) add 180 " total 272 degrees duration so i guess that makes it 272/272 with 318 lift...does that sound about rigth? What do you guys think? Quote Link to comment Share on other sites More sharing options...
Drax240z Posted August 13, 2004 Share Posted August 13, 2004 We have a lot of success with this cam: Cam lift: .338 Valve lift (1.5:1): .506 Intake opens 30* BTC, Closes 70* ABC Exhaust opens 70* BBC, Closes 30* ATC. Works out to ~280 duration. Good power from 3000-6500. Really works well with triple 40's in street/autocross trim. Slightly lopy idle. What size chokes are you running? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 13, 2004 Share Posted August 13, 2004 I gotta agree with Drax on this one. I think my cam could be a little bigger. I have a .490/280 with triple 44s. Usually I think people tend to go too huge most things, but for some reason I've been hearing about or seeing lots of sidedraft carbed Zs with .460/260, which IMO is just not enough cam. Low end cam and top end carb = crappy. Sunbelt makes a really cool sounding cam with .537 lift and unspecified duration that John Coffey and I think another John (sorry I forgot your name) are using. It only uses one valve spring, so you reduce friction by a lot, and you can still spin it up to 7200 rpm. I think that will probably be my next cam. Only issue then is will it be necessary to fly cut the pistons for clearance. Search for Sunbelt cam and I'm sure you'll find the info on it. The last guy to get one actually got the phone number for Sunbelt and a price of something like $400 for cam AND the single valve springs. EDIT--Just noticed you're in Oz, probably better to go for the next hotter grind from your cam grinder then. Something in the .500 to .510 lift, and in the 290 to 300 duration range. Yes, it will lope. Quote Link to comment Share on other sites More sharing options...
johnc Posted August 13, 2004 Share Posted August 13, 2004 Sunbelt makes a really cool sounding cam with .537 lift and unspecified dura I would not recommend my Sunbelt cam for a street engine. Idle is 1,800 to 2,000 rpm and there's no power below 4,000 rpm. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 13, 2004 Share Posted August 13, 2004 I would not recommend my Sunbelt cam for a street engine. Idle is 1,800 to 2,000 rpm and there's no power below 4,000 rpm. Really? I thought high rpm idles like that were either for super long duration or very very stiff springs. I don't think you're doing the super stiff spring thing, because that would defeat the purpose of having the single springs... long duration??? The other guy was Mark, not John. Wasn't Mark going to put his in a semi-street car? Like something you just drive to the track... Dan Baldwin has a similar cam in his engine, but with more lift (possibly less duration?) He drives to the track. I wonder what his idle is set at? Here's that thread:http://hybridz.org/nuke/index.php?name=PNphpBB2&file=viewtopic&t=30595&postdays=0&postorder=asc&highlight=sunbelt+cam&start=0 Quote Link to comment Share on other sites More sharing options...
johnc Posted August 13, 2004 Share Posted August 13, 2004 super long duration Exactly. Idle rpm constantly varies from 1,800 to 2,100 because cylinders only get a good mixture every other or every third firing. Sometimes its only idling on three cylinders for a few seconds. Its a "special" cam... Quote Link to comment Share on other sites More sharing options...
johnc Posted August 13, 2004 Share Posted August 13, 2004 super long duration Some of it might also be the lack of a real flywheel, the Quartermaster 5.5" double disk clutch, and the 35lb crankshaft. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 13, 2004 Share Posted August 13, 2004 Good point. I wonder if might be at least marginally streetable with some rotating weight. Quote Link to comment Share on other sites More sharing options...
Dan Baldwin Posted August 13, 2004 Share Posted August 13, 2004 Mine ain't exactly like John's, I don't think. ~.550 lift, ~310 duration. Idles ~1000-1200, I do have to help it with the gas pedal sometimes, VERY lumpity:) Frequently accused of being a V8. Not too bad on the street as long as you don't care who beats you across the intersection! Nobody home below 3k. I think the 272/.477"(?) cam he's got sounds good for the street. I wouldn't go beyond ~290/.490" for a non-competition car. I've got 38 (39?)mm chokes in my 45mm carbs. Figger maybe 36mm chokes would be appropriate for this setup. Should be fun! Quote Link to comment Share on other sites More sharing options...
clarkspeed Posted August 13, 2004 Share Posted August 13, 2004 Keep in mind the compression of your motor has impact on how much cam you want to run. If your going to be over 10:1 with the flat tops and P90 you can run pretty good lift. If your at 9.5 or so then you will be limited more. I've been playing with cams for awhile trying to get the most power on pump gas (10.5:1). I ended up with 490 lift/290 duration being about the best. However, I RACE on this set up and I don't really like it at all on the street. Idle at > 1200 and dead until 3.5k on RPM. Great power 3.5-7k though. I had an old cam a couple of years ago I loved on the street. It had about 450 on lift with some extra duration. The bottom end torque on that engine was awesome and mucho fun on the street. I feel bottom end torque is most important for street engine vs. ultamate power. Much more fun to drive around. As much compression as you can stand with mild cam seems to be the best bet. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 13, 2004 Share Posted August 13, 2004 Maybe I'm crazy, but I used to drive my L28/E31 .490/280 with the triples in traffic with a 12lb flywheel and ACT clutch every day for ~5 years. Never bothered me, did just fine. I feel bottom end torque is most important for street engine vs. ultamate power. Much more fun to drive around. As much compression as you can stand with mild cam seems to be the best bet. Totally agree with this statement, which is why SU's are better street carbs, I also agree with the second part (with SU's). With triples though, I just don't see these standards holding up. I have a friend who just built a race motor and used the .460/270 cam and is now kicking himself over it. My first engine used a milder cam like that, and the triples couldn't suck enough air with it. Bottom line for me, if you're going to go triples, you might as well get a cam that allows you to use them for what they're good for--3K and up power. They aren't good for 1500 rpm pulls, if that's what you want you should sell the trips, buy some ported SU's and get the smaller cam. But that is just my opinion... Quote Link to comment Share on other sites More sharing options...
Drax240z Posted August 14, 2004 Share Posted August 14, 2004 The cam I spec'd above we've used on the following engines with EXCELLENT results: - Dished piston L28/E31, SU's. (8.56:1 CR) - Dished piston L28/E31, triple 40mm w/ 32mm chokes (8.56:1 CR) - Flattop piston L28/E31, triple 40mm w/ 34mm chokes (10.2:1 CR) - Flattop piston L31/N42, triple 40mm w 36mm chokes (9.8:1 CR) It works out as a great slalom grind. Very streetable. A bit lopey at idle but not bad. Idle ~800rpm. And as I said great results from 3000-6500rpm. (however still with some kind of power below 3000rpm, you can drive daily) Quote Link to comment Share on other sites More sharing options...
DAW Posted August 15, 2004 Share Posted August 15, 2004 I would not change to a bigger cam than you're using unless you increase your compression ratio. You're present ratio, unless you have overbored, is 8.8:1 because you have an F54 flat-top with a P90 (same cc as a P79), i.e., you have a stock 280ZX compression ratio. Unless you go to an N42/47 head, you would need to overbore to block oversized flat-tops), install Euro L28E pistons (pop-ups), or stroke it. I'd use the P90 head (it's already been reworked, overbore the block to 87mm and use +1mm oversized Euro pistons. Alternatively, especially on a budget, I'd just install std Euro pistons without disturbing the crank in the block and possibly not removing the engine from the car. If you do this, pull the head as an assembly with manifolds, etc., on it, using an engine hoist to make it easier and it becomes a weekend project if you just replace the pistons. Once you've increased the compression, your throttle response (and gas mileage) will increase and you could consider a bigger cam. I suspect Drax's performance gains were significant when he went from 8.56:1 to 10.2:1 on his L28/E31 engine, both with same triple sidedrafts, displacement and cam but a change in pistons to increase compression ratio. DAW Quote Link to comment Share on other sites More sharing options...
DeusEx Posted August 15, 2004 Author Share Posted August 15, 2004 Wow Thanks for all the input, didnt expect to get such a good resonce. Well i got the cam in anyway, its a 272/318 (cam duration, not sure what the whole duration is with lash pads and tappets). Its noticeibly lumpier, power comes on from about 2.5-god knows what (i cant tell cause i have no tacho, damn MSD ignition and no one knowing how to get the tacho to work). So the results are good, i lost the smooth acceleration and low down power, but it now revs alot harder and the power increase is noticible. My compression is roughly 8.75 (slightly bored out) and im assuming with an N42 the thing would really fly. It seems to starve a little up top (for fuel) but im gonna ring around today and see if i need bigger jets or a new tune for the new cam. (btw they are 45mm chokes) So time will tell if im happy with the setup, and explaining to people that yes..that noise is a good thing, yes...its not meant to be smooth. Thanks for your help guys Quote Link to comment Share on other sites More sharing options...
JFryer Posted August 16, 2004 Share Posted August 16, 2004 What year Tach? 74-78 Tach is vey easy to mod to work with the MSD. Check out Zhome.com for instructions. Quote Link to comment Share on other sites More sharing options...
clarkspeed Posted August 17, 2004 Share Posted August 17, 2004 To each his own. I guess everyone has a different view on what a street engine should be. Personally, I've never liked driving a race engine on the street and consequenty never liked racing a street engine. Anything in between is a compromise. Bottom line for me, if you're going to go triples, you might as well get a cam that allows you to use them for what they're good for--3K and up power. They aren't good for 1500 rpm pulls, if that's what you want you should sell the trips, buy some ported SU's and get the smaller cam. You can tune the trips for a good bottom end torque also. A friend of mine, best webber tuner I know, built an excellent set up street 10:1 L28 240 recently. I know he choked down the carbs some. He ended up with around 480" lift. Good gas mileage, and instant power off idle. Waste of good carbs? It still looks, drives, and sounds cool to me. Quote Link to comment Share on other sites More sharing options...
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