datsunlover Posted December 30, 2004 Share Posted December 30, 2004 Ok, I'm getting things going fianlly.. I droped off my N42 head to my friend/engine builder a few weeks back. I talked to him yesterday, and I'm just wondering what you guys think of my 'game plan' here.. He's gona put in new valve, seals, springs, shave .010 -.015" off it, port match the intake/ehxast maifolds to it, and instal a cam from Colt cams (out in B.C.) Yes, he's going to shim the cam towers and get new lash pads as well. I think (shoud have writen this down.. doh..) the cam has 280* duration and .510 lift, with 108* lobe separation... does that sound right? My builder figures with the head work and this cam, I should be able to spin it to 6500+ RPM reliably, and will have loads more torque from about 2500 all the way up. Ready to bolt on my engine, $650 cash. The bottom end wasnt making noise or anything, so I'm hoping I can get away with new rings and hone it/re-bearing and new gaskets. (waiting for a price on that stuff) What do you guys think? Gona run SU's, 2.5" exhast, and zx dizzy w/MSD box.. power guesses anyone? Quote Link to comment Share on other sites More sharing options...
drzed Posted January 5, 2005 Share Posted January 5, 2005 I have used that cam from Colt Cams in several motors before. Depending on the rest of your combination it should make excellent power from 3000 - 7000. Geoff knows his stuff and is one of the most honest people you could deal with. He also has a great turbo cam if anyone is looking for one. Tell him DRZED sent you "www.coltcams.com". O.K. now to the engine. I need to know piston and block specs in order to determine the compression ratio. That cam worked "good" in my 240Z when it had 9.0:1 compression but when I bumped it up to 10.6:1 it was way better. The engine makes more bottom end torque and has lots more power everywere. Post more details and I'll give you my .02 So far your combo sounds similar to my 240Z engine (less the carbs). Also what do you want out of the car in terms of performance? What do you do with the car? 1/4 mile? AutoX? Quote Link to comment Share on other sites More sharing options...
datsunlover Posted January 6, 2005 Author Share Posted January 6, 2005 Well I'm still not sure what I have for pistons (have yet to pull the motor.. soon..) but it is stapmed N24 onthe drivers side of the block.. I'm assuming it has dished pistons.. It's been rebuilt (10+ years ago) already, so I have no idea what my piston hight/ect is going to be, but in the end, I'm going to be shooting for close to a 10:1 CR. As for what I want out of the car, well.. it's a toy. I'm not much for 1/4 mile racing.. I'll probly run it a few times, just to see what it'll do.. But mostly, I just rip around town.. drive double the posted speed limit on ocasion down curvy/hilly back roads, and sometimes put a Civic in its place.. (Although one civic put ME to shame last year.. ) I'd like to get into autox maybe, but mainly it's a street car. I don't mind a bit of a rough idle/ride or bad gas mileage so much.. it IS after all a 30 year old carb'd sports car.. They're suposed to act up a bit.. it's part of the fun! I'd like it to be a quick as it looks though.. getting spanked by 4cyl ricers sucks. I'll hopefully be getting the engin torn down next week, and I'll have my friend come over and take a look at it. Then we'll know what I'm dealing with, and can go from there. He's gona start on the head work, but doesn't wana take too much off it untill he knows what kind of 'room' he's got to work with. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 6, 2005 Share Posted January 6, 2005 That cam is a little bigger than mine which is a 490/280. I wish mine were a bit bigger than the one you're looking at but I think that's because of the triples. 510/280 sounds like it will do fine with SU's, and the build sounds good. Make sure he takes all the sharp edges out of the combustion chamber, even the spark plug threads that stick into the chamber. $650 sounds more than fair. That's a really good deal IMO. Power I'd guess somewhere in the 200 range. Should be fun. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted January 7, 2005 Author Share Posted January 7, 2005 I'm gona try to get over to my builders place tomorrow and see if he got pricing on my bottom end gaskets/bearings/ect, (I have to drop some cash off too so he will start the real work..) and I'll talk to him about the head. I'm sure he's already looked at it and decided what has to be done. I'll mention the sharp edges though.. He ussualy builds performance stuff, rather than just 'basic rebuild' engines.. This guy seams REALY interested in doing the head too..his words were; "A really interesting piece.. different and unique..I'd like to see you wooping stangs with it.." He said it looks like nissan did their homwork on the head design too.. he was suprised that it's from a 75.. and figures it sould make good power with the cam/better breathing. I'm getting excited already... Quote Link to comment Share on other sites More sharing options...
drzed Posted January 7, 2005 Share Posted January 7, 2005 The N42 block has dished pistons (this is what I used on my 9:1 engine). With your N42 I think you will be between 8.5:1 and 9:1. There is a program somewhere on the net called "lengine" which will help you calculate the compression ratio (Look up under Google). Try to go at least 9.5:1 to capture as much cylinder pressure as possible. Too low compression and that cam will make for a lazy engine. Other than that everthing sound great - including the price. You do have to watch those Civics - one of my buddies at the track runs 12.6 with the most plain looking NA civic - a real sleeper. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted January 7, 2005 Author Share Posted January 7, 2005 Well, next week when the motor comes out, he's gona come over with a depth mic and check things out.. My motor was rebuilt once already (10+years ago) so I have no clue what's been done to it, or what's in it.. and the head I'm working with has ALSO been rebuilt once, so we'll have to crunch some numbers to see where it ends up.. I could get the head milled to bump C/R I supose, but I don't really wana take more than about .030 off the head..(big cam tower shims, possibe timing chain issues..) I don't know what (if any) has been decked off the block either, so I'll have to wait to see.. Quote Link to comment Share on other sites More sharing options...
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