Guest RCNSC Posted June 21, 2004 Share Posted June 21, 2004 I bought my 240Z on March 30, 2003. Its a yellow/orangy on black. 4 speed. Original motor with E31 head. One of the rocker arms is missing. It looks like the previous owner tried to replace it and chipped off a rather large chunk of a cam lobe. So... found an L28 in the paper. I was told it came from a '79 280ZX with 68K miles on it. It has the N47 head. I don't want to mess with the fuel injection. I want to keep my SUs, soooooooo is it pretty much just a bolt up install or what? Any tips/tutorials? Ricky Quote Link to comment Share on other sites More sharing options...
evildky Posted June 22, 2004 Share Posted June 22, 2004 with just a simple cam replacement your engine would be fine right? why not just throw a bumpy cam in it? if you want the larger cubes I'd look for a F54 N/A block, it has flat top pistons and if you stick your E31 on it you'll get over 10:1 comp ratio, the carbs will not bolt to the N47 head, the only injected heads thet readily accept carbs are the N42 and the P90, the N42 is basically the same as the N47 but without the sleaved ports so it flows better, do some searches on various head and block codes and you'll find tons of info here Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted June 22, 2004 Share Posted June 22, 2004 E31 on flattops on a street driven motor, I wouldn't do it, I believe compression would be closer to 11:1 wouldn't it? I know N42 no flattops is 10.3:1, and I know E31 is higher. Really, that would be too much compression for the street, IMO. I am also pretty sure that SU's will not bolt up to the N47 head. E31 on a 2.4 can make a nice, higher revving street motor, I do agree that it's not a bad idea just to replace the cam with a hotter one and replace the rocker arm and go. E31's are pretty rare/pricey/desirable these days as well... maybe a good reason to keep it, maybe a good reason to sell? Quote Link to comment Share on other sites More sharing options...
Guest RCNSC Posted June 22, 2004 Share Posted June 22, 2004 Ok I we talked it over and decided I'm going with L28 block, E31 head, new cam (cant afford hopped up one) and the SUs. Thanks for the replies. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 22, 2004 Share Posted June 22, 2004 I can tell you that from personal experience a flat top L28 with E31 head won't run on pump gas. I used the compression calculator and calculated mine at 10.3:1, but I now think that it is actually higher than that. I cc'd my chambers and polished them in an attempt to reduce pinging (even removed all of the spark plug threads that extend into the chamber), but I could only run pump gas with the static timing at about 5* BTDC. The car didn't make very much power with the timing set like that. When I put some higher octane gas in (mixed AVgas with 91 and also used Tolulene) and advanced the timing the car runs GREAT. VERY strong. But for day to day it is too much for pump gas. I think part of my problem was that I cc'd the chambers and then the head was shaved about .015, which upped the compression again. Sorry for the late reply, I read this before but I thought you were just swapping in the whole L28. If you do decide to run the L28/E31, get a BIG cam. It will help to bleed off the compression, and you MAY be able to run pump gas. Something along the lines of 300* duration should work. My .490/280 isn't enough. Jon Quote Link to comment Share on other sites More sharing options...
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