Guest RCNSC Posted August 4, 2004 Share Posted August 4, 2004 Ok so this is the dealio. I bought my 240Z earilier this year. We started tearing into it lately. I planned on running an L28 block with the E31 head and carbs. Today Robert came over and we took off the head. To my dismay, the number 6 cylinder is FUKKED! He assumes it from detonation. Ok so no biggie.... Im not using that block anyway. Then I look at the head :( Im going to reuse it anyway. Now, I have an E88 head I can use... but its FI. It has the little grooves for the injectors AND it doesnt have the hole for the mechanical fuel pump arm thing. Is there way to use the E88 head with Carbs? If not, what if I use the E31, just smooth it out. Its going to be a daily driver, so if my performance isnt stellar oh well. I have to have a car to get to school with. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 4, 2004 Share Posted August 4, 2004 That thing looks like it dropped a valve and they just stuck a new valve in and put the head back on to me. I've seen engines put holes in the piston from detonation and the chamber didn't look that bad. If that happened from detonation that was a lot of detonation for a long time. The E88s all came with carbs. Even if you had a FI head, SUs bolt right up, so no worries. If you use an E31 head on an L28 with flat top pistons you'll be really detonation prone already (ask me how I know) and any sharp edges in the combustion chamber are going to have to be dealt with. You'll have to have that chamber welded up and then reground by hand, very expensive. Get another head is the answer to this one. I'm assuming that is the L24 block, if so no big deal, basically all that stuff is junk and you start over. If that is the L28 you could probably bore it and put new pistons in it, but a machinist could tell you for sure. Quote Link to comment Share on other sites More sharing options...
Guest RCNSC Posted August 4, 2004 Share Posted August 4, 2004 The L24 is the one with the bad cylinder. And yes, the previous owner said he dropped a valve and tried to fix it. The E88 came on my L28. Both the block and head are in good shape (68K miles) but its an EFI motor. How do I use the fuel pump with the E88 head? It doesnt have a hole cut into it for the fuel pump arm to go to the timing gear thing..... Plus the (intake?) ports have injectors spaces. Anyone got an extra E31 head theyll let me have for cheap????? Just let me know how to convert my FI E88 head to carbs and Im gung ho! Im broke and I realllllly want to go to the Z show the 14th. Plus, I can't do EFI because my dad stupidly cut the injectors trying to "help" me..... and thatd add another 6 months to my project at the rate Im going. I reallllly want to drive my car and school starts next week. BTW - the L28 has dished pistons. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 4, 2004 Share Posted August 4, 2004 The E88s all had mechanical fuel pumps AFAIK, because they came on 71-74 cars, which all had carbs. If I'm wrong, then just use an electronic fuel pump and just don't worry about the mechanical fuel pump. If you take a picture of the E88 we can tell you if it is the small chamber (will give you about 8.5:1 compression, same as an E31) or the open chamber (8.3:1 compression with the dished pistons). Either way it's not going to be a very high compression engine. You should be able to run 87 octane NO PROBLEM. Really doesn't sound like an E88 to me though. Have you SEEN it, or is someone telling you what it is? Have you got the L-series engine calculator? That would really help you about now... Quote Link to comment Share on other sites More sharing options...
CruxGNZ Posted August 4, 2004 Share Posted August 4, 2004 I was going to say the same thing about dropping a valve. My sisters '91 CRX had an exaust valve snap and fall into the cylinder creating almost exactly what your #6 cylinder shows. Her piston was cracked, exaust valve was gone, intake valve was cracked with pieces missing, and those valve chunks smashed the heck out of the spark plug. All these pieces from that one cylinder traveled from the #1 cylinder to #2, #3, and #4 cylinders, with less destruction the further away from #1 you got. I didn't know that debris could travel through an engine like that. The whole engine was toast and I had to replace it for her. She dosen't have good luck with cars. She recently bought a '94 Camry and 2 weeks later, #1 cylinder was toast. A simple test showed that the compression rings on the piston were shot. Opened up the engine a few days ago and found out the cylinder wall is gouged. Now I have to replace the engine in her Camry too . So much for getting work done on the Z Anyways, the point I was trying to make is look closely at the head that you want to reuse. Use some parts cleaner and get that carbon off of there to see what the rest of the head looks like. There may not be damage to just your #6. Also, debris can get caught between the valve and the valve seat, so check that also. If this were my engine, it would be a smart move to just get a junkyard head to throw on there, instead of the smashed up one you have now. !M! Quote Link to comment Share on other sites More sharing options...
Guest RCNSC Posted August 4, 2004 Share Posted August 4, 2004 I feel like a dumbass. Thanks Jmort - I wouldn't have looked twice otherwise. For some reason I kept thinking E88. I just went out and looked at it. Its an N47 head. Ok so can I use the N47 head? Can I punch out the hole for the mechanical fuel pump? Anyone wanna donate an E31 head to me?? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 4, 2004 Share Posted August 4, 2004 With dished pistons and N47 you'll have 8.3:1 and big valves, with E31 you'll have small valves and 8.5:1 compression. Just use the N47. Quote Link to comment Share on other sites More sharing options...
Guest RCNSC Posted August 4, 2004 Share Posted August 4, 2004 But HOW do I make the Carbs/fuel pump work with the N47????? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 4, 2004 Share Posted August 4, 2004 If I'm wrong, then just use an electronic fuel pump and just don't worry about the mechanical fuel pump. Quote Link to comment Share on other sites More sharing options...
fl327 Posted August 4, 2004 Share Posted August 4, 2004 If I'm wrong, then just use an electronic fuel pump and just don't worry about the mechanical fuel pump. Quote Link to comment Share on other sites More sharing options...
280z-racer Posted August 5, 2004 Share Posted August 5, 2004 couldnt you just remove the block off plate from the side of the head up at the timing chain sprocket?? i f i remember correctly my n47 n42 and p90 heads all have that block off plate. but otherwise just use a low pressure electric fuel pump Quote Link to comment Share on other sites More sharing options...
kalium99 Posted August 5, 2004 Share Posted August 5, 2004 I've got a feeling that the N47 you have (if it is EFI) is actually a late model job with small CC (i.e around 40cc) and small valves. Basically the CC is a cut down P90 (If it is the same as our EFI E88 and from all reports it is). Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 5, 2004 Share Posted August 5, 2004 If it is an N47 off of an L28, then it should have the larger valves and combustion chamber. If it's off of an L24 Maxima, then it would be the smaller valve smaller chamber design. Visually, if the combustion chamber doesn't have much shape, then it is the L28. If it looks like a kidney bean or a heart then it is from the Maxima. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted August 5, 2004 Share Posted August 5, 2004 Just wanted to add something here.. I dont know what head I have, but on my 75 280z, there apears to be a block off plate where a mech/ fuel pump could go.. I didnt use it though. I ripped off my FI (literally just ripped it all out and made it go away! ) and instaled SU's from a 72. (E47 on the manifold I think..) I had to build 3 flat bars (1/4" thick) with holes in them to bolt the maifold on to my head. (just like the lowwer portion is held on with the exhast using big washers..same principal) The SU maifold used a diffrent bolt spaceing with fewer bolts (my FI manifold had two extra bolts) than my FI but it works just fine. I used a generic LOW presure fuel pump (aftermarket replacement for 74 260Z) to get the fuel from the tank to the engine bay. Just pluged it in to a stock 240Z fuel line to the carbs. I have had no problems yet, (unless I forget to turn on the switch! ) and have put 2000 miles on my car in the past 3 weeks set up like this. Quote Link to comment Share on other sites More sharing options...
zolorin Posted August 5, 2004 Share Posted August 5, 2004 Ok let me clarify on the head business E31 -- 42cc combstion chaimbers with small valves, carbs E88 -- a bit larger combustion chaimbers 45cc, carbs N42 -- bigger vavles 45cc chaimbers, hole for the fuel pump is closed through casting N47(early) -- on 280Z open chaimbes 45cc, round exhaust ports P79 -- 54cc chaimbers, heart design, round exhaust ports P90 -- 54cc cahimbers, heart design, square exhaust ports N47(late) -- Maxima; came with small valves and large valves (depending on the year) heart shape, round exhaust ports, 40cc I would find a maxima head since its design can hold higher compression; preferebly from the 84 maxima (I have that head brand stinking new) Quote Link to comment Share on other sites More sharing options...
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