veritech-z Posted September 24, 2006 Share Posted September 24, 2006 I posted this on another thread, and it got a little sidetracked from its original topic. I've got what appears to be a round port N42 head, and I'm being told this can't be. Speeder said he had a reman engine that had the ports ground out to round, and I'm inclined to agree that of the likely scenarios, this is the most probable. So far, at least BRAAP is stumped. It looks like the square port was welded up, and then cut out with some kind of valve seat cutter (or something similar), because the basic shape of the port seems roughly rectangle, but the opening is round. Whatever the situation, it looks extremely proffessional, and borderline factory. I took some pics with my digital camera, but they aren't especially clear since it wouldn't focus that close to the head. Any ideas? I swear this is like trying to photograph bigfoot...my stupid digital camera wouldn't focus close enough for me to show inside the port, but here's what I got: and here is the combustion chamber, in case anybody is interested: and before anybody says anything, I cleaned out number one cylinder's combustion chamber and exhaust port to aid in the clarity of the pictures. __________________ Quote Link to comment Share on other sites More sharing options...
george.bryant Posted September 24, 2006 Share Posted September 24, 2006 Its not a 05L head is it? Quote Link to comment Share on other sites More sharing options...
BlackBeaut Posted September 24, 2006 Share Posted September 24, 2006 Has your camera got a macro mode for super close ups? If not then stand further away and use the zoom. Looks mad though, it does look like someone's fitted a valve seat in the port entrance, it's square behind that round area right? Seems like an utterly daft thing to do!! Cheers, Rob Quote Link to comment Share on other sites More sharing options...
veritech-z Posted September 24, 2006 Author Share Posted September 24, 2006 No, this particular camera hasn't got a macro mode, it's just a digital point and shoot, but I do have a 35mm SLR with a macro lens, so I guess I'll have to break down and shoot some actual film, and scan the results. I agree, whatever this operation was, it seems completely pointless. I'm not familiar with an 05L head, what's the story with that one? Quote Link to comment Share on other sites More sharing options...
george.bryant Posted September 25, 2006 Share Posted September 25, 2006 The 05L head is the head used on the L20et. It looks very similar, I dont know what the story is with the crazy port matching... Quote Link to comment Share on other sites More sharing options...
veritech-z Posted September 25, 2006 Author Share Posted September 25, 2006 Would that head have been stamped N42, though? The problem with this head is that it has n42 cast right into it, but the ports are most definitely round... Quote Link to comment Share on other sites More sharing options...
Yorgee Posted September 25, 2006 Share Posted September 25, 2006 I think I have that same head, besides those inserts in the exhaust holes. Quote Link to comment Share on other sites More sharing options...
cheftrd Posted September 25, 2006 Share Posted September 25, 2006 It's an N42 that someone has modified. The chambers are welded and there appears to be around 2mm taken off the deck. Why they would do that to the exhaust ports?? Quote Link to comment Share on other sites More sharing options...
veritech-z Posted September 25, 2006 Author Share Posted September 25, 2006 That's what I was thinking, I can't imagine why, because they left a significant ridge at the top of the port... Quote Link to comment Share on other sites More sharing options...
JMortensen Posted September 25, 2006 Share Posted September 25, 2006 It's an N42 that someone has modified. The chambers are welded and there appears to be around 2mm taken off the deck. Why they would do that to the exhaust ports?? The pics aren't very good, but I don't see welded chambers there. As to the exhaust port, the only thing I can think of is maybe someone had a round port header and was trying to make it work with the N42 head and that was the best they could come up with... Quote Link to comment Share on other sites More sharing options...
veritech-z Posted September 25, 2006 Author Share Posted September 25, 2006 I guess I'll have to try and get some better pictures then. Does anybody have an unmodified N42 exhuast port picture they could post? Quote Link to comment Share on other sites More sharing options...
naviathan Posted September 25, 2006 Share Posted September 25, 2006 It has definetely had the deck dropped quite a bit and the intake valves look as though they've been enlarged, but the exhaust hasn't been touched in the chamber. The exhaust ports however are very odd. The only possible reasoning behind that setup I can think of would be an increase in low end torque. Could that be a Maxima N42? Quote Link to comment Share on other sites More sharing options...
veritech-z Posted September 25, 2006 Author Share Posted September 25, 2006 It has definetely had the deck dropped quite a bit and the intake valves look as though they've been enlarged What should the stock deck height be? I could probably arrange to measure that to verify or dismiss this. Could that be a Maxima N42? I guess I should clarify the story behind this engine: this head came off the N42 engine that was in my automatic 1977 280z when I got it. It had the EGR intake manifold withOUT the webbing, and the block has L28 scribed into it. The guy I got the car from said the guy HE got it from told him the motor was a remanufactured engine that he had put in shortly before th car died. The car came with no paperwork to confirm or deny that claim, however, so I was operating under the assumption that it was not true. I was driving this car with an underpowered electric fan and no guages for a bit (not much, just here and there), but evidently it was enough to blow the headgasket, causing the engine to hydrolock on me. I had access to a parts car with a P79 head, and I had previously removed that head on the off chance I would need one. I just refreshed the P79 so that the down time of taking the old head off would be less, and this N42 head has been in the closet ever since (along with that electric fan, I switched back to the mechanical and shroud at the same time). Quote Link to comment Share on other sites More sharing options...
naviathan Posted September 25, 2006 Share Posted September 25, 2006 The reason I say the deck has been dropped is because it looks like the edge is really close to the ID Stamps. This is a race prepped N42, see how close the stamps are on it to the deck? Looks about the same as yours. The only way to tell for sure is to find out the original cubic centimeters of the chambers and measure the current cc's of your head. The Z calc in the downloads should tell you what the N42 cc should be. I was mistaken on the Maxima head, it's an N47 variant. I couldn't say for sure if the intake valves are larger, they just look that way. Quote Link to comment Share on other sites More sharing options...
veritech-z Posted September 25, 2006 Author Share Posted September 25, 2006 The other thing I forgot to mention is that the car had a square port header on it when I got it too, so that confuses me even further about why the circle job might have been performed. Quote Link to comment Share on other sites More sharing options...
naviathan Posted September 25, 2006 Share Posted September 25, 2006 I'm stumped, clearer pics please. Quote Link to comment Share on other sites More sharing options...
veritech-z Posted September 25, 2006 Author Share Posted September 25, 2006 I'll see what I can do. Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 26, 2006 Share Posted September 26, 2006 I took a 77 EFI system off a complete original car out in ElPaso Texas. I know it had a round-port manifold on it, but can for the life of me not recall the head casting number. I don't even recall if there were port liners. There are some odd variations of N42 castings out there from overseas, not all "N42's" are the same as what we got here in the USA. They used N42's on Cedrics and Glorias for years after they were out of the production run for the USA. I have a 1977 N42 head from a Cedric in my 73. had only 44000KM on it when I got it, from the original owner with all maintenance documents available. But that head has the Rectangular Ports..... which gives me pause to also go "hmmmmmmmmmm..." Quote Link to comment Share on other sites More sharing options...
veritech-z Posted September 26, 2006 Author Share Posted September 26, 2006 I'm just going to have to take better photos I guess. Is there anything in particular that would be helpful? The cam, anything? Quote Link to comment Share on other sites More sharing options...
naviathan Posted September 26, 2006 Share Posted September 26, 2006 The shots you took already were good angles, we just need something higher quality. Although one of the ends of the cam does have a letter stamped into it, if you could find that we could identify the cam. Someone doing performance work to it would either have an aftermarket cam, with no stamp, or a 260 cam, with an "E" stamp I think. I'll double check the letter. EDIT: My mistake, the 260 cam is stamped "C" Quote Link to comment Share on other sites More sharing options...
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