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I'm pretty sure you guys can, but I'm not sure if the L4's have that steel ring around the exhaust valve stem or not...the way I see it, a welded and machined head is a welded and machined head...I know you guys are up to it... Found it here: http://www.the510realm.com/phpBB3/viewtopic.php?f=2&t=9756 Posted By Baz: A few pics with recent development on L series engines. By altering the angle of the valve guides the valves are shifted away from the bore allowing more flow plus some tricky work on the exhaust ports. Apparently there are differences in down under dyno readings from the US readings. Ours are more conservative. To give some real world comparison, these heads will flow the same as an SR20 head. These heads are used for class racing where the original L series heads must be retained. Some serious HP has been achieved. Throttle bodies fit straight on the head with out the use of a manifold or adapter. Ram tubes of many sizes can be used to tune for rev range. So, what do you think they've done? Looks to me like they took the valve stems and layed them over to the manifold side, to try straightening out the ports. seems like you could really help the exhaust flow, at the expense of a LOT of work. I think it could be worth it, if they are getting the L4's to flow the same as an SR20!

That makes a lot of good sense. I think I'll keep the E88 around, practice porting with it, practice welding the chambers, maybe build a hot L24 sometime later for another Z. (We all know these cars are like potato chips, you usually can't have just one.)

Ok. To keep the PCV system active, and remove the hose, here's the scoop: 1. Put filter on valve cover. This is just a breather. 2. Cap the hose barb that you removed the opposite end of the valve cover hose from. This barb is a vacuum port, and if you don't cap it, it'll let unmetered air into the intake. 3. DO NOT remove the hose connecting the side of then engine block near #1 from the manifold. You need to keep this if you don't want to be washing engine oil off from around every seal and gasket. This helps to keep your crankcase in a vacuum condition, lessening the chances of blowing an oil pan or front cover gasket. (Or valve cover gasket, for that matter.) As far as I can tell from the engine diagram, limited personal experience, and hundreds of internet posts, this is the proper way to remove that ugly tube. I could be wrong, but I'm pretty sure this is the right way to do it.

Hey, No offense taken. If I was as sure of my skills as I must've sounded, I'd already have welded up the head. As it stands, I'll be buying another (mostly) complete L28 this weekend, that already has an N42 head on it. Missing the Dizzy and damper. 1 fast Z, why the MIG? better fill characteristics? Lets just say I were to repair both of these heads (I have two like this, pitted around the exhaust valve seat on cyls #3&4) Would installing the larger exhaust valves and seats (this would take out most of the pitting around the valve seat area, combined with unshrouding the valve) make it worth trying to repair the pitting on the "quench pad"?

That sucks to hear. the Magic Smoke is never a good sign. Like others have said, just step back a bit, and work on something else. Hell, I've got 10-12 months of bodywork done, and another 10 months worth to go before I can even think about the motor, but sometimes I just have to let the bodywork go and play with engine parts for a while. Hammers and Bondo gets easier after that. these cars aren't like the mustangs and camaros. You've really gotta work on them to get it running good, but by god, i'd never trade it for anything.

Now that's something to know. Looks like then N-36 manifold has a straighter shot into those particular runners, than the two E-series manifolds. I wonder if the N-33 intake is similar?

Hmm...I have a '72 E88 head casting, (the pitted up nasty one) that has chambers IDENTICAL to the E30 castings shown in this thread, but different from the 260Z E88 and the shaved and valved E88 also shown. the camshaft is marked E30 as well, nothing special there, but it's funny that we find so many head casting codes, and so few changes between them.

I cast aluminum at home, and have welded castings before. That's not a big problem, but if you look closely, you can see that the pitting in the combustion chamber area is in deep around the valve seat. Portions of the top edge of the exhaust valve seat are exposed. I do not know if this is a problem or not, I can see the valve seats on all the other exhaust valves as well, but they are not pitted like this. The "corrosion around the water jacket holes" is leftover gasket and dirt, I have since cleaned the area and there is no pitting or other nastiness. The head will be used with dished pistons, so a high quench chamber is a moot point. 9.0:1 compression is the target, and maximum usable valve unshrouding is a goal as well. If the pitting is really that bad, then I'll just get another head. the spare head has these pits as well, in both #3 and #4, around the exhaust valves. the other chambers look to be in good condition on both heads...it's really weird.

Well, about the valve unshrouding, yes, that portion is correctable. I was more worried about structural concerns about the valve seat area. I can weld aluminum, MIG/TIG/Torch, just didn't know about the durability of the welded area around the valve seat. It's getting N42 valves anyway...

1. No, this chamber (#3) is the only one that looks like this. 2. Because this head is in overall better condition, regarding stripped out bolt holes, cam and valvetrain wear, and port sizing. (Head was ported in the past.) The PO was running this head with two headgaskets stacked, flattop L24 pistons, and a stock exhaust manifold/carbs. (I don't believe it was a turbo motor...could be wrong though. Why else the two headgaskets?)

Well, I went to check out my first E88 head, (got two now) and found what looks like detonation damage or something. (maybe some rocks in the cylinder? who knows?) Can this be fixed, or is it time to look over the spare head?

Wiring is not that bad. Lay out the entire '81 engine bay harness on the ground, and lay out the entire '75 engine bay harness on the ground. Arrange them as they would sit in the car, and compare the two. Check to make sure all the plugs on the '81 are there, intact, and clean the contacts. Get the harness in the car, and try to match up things like oil pressure sender wires, alt wires, coil wires, gauge wiring, things that you know, and then work on things you don't know, like injector wiring, the computer, temp sensors (all three of them), oxygen sensor, etc. Work it out section by section, use the '81 as a reference for mounting the computer, be methodical. You'll get it. Like the others are saying, don't give up now, it will be so worth it in the end.

heheh...300whp from a 3.1L L6 on carbs....You're funny, I think. Normally you'll get somewhere around 195-220hp from that motor, carbed. EFI might bump that up as high as 240hp. You can coax 200 crank horses from an L24 if you are really good and determined, but really, to make L6 power, you need to dump a lot of money in the cylinder head. Lots of posts around here on it, for NA L6 engines, stroked or not does not matter.

Indeed, these look like something I could use. Not obstructing the throttle plate, AND what's more, I can actually see how the adapters work/fit. Time for me to get crackin' on those... EDIT: I spent a little time out in the shop this afternoon laying out the bolt patterns and such for the 4-screw roundtops I've got. From what i can measure not having injectors or mounting plates, if you rotate the injector 180 degrees and move the fuel barb 90 degrees clockwise from what Caen Fred has shown us, the injector wiring could be hidden inside the orange "plenum" and the fuel hoses will look even closer to stock.

Still, you should see some tremendous gain if you could get the exhaust flow up to match the intake. What you can suck in, you still have to get pushed back out, and it takes just as much horsepower to pull something in as it does to push it. And you'll be pushing out even more than you pulled in due to combustion products. Maybe I'm wrong, but I'm still interested in upping the exhaust port flow in my E88 head. Anyone got some pointers that aren't explicitly outlined in our other head threads?

It seems, from the searches I've done, that most L heads can be lumped into two categories. Those that flow 180cfm++ on the intake, and those that don't. But I'd think the exhaust is just as important, and seems to get forgotten, or maybe it just flows less even best case. 150CFM seems to be considered excellent, whereas the intakes are flowing as much as 2000-210cfm. Doesn't that ultimately mean that the intake can only flow 150cfm, since it's limited by the lesser exhaust flow? What goes in, has to come out, plus some from the combustion process. I guess what I am asking, is how much would it take to get a head that flows as much on the exhaust side as it does on the intake, and why does it not seem to cause a big problem if the flows are that unequal? Would it make a difference?

Nope, that's a P79. It's just clean.

To answer your questions, run the high lift cam, port the head, and get the valves changed. If you don't do all the above, especially the valves, you may actually lose power...But if you do all the above, you will undoubtedly make more power.

I would prefer english, instead of lazy internet language. But, you are right, hell, if you made the kit in pieces about 4ft long, then you'd have no problem shipping them anywhere. it'd cost something like 60$ to ship...

Mods, I'm not sure where this goes, but this seems a likely spot. Please move it if needed. I was talking to a gentleman today who is in possession of an unwanted 280Z. Original paint is faded badly, gold-orange color. Runs, drives good. Needs paint, has no floorboard rust, or battery tray rust to speak of, currently owned by a "kustom" bodyman, so it's not his kind of car. He bought it for his son, son doesn't like it, and so he is looking to sell it for 1500$. I don't have the money or the room, but I figure that somebody here might be looking for one. IF anyone is interested, I'm sure I can get his name and number to you. I don't have any more information than what has been given, but it sounds like a good start for a restoration/modification, as I know the gentleman who owns it, and he won't buy anything that isn't worth having.

PRACTICE PRACTICE PRACTICE with that 24g, and when you can do it every time, all the time, no flaws, then you can use that stick welder to weld on the car. Really, get a GOOD mig. They hold there value well, just sell it when you are done.

I don't mind at all, it's a valid question. I think that most bore to 89 because pistons are available, but if a 9.5cc dish is ok, 88mm pistons are available as well, using an L28 crank and L24 rods. Not sure about the LD crank, you'd have to measure carefully. Personally I would not go thinner than 0.93" wall for an engine that won't see much time, and .120" for anything reliable.

BTW, the answer is no. No one has done anything like what you are thinking about. You will not find the answer in the Drivetrain forum, located about 6 inches below the Nissan L6 forum on the main page. The transmission will explode and little purple aliens will run out of the shattered casing and you will have gremlins in your car for the rest of eternity. ;-)

After getting the block tested today, I have no qualms about it. They pulled the sleeve in #1 out (it was a thin one, for a scored cylinder he thinks) and magnafluxed the whole block. No cracks or weak spots. My machinist told me he'd have absolutely no problems boring it as far as 90mm, although I would have a 0.92" wall thickness (just a hair under 3/32. Too thin for me.) They replaced the sleeve and bored the block to 88mm, all the bores cleaned up fine. Does this sound like it'll be ok for a NA engine? As far as getting another block, I'm stuck with this one. Already bored and cleaned up...After this engine is running, I'll start looking for another block to build...I'm sure I'll find a use for it. I did find pistons to fit, with the help of my machinist. I will look tomarrow and see what they came from.

Ok, so the block I purchased is not exactly what it was sold as. Not a real big deal, or so I thought. I knew the block had been "freshly" bored to 87mm, no big deal, that's great. Turns out, #1 has a sleeve in it. No problem. after a quick hone to clean the surface rust out, #5 is seriously scored and pitted. Time for new pistons, in 87.5mm bore. Does anyone know a source for these? ITM part number should be (and ITM's catalog says they make them up to 0.060" oversize) RY2701-060. Anyone know another source of oversize pistons?