Tony D

Exactly, most guys with fours run the Nissan KA head conversion. Far cheaper and practical than a custom casting with mixed heritage components. From what I understand the KA bottom ends come apart often enough, the head is usually not in short supply! LOL

The rollers will allow for that indeed. There are a lot of Honda guys running exhaust rockers on the VTEC Cam full time to good effect. With two more cylinders, I think it will work out fine.

Well, Mike made his swap-meet buy pay off. And you guys thought buying parts for cars in the 90's and hoarding them for two decades wouldn't pay off! It will be interesting to see what is revealed as to original intent of that head and what the ports flow, compared to modern designs.

Actually, I bought a car out of Texas (Black Pearl, actually) that defeated the local mechanics who had done the "overhaul" of the engine but could no longer close the hood. They had exchanged L & R Engine Mounts an the engine sat bolt upright! It was arduous duty troubleshooting that issue, something they gave up on almost 8 years prior as a mystery and unsolvable. So a simple swap L & R Mounts puts it almost level....it needs to be determined if the head is shorter in this configuration than the L-Series.... Haven't seen dimensions, but that was my first step, second was as Xnke suggested: Z24/KA24 Mounts and bell housings are there... Yeah...this is in the back of the shelf for when we come to that bridge...

Well...there is a fresh new head you might be able to use, I'm sure it would fit the bill for a basically hot street car: http://forums.hybridz.org/topic/119641-twin-cam-head-for-the-l6-from-derek-at-datsunworks/

What's captive oil volume in the head, before it starts draining? Easy enough to check now with coolant while you got it there!

Make it go-kart sized!

Ex-cellent!

How to Modify is an expedient check. It's supposed to be the same as the Mikuni Method mentioned immediately above. As I often say in my training classes, "I will teach you the right way to do it so you know how....I will also teach you handy shortcuts. Remember, if a problem arises, stick to the proper method, no shortcuts so you know there is no question it's been done right!"

At 172.325+ mph...I want all the wheelbase I can get...

No, now...c'mon! "Carbs are easy!" Says the guys on the Internet that pontificate and who have never walked this road! Anybody saying "carbs are easy" has never tuned them for total performance. It's always "it works" or "it runs fine" heck, they may even say it's run that way for XX Years "without any problems".... But as you see, it runs fine rich. They even may make a bit more torque on the bottom end...somewhàt. But compared to a proper crisp-clean & borderline lean response, it's just mushy performance that they find acceptable. It takes work, and experience comes through doing. The biggest bit of advice comes in only changing one jet or variable at a time and observing for yourself what it affects, and drawing your deductions on crossover and how the parts interact. Generally, I shy away from specific jet numbers... Learning the interaction becomes more valuable later on if something gets clogged!

It ate my response. On stock valves and a light port cleaning that head will flow 320cfm at 28" @ 0.500" lift. On the stock head they flow 200 CFM @ 0.250", 260 Cfm @ 0.350", 275 CFM @ 0.450", and over that they flatten out around 280/290cfm at 0.700" Best you're going to see on an L-Head Intake Side is around 220, and you will need 0.575 - 0.620" to do it. Going radical with 1mm oversize valves, removing valve guides and flow dividers you can get crazy flow numbers for NA, sized for 600cc cylinders and similar bore sizes. The idea was to not HAVE to do that work. Think about the streetability of a roller cam at 350" lift, with strong vacuum for an EFI MAP signal and those same camps being able to have timing events altered independently to work well NA OR turbo. And now...MS3 can do VVT control...

You may as well just disconnect the accelerator pump. Your engine will (should) experience a lean stumble on tip-in, followed by the jets doing what they should. From there, try the jet you have with the larger corrector. That should give you a quantifiable different fuel curve than what you're now seeing, and from there get one part of your graph correct...then tweak the other variable until it's section of the chart comes in where you want it.

I don't have Bryan Blakes stock head flow data... A cam that peaks flow around that as a stock port and 470 lift. Talking quickly with Ron at Isky (after 2PM PST) should get you a "Kit" that should maximize what you have. Stock Pistons power peak between 6000-6500... The cam you get will give the same rev-characteristics as the original L20A...make sure you tell Ron what gear you have in the differential. Most ZS Fairlady Z's have a 3.7, but the GL may have 3.9 or even a 4.11, that can be a big factor in cam selection. You will be running 3,500 on the freeways in an early five speed...which I find just FINE in my 260Z, you are RIGHT THERE for passing in top gear, pulling as fast as possible to redline. Gear it according to capabilities...a four speed car with a 3.70 would be 6,350... Meaning a cam that peaked in that range would be well matched. My standard for stock performance was my old 75 FLZ S-Model, it plain had the best overall all around performance I found. I've tried emulating that and found an L28 cammed like that matched with the 3.7 or 3.9 really makes for the same driving experience as that car had....but with a bit more traction difficulties. Good tires fix that! LOL Really, the money you planned on spending doing the bottom end...ship your E31 head off to Slover's Porting in LA (ONLY IF YOU KNOW THAT E31 IS NOT CORRODED!!!) and have him install the valves, port it properly to give you the optimal flow for your cam. The power is in the head, so is the fun in driving. Money spent in the head is easily transferred to multiple blocks if something goes wrong down below. At least, that's the way I'd go about it. Having dished Pistons may be an advantage as Ron will AK's "do you want to cut your Pistons?" Well, dished domes are "precut" a few mm, so you can tolerate a bit more lift....since you are doing springs anyway, take all the lift you can for all the cylinder filling you can. I digress...

Oh man, I got to get my Microsquirt crap ordered...ARGH!

Nowhere to do a screen shot of what I started with. Have you gone to DIY Autotune for their mapping images of various setups? Mine ran out the box on the fueling map for a 383 Stroker after changing the defaults from "8" to "6" Cylinders. Rich, but it was driveable. Restating the obvious in my mind, but ANY map from an L28ET is going to work...put one in for what you can find. Worst case if they are HP, is you're rich. It's a similar curve, you just click-drag, shift arrow down down down to lean it out a whole series of cels at a time. Not really difficult and fast.

Why did you change the air corrector at the same time? 140 Main 220 Air Corrector, less acceleration volume or duration... Main choke size should be near right for a power peak around 5,800-6,200. Try changing one variable at a time to affect the area it affects most. Once you are going in the correct direction, then follow with the second item to see the interrelationship between the two. Once you do it like that you will get a feel about what does what, when as later on you will need to go after targeted spots in the RPM/TPS range... If proper, you can go WOT at 1,000 and you will accelerate sloooowly, but your AFR will remain constant through transition, and any fuel shot by your Accel nozzles will definitely be cleared by the time the mains are in.... It will start "pulling" harder at around 3,000 ~ 3,500 and you should be able to hear the acceleration get quicker when your cam "comes on".... AFR's are pig rich, need to be around 11.8~12.5 and closer to 13.8:1 after torque peak. "Shift, Click-Drag, Control, Arrow Down, Down Down..."

Nope, go back to the Ref with your Smog and get the conversion registered with the sticker in your door. A STOCK replacement part does not come with an EO Number...unless the smogger is implying non-nissan parts require an EO Number...which is BS, and which is why you need to take the "fail" to your Referee.

Why are the injectors different between turbo and NA again? I think this is in error. Just because there is no resistor pack doesn't mean the injectors changed, just the driver circuits in the ECU.

Bottom End: Adding a lot of cost with no appreciable benefit using replacement parts that are almost positively of lesser quality than what you removed. Farthest I would go in this situation would be to replace the rod bolts with ARP's, clean and MAYBE replace the oil control rings, with a deglaze and run it with a new water pump. Top End: E31 Mythology...sell it to a racer that needs it to remain in class, buy another head and mildly cam it accordingly. Worry about the bottom end in another 200,000 miles...

"Quench Area" exists in no L-Series with dished pistons unless the dish mirrors the combustion chamber...so there goes that rationale! The boom mom end having Flat-Tops...you could have this discussion. With dished Pistons you may as well just run what you got...the P79 flows well...and you won't have any problem with gas anywhere.

They are, actually. I bought one in brass, and one in SS from the local Swagelock Distributor. They have Adaptors for most anything NPT, ISO, AN, Metric, etc.... I went in initially for an NPT to 1/4" Thermocouple adapter....found out with their gauging it was NPT to a 10mm Thermocouple! They had that there, in stock, as well! Distribution worldwide on local level, and shipping to you from the local branch stateside. What is the bend radius on your bender? (Should be on the saddle portion.) I can't remember mine, but that radius is critical for getting the nice line-up you got on your adaptation. I like Loctite PST for thread sealing on NPT. On a 1/2" NPT about 3/4 turn from finger tight is all you need to effect a proper seal. On elbows than require positioning that flexibility makes it nice.

Flow Testing is basically greed speaking. The ports should flow more than 2X what a stock L28 (take your pick) head, and at least 50-75% better than the most advanced ports out there currently. Technology exists from several vendors that get this port flowing over 400CFM. The down fall to any Datsun DOHC Conversion has always been cost versus flow...and the ability of "just anybody" to get the parts to do the conversion. I believe this project addresses these concerns,

On a Mikuni, pulling the spring, washer, and cotter key allows the Accel pump rod to just slide without moving the pump mechanism. Really you get a long incline or straight level stretch of road and get the car into fourth or fifth at 1000rpms. Set your throttle position and leave it there, Even if the pump squirts some, that gas is out quickly and you are in the idle jet, sloooooowly accelerating through transitions. With a GTECH-PASS and WBO2, you got VERY powerful tuning tools.

So what's the cost for a 3D printed plastic head?