madkaw

Take good care of that head if it’s really a MN head . Like said - a compression test would show pretty stout numbers with any combo involving a Maxima head . CC’s are about 39 which should show 180-200 psi compression check . I’ll also say the Maxima head would be about better than anything you could pit on that engine . But it also would be a challenge for stock EFI to keep up with the compression - not even talking ignition timing issues also .

I thought it was rubber soul version which might be larger . I’d like to run 75mm horns but might be limited to 50mm . I’ll be running 45 ITBS . I still have my custom air box I might run . thanks

Trying to find info on this cold air box . How tall of velocity’s fit under there ! I’m doing ITBS and contemplating stack heights thanks

Trying to find info on this cold air box . How tall of velocity’s fit under there ! I’m doing ITBS and contemplating stack heights thanks

Trying to find info on this cold air box . How tall of velocity’s fit under there ! I’m doing ITBS and contemplating stack heights thanks

Trying to find info on this cold air box . How tall of velocity’s fit under there ! I’m doing ITBS and contemplating stack heights thanks

I got it figured out . I found my old email address and was able to sign in as Madkaw

I run BPR6 - es11

View Advert L28 thermostat housings I have 2 clean housings with no pitting and good threads . 100$ each includes shipping sfinnerty1018@gmail.com Advertiser madkaw Date 01/23/2024 Price $100 Category Parts for Sale

Triple sure look cool but I don’t miss them - especially what you are going thru plus all the tuning .

Well this is the point where you need to decide whether to continue with the OEM EFI or go programmable . Yes the 123 ignition basically drops in with some wiring to adapt to factory wiring . It’s 600$ approx. You should watch a you tube video on it . Same amount of money would get you a basic programmable ECU like a Megasquirt . Then you would have full control of the engine with many options - ESPECIALLY if you want to modify your engine one day .

As said above - using MAP density tuning - KPA would be your measurement for load. Tuning for cruise would be difficult not knowing how the engine is loading . Loading can change a lot just climbing a slight grade though you aren’t putting much throttle to the engine . The OEM injection biases everything to the rich side to be safe . Those plugs took a while to look like that and most of the time we spend in cruise . That’s why the 123 ignition is a nice supplement to help keep the engine safe while tuning since it does have MAP sensor

What KPA is cruise running ?

Plugs can verify what you think is a proper tune . I’ve been running programmable EFI for years - those plugs look bad . Something is not right . 17’s would be terrible for an engine that doesn’t have full spark control. I run my engines lean - even my stroker and 15.5-16 is a lean burn for these old engineered engines . I appreciate your effort to make these old Bosch systems tunable - but without any load readings( I assume you use standard dizzy) you are guessing . i would recommend a 123 dizzy if you don’t already run one .

Those plugs show lean and or hot - I would be concerned if my plugs looked like that . I haven’t read your complete thread , but those do not look good

I had issues with an AEM wideband myself . The O2 sensor was bad and the gauge would go full lean after running the engine for juts a minute . They send me another one and mad me cut the old one in half and send them a pic of it cut in half . Got another sensor - same freaking thing . This time they said they wouldn’t warranty it - only get one sensor . Googled all this and read of the many complaints of customers . Bought a different brand sensor and no issues

While you’re at it 🙂 - take your dremel tool with the biggest drum sander you have and clearance those areas I highlighted . Installing the larger exhaust valves will have a harder time breathing with the shrouding of the chamber . Etch a line from the HG and sand a nice radius to allow them valves to breathe . The engine will appreciate it .

Yes - you have tons of room away from the detonation holes . I would unshroud those chambers . That engine will breathe much better and it’s easy to do . 1” drum sander with 80 grit is about ideal. You can use that on the chambers and on the block to clearance everything. Just email me and we will work out a deal on the valves Sfinnerty1018@gmail.com

Upgrade valve size is no brainer if you already have to replace the seats and yes it might raise CR slightly . To mitigate that you could unshroud the valve areas which would help it breathe and slightly enlarge the combustion chamber. BUT - you will have to clearance the cylinder bores unless you have over sized the pistons. There is a chance the larger valve will catch the edge of the bore . There are plenty of threads addressing this . This will also decrease CR - but with added benefit of better breathing . I do have tons of used 35mm exhaust valves if you want to run Nissan stuff . They all in good shape and I would about give them away . They all came out of Maxima engines so maybe less abused than Z stuff . Not trying to increase your work - but the seats MUST be addressed or all your work will be in vain.

Might want to check how close those dings are to the fire ring on the HG - they look close

For a split second on start up . I had been welding dirty steel on my work bench and the head was also on the bench . One of those molten BB’s must have danced right into the port opening . Some more had burned themselves into the side of the port that I found later . That’s how I figured out what happened . It did take a while if scratching my head . What made it more strange was I had a rod bearing go on that engine . They issues were not related

If those are original seats I wouldn’t skip that step . I doubt they are steel . You’ll really have some dings if one of those let loose .

So was this head worked previously ? Are those steel seats ?

Here’s a pic of known FOD . This was done by a small bee bee of weld that found its way in the intake and got sucked in the engine - it’s a long story . That head is still in use on my 3.2 stroker Are you going to do anything to the head ? New seats , bigger exhaust valve, unshroud the valve areas.

That’s a crap shoot . Not sure if you’ll pass smog because that will probably change the way it runs . And be ready for a fight . One might have fell out , but I bet the others won’t 🙂 .