Captain Obvious

As I continue to work on the crank nut as I get the chance... Some questions. Do the motors still have the oil pans on them? The reason I ask is that if the do, the insides are maybe less rusty than the top sides? And the reason that may be interesting is that it may be easier to push a piston DOWN rather than up. I'm thinking there's no reason you couldn't pull the crank and try to tap the pistons in the downward direction is there? Block of wood covering the entire piston face (for protection and force spreading) and a hammer? Thinking that if you could move them into a clean spot. Or do you think they were maybe heat seized and have rings welded to bores? Reason I ask THAT is because if that's the case, you'll need to get the block bored and the old pistons won't work anyway. Might just crack them and pull out the pieces? Anyway, just thinking of other alternatives in parallel of me working on that nut.

Awesome. So while you were in there messing around, did you peek inside the brake booster and verify that it is clean and dry? It hasn't sucked in any brake fluid in the past, right?

Derek, That gives me a thought... Instead of spending time on the nut portion of the equation, how about spending it on the TOOL portion. Build a chain wrench designed to grab the teeth on the crank sprocket. Like this, but designed using a length of two row Nissan timing chain: That'll be a project for the next guy...

Thanks much for the offer! I'll keep in mind.

I said wrench, not "wench". Thanks for the data. I'll make sure my opposing flats are within that range. I had already started aiming at 2", but since your wrench will go bigger, I might too. Less metal to remove.

So about these two opposing flats... How wide does your wrench open?

Creative thinking, but having the shaper (and hopefully a broach close to what I need?) I don't think it would save me much. I'd still have to put the slot in the inner piece and for that, I'd use the shaper. Would be a little easier since I could do it as an external operation instead of internal, but not enough to warrant two pieces and welding. I'm not stifling the creativity though! Certainly a way to make use of the tools you have to accomplish the task in a different way. And I like your pic a lot. I wish I had a CAD package I could use to whip up stuff like that! I'm still drawing by hand! LOL!

Cool. I've never owned one, but I've driven one. Fun cars.

.100 deep it shall be. And two flats.

Broaching would certainly be the fastest and easiest. The problem, however, is that I don't have a broach that width. I know I have 1/4 (.250), and I think I have 3/16 (.1875), but I'm positive I don't have .205 I'm thinking I might broach to 3/16 and then finalize the width of the slot on the shaper. That would be a lot faster than hogging all of it out on the shaper. So to answer your question... I haven't completely decided yet? Haha!!

Welcome to the club! Flat tops rule! Is that your 2002 as well?

I don't like the whole "shared hold down" thing between intake and exhaust. It's what we got, but I just wish they hadn't done that. Hopefully Pacesetter can hook you up.

So I found a chunk of stock that would probably work for a crank nut. It's not as thick as I would have liked, but it's what I got. However, before I got too deep into it, I wanted to verify measurements: I'm going to make the ID to be a slip fit over a 1.378 shaft. Couple thousandths over. You had previously mentioned that the key is .205 wide? I'm thinking "as long as the slot is wide enough that the device fits over the key, it will work". The goal would be to keep the amount of slop to a minimum, but since you're just using it to turn the crank, it really doesn't matter. There could be 5 degrees of slop and it would still work, right? I'm thinking you'll want to rock the force back and forth to get the motor unstuck, so slop like that would be "uncomfortable and feel cheap", but it would still work. So how about the DEPTH of the slot? How far out of the crank does the key stick up? And we already talked a little about the flats on the outside for using a wrench. Would just two flats on opposing sides work for your BFA? That would be the easiest to make. Square would be second easiest. And I could do hex, but it's just more work.

Here's another thread for some input: https://www.classiczcars.com/forums/topic/62535-thick-manifold-washers-notched-wanted/

Wow. Me neither!! Hope those find good homes.

Glad to help. I'll take a look at what I have for raw materials around here and let you know.

And forgot to mention... The other small numbers with the lines that run parallel to the thimble are vernier lines to estimate between the other lines. So since your .003 doesn't line up exactly with the fixed line on the sleeve, you could use the vernier lines to get one more digit of accuracy. You are alllllmost at 1.378, but an RCH below that. Eyeballing it, I estimate it to be a tenth of a thousandth smaller than 1.378, or 1.3779. You can't see it around the back side of the mic in the pic, but I bet the small "9" line is lined up-ish with one of the marks on the thimble. But for what you're doing, we don't need to split thousandths. 1.378 is good enough for me. (As a side note... 35mm is 1.37795 inches)

OK. I thought it might be aluminum. I know I found a bunch of aluminum ones when I was searching around, but wasn't sure if that's what you had. As for the micrometer... You got most of it right. It's a 1-2 inch mic, so yes, it's 1+something. And yes, the numbered hash marks make it 1.3 something. And yes... The un-numbered hash lines are each 1/4 of the major hash lines But since each of those minor hash lines is 1/4 of .100, it works out to twenty-five thousandths (.025). And as you turn the thimble (the part that spins), you are counting up thousandths to add to the previous .025 hash mark. So if the zero on the spindle lined up perfectly with the third minor hash line, you would be at 1.375 (1.3 + .075). But you're actually three thousandths beyond that 3/4 hash mark, so you have to add three more thousandths. 1.375 + .003, or 1.378 I whipped this up to hopefully help:

I get 1.378 OD off that mic (not 1.373). So it looks like that crank snout is 35mm. So the one you ordered from Summit looks like aluminum? That would be easier for me to work with. Wouldn't last as long, but certainly easier to produce.

Well if you're hitting the brakes and the RPM's are going up, then that's most often an indication of a leak somewhere. And most often that is a hole in the booster diaphragm. So are you sure that when you actuate the booster and hold the pedal position constant, it doesn't continuously bleed off your vacuum on the bench?

Yes... 2% of the hole. Considering the hole (nozzle) to be 0.100 inches diameter, the "whole hole" area would be 0.00785 square inches. The difference in the amount of the hole open for fuel flow is 2% larger using a .094 obstruction as opposed to a .095 diameter obstruction. As far what the direct impact is on richness, I don't know. I doubt it's a simple calculation and don't know if it could be modeled easily. In other words, the area calculations are easy... The exact IMPACT on the bottom line (mixture ratio) is beyond my pay grade.

Right. The slope of the taper (rate of change) may be different across the stations, but it's always a "slope" and not a step. Looking at the .095 vs .094 example above in a different way: If the needle is .095 and is in a .100 hole, you have 90.25% of the hole filled up (with needle) and you have 9.75% of the available area open to fuel flow. Changing the needle diameter to just .094, you have 88.36% of the hole filled which results in having 11.64% of the available area open for flow. So changing just one thousandth like that results in an approximate 2% increase in the area available for fuel flow.

So who is Aitoku? Is that supposedly the company that cast the valve covers? Seems weird to put that label on it that talks about making sure you have oil. "NOT INSTALLED ANY OIL ON THIS ONE!" Like someone bought a valve cover from the local Nissan dealer 35 years ago with the intent of making it a show piece or collectors item? Who does that for a car that's only ten years old? The labeling just makes it weirder.

There should be some decrease in the vacuum on pedal push, but I would expect there to be more on pedal release. As long as it doesn't continue to bleed out when you hold the pedal push constant, then I don't think you have a leak in the booster diaphragm. I'm no booster expert and I hope I'm not coming off as one, but from my looking at the design, I believe that's the case. The whole thing is actuated by a pair of valves on the pedal shaft. With the pedal not pressed, it opens a valve between the two sides of the diaphragm and allows vacuum to build and equalize on both sides. Then as you press the pedal, the first thing that happens is it closes off that valve between the two sides. Then as you continue to press further, it'll open up a second valve to vent off some of the vacuum on the rear side. What I'm trying to test with the "set amount" of vacuum bleed on pedal push is... Does that "close before open valve" work properly and are there no other parallel paths between the front and rear sides of the diaphragm (like a hole). I'm trying to come up with scenarios that you can look for on the bench that give you some confidence in the operation. "Holds vacuum indefinitely while static" is a good first start. "Goes whoosh when you press the pedal" is a good second test. "Drops a set amount, but not all the way when you press the pedal" is a good third test. if it passes all three of those I expect it's good enough be worth the time to install it and give it a try.

I think as long as it depletes a set amount, the diaphragm is intact. The "set amount" thing is promising. From what I can tell (from a distance and all that) it sounds like a good booster. How much vacuum are you able to draw down on it? Hand pump, or you got something powered?