1973 Rebuild

[Matthew Abate]

More tear down pics:

[Patcon]

Mathew,

Do you have little kids that walk? If you do, be careful about leaving things that could turn over on them as they toddle about the garage. The engines aren't very stable and they are about 600#'s or so. Think about a ratchet a strap or bolt them down. I saw the screw into the block in the later pictures but probably needs to be a little more stout. Would hate to see something bad happen...I have had them turn over...

[Matthew Abate]

It's actually at the machinist now, so all clear, but thanks for looking out.

Normally I keep all this under a staircase in the basement with ratchet straps holding everything in place and 4x4s wedged in as bracing.


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[Captain Obvious]

So what's the other work in progress in the background with the MM wheels and the multi-color paint scheme?

[Matthew Abate]

4 hours ago, Captain Obvious said:

So what's the other work in progress in the background with the MM wheels and the multi-color paint scheme?

That would be my dad's 5.0. He's going nuts with that thing. Last we talked he just finished fabricating a K-member and front fenders to move his engine back multiple inches, rebuilt his carb to sit sideways to eliminate fuel starvation in corners, and fabricated a baffled oil pan with wings to bring his capacity way up. He's in Arizona, so his oil situation has to be just so.

 

In other news, I bought an Exedy clutch kit that can with an FX flywheel off eBay. Hoping this is as good as I have read and won't regret getting a separate flywheel that's a little nicer. I decided not to get a lightened one in order to keep rotating mass near stock to keep inertia up at idle and reduce the tendency to lug down the engine from stop, even though I expect higher-than-stock torque numbers.

 

I also just bought a set of brand new OEM rocker arms. Let me tell you about my little rocker-arm-research saga…

first I was about to go insane and buy a set of Kameari rocker arms off RHD for over $600. Then I looked into it and found a couple of places where people recommend that the rocker arm be softer than the cam in order to reduce cam wear. This sounds logical at first, but then I realized there is a reason Nissan brazed on different metal. The three pieces in question (lifter, cam, and arm) are all different hardnesses and there is some intention in having different metallurgy for each contact point. So the ZCC CNCed ones are a no go from the start and the Kameari don't provide enough information to verify that they are or are not going to match with this design intention.

I had been reading that the OEM arms are super hard to find, so I looked into sending the 36 arms I have from my three heads in to have them done at Rocker Arms Unlimited, which Madkaw had recommended as superior on another forum. This would cost me $350 or so including USPS Priority Mail in two directions. Just having 12 done would be $217.

After a little research I found new OEM arms at Z Car Depot for 36.99. This came to $460 after shipping and seemed like a pretty good price until I realized that if they can get them brand new on a regular basis, they are probably available from Nissan. I really like the guys over there, but every time I go to buy something from them I either find it for less somewhere else, or the shipping expense pushes me toward something else.

I dug around a little more and finally found a few part numbers (13257-W0300,13258-21002, and 13257-21000) on the Nissan parts site. A quick google search and, lo and behold!, Courtesy Nissan has them for $29.13. The little secret is that they came on 1984 Maximas and have not been discontinued yet. All told $363.53 shipped.

I chose to go the route of 12 brand new OEM rocker arms from Courtesy Nissan for about 50% more than the junk on eBay or having the ones I have reground, and $100 less than Z Car Depot. I still have my pile of 36 arms that I can send to Rocker Arms Unlimited if I want to have spares or sell them, and I don't have to worry about whether or not I got a good grind for my initial application.

Edited August 22, 2016 by Matthew Abate

[Mikes Z car]

On May 24, 2015 at 0:39 PM, Matthew Abate said:

Speaking of previous owner body work, here's a question: have you ever heard of anyone skim coating the roof with bondo in order to strengthen it? This is the one thing (other than riveting metal to the floor) that I feel like I have to undo immediately.

I knew these cars have thin metal, and I knew people did things to them to "fix" it, but this is the first I've heard of this.

He said it was rust free before he did it, and looking from the underside there aren't any dents, but this seems like a recipe for an unintentional convertible to me.

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My first Z, a 1971 model had paint coming loose a bit right above the rear quarter window which I took to be caused by roof flex at the joint where the roof was welded to the upper forward part of the rear inside quarter panel, not sure what that area is called.  I understand modern adhesives can be stronger than steel (?) and have speculated on the idea of gluing a flat reinforcing plate on the inside right above the quarter window.

[Matthew Abate]

My first Z, a 1971 model had paint coming loose a bit right above the rear quarter window which I took to be caused by roof flex at the joint where the roof was welded to the upper forward part of the rear inside quarter panel, not sure what that area is called.  I understand modern adhesives can be stronger than steel (?) and have speculated on the idea of gluing a flat reinforcing plate on the inside right above the quarter window.

When I was a kid I used to use paper towel and superglue to make a cast to reinforce the inside of the joints on my models. I'm wondering if carbon fiber adhered to the inside of the roof with some kind of thin adhesive might do it.

[ksechler]

12 hours ago, Matthew Abate said:

When I was a kid I used to use paper towel and superglue to make a cast to reinforce the inside of the joints on my models. I'm wondering if carbon fiber adhered to the inside of the roof with some kind of thin adhesive might do it.

Yep, I used to do that.  Superglue and baking powder, too.  Man that stuff would cook off quick!  And that little puff of smoke would burn the hell out of your eyes.

Seriously, though, why reinforce the roof?  That seems like a solution to a non-existent problem.  

[Matthew Abate]

6 minutes ago, ksechler said:

Yep, I used to do that.  Superglue and baking powder, too.  Man that stuff would cook off quick!  And that little puff of smoke would burn the hell out of your eyes.

Seriously, though, why reinforce the roof?  That seems like a solution to a non-existent problem.  

I brought it up at the very beginning of my Z lifespan, mostly because the seller told me this had been done and I was sort of incredulous. I'll be stripping the car, so his effort will have been a waste, but one of the body shops I spoke to said they would probably do it anyway. I think it sounds like a great way to cause a rust problem.

One thing I WILL be doing, though, is spraying the inside of the roof with Lizard Skin or something similar to cut noise.

 

Switching gears, right now I am looking into the gains that come (or don't) from boring. It turns out that my block and crank are pretty much immaculate. The machinist said I will probably be able to just go with a quick hone on the cylinders and polishing the crank, so we are trying to decide whether or not to spend the $150 on boring it out. This will have zero impact on the budget beyond the machining costs, but I am suspicious that the performance gains would be canceled out the increased weight of the pistons.

From what I can tell from the internet, there's no one out there who has figure out what boring to 87mm will do when no other changes are made. Going from the gains from the non-US 240z to the non-US 260z was about 10-12 PS, but that was accomplished by increasing the stroke. Going from 83mm (L26) to 86mm (L28) is inconclusive because I can't find data on the L28 that came with carburetors other than that the Nissan 280C only made 127 PS, probably because of the head or other junk.

I need to figure this out so I can move forward. If going to 87mm won't change the budget other than the $150 machine cost and won't change compression because the pistons are being designed after this decision is made to hi 9.9 no matter what the bore is, the only real considerations are how much mass will this add to reciprocation and how much PS will I get?

Edited August 23, 2016 by Matthew Abate

[Patcon]

Mathew,

Are you asking about gains from boring a stock L24 block? If you are, there aren't going to be any! Admittedly there will be some small gain but it will be negligible. Not worth the cost. Also does your $150 increase in building cost include the new pistons and rings? That seems kind of cheap for the machine work and the new parts...

Now increased compression will help but the small over bore not so much

[Matthew Abate]

The compression will be 9.9 either way. The $150 is the cost to bore six cylinders only. The cost of the Pistons is exactly the same whether they are 86mm or 87mm.

Everything is literally the same except for the bore in this scenario, and I think the gain in PS/HP/kW is cancelled by the increased mass, at least partially.

If I could find out what the factory specs on an L28 set up like an L26 (same or similar head, fuel system, etc.) I would at least have a place to start, but I can't find specs on an L28 anywhere. L28e and L28et? Sure, all over. But nothing from 1975 with factory carbs.

I suppose the flip side of this would be if it's only $150 and nothing else is changing why not do it.

[madkaw]

Delete !

Edited August 23, 2016 by madkaw