1973 Rebuild

[Matthew Abate]

Okay, with that sort of sorted and on the back burner I'm switching gears and have a noob question: How does one test run an L6 engine without a transmission attached? This is impossible since the starter mounts to the transmission and not the block, right?

My transmissions are in New Jersey and my engine is in Arizona, so I can't just plug them together. Do I have to source a junk transmission or something so we can start it, or is there a secret trick to mounting the starter I am not aware of?

[SteveJ]

Why do you want to run the engine?

[Matthew Abate]

My dad wants to test run it before he ships it to me to be installed.

[Yarb]

That’s quite a bit of work to build a engine run stand. Are you suggesting installing it in the car and cranking it there?

[Dave WM]

You only need the adapter plate to attach a starter to an engine. A simple test short of actual running it would be to remove the plugs and while its on an engine stand (not a test run stand just the normal engine stand), bar it over by hand as quickly as you can and get a single bump compression reading. I was able to generate about 75psi this way. OR you could attach the starter with the plate that mount between the engine and the trans (what I called the adapter plate, its really not adapting anything) and spin it with a starter. I would just set the engine in an old tire for this test. while you are at it check the oil pressure with a manual gage.

this would allow you to get some idea of the overall condition (should build even compression of about 150 psi or more, and should get some reading on the oil pressure, maybe in the 20psi range with just the starter and no spark plugs IIRC.

I have some old videos showing turning and engine over for compression and oil pressure test, I did it with the trans on before I realized just the plate alone was enough.

Edited July 21, 2022 by Dave WM

[Matthew Abate]

Okay, cool! Thank you. I passed this info along and we will see where it lands.

In other news, I have the dash harness out and have been investigating the condition of the dash and all of the components. One thing I want to do is figure out the tach + ignition combination I want to go with. I am trying to make this electrical system as clean as possible from the get go, so if I can figure this out now it will be better.

I am 90% sure I am going to go with an E12-80 ignition on a 280zx distributor. My engine is a ZX block and head, and even though it’s set up like a 1972 with SUs, that ignition feels right.

So that means tach problems, since mine is a ‘73 tach. I watch a video on swapping a ZX tach instrument into a 240z tach housing, but upon further investigation I think the guy misspoke and actually used a 280z tach instrument in his mod.

I know there can be issues with a 280z tach and an E12-80 ignition, so I want to look into this further. I see a clean 280z tach online that is complete, but I also see a few 280zx instruments that are in my budget.

@SteveJ @Patcon @Captain Obvious, Based on your comments on other threads related to this I thought maybe you guys might know if the ZX instrument has the same bolt pattern and dimensions that the 280z and 240z instruments have. If so, this really simplifies my approach.

[SteveJ]

I'm not sure what issues you are referring to. I'm pretty sure the 240Z tach will work with a 1.5 or 3 ohm coil. There are no issues that I'm aware of with a 280Z tach and matchbox. A previous owner swapped out the distributor in my 260Z for a matchbox, and the tach works fine. I've helped a friend with the conversion, too, on a 260Z. That tach is the same as a 280Z tach for all intents and purposes.

[Zed Head]

Page 16 here might help if you run in to problems.  The Crane systems are electronic, like the ZX modules, and, apparently, people occasionally have problems when they convert from points to electronic.  They describe how to adjust the tach.  It's the system that the 240Z uses.  Pretty sure that others have mentioned the same adjustment in past threads on the forum.  It's not obvious.

https://static.summitracing.com/global/images/instructions/xr700 instructions.pdf

I also uploaded these to the Downloads area - 

 

[Matthew Abate]

There sure are a lot of ifs in that write up. Given the state of disassembly of my car I’m wondering if there’s a way to eliminate some of them in advance.

But if I’m understanding @Zed Head correctly I may be able to use my 240z tach with a 280zx distributor, which will same me a pile of cash, for sure. Would be nice to wire this up correctly so it’s nice and clean and doesn’t need to be opened up later.

[Matthew Abate]

I had posted an ad for a mechanical fuel pump eccentric and it looks like both of the respondents were scammers. Anyone have one for an L-series engine they are willing to sell, or know a reliable source for one?

I am referring to this one:

Edited August 1, 2022 by Matthew Abate

[SteveJ]

Let me ask around. 

[Matthew Abate]

Back to the tach… I’m getting ready to choose a coil to go with the e12-80 ignition on the rebuilt distributor I just bought. @Zed Head posted an image from an 81 FSW that says the correct coil resistance is 0.84 - 1.02 ohms in another thread on coils for this ignition.

I guess what I’m wondering is if this will impact what we were talking about with the 240z tach continuing to work with this ignition/coil combination, or if maybe it might present an issue. I don’t fully understand this stuff.

I’m going to get a coil in this range either way because I want to match it to this ignition, it just impact other stuff down the road.

Edited August 3, 2022 by Matthew Abate