The 510 Realm

RMS wrote:if you can see the flywheel to the left and right of the block its not installed. flowing your thought that "it wasn't going far enough"..... I split a trans off the back of an L16 to find a flex plate adapter used between the crank and flywheel in a failed auto to 4spd swap.

Duuuh, now I see this post. haha. Well, great minds think alike!

In this case...


+1

I don’t think it’s a matter of a spacer left on the end of the crank.
It may be hard to see in the first pic but there is a lip on the crank side of the flywheel which makes the ring gear set back away from the block. This lip is part of the flywheel and is visible in the first pic
Is it possible to have bolted the flywheel to the crank backwards and then install the clutch/pressure plate on the incorrect side? I can’t imagine doing that. Since I wouldn’t think there would be a finished surface for the clutch but like I said I’m not familiar with Datsun yet.

all the "heavy" flywheels have this lip. the starter would not reach the teeth if installed backwards.ring gear cannot be installed too deep as it buts up to the flange. with it being less than a days work to pull the engine and/or transmission and reinstall.... I would tear it down...... I bet the other "wingnut" will say the same

tl/dr - Perfect! Yes! The flywheel must have been installed backwards. You'd better take it off and check. While you are in there, have a look and see if there is a silly little crank spacer that was left in there before.

Before the ring gear is shrunk onto the flywheel, the flywheel is machined with a shoulder so that the ring gear has a shoulder to locate against; it is tricky to locate scalding hot parts that you are trying to shrink onto a large cold mass - best plan is to machine a shoulder onto the large cold mass; let the shoulder locate the scalding hot part! This is all an elaborate way of saying that the ring gear can only be in it's located position, unless some shady-tree machinist fucked things up, which is always a possibility with a 45 year old car and a 'rebuilt engine'...

The ring-gear mounting shoulder is cut into the flywheel in a lathe operation, as is the flywheel's mounting face area; the relative linear displacement between 1[the flywheel mating face] and 2[the ring gear shoulder/face] is a constant maintained for all L-series flywheels (ok, someone go find a case-breaking exception now!).

If your two starter motors each work acceptably with engine-1 but do not work acceptably with engine-2, then it stands to reason that there might be some mechanical anomaly with engine-2. (just so we are all on the same page)

The quickest check you can do at this point is take out the transmission, take off the pressure plate off, take off the flywheel, look at what the fuck is going on in there because something is screwy with either the flywheel or the mystery spacer. It is a Scooby-Doo mystery at this point. Blame Mr. Jenkins, the Amusement Park Manager!

review...

[*]I recently acquired a 71 510
[*]I purchased it as a non runner <--- implying that the former owner was defeated by a mystery problem
[*]I'm not very familiar with Datsun
[*]I believe that the engine has been rebuilt <--- implying that the engine might contain problems. also, define 'rebuilt'
[*]It's too clean to have been run, the oil is new, etc. <--- implying that there is a major problem yet to be diagnosed
[*]It's a manual transmission <--- but the engine might not have been sourced from a vehicle with a manual transmission
[*]I tried to start it the other day
[*]It turns over by hand ok.
[*]the engine began to crank but the starter would not stay engaged in the ring gear
[*]the motor [turned] over for a few seconds, then... sounded like it was grinding against the ring gear
[*]the ring rear and the starter gear both [inspect as] ok
[*]the starter [was tested] off the car - the starter gear was fully advancing (extending)
[*]the starter from [a 72 510 with and auto trans that starts and runs fine] did the same thing when tried with the 'rebuilt engine'
[*]I'm hoping someone can direct me in the right direction as to why the starter is not engaging in the ring gear properly so that I can start the car and move forward with this project.

Other than that, I'm kind of stumped myself.

Also, +1 on what Robyn said.

RMS
That’s exactly my problem is the starter is not engaging the ring gear because it’s to far from the block.
That’s why I was wondering if it was possible for the flywheel to be put on backwards. I can’t imagine anyone doing that but I’ve seen some dumb things before.
I can see that the ring gear is installed properly and fully so looks like I’ll be pulling the assembly and inspecting it.
Thanks,
Rob

for me its faster and easier to pull the engine than to bench press the trans back in. for easy in and out disconnect the idler arm from the frame allowing the steering link to drop down to make extra clearance for the flywheel and splash plate.

Thanks for the advise. Probably won’t be able to get to it until next week. I’ll check it out. I have a car hoist and trani jack so may do it that way.

510 rob you were right.
I had a chance to pull the trani today and found that someone had left the spacer from an auto between the crank and the flywheel.
I removed it and reinstalled the original starter and was able to fire up the motor.
Thank you everyone for you help.
Rob

If you have ever had a flywheel off and put one on you will know that the flywheel actually slips over the end of the crankshaft and will sit in place even without the bolts. The auto spacer would prevent that and you would have to hold the flywheel in place while fumbling with the bolts. This would be about 1/4".

You are very correct.
I pulled the last bolt of the flywheel and it almost killed me. I expected it to stay put but it sure didn’t.