F54/P79 Swap Project

[Captain Obvious]

A while ago, I picked up an 83 ZX non-turbo and (with my recent calamity with my Z motor*), I've been working on pulling the motor with the intention of moving over into my 1977 Z. It's a stock F54/P79 combo and I'm not going to do a big time rebuild at this time, but I do want to do some clean-up and maybe some easy low hanging fruit improvements. I'm no engine expert and I'm going to have some questions for the collective along the way.

I think there was a slight head gasket issue with the engine, so one of the things I wanted to do was replace that. Here's where I am right now. Head is off and block is stripped ready to be pulled from the donor car:

So my first question is.... After I pull the block and have it on the engine stand, I have aspirations of removing the freeze plugs and sticking a power washer into all the block orifices and blasting out as much crud as I can. Anyone want to talk me into or out of that plan? Is the installation of new freeze plugs a straight forward and reliable process? I've never messed with them in the past.

*https://www.classiczcars.com/forums/topic/62173-complete-misfire-on-three-cylinders/#comments

 

[Dave WM]

if you are going thru the effort, I would take it to a shop and have it hot tanked. Unscrew the block drain and check out the crud. But I guess that ups the ante a lot as far as having to tear it down. OK strike that comment about the hot tank idea.

Edited June 25, 2019 by Dave WM

[Captain Obvious]

Yeah, I have no reason to believe there is anything wrong with the bottom end and I'm reluctant to pull the pistons and crank. I was going to pull and replace the oil pan gasket because the old one is seeping a little, but other than that, I was hoping to not mess with the bottom end.

Oil pressure was great and no unusual noises from the lower end. I was hoping to let it be.

[SpeedRoo]

I'm doing the exact same transplant at the moment. The pressure wash wont clear out the inside of the engine, either have it hot tanked or baked. I just had mine baked then shot peened. Did a 40 thou over bore and some new flat top pistons. Check inside the block to make sure there are no stray freeze plugs that the last rebuilder pushed in and didn't retrieve, I found one in mine. I went with brass plugs when I replaced them.

Roo

1973 240Z

1970 240Z

[Patcon]

You aught to be able to turn the freeze plugs out and with the head off blow the majority of the block clean. I know Rossiz did something similar and said he was surprised at the amount of gunk that came out.

The freeze plugs can be difficult to get out. I have struggled to get them turned sometimes but a fabricator at your level will grind out some interesting little widget to make it easy peasy!

[jonbill]

If you've got it that far stripped, I'd always clean it and put new bearings in, give it a hone and new rings.
It's fun!

[grannyknot]

When you do the freeze plugs tap it in on one side only, you want it to pivot on the center, once you can get a pair of Visegrips on the lip pull it out.  Set your pressure washer nozzle to the needle setting, all kinds of crap will come out and get everywhere so if you are going to keep the pistons, rods and crank in make sure they are sealed off.  But it is just as easy to pull all that stuff and then you can clean them, check the measurements and inspect the bearing wear.

[Diseazd]

4 hours ago, jonbill said:

If you've got it that far stripped, I'd always clean it and put new bearings in, give it a hone and new rings.
It's fun!

Absolutely......and maybe a .040 overbore with new flat tops. Don’t stop there, go ahead and shave the P79 .080 and jack up the cam towers and valve springs using the early longer 280 swirl valves. Don’t forget to ship the old cam to Isky to make her a .490 lift stage III.    It’s fun!

 

[Captain Obvious]

Thanks for the input everyone. All that sounds like fun, but in the cause of expediency, I'm really hoping to leave the crank and pistons in for now.

Diseazd, Question for you while you're here... I remember talking to you in Atlanta (over drinks and pool) about that .080 cut off the P79 head. So how far can I cut the head before I need to shim the cam towers? Do you know how much change can the chain tensioner account for before needing to mitigate with shims?

 

[Zed Head]

Core plugs.

My thought on the coolant passage flushing is that you're just blowing out stuff that settled in a dead zone.  No flow.

You should get the "How to Rebuild.." book.  Lots of good stuff in it.  Also, ponder what, exactly, happens when a head is milled.  Bottom alone, or top and bottom.  What about cam tower alignment if the head is warped? Aren't they out of alignment also?

https://www.thezstore.com/page/TZS/PROD/10-1151

[Diseazd]

9 hours ago, Captain Obvious said:

Thanks for the input everyone. All that sounds like fun, but in the cause of expediency, I'm really hoping to leave the crank and pistons in for now.

Diseazd, Question for you while you're here... I remember talking to you in Atlanta (over drinks and pool) about that .080 cut off the P79 head. So how far can I cut the head before I need to shim the cam towers? Do you know how much change can the chain tensioner account for before needing to mitigate with shims?

 

I would suggest as little as possible to clean the head up. I’ve heard .030 inches is about all you can cut without affecting the timing. Maybe someone else knows the exact number. .010 to .015 is where I would try to stop.

Guy

[Zed Head]

I think that number is in the "Rebuild" book.  Mine is boxed up right now otherwise I'd find the page.

The MSA page says 7 thousandths, but they don't give a reference for the number.