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Round 1, Fight!
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Alleycat_Joe  



Joined: 14 Sep 2020
Posts: 21
Location: Florida
PostPosted: Mon Jun 13, 2022 2:25 am    Post subject: Reply with quote
Apologies for the radio silence, life is busy and progress has been slow.


924RACR wrote:
Very nice work. I'd be interested in hearing more about how you used the TIG to straighten the head?





Posted below is a fantastic video description of the process. I used a tig torch to create stress concentrations in the cylinder head walls and used the arp studs in the engine block with paper spacers on the outer ends to bow the cylinder head down into position while introducing the stress concentrations. This took the warp from 7 thousandths of an inch to 3 thou. I had to repeat the process several times. I also verified the straightness by feeling if there was any binding in the camshaft when installed without valves and unbolted from the block. Before the process the camshaft was impossible to turn freely, after the process the camshaft was able to spin freely for a full revolution. It spins even more freely with the head bolted down, so I know the block is pulling the head straight.

https://youtu.be/hKgaE4z3Q9A

MikeDanger wrote:
while your in there youll want to check the firewall at the clutch master for cracking.

also don't use the hatch struts they will seperate the glass from the frame at the hinge (I just pop them on and off as needed when I open the hatch, remove the metal clip)




Good call on the firewall crack. I tried to repair it with the tig welder but my skills need to improve before I'm willing to post the results. I am using used hatch struts from a Jeep Cherokee so I'm hoping they're weak enough not to cause the separation issue, however I'll proceed with caution.



I replaced my intake valve guides since they measured out of spec for "wobble." Naturally I had to bore them, but valve wobble is well in spec now. FYI our axle bolts are the prefect size for hammering the valve guides in and out using a punch in the bolt head and a paper towel to protect the inside of the guide.



Test fitted the chevy cruze 1.4 fuel rail and started mocking it up for mounting points.




Started making the custom exhaust manifold with a hand drill but gave up and bought a used floor drill. Luckily the whole drill fit easily in the trunk of the 240D.



Got tired of hauling the tig welder around the floor, so I whipped up this welding cart with harbor freight wheels and angle iron for less than $50 total. Took lots of time though.




Test fitting the t3/t4 location. Its tight and I facetiously hope oil flows horizontally, because I can't get the turbo much higher and don't want to use the stock oil air separator solution.



Cutting tube notches with a discount setup.





Manifold progress to date.
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1980 931 | 1981 240D 4spd

Last edited by Alleycat_Joe on Wed Jun 15, 2022 12:39 pm; edited 1 time in total
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Beartooth  



Joined: 05 Apr 2022
Posts: 205
Location: Roberts, MT
PostPosted: Mon Jun 13, 2022 11:35 am    Post subject: Reply with quote
Wow, you've got quite a project! I picked up a 931 project in similar condition to yours, but thankfully not quite so bodged up by the PO. I wasn't looking for a turbo, it's just what I stumbled on. And I'm working through similar title issues... My engine had similar compression results, although a little more consistent: the weakest cylinder was also #4. Still, I'm hoping it'll run ok as-is. I'll definitely be tapping into some of the same resources if I have to rebuild it.

I agree with your thoughts on the turbo: it's not the most elegant setup. I've got a 300D (turbo) flip project, and it's simple as a rock by comparison. My sister and brother-in-law have a 240D, BTW; you can swim laps around that engine bay! The thing is, having all that room at the front end an upright engine made the W123 a lot easier to turbo. My suspicion is that the turbo wasn't originally part of the plan for Porsche, but then competition pushed them to offer the turbo, and at that point, changing anything major with regard to engine layout wasn't an option. Canting the engine over made a lot of sense in terms of allowing for a lower nose and lower CG, but the turbo setup would have been so much simpler with the engine upright that I'm sure they'd have gone that way if it weren't cost prohibitive.

Anyway, this is an ambitious build, and hope it comes out well. It's not many men I can say "you're a braver man than me [mechanically]" of, but you've way deeper on this than I have any intention of going on mine, or have gone on any previous project!
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