1973 2.4T Engine Rebuild DIY Cost
 

Anyone have a rough ballpark cost to do a DIY rebuild on a 2.4L T 7R engine? Roughly 140,000 miles, pulled a decade ago because of a broken rocker. Was running when pulled, but upon inspection when owner pulled valve covers the broken rocker was found.

Turns freely by hand. Engine is complete with MFI and heat exchangers. I picked up thinking I could try my hand at rebuilding a 911 engine over the winter and maybe someday find a nice 912 to drop it in.

Have a well known air cooled engine builder near me that does all his own machine work in house, so I would hope to give him the heads for the valve job.

https://live.staticflickr.com/65535/...99f7cb5e_b.jpg20190914_140149_resized by HKnut, on Flickr

https://live.staticflickr.com/65535/...17d0aa75_b.jpg20190914_140219_resized by HKnut, on Flickr

https://live.staticflickr.com/65535/...184e5758_b.jpg20190914_140206_resized by HKnut, on Flickr

https://live.staticflickr.com/65535/...7ef34ba8_b.jpg20190914_140158_resized by HKnut, on Flickr

15k+ in parts, machine work, sublet, etc.

Plus labor. This assuming you rebuild to stock specs.

Holy crap! What would it cost if I gave to someone else to rebuild? $20k plus?

I was expecting roughly $5,000ish..... Guess I was dreaming!

Doing all the work myself except rebuilding heads and rods I dropped 10k on my 3.0 and it was in running and driving condition. That was just a basic rebuild, not a performance build. Yours looks like it is going to need the full Monty so yes, $15k+

I guess rebuilding an engine I don't have a car for, simply for the "fun" of it isn't an economically viable option for me at the moment........

My wife for some reason thinks that saving for kids college is more important..........Dang rational women!

That MFI motor is probably worth $$$$ as is.

Just to have that MFI pump done is not cheap.

If you poke around here there are some build sheets with numbers.

If you have Bruce Anderson's book he details all that is needed, and you can add it up.

Just the pistons and cylinders are $3-4k. Machine work on the case is probably around $2k. And you have to assume the crank and other internals are in serviceable condition.

Thanks Gordon. I'll be selling the engine. Found it for a decent price on Craigslist and bought it on a whim thinking it would be a great candidate to learn about these engines. Don't know much about these early MFI engines and didn't realize the MFI system was that expensive to refurbish. I did consider selling off the MFI stuff and going with 40mm PMOs, though not sure it would be a net positive since the PMOs alone are $5k. Would have to wait for a set to pop up on the parts for sale forum, and that's probably rare. Thanks for the input guys.

You can easily spend 5K on the MFI alone.

So, I'm in Europe and prices may be different.

But over here, a complete MFI rebuild is 2K. Complete rebuild of 6 heads is another 2K (incl 12 new valves, CNC grinding seats, shims etc). Line bore (if needed), cylinder hone and crank polish is approx 1K (maybe 2). So max 6K in machine work.

Then add new hardware of your choice. I don't see how a DIY rebuild comes to 15K unless you buy new cylinders/pistons etc.

Bearings, cams, gaskets, chains, sprockets, sealants, hardware, tools, etc. it’s easy to spend $3k just machining the case. Head studs, refurbish rods with new bushings, bolts and bearings, refurbish rockers. Oil cooler needs cleaning and maybe replacement. Maybe you get lucky on the p&c’s, maybe you don’t. It’s better to count on the $15k and have it be less than run short of cash to complete the build.

If you’re just freshening up the engine, hand lapping valves, honing cylinders, gaskets, rings, bearings, seals, it dan be done closer to $2k. Of course you’ll want to ensure you’ve upgraded to hydraulic tensioners, and turbo valve covers which will push it closer to $3k.

There are really two issues with that motor, aside from the MFI.

The cylinders are iron. They will need attention. I can't imagine they will be in spec. So they will either need to be replaced, honed and plated if they aren't too worn, or bored out and fitted with new pistons.

Then there is that mag case.....

I wonder why that motor was taken out to begin with? Might very well have had some issue.

Carrera tensioners seem over kill IMO.

Gordon,

The engine was pulled due to a loud rattle. Pulled valve cover and intake rocker #4 was broken. Everything was running fine otherwise. Was told engine ran well and didn’t smoke. I understand there is always a large range in cost due to actual condition and the slippery slope. Do you think it’s absolutely necessary to crack the case and go after bottom end at 140,000 miles?

Sooo why did the rocker break? Overrev? Valves hit the piston? Piston (s) damaged? When I did my 2.4 E it was roughly $10 k in parts and machine work. Did nothing to the MFI as there were no issues with it.

Chris
73 911 E

^ My point exactly. Also very concerning is the corrosion on the cam and lifters......

Don’t forget to allow 2 years of your intermittent time...

And you better have a great collection of tools. Powder coated, lathe, sand blaster, welder, micrometers, bore gauges, yada, yada, yada.

I totally see why a pro build is $20k+...

A mild conservative build with good pistons is 10k if you do it yourself...

I’d take it apart and see what you’ve got and what may have been done before. If it is a 73 2.4 with a 7r case AND MFI Don’t think there was any such thing from the factory. 73.5 cars were cis.

My car was a 73 E, 2.4 7R case with MFI. Know it came from the factory that way.

Chris
73 E

Too spendy of a project for me at the moment. Better suited to someone who needs an engine or MFI parts. Listed on ebay, link below. Interestingly a 1973 MFI kit just sold on BaT for $3,200 the other day. I was a bit shocked at that price.

https://www.ebay.com/itm/Porsche-911T-2-4-Liter-Motor-1973-with-7R-Case-Incl-MFI-and-Heat-Exchangers/143391534970

https://bringatrailer.com/listing/complete-mfi-system-for-1972-3-porsche-911t/?utm_source=dailymail&utm_medium=email&utm_campaig n=2019-09-23

73 Es and Ss starting getting the 7R cases mid year in addition to the 73.5 CIS. I have seen several 73 MFI engines with 7R cases.

I guess I got lucky, my MFI pump worked right off the bat when I put the engine back together. If you do a basic rebuild, ie gaskets, seals, bolts, rings, etc, it's not hugely expensive in parts. Then, you need basic tools and a bit of ingenuity to fab or borrow those you aren't going to buy for a one-time use. A good machine shop will clean and refurbish the heads for a reasonable cost. Do you have Wayne's book? That's the first place to start. I did my 2.4 in about 4 m working evening and weekends, and really enjoyed it. My total came to a little over the 5 grand you mentioned, but I had the pistons and cylinders nickasil-coated. There's a lot of great help here, and if you take your time it's a treat. On the negative side, I doubt that you'll get any investment back: A future buyer will pay extra for an engine that comes out of a reputable shop, not our back yard.
happy wrenching :)