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Thumbs up Newbie '73T 2.4 MFI Engine Rebuild

Hey All,

Longitme lurker, first time posting. I've been inspired by so many of the other engine rebuild and restoration threads on this forum; it's finally time for me to give it a go, and hopefully contribute back in some small way by documenting the process.

I've had my '73 911T (MFI) in and out of storage for about 9 years, after purchasing it and driving regularly for the first 2 years. I'm learning the hard way that I didn't do the motor (and many other bits) any favors by letting it sit. Now it's time to make things right My plan is to pull the motor and tranny, and perform as much of the teardown and rebuild as possible. I've got Wayne's book, this forum, and a healthy dose of naiveté... what could go wrong?

My 911 is a numbers-matching high-milage (285k) highly-original survivor. I've got records back to '75, which indicate that the case has never been opened, and that there was a top-end rebuild back in '82 at 93k miles. Previous owners were good about keeping records of their regular maintenance, and it's just amazing that the odometer has flipped almost 3 times since then without major service.

Before going in to storage, my compression/leakdown numbers were ok but not great:
Compression Check: 1-135, 2-130, 3-130, 4-135, 5-135, 6-115
Leakdown: 10,48,18,8,11,52

At various times during storage I would fire it up; always started without issue, but over the years became increasingly smoky. Last few starts (roughly 12 and 24mo ago) had a fairly significant amount of fuel leaking out from somewhere near the base of the MFI pump. I had done basically nothing to prep the car for storage- I was perpetually just a few months away from getting to it- then life happened and 10 years went by. Goes without saying, but this was VERY STUPID, and will certainly add to cost of my rebuild project! People, store your P-cars properly

So, back to the rebuild; here are my priorities:

1. Bullet-proof reliability. I'd like to think that this lump will be good for another few flips of the odo when I'm done with it.

2. Originality. I love love love long hood narrow-body hotrods, but I've decided that this 911 is not a candidate for that kind of build. I'd like to stay in the 'original survivor/driver' realm. I think a few tasteful upgrades (especially in the interest of reliability) are acceptable, as long as there's a clear path to return to stock.

3. Zing. I dunno what else to call it, but I'd like this engine to have just a little something special when compared to a stock 2.4. This could be a little more power, or maybe just the right exhaust note. I realize that this desire can come into direct conflict with both #1 and #2, and so I'll need to keep my hotrod dreams in check.

In other words, I don't know what I'm building yet- and looking for advice. Knowing nothing never stopped me from doing something, so on to the removal and teardown!


Jake
Old 09-09-2017, 10:24 AM
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Ok, let's figure out how to pull this motor out!



Really, this thing is supposed to come out this way? Gotta get higher!

After lots of head-scratching and creative placement of wood blocks, we have clearance!



After some hi-fives, reality sets in. "Now what?!"



Anyway, there it is- one honest 2.4 MFI motor ready to be brought back to life. Looks so easy in the book My brother and I spent an inordinate amount of time, during each phase, staring at the car, staring at the jack stands, staring at the jack, staring at a pile of wood, thinking: Ok, now how do we jack the car up higher when the jack is already holding the motor? How come these jack stands don't go higher? Now that the motor's out, how do we get it off the jack? Once off the jack and onto blocks, how do we get the jack back under the lump to lift it up onto the cart? And on, and on, and on... but we got there. Beer helped (or so we told ourselves).



Jake

Last edited by Inkblot; 09-09-2017 at 10:55 AM.. Reason: wrong photo
Old 09-09-2017, 10:53 AM
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Here are some more pics. Pretty dirty, but everything looks straight.







Now starting to remove bits and pieces:


Some MFI action:








Man that fan shroud was nasty! But totally intact/undamaged.

So that's what it looks like underneath:



Lots of oily gunk everywhere, but so far, so good. Now that we've got some of the parts removed, it's time to figure out how to move the motor from the cart to the engine stand. I'll restock my fridge, and try to bribe a few friends with beer.



Jake
Old 09-09-2017, 11:14 AM
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Here's my box of MFI bits. Pump and injectors are off to the OG MFI guru Gus at Pacific Fuel Injection. He was great- took the time to show me around his shop, and to explain what all of those old Bosch machines do. We need more guys like him.



Here's my engine #, for posterity... no surprises here, matches the COA.



Ok now the fun part. It's amazing how hard things can be when you don't think them through! I thought I'd just roll my cart right into the engine stand, easy peasy. Of course, the cart runs into the feet of the stand, so close, but no go. Many immature jokes were had at this stage, for reasons the pic should make obvious.



Time to bring in some muscle! Nice to have friends willing to help. By "help", I mean drink my beer and ridicule my obvious lack of foresight.




Success! Plus, everyone still has all their toes.





Jake
Old 09-09-2017, 04:26 PM
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Ok, now that the lump is on the stand, I can finally turn it over to get to the exhaust manifold bolts. As my floor and I learned, there is still quite a bit of oil in there! Costco shop towels are a must

Lots of oily grime all over, and you can see the wet-looking discoloration around cyl 123 from the fuel leak.





I let the manifold studs/nuts soak in some thread penetrant. Still, these things are a pain to remove. I broke two studs, and two more decided to unthread from the heads rather than release their nuts.



Success! Everything's a bit harder than you think it should be...



Here are the removed heat exchangers. Looks like mostly surface rust, with some small areas of more serious erosion.



My plan was to replace these with SSIs. Any opinions out there as to their restorability? Or would they ever be worth anything to anyone?

Jake
Old 09-09-2017, 04:50 PM
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Now we're gettin' to it...

Valve covers off:



Records show the lower turbo valve covers were added back in 1990, while the intake covers were swapped in 2003.





and Carrera chain tensioners added back in June '86 at 131k mi. Looks like the right chain cover was swapped at the same time- it's got a 930 part number.
Correction: They're both newer 930 parts.





I gather it's wise to replace the tensioners, as they've seen 150k mi. I can't see anything wrong with them, but then again I really wouldn't know what to look for.

Jake
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Last edited by Inkblot; 09-10-2017 at 08:33 PM..
Old 09-09-2017, 06:11 PM
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Cool project and car! One thing to keep in mind is that if you decide to change your cams for more zing as you put it, be sure to give Gus a heads up at Pacific Injection as you might need to change the space cam in the injection pump. Going to 911e cam or DC 40 might give you some more zing without going down the slippery slope. I'm assuming you're doing a complete rebuild from the bottom up with possibly new pistons and head work. A good machine shop in the Bay Area is German Precision (talk to Ted Robinson) if you're going that route. Good luck and I'll be following it.

Last edited by MST0118; 09-09-2017 at 06:31 PM..
Old 09-09-2017, 06:28 PM
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@MST0118 Thanks for the feedback, and good tip on German Precision.

Yes, planning on a full bottom's-up rebuild. I'm hoping to keep as many of the original parts as reasonable; but I do think P's and C's are on the menu.

Sorry for the dumb question, but what is a DC 40?

Best-

Jake
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Old 09-09-2017, 08:18 PM
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Quote:
Originally Posted by Inkblot View Post
@MST0118 Thanks for the feedback, and good tip on German Precision.

Yes, planning on a full bottom's-up rebuild. I'm hoping to keep as many of the original parts as reasonable; but I do think P's and C's are on the menu.

Sorry for the dumb question, but what is a DC 40?

Best-

Jake
DC 40s are similar to the S cam. Dougherty Racing Cams Porsche 911, 930 and 964 camshaft profiles Might be more than what you need.

A little larger bore. You could have you cylinders bored. Matching JE pistons with more compression and some reground cams and you should be happy.

Your limiting factor is your intake port size which will limit your HP increases.
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Last edited by Trackrash; 09-09-2017 at 09:15 PM..
Old 09-09-2017, 08:53 PM
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Quote:
DC 40s are similar to the S cam. Dougherty Racing Cams Porsche 911, 930 and 964 camshaft profiles Might be more than what you need.

A little larger bore. You could have you cylinders bored. Matching JE pistons with more compression and some reground cams and you should be happy.

Your limiting factor is your intake port size which will limit your HP increases.
@Trackrash Thanks for the feedback. A slightly more aggressive cam is interesting, but I don't want to go too far... my plan is 100% street-oriented. An S cam might just be the sweet spot.

Regarding a slightly larger bore, are you suggesting I could run new JE pistons within my stock (though bored) cylinders? That would certainly help on the cost side, as a full set of JE p's and c's is a bit spendy.

Understood regarding the intake port size. Not looking for big power gains here, just a slight "edge". It's a very, very slippery slope

Cheers,

Jake
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Old 09-10-2017, 01:24 PM
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Making more progress. Here are some shots of the clutch, pressure plate, and flywheel. Everything looks pretty good. Clutch definitely needs replacing... any reason to go non-stock/OEM for a mild street build?










-Jake
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Old 09-10-2017, 08:59 PM
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Might be a trick of the light but with what looks like a lot of wear I'd replace all cam drive sprockets and use a new non-master link chain. New tensioners would be wise.

That's a good bit of mileage. Get the case checked out to see if it's viable for the needed basic machining mods before spending even one dollar. There was a 72S in Hemmings Sports and Exotic Car magazine (when they were still around) that had 651K miles. But it was on its second case. Here is the car: https://www.google.com/amp/s/www.hemmings.com/magazine/hsx/2013/10/Marathon-Runner---1972-Porsche-911-S-Targa/3730381.html%3famp=1
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Finally getting into some of the good stuff.

Wayne's book is right- it takes a serious amount of force to get those cam nuts off, even with the proper crow's foot and special cam socket tool. I was able to do it by myself, but would have been much easier w a second set of hands.



Lots of gunky stuff on the case. I guess I'll try to figure out how to clean all of that once the case is split.





Right side chain housing is a 930 part, left is stock.




- Jake
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Old 09-10-2017, 09:21 PM
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Quote:
Originally Posted by manbridge 74 View Post
Might be a trick of the light but with what looks like a lot of wear I'd replace all cam drive sprockets and use a new non-master link chain. New tensioners would be wise.

That's a good bit of mileage. Get the case checked out to see if it's viable for the needed basic machining mods before spending even one dollar. There was a 72S in Hemmings Sports and Exotic Car magazine (when they were still around) that had 651K miles. But it was on its second case. Here is the car: https://www.google.com/amp/s/www.hemmings.com/magazine/hsx/2013/10/Marathon-Runner---1972-Porsche-911-S-Targa/3730381.html%3famp=1
Thanks for noticing- yeah, sprockets and chains will be replaced. I'm not sure how much wear is too much- but these parts are definitely showing some rounding around the edges, etc. Here's a slightly better pic:





-Jake
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I gather it's wise to replace the tensioners...
These are easily replaced without having to remove or even lower the engine. I'd box 'em up and reuse especially if they worked fine before disassembly. I would be sure to look at the idler and upgrade if it has the narrow arm and washer arrangement.
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Old 09-11-2017, 08:51 AM
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Just did my own rebuild this year using Waynes book! Def. go 2.4S ,I even used 2.2s pistons. Check it out but your intake ports look like they have been opened already. Have fun ,take your time.
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These are easily replaced without having to remove or even lower the engine. I'd box 'em up and reuse especially if they worked fine before disassembly. I would be sure to look at the idler and upgrade if it has the narrow arm and washer arrangement.
Thanks for the note. Good to know that replacing the tensioners isn't an absolute requirement. I'll probably err on the side of over-replacing; one of the main things I'm looking for out of this project is some piece of mind (as much as can be expected out of a hi-mileage 44 yr old car...)

Quote:
Originally Posted by chiroracer View Post
Def. go 2.4S ,I even used 2.2s pistons. Check it out but your intake ports look like they have been opened already. Have fun ,take your time.
Thanks for the feedback. I'm definitely considering a similar setup. Any lessons learned you'd be willing to share?

More pics coming soon...


-Jake
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Old 09-12-2017, 01:17 PM
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If you decide to run S cams, then you'll need to give Gus a heads up to put in the right space cam for your pump.

Also, you may want to consider opening the ports to "S" specs (think 36-35 for intake/exhaust?). If you increase ports, then throttle bodies and stacks should also be bored for that accordingly. If you'll be doing your MFI stacks/TBs, a good place to have this done is Eurometrix or Supertec.

This is in addition to getting pistons with deeper valve pockets for the S cams.

Last edited by MST0118; 09-12-2017 at 02:10 PM..
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If the tensioner's plungers were firm, they are OK to reuse.
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Old 09-12-2017, 02:11 PM
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Your heat exchangers look to be in good condition. You could have them cleaned and coated for protection. I had mine Aluminum Plasma metal sprayed. Hot jet ceramic coating is another option.
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