Stripping 951 Block
 

Motor is an 86. Block is questionable, so I want to use a 2.5 NA block to refresh the motor. I know the pistons and rods are different, anything else I need? Will I be able to modify the NA balance shaft cover for turbo oil supply?

TIA


rasta

Yep, just drill and tap the upper cover for the oil feed. Im not sure however if the early n/a blocks have the boss in the cover though, but either way i would stick with an '86+ block. Also make sure you use the correct oil pressure regulating valve.

Rasta, you putting a 951 engine in the 924S? With an 86 951 engine I'd update to the late style oil pan baffle while you're in there, unless you have other plans (dry sump? LR baffle flap?).

Now, that is just crazy talk. Muah. Muah. MUAH HA HA HA HA HA!

Might as well ask about the actual problem. . .some genius ran a standard threaded upper bellhousing bolt into the block and destroyed the hole. Would y'all be comfortable with a thread repair at this location? There is not a lot of material there for the boss, and the upper holes are closed at the end.

Hmmm. That is a problem. I wouldn't want an insert repair, but that's just me, some might be comfortable with it. Can you drill it and tap to the next larger size? Even if you had to use a shorter bolt (since you aren't working with an open hole where you can run a tap right through) I'd be happier.

But seriously, if you're building a 924 S51 I need details, that's my dream car. Better looking narrow body with so much power potential. Tasty.

Parts are currently accumulating for 931 S3. . .just need a good shell.

Good lord, the 931-51, that's awesome! I've got a stock 951 intercooler sitting on the workbench, let me know if you need it.

And you have the space to accumulate them. Good Lord. :eek:

Absolutely perfectly comfortable with SS coil type thread inserts Rasta. More than comfortable, snug and smug in fact. Will be stronger than the original thread, permit greater torque & clamping force and have a larger load bearing surface. Recall posting pics and details on 924 board of the inserts & tools. Deliberately put inserts in ALL the aluminium head threads. Never had a stripped thread or any dramas since. Helicoil, Recoil, Permacoil, etc will be no drama in a blind hole. The appropriate tap will come with the kit, just ensure it does not have a lead section of the original size which will bottom out. Most have an intermediate style tap anyway.

On the other hand, drilling and tapping for the next size will likely have fitment issues. Bigger bolt needs more torque to apply correct stretch so will compound the problem, possibly stripping again or worse still, fracturing the boss. They`re M12, aren`t they? M14 (plug thread size) is massive in comparison. A 1/2" (UNF or UNC) will have insufficient thread engagement in a stripped 12mm hole. There`s still 3 other good bolts, holding the bellhousing. More than sufficient even if the bolt in question is not torqued to maximum and loctite is used.

The only real issue is the amount of metal surrounding the hole. Realize the boss is not too large or substantial, however a minimum wall thickness of say 6mm will suffice. Again, the insert has the advantage over an oversize bolt. Perhaps post a pic of the area since it sounds like the block is out and easy to access.

So will it now be a 941 or has Ideola patented that #? ;)

I would not be concerned using a helicoil on the block for the bell housing. No sense in going through all that trouble for something minor like that.

+1 techno

I would use a timesert in that location, not a helicoil. Time-sert kits are a bit more expensive, but we have had very good luck using them in that location on a couple of 911 race cars at the shop.

It will be a 951 powered 924S. I am claiming "931 S3," since there don't seem to be many numbers left in Toofah Nation.

hellicoils
 

when i used to build and race vw's we hellicoiled every case stud in the engine never had a case/ head stub pull out or pop out from the compression and fly-cut heads. but as for the stock threads they pulled and stripped all the time. you won't have any issues !!! :D