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Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
I have a line on another 86 engine purportedly out of an 86.5 five speed locally. Hoping this is not another frog as I look for a prince.
I don't think the mileage is as important as how long the engine has been sitting in storage. That's the killer. Was in this case ( piston rings stuck) and another S4 I bought that grenaded.
There's a storage unit locally slowly filling up with S3 engine parts. Glad it's not mine.
If anybody knows somebody in need S3 engine parts let me know. I'm keen to keep one set of the cams (2 sets are available), But pretty much every thing else is available. The block in this thread was going to be scrapped, but a local wants it.
If anybody need a S3 block for a future stroker project we have good candidate.
P.S., I like Greg's suggestion for a bore gauge. That could be in my tool box soon.
Well, a RL'r has offered me a manual 86.5 long block. From the pictures it looks like the heads have been rebuild.
But, one stud is out of the block. The car and related parts have gone through three sets of hands.
So, there is no one that can explain why the bolt is out. The was in the block with a double nut on it.
The rest of the block and the bores look ok. I am a bit concerned about the stud. The seller pulled the stud and the threads were clean.
What should I be looking for? Can I ask the seller to see if the bolt holds the required torque or should I return to my search?
Why would a stub pull out?
Pulled the threads in the block or just removed from the block?
Huge difference!
Why do studs pull?
Because random people rebuilding one '85/'86 engine don't know WTF they are doing, because they only have the information that Porsche supplies.
It takes many years (and a few expensive mistakes) to figure out what Porsche was doing/recommending to be done on all of the 928 engines.
And knowing what to do and what to ignore.
Which makes it very difficult for a random, single individual, to be able to build one of these engines.
Blindly following the workshop manual (which was really made for dealer warranty work, on low mileage 928's) just doesn't work.
I'm guessing that I follow about 75% of the information in the workshop manual....tops!
If the engine you are looking at is an '86.5, it should have a set of the gold (mostly threaded all the way) studs.
They probably have a severe case of hydrogen embrittlement and are likely junk.
Earlier engines had traditional looking black studs....threaded only at the ends.
These are almost guaranteed to have hydrogen embrittlement and will probably be junk, as they had minimal protective coating.
"Replacement" 928 studs are the gold "all thread" studs.
Made of a different "grade" of steel than the original gold studs....just to make rebuilding extra cr@ppy.
There's also three different varieties of 944 studs...just to make life even more confusing, if you think too much.
And of course, there are probably Raceware/ARP studs still available...in case someone wants the head gaskets to fail the first damp/cold morning.
Every single one of the above requires difference tightening approaches!
It's like playing Russian Roulette with four or five bullets in the gun!
For the 85-86.5 is it not recommended to replace all the studs if the heads are removed? If I remember right the three 90 degree turns the WSM calls out was incorrect and it was recommended here to do two 90 degree turns instead of three. There was a thread about it here about 8 years ago.
Edit: disregard what I said above. read through the thread below. After reading that thread years ago I've always said to myself if I ever buy a 85-86.5 I would remove the studs and convert to the head bolts used on the 87-88 cars when doing a rebuild.
This latest engine is not a good candidate both for the pulled stud and my skills. I'm not going to risk being right back here in a year.
So, the search goes on.
I think it important to realize that we are dealing with over 35 year old alumimum/silicon blended metal, which has been subjected to various types of use/abuse.
This combination of aluminum/silicon is remarkably brittle and somewhat prone to age related failure.
Many of my engines receive Timeserts in every threaded head bolt locations and in some cases, also in the girdle stud holes.
(Note that Porsche actually installed 12mm "Bigserts" in the upper two holes where the bell housing attaches to the block. Good clue of what they expected in high load conditions that moght be taken apart a few times!)
Just like all of the magnesium cased 911 engines (which all need Timeserts for all of the head studs and all the 8mm inner and outer stud locations) all 928 engine crankcases will eventually need Timeserts in all locations.
Get used to doing this proceedure.
The insertion of Timeserts makes these threaded areas incredibly strong...way stronger than original, because of the increased outer diameter of the steel insert. Virtually a "forever" repair.
Timeserts "open up" more choices for studs/bolts, because of the increased strength of the bottom threads.
There's a rather large "learning curve" for doing this job. I started to write some clues, but my finger got really tired and I decided that experience was the best teacher.
I think it important to realize that we are dealing with over 35 year old alumimum/silicon blended metal, which has been subjected to various types of use/abuse.
This combination of aluminum/silicon is remarkably brittle and somewhat prone to age related failure.
Many of my engines receive Timeserts in every threaded head bolt locations and in some cases, also in the girdle stud holes.
(Note that Porsche actually installed 12mm "Bigserts" in the upper two holes where the bell housing attaches to the block. Good clue of what they expected in high load conditions that moght be taken apart a few times!)
Just like all of the magnesium cased 911 engines (which all need Timeserts for all of the head studs and all the 8mm inner and outer stud locations) all 928 engine crankcases will eventually need Timeserts in all locations.
Get used to doing this procedure.
The insertion of Timeserts makes these threaded areas incredibly strong...way stronger than original, because of the increased outer diameter of the steel insert. Virtually a "forever" repair.
Timeserts "open up" more choices for studs/bolts, because of the increased strength of the bottom threads.
There's a rather large "learning curve" for doing this job. I started to write some clues, but my finger got really tired and I decided that experience was the best teacher.
Yep, that's why I would trust you to do it right and me ... well as the movie quote "a man needs to know his limitations".
Nice.
I don't understand the usefulness however of a setting ring in conjunction with a modern bore gauge.
I expect they were necessary for establishing dimension while using an earlier three anvil gauge but because the modern gauges have 2 opposing anvils, a dimension can be taken from anvil to anvil with an outside micrometer. Here's my process to observe cylinder shape and measure piston to wall clearance. I first measure the piston with an outside mic, then, utilizing the same mic and setting, I position the bore gauge anvils between the micrometer anvils and set the bore gauge to zero. This removes math from the process. Now with the gauge back in the bore, it will directly read the piston to wall clearance.
Of course, I could use a new tool... what is it that I'm missing out on without having a setting ring?
Nice.
I don't understand the usefulness however of a setting ring in conjunction with a modern bore gauge.
I expect they were necessary for establishing dimension while using an earlier three anvil gauge but because the modern gauges have 2 opposing anvils, a dimension can be taken from anvil to anvil with an outside micrometer. Here's my process to observe cylinder shape and measure piston to wall clearance. I first measure the piston with an outside mic, then, utilizing the same mic and setting, I position the bore gauge anvils between the micrometer anvils and set the bore gauge to zero. This removes math from the process. Now with the gauge back in the bore, it will directly read the piston to wall clearance.
Of course, I could use a new tool... what is it that I'm missing out on without having a setting ring?
Finding the exact perfect spot between micrometer anvils with the rounded tips of a bore gauge is, at best, very tedious.
And typically not very accurate....
That is why setting rings are made.
08-25-2021, 09:19 PM
what is it that I'm missing out on without having a setting ring?
