Estimate to fix head studs yourself?

[bpu699]

Following up on a different thread... Found broken head stud and pitting on one cam...

Trying to nail down what would realistically be involved to fix this, might be my winter project...

Assume the following which I have been told by the prior owners, and will verify is true on disassembly...

1) motor reported to have top end done 5000-7000 miles ago. Car ran great until above issues found. Let's presume heads were rebuilt.
2) main bearings seem fine, no reason for me to assume otherwise
3) figure 1 cam, sc grind, needs replacement or regrind to be safe

What's involved in doing this in regards to a reasonable approach?

I know it's easy to go nuts while you are in there...

Would it be recommended to check rod bearings and add ARP? Car will be used mostly for hpde, seems like a good investment...

Change anything else?

I know costs can rise if you need head work/etc, but that seems to have been done from what I was told.

I have Wayne's book on engine rebuilding, but this engine was strong just looking to fix the above which I found when I went to adjust the valves...

What would a reputable shop charge nowadays to correct this? What about a full top end rebuild if needed?

Thanks

[Tippy]

Leave the pistons in the cylinders and you are only out top end gaskets and head studs cost wise.

I wouldn't go crazy inspecting parts as it's wise to resize big ends once seperated. Slippery slope.

If oil pressure is good, no cam lobes worn, sprockets look fine, and no knocking sounds, I wouldn't touch the reciprocating parts IMO.

I'd think you could do it for about $1k...

[bpu699]

Originally Posted by Tippy

Leave the pistons in the cylinders and you are only out top end gaskets and head studs cost wise.

I wouldn't go crazy inspecting parts as it's wise to resize big ends once seperated. Slippery slope.

If oil pressure is good, no cam lobes worn, sprockets look fine, and no knocking sounds, I wouldn't touch the reciprocating parts IMO.

I'd think you could do it for about $1k...

You just made my day... I do plan to regrind one cam...

Can you change to arp hardware without resizing? Could use the extra insurance on the track...

Any point in honing and reringing? Or leave it alone?

Motor has 60,000 miles.

Thanks

[Tippy]

Putting in ARP rod bolts does require resizing***, at least what the engine builders say.

It's pretty cheap, but then it leads to new rod bearings, unless you're comfortable reusing.

That's a tough debate I have with myself, honestly. I'd think the board would be pretty unanimous with putting in new.

See where this is going?

If it has Nikasil, there is no point in touching the rings or cylinders IMO at that low of mileage.

*** Maybe swapping 1 rod bolt at a time WITHOUT pulling the cap off or loosening the opposing stock rod bolt would NOT require resizing???

Dunno?

Better answered by others as I've never done this but throwing out there you wouldn't loose the concentricity IMO.

[bpu699]

Alright, scratching my head on this one...maybe I am old...

I remember dilivar studs... And magnetic studs...

Pelican shows race ware and super tech, for $600. And genuine Porsche for $15 or so each...

That's quite a spread... Are you guys suggesting the high end stuff or the stock stuff?

[Flat6pac]

IF I were doing aftermarket head studs, or the owner wanted to go that way, I would only do
Supertec because the outer ends are fine thread, enhancing the adjustment of torque.
Bruce

[bpu699]

Originally Posted by Flat6pac

IF I were doing aftermarket head studs, or the owner wanted to go that way, I would only do
Supertec because the outer ends are fine thread, enhancing the adjustment of torque.
Bruce

Bruce, respect your opinion. Pelican only lists one head stud as "Porsche." And, it's the cheapest at $10. That's 240 for a set? Doesn't say what it's made from or type, which is odd...

Is that what you mean by non aftermarket? Seems cheap. Am I missing something?

Oem is $14.

[Flat6pac]

I pay about $12 each for factory studs, most time you just need 12 for street and light competition
Bruce

[Trackrash]

Originally Posted by Flat6pac

I pay about $12 each for factory studs, most time you just need 12 for street and light competition
Bruce

Yes. You only need to replace the lower studs with OE steel studs. Those are what the factory used for the upper studs. The divilar studs are much more expensive and not needed IMO.

[mikedsilva]

Originally Posted by Tippy

Leave the pistons in the cylinders and you are only out top end gaskets and head studs cost wise.

I wouldn't go crazy inspecting parts as it's wise to resize big ends once seperated. Slippery slope.

If oil pressure is good, no cam lobes worn, sprockets look fine, and no knocking sounds, I wouldn't touch the reciprocating parts IMO.

I'd think you could do it for about $1k...

Very sensible post... I would refrain from changing rod bolts..
Do what this man says.

[Tippy]

Don't give that much credit, Mike! 😂 😂 😂

[bpu699]

Originally Posted by Flat6pac

I pay about $12 each for factory studs, most time you just need 12 for street and light competition
Bruce

Well... that's sounds way cheaper than I anticipated...

When you say factory stud... is there a part number? I thought Porsche sold various types of studs... My 930 currently seems to have dilavar studs (nonmagnetic that look brand new...other than the one that broke .

[bpu699]

Originally Posted by Tippy

Putting in ARP rod bolts does require resizing***, at least what the engine builders say.

It's pretty cheap, but then it leads to new rod bearings, unless you're comfortable reusing.

That's a tough debate I have with myself, honestly. I'd think the board would be pretty unanimous with putting in new.

See where this is going?

If it has Nikasil, there is no point in touching the rings or cylinders IMO at that low of mileage.

*** Maybe swapping 1 rod bolt at a time WITHOUT pulling the cap off or loosening the opposing stock rod bolt would NOT require resizing???

Dunno?

Better answered by others as I've never done this but throwing out there you wouldn't loose the concentricity IMO.

Ah... the slippery slope. Like everyone else with a bad stud, I had a great running car before I found this. I just want to get it back to where it was and go back on the track ...

I read as many posts as I could last night, see people have managed to change to ARP with the crank in, using custom made stretch gauges... Rods were resized...

I was pondering your suggestion, of changing the rod bolts to new standard rod bolts, one at a time. That would just provide additional insurance on the track. Using the same rod bolts would require the same pressure/stretch... would think that wouldn't effect the shape of the big end... Need to do more reading... I tend to agree that leaving it alone would be best...

Is there any way to tell in situ if there are any issues with rod/bolt stretch? Can you put a dial indicator on a rod that's still connected to the crank and see how much "give" it has? I assume not, and if its a stupid question I apologize .

How does one assess rods/crank with the case together? Other than going by the fact that the car ran fine? If something is worn now is the time to fix it. But don't want to go fixing things on a 60,000 mile motor that probably are fine...

[Tippy]

The low ends on these motors are virtually bulletproof. At 60k miles, I suspect nary a witness mark of wear will be shown. When I tore down my 3.2 (same low end), the bearings looked perfect. The journals were perfect. It had a very hard life with 500+hp for years.....

If it were me, I'd simply inspect what you can see without tearing down anything beyond that and simply put in new head bolts.

2nd, I'd await more opinions on the rodbolts, as it seems some here have used bolt stretch gauges with the cases together. Doesn't seem hard at all, especially with studs removed.

Supertec headbolts are good in the way you can install the piston and cylinder on the connecting rods before installing the head studs. This makes installing the wrist pin clips easier.

[Flat6pac]

Turbo? That will be 24 studs to replace, just like C-2 as they are all dilivar
Bruce

[bpu699]

Thanks guys... started watching 911 motor rebuild shows on youtube to get a feel for it... doesn't look too bad. Some guy filmed their car being modded at turbokraft, with a step by step disassembly and assembly... At least it gives me an idea of the broader points. Disassembly looks like it went really quick...

Bo

Another newbie question...

If you repair a cam shaft with pitting on one lobe...do you just need to refurb the rocker arm on that lobe? Or, all the rockers?

[911pcars]

How come no one mentioned that factory rod bolts are of the "stretch-to-yield" type? New bolts (and nuts) are needed after disassembling the con rod assy. Don't reuse existing cod rod bolts/nuts.

Bo, Get yourself a factory repair manual or equivalent (B. Anderson or W. Dempsey reference manual).

Sherwood

[Trackrash]

Originally Posted by bpu699

Another newbie question...

If you repair a cam shaft with pitting on one lobe...do you just need to refurb the rocker arm on that lobe? Or, all the rockers?

I would imaging that you would get a cam that had all the lobes reground. I don't know of any cam grinder that would just do one lobe. Most would insist on doing both cams.

SC motors have a robust bottom end. If it were me I would replace the studs and cam and get on with it.

Now, if you are curious about the crank and bearings, what some do is pull out the rods and look at those bearings. That will give you an indication as to the health of the bearings and crank. As mentioned you will need to replace the rod bolts if you do this. It's a slippery slope once you are in there.

[bpu699]

Originally Posted by Trackrash

I would imaging that you would get a cam that had all the lobes reground. I don't know of any cam grinder that would just do one lobe. Most would insist on doing both cams.

SC motors have a robust bottom end. If it were me I would replace the studs and cam and get on with it.

Now, if you are curious about the crank and bearings, what some do is pull out the rods and look at those bearings. That will give you an indication as to the health of the bearings and crank. As mentioned you will need to replace the rod bolts if you do this. It's a slippery slope once you are in there.

Car is a 930, reportedly with SC cams (that was an upgrade for drivability)...

I hear you on the slippery slope. Motor was working fine, don't want to do a full rebuild "just in case."

So it sounds like I need to do the following:

1) All the head studs... Either Porsche metal ones or upgrade... $300-$1000
2) Regrind one cam... $300?
3) Regrind 8 rockers... $300
4) Gasket set...$400

plus miscellaneous stuff

Does that sound about right assuming heads otherwise ok?

Silly question, but if one buys a good used cam, you still regrind the rockers?

Can anyone clarify, when folks on here refer to using Porsche steel studs to replace the dilavar, are they refferring to the following:

Pelican Parts - European Automotive Parts and Accessories - Porsche • BMW • Mercedes • Volkswagen • Audi • Saab • Volvo • MINI

My car will be fairly close to stock HP wise + 50hp or so...

[timmy2]

Part Number: 911-101-172-00-M260
Are the steel head studs.