Intake stud replacement...

targa44 · 08-21-2019, 09:49 PM

I've ordered new (longer) intake head studs for converting a 3.0 ltr engine to accommodate a 3.2 ltr Carrera intake.

I'm nervous about this. What is the best way to remove the old studs? i.e. double nut the old and rotate out?

Are they usually loctited in?
Use PB blaster to soak in for a few days?
Do you have a special tried and true way of removing?

thanks,

Marwil · Marwil's Garage

I would suggest heating them, soaking with PB blaster, heat, soak. Double nut, heat, and slowly, gingerly twist them out. If they snap off you may be able to rescue them by welding a nut on. Snapped studs are not fun, particularly if the engine is still in the car. Good luck with it, I've got my fingers crossed on your behalf.

Flat6pac · 08-22-2019, 04:36 AM

You’re not going to be able to use the insulators because the the carrera heads intake are shorter by insulator thickness. On an SC head, you’re going to be 1/2 inch higher.
The studs are just screwed in.

Bruce

targa44 · 08-22-2019, 10:18 AM

Marwil - thanks... I read your expose' about your conversion and that last stud. ugh.

Bruce - I think I know what you're saying about the different heads. That's why I'm thinking I should get the ~7mm longer studs in there (to use the insulators). Are you suggesting don't bother with the insulators or just saying it won't work as is?

thanks,

Flat6pac · 08-22-2019, 02:58 PM

Just for you to realize that the intake will be sitting higher and match up the intake size could be a problem.
Bruce

Walt Fricke · 08-22-2019, 08:03 PM

The "best" way to remove studs is with a proper stud remover. It has threads (in this case, for M8x1.25 threads)which clamp tight, so you don't need to double nut. Much faster for batch work. The intake studs are unlikely to snap off - they don't get the heat and whatnot that the exhaust studs get.

Do you have the "big port" 3.0 heads, or you bored them out to match the 3.2 intake?

targa44 · 08-22-2019, 09:25 PM

I'll check in with some P mechanic friends and see if I can't borrow the stud remover. Thanks for that lead.

Yes, the big port heads... actually, maybe a fraction larger. It's for a Euro 930/02 3.0 ltr and I measured an average 39.5mm bore. I'm thinking I don't have to modify anything (besides the studs) to change over to the Carrera intake.. it would leave a very small lip exposed at the head.

thanks,

Trackrash · Trackrash's Garage

Let us know how this works out. I would like to replace my intake studs with longer ones to accommodate thicker insulating spacers.

I did this once on VW heads and am very hesitant to attempt it on my 911 motor.

targa44 · 08-24-2019, 03:39 PM

Hi Gordon... just started with the PB Blaster. Instead of spraying it all over the place, I squirted it into a jar lid and applied with a small 1/4" brush and let it dribble down the threads. I'll repeat for a few days and take a whack at it. I bought a stud remover (generic) just to have. But, I'll follow Walt's suggestion of getting the right (M8 threaded) tool. One of my mechanic friends said I could borrow his (Snap-on) for a few hours at a time - he doesn't want to be without it!

targa44 · 08-27-2019, 07:55 PM

11 out of 12..... broke #6. Now, flatbed to a mechanic.

Marwil · Marwil's Garage

That sucks! My condolences.

targa44 · 08-28-2019, 07:58 PM

Already fixed. Pick up car tomorrow and press on... when I left the shop this afternoon, he agreed it was a bugger. We (he) tried the weld a nut on method, but that wasn't working either. So, I'm guessing he bored it out?

Marwil · Marwil's Garage

Glad you have it sorted so quickly. Press on!

dap930 · dap930's Garage

kj,

Be aware that the injector flow notch in the Carrera head/intake manifold does not exactly match up with the flow notch in CIS heads. You will have increase the notch size in the CIS head or use adapter insulators that Turbo Kraft sells that allow the use of the CIS gasket on the head and the Carrera gasket on the manifold side.

targa44 · 08-29-2019, 08:00 PM

Hi Dennis,

…. didn't go back to look, but I think that came out in Marwil's posts. However, in checking with Clewett, he mentioned that since I have the large bore heads, it was a straight swap... hope I interpreted that correctly.

I plan on looking very closely at the alignment and small exposed lip on the head from the slight variance to the runners. Thanks for the heads up. I'll do my best to keep an eye out for that and the 2 types of gaskets (which, fortunately, I have).

dap930 · dap930's Garage

kj,

I bored the top of my intake ports to 41mm to match the Carrera manifold and then tapered it to throat. But the CIS notch does not match that of the Carrera manifold. I carefully machined the CIS notch to match the Carrera manifold notch, but you can not go too far or you lose too much gasket sealing surface when using the Carrera manifold gaskets.

'76 911S 3.0 · '76 911S 3.0's Garage

I made a jig to perform the notch match in a mill:

targa44 · 09-03-2019, 04:07 PM

Hi Jayson,

This has been fun having people who've helped / suggested things in the past come back and offer up more. Wow - very impressive procedure. Thanks for that.

From the photos, it begs the question about the bore diameter on the heads:

1) Are those 34mm bore?... it looks like there's a whole lot more lip exposed than mine or did you ultimately taper or enlarge that too?
2) What injector type are you using - EV1, EV6, other?... something that squirts above the notch or below?...?

I'll get some photos soon and compare.

thanks,

'76 911S 3.0 · '76 911S 3.0's Garage

Hi KJ,

The heads are late SC heads that have been opened up to 39mm. I originally had big port heads on the engine but opted for the later heads so as not to have to worry about the air injection ports as I had one plug eject while driving. I have not touched the inlet bore size beyond what you see, I'm not terribly concerned with the minor lip between the insulator and the head. My big port heads had the same lip and there was no noticeable adverse affect.

I am using ID725 injectors (EV6 connector), these spray above the notch. Previously before I turbocharged, I had HEMI injectors that had a long reach pintle on them that would inject beyond the notch so it was not so much a concern. These, however, were only 330cc injectors and would not support the power levels I'm after.

targa44 · 10:10 PM

thank you.

I need to take a new tack now. I'm not going to try and grind the notch with the engine in the car. I'll start a different thread to isolate a topic to the phenolic spacers... it's difficult to see from the Turbocraft website, but it appears that the spacers are just deeper than the Porsche part. Maybe twice as tall and therefore introduce the injector notch higher and just avoid staring at a flat spot on the 3.0 ltr head. I've looked at a few phenolic products on-line and they run about $30-$40 for a 12x12x 5/8" sheet... that, to me is worth a try.