broken head stud

[T77911S]

86 930
82k miles
re-ringed at 40k
comp test last week
all 120psi for 6 revs
130-135 for 12 revs.

broken stud at the bolt so the stud is almost full length, lower stud on #2.

a few options I have
replace just the one stud or replace all. if all which brand.

I think I can get it out without removing any cylinders, if I can should I do that.
or should I pull all cylinders and inspect the rings or just remove the one. I did over boost by accident twice.
I am concerned about the rings seating if I just pull the cylinders.

I need new cams.
what cam should I put back in.
7006 turbo with an old B&B style header. RUF IC.
all new CIS system.

considering porting the heads but to what size. would influence cam selection.

other option or in addition is to twin plug, but what ignition system.


I will have valve job done with new exhaust guides.
resurfaced rockers and new bushings along with the new cams

[1979-930]

I would try re-torqueing the rest of the studs. If they are at spec or tighten to spec without breaking I would replace the one stud with a matching brand.
The SC cam seems to be popular. You can get Elgin to regrind them and rebuild your rockers for a lot less than new. He can recommend a good grind for your application.
My old cams had too small of a factory journal to grind to SC spec. He has a different Sport grind he used on them. Per Dema Elgin, Chris at TK, Ben at Salerno there are other cam grinders with good names that will grind whatever you want without letting you know the cam won't work correctly. The lobe will be so small the rocker adjuster will be completely maxxed out. I think your year has a larger journal that can be ground to SC specks. But Dema will let you know before doing anything.

It's too close to spring to go down the rabbit hole of twin plug. Save that for next winter.

[T77911S]

what about having the heads drilled for dual plugs now.

how about porting the heads. I would like to try to get a little more out of now while I have it down this far.

[gumba]

I would take it down to a short block. Replace all the head studs. I sent my cams & rockers to Elgin who did a turbo sport grind. I sent the heads to TK for a valve job, port & polish, matched aluminum injectors and ported the intake manifold. I'd ask about twin plug but not sure you need it. I went with the XDI ignition which was very simple to set up. The XDI 2 is more involved using a lap top to program. While the motor was down, I sent the short block to TK to check the rod bearings. TK stated they could change the bearings without splitting the case.
Ollie's is another good machine shop choice.
I'm sure the turbo guys will pipe in. I think the 7006 boosts to a higher rpm than the 7200.
All the choices are going to be based on how you plan to drive the car, street/track?

[quattrorunner]

Honestly it's a large job so it's a great time to just replace all. Try arp or supertec and be done worrying about when the next will break.

[pkabush]

Even though I considered it (thanks for talking some sense into me Raw)and some members here have done full rebuilds reusing the original Dilivars I’d definitely get rid of the studs while it’s apart. I had John Walker put my motor back together. He recommended using Canyon steel studs. His rationale is that our motors are relatively low boost and quite low torque ratings for the head studs so, no sense spending $600
This made good sense to me so that’s what we did.
If you send your heads out for machine work I’d definitely have em drilled for TP
It’s cheap and you don’t have to utilize them until you’re ready with the rest of the ignition system. Simply fill the holes with plugs and ride single plug until you’re ready.
I opted to scour the classifieds here for heads rather than rebuild mine. It took awhile but I found a set of SC heads that we’re freshly rebuilt and drilled for twin plugs for $2500. I did use ARP bolts on the rods as well as new rod bearings. No need to split the case for any of the above mods. Oh yah, and I pulled my cams in favor of SC cams.
I got the cams here in the classifieds as well. As you know these motors are stupid expensive to rebuild do to the insane P-tax on the parts but even so, I was able to complete my rebuild for a bit over $6,000 all in. Good luck and have fun.

[356911930]

I agree with Quattrorunner,

It's probably best to plan everything you want to do and do it all at once. It will take a while and serious cash but it will be one large project behind you.


Rahl

[svcetiquette]

Bummer, this just happened to me too. #4 cylinder popped a stud on New Years day. '86 with 65k miles. I've been waiting for an excuse to go efi, this is probably it.

I had put high lift versions of sc cams in mine, iirc commonly referred to as "sc330". They really woke the car up in combination with the other mods. If you pull the cylinders, your rings will reseat fine given they're intact and go back together in the same location. I'm in the camp to get good quality aftermarket steel studs. Overkill but I'll probably use the supertecs, mainly because I'm happy with them in my racecar engine.

Best advice is come up with long term goals and a plan before buying parts. There are plenty of good formulas documented on here.

[T77911S]

Take a look at my heads
I have some pitting where the cylinders meet the head.
Going to replace all the studs.

[Rawknees'Turbo]

^^^

About 12 years ago when I had my engine apart, I had similar pitting and scoring in those areas, and a machinist that did the work on my heads said it was due to the insufficient clamping force of the original, Dilavar studs.

Originally Posted by pkabush

Even though I considered it (thanks for talking some sense into me Raw)a . . .

Anytime, 70'sBush!

[T77911S]

Are the heads bad.

The head bolts were pretty hard to get off.
Would they need to be machined then I would have to use head gaskets

[TurboKraft]

Those heads will need machining (aka flycutting, decking, etc. ) to clean up the sealing surface. Remove *as little as possible* from all 6 heads evenly. No head gaskets.

Check the cylinders as well, they may need minute clean-up machining.

Twin-plug: it's one of those things to do if you're already porting and overhauling the heads. Even if you cannot do the rest of the twin-plug conversion right away, just grind the electrodes off an old set of plugs and install them in the lower holes until you're ready. Then it's all external bolt-on conversion stuff, no going back inside the engine.

PM'd you about the porting, cams, etc.
Sport-SC aka SC330 works fantastic with basic 7:1 CR pistons, helps liven it up. Seems like when we have sent Elgin any OEM 930 cams, the answer is always "no" when it comes to re-grinding, and he supplies new. Not cheap, but high quality you can trust to be consistent.

[T77911S]

thanks.
is that pitting common?

wont machining the heads/CYL throw off the cam alignment to the chain box?
should I have the chain box machined too

[Black_Hat]

I had the same happen. I decided to do it all once . I had Chris at TurboKaft supply parts and machining. I did all the wrenching & tuning.

10k plus miles no leaks, no smoke, perfect leakdown - compression and I could not be happier.

I’ve been really busy so I have not gone to the next step – EFI – but car is brutally fast and reliable.

Do your self a favor, do it once , do it right.

Forced to Deal with This

[TurboKraft]

Black_Hat has some angrier, high torque cams that require additional piston clearance.
So if you like how his engine idles and revs then we have to machine valve pockets in your pistons.

[T77911S]

i have the left side head studs out and the holes cleaned up. did the top row before removing the cylinders to keep the dirt out of the engine. this is one of my biggest obstacles, keeping the inside of the engine clean. I keep it bagged when not working on it.
studs came out pretty easily with this remover, only $20. was going to get the snapon but thought I would give this one a try on the broken stud.

https://www.amazon.com/gp/product/B00265M8N4/ref=oh_aui_detailpage_o02_s00?ie=UTF8

it gets a little "slippery" on the coating on the dilivar but once that is gone and it is tightened again it works really well.
I may still get the snap-on to replace the exhaust studs.

any ideas on cleaning the tops of the pistons and the ridge on the cylinders.

I am really considering replacing the rod bolts with ARP. I want to see the bearings and maybe replace if bad or should I reuse if good.
do you measure the stretch of the ARP bolts

this cylinder head thing has really got me flustered.
if I machine the heads to eliminate the pitting should I machine the chain boxes?
one benefit is it could raise the compression.....a little.

[T77911S]

naaaaa, don't want to get into that big of a cam.
I think I have too much back pressure with my turbo to go with too much overlap. been wanting to measure it but have not made the effort to connect up a gauge.
the super SC grind will be fine.
im not on a budget but I may have to sell my tractor or get into the wifes kitchen money.

[gsxrken]

That blows dude, but if you have to crack it open, might as well add some power to make it worth it!

[T77911S]

ehh, not too bad. I was wanting to look at it as I still had a funny sound when driving and a slight miss at idle. I really suspected broken rings.
so other than the head pitting I am not upset over it.
I also needed to replace the cams and 2 rockers which I new were bad.

If the heads are machined .25mm can I double shim the cylinder base with a .5 and a .25 gasket or will it leak oil

[Alan L]

I had my SC heads machined 0.2 or 0.25mm,and picked up the squish in the cylinder base gaskets. You don't have to worry about the cam boxes.
Good luck - while you are in there.
Alan,