Remove heads and replace studs?!

kstylianos · 02-25-2003, 09:55 AM

The engine in my 82 SC came out last weekend for minor R&R, exhaust and cam upgrades. Last night I completed stripping the engine down. No exhaust, CIS, fan or shroud, bare engine hanging on the stand. The cams will come out later this week to be shipped to Webcam for their 20/21 grind.

We checked for broken/loose head studs and all were tight, but from what I've heard, they can 'snap' at any time. I also pulled a couple plugs (10K miles) to check their condition and they looked beautiful, not oily or sooty. So my valve stems/rings 'seem' to be in good shape.

My question is this, should I remove the heads and send them in for general cleanup and clearance checking? This would also allow me to replace the head studs with the stronger units. I'm soo close as it is, once the cams and rockers come out, only 4 nuts hold each head in. I'd hate to put all back together and find out a stud broke 2 months later. I don't have any leakdown figures (good or bad) to justify pulling the heads, but if I'm this close, should I just do it, for piece of minds sake?

What is the general concensus?

I'd like to hear more than "well if it makes you feel better, then do it".

Thanks for any advice guys,

marcesq · marcesq's Garage

John Walker may be able to help here, but I believe he suggests that good ole Stainless steel studs are the fix for top and bottom.

I don't know enough about the last steps involved in removing the heads, etc with a 911, but I do know one thing about XJ6 head studs, and that is if the head comes off, so do the studs. FWIW.

kstylianos · 02-25-2003, 10:09 AM

The 911 head studs are attached/screwed into the case itself, the heads will slide right off once the barrell nuts are removed. Just like the old KZ series Kawasaki's

.

john walker's workshop · 02-25-2003, 10:12 AM

most 82's had the powder painted dilivars, which seem to last, so far. stock steel ones would certainly be better, with no chance of breaking in the long run. it's a toss up. if you end up sending the heads out, then i would replace them, as it's not a big deal at that point. probably another 4 hours or so, if you have the tools and know-how.

kstylianos · 02-25-2003, 10:30 AM

JW,

From peering around the cylinder walls, the studs look sliver/goldish in color. Dosent look to be from rust or other type of discoloration. This sound like the powder painted dilivars?

Thanks JW

Superman · 02-25-2003, 10:51 AM

Ummm....how many miles on this engine? My exhaust valves, at 182k miles, were worn like JW predicted, so I replaced them. And the intakes, and guides, etc. And while I was that far, I split the case and freshened the bearings. That part is easy easy easy. So, essentially, I got a pretty fresh motor. My pistons and cylinders were in GREAT shape, but the rings were worn. I'm glad I did it. If there are many miles on your engine, I would consider looking at the rings. and if you're there, you can remove a valve or two and mic them. You're really going to like those 20/21 cams. You might want to make sure the rings and valves are ready for them.

kstylianos · 02-25-2003, 11:27 AM

Sup....The speedo shows about 75K. One of the PO's replaced the 80mph speedo at one time. CarFax shows clean (no odo fraud), so I'm hoping he matched the new speedo odo with what the old one had. From what I can tell, the engine has at least 75K and runs very strong. I'm hoping the valves/rings, etc. are still in decent shape.

john walker's workshop · 02-25-2003, 12:22 PM

the gold studs without the black powder paint, are not to be trusted. they can break at any time. so might as well start in. you wanted to do the heads anyway.

kstylianos · 02-25-2003, 12:44 PM

JW....Thank you. I'm digging in tonight

Hey, have you seen those used studs on Ebay........

Rick Lee · Rick Lee's Garage

I'll chime in since I did this job with Charlie last Sunday. When peering down the intake ports, it looked to me like there was considerable carbon, gunk or something on the back of the valves. Nothing looked broken or cracked, but I'd say those valves looked like they needed a good cleaning. I urged Charlie to bite the bullet and send the heads out and do the lower studs while the heads were getting done. Like he said, he's so close it's just too tempting to not do it.

As I learned during my recent engine swap and suspension upgrade, these projects always end up costing about twice what you budget for them. But it sure is worth it to go all out and do it right. With all the work that's already been done to get his engine where it is now, it'd be a shame to have to do it again because he skimped on a few more hours of labor and a few more bucks. I know, I know. It adds up. But you're good to go for many years once this is done.

john walker's workshop · 02-25-2003, 03:15 PM

$tainle$$ is overkill on a stock engine. the steel ones, just like the upper row, are all you need.

David · David's Garage

I'd replace the lower studs with steel like the upper ones since your already that far. They sure are a b!tch to get out once they've broken. While your at it, a set of rings is only about $80 from Pelican. If you don't send the heads off, you could at least pull the valves, mic the stems and guides, clean everything, lap the valves, and replace the seals.

kstylianos · 02-25-2003, 05:03 PM

So, from what I've been reading, the upper studs DO NOT need replacing? I was going to replace the uppers as well, but if it's overkill I'll pass.

I'm not going to do the heads myself as the light at the end of the tunnel is getting increasingly dimmer. I'm going to either find a local shop or send them out. I'll also have them remove/replace my exhaust studs

JW...I've been reading past threads regarding removing the head studs. Looks like the cylinders need to be removed to gain access to the inner case wall for heating/stud removal. Any way of effectively/successfully removing the studs w/o heating from within? If not, then new rings as well. And while I'm at it, how about some rod bearings.

Like I said earlier....I NEVER thought I'd get this deep.

Rick Lee · Rick Lee's Garage

Give Stan Fox at RPM a call. I think they're the local experts on head work. Or Dulles too. Since the upper studs are steel and it doesn't get as hot at the intake as at the exhaust end, they're ok.

john walker's workshop · 02-25-2003, 05:17 PM

you have to use an oxy/acetylene torch to heat the case enough for the studs to come out. don't heat the stud, or it can twist and break. there's a picture of where to heat the case in the archives. a bernz-o-matic torch doesn't cut it, as the case is a giant heat sink. you're getting real close to a case split at that point, and it's pretty easy to do the bottom end. nod nod, wink wink.

kstylianos · 02-25-2003, 05:37 PM

Thanks guys,

Looks like I have this one pretty well sorted.

JW....I bought the OXY/MAPP setup from the Home Depot to take off the old HE's. Worked like a charm. Looks like I'm keeping the extra bottles of O2 after all

Doug E · 02-25-2003, 06:27 PM

Keep your chin up there buddy just don't stop thinking about how great it is going to feel the first time you take it up to the redline on the 3 - 4 shift!

It sounds like you are on the right path and it's nice to know that we will have another "expert rebuilder" on the NoVa staff