3.9 Cylinder Head Bolts

[aRRon]

I'm about to refit cylinder heads to my '89 RRC 3.9 and read that Loctite should be used on the threads (manual says Loctite 972). Am I right in assuming that it should be high strength/hi temp loctite which is hard to get or will high strength do (claims to be ok up to 150 degrees C)? Is this really necessary or good old cleaned and oiled threads will suffice?

Also there is one medium length head bolt with a threaded stud extending out of the bolt head - I vaguely remember this is for mounting something like the lifting eye or earth strap - can anyone advise where it goes on which head and what it's for??

[LOVEMYRANGIE]

I'm about to refit cylinder heads to my '89 RRC 3.9 and read that Loctite should be used on the threads (manual says Loctite 972). Am I right in assuming that it should be high strength/hi temp loctite which is hard to get or will high strength do (claims to be ok up to 150 degrees C)? Is this really necessary or good old cleaned and oiled threads will suffice?

Also there is one medium length head bolt with a threaded stud extending out of the bolt head - I vaguely remember this is for mounting something like the lifting eye or earth strap - can anyone advise where it goes on which head and what it's for??

Never heard of thread lock being used on headbolts in my 20+ years in the industry :eek:. If your doing a stud kit into the block then OK but not on bolts. Headbolts use antisieze on the thread only and either antisieze or plain clean oil under the bolt head.

As for the double bolt, this goes on the LH head at the front middle row (for 14 bolt 3.9L head). Its for the steel bracketry for the PS/alternator mount.

For the 4 external headbolts, only tighten to about 20Lb/ft and do them last or just leave them out altogether. Later 10 bolt heads are identical minus these bolts.

There has been evidence over the years that these bolts are a cause for warpage and cracking. LR finally removed them with the release of the 4.0L engine.

Cheers

Andrew

[Bigbjorn]

Not strictly correct. Where bolts/studs go into through holes into the water jacket, not into blind holes, then the threads need to have a sealant applied. There is a GM product specifically for this. It is mentioned in Holden workshop manuals and is readily avalable from GM-H dealers. If a locking compound or other is not required by the manufacturer's workshop procedures then anti-seize or oil is acceptable. Otherwise do as you are told by the maker.

As an aside, Loctite thread locking products are compounded to have the same torque characteristics as oiled threads.

[PhilipA]

I have always read that a thread sealant should be used to prevent electrolytic corrosion between the dissimilar metals.
I use GM thread sealant which appears to work well. I will confirm when I next take the heads off.LOL.
Regards Philip A

[aRRon]

Thanks so much Andrew, feel I can go ahead confidently now with maybe using some anti-seize. When they came out there was no corrosion after 20 years but the most pungent chemical smell you could imagine, I 'm guessing they were coated wth something. I also believe in oiling well under bolt heads/washers to enable accurate torqueing.

[PhilipA]

Where bolts/studs go into through holes into the water jacket


When I used my dental pick to clean every head stud hole on my 92 3.9 I found none of mine were wet. However I still used the GM sealant and the second time I swapped the heads they came off easily.

Regards Philip A

[clubagreenie]

Never loctited but have always used the GM stuff as mentioned. Comes (well did) in a tin, lasts forever. Do yourself the biggest favour and get a ARP stud kit. Part no 123-5401 also main stud kit for ref is 124-5401. You get stud for all three rows (as per early heads, washers and nuts. Lube with assembly (moly lube), the rear most studs may need to be fitted after fitting head as (in Disco at least) head won't pass over stud without fouling in the firewall.

Fabre at Lakemba Sydney has them off the shelf, was around $200- plus shipping at christmas, VPW in Vic has them also (avoid Rocket Industries, unless you like long drawn out masochistic sessions). They are listed as buick V6 215cid for some reason, could never work out how a V6 has the same no of bolts has a V8.

[Bigbjorn]

They are listed as buick V6 215cid for some reason, could never work out how a V6 has the same no of bolts has a V8.

Probably meant for Buick Motorsport High Performance V6 blocks and heads. The Stage 1 head uses a four bolt attachment pattern and the Stage 2 uses a six bolt attachment pattern. Buick Motorsport says if using the Stage 1 head and four bolt pattern, power level is limited to about 600 hp before gasket failure. Stage 2 heads have six extra bolts. Stage 2 uses all different gaskets to Stage 1 but can be used with a four bolt pattern and is then horsepower limited as a Stage 1.

[clubagreenie]

Buick Motorsport High Performance V6 blocks and heads.

Contradiction in terms?

Many thanks for solving that one for me.

[PhilipA]

Do yourself the biggest favour and get a ARP stud kit. Part no 123-5401

What do you torque the nuts to with these?
AND are you SURE that you can get the rear studs in both sides with the head in place? You have actually done it? How do you get the head on the other studs?
I think 70Ft lb is not enough with composite gaskets as mine drool coolant out the head ends, but the stretch bolt tensions are too much as the start of sleeve slipping is invariably a crack in the block just near a head bolt thread.
Regards Philip A

[clubagreenie]

Torques are specified by ARP. You NEED to follow their proceedures. With sacrificial gasket for first torque sequencing, tension in factory sequence in 3 equal progressive torques to max, 5 times to pre stretch studs, measure before and after stretch sequence.Check for any over spec.

Yes you can fit the head over the studs save for leaving the rear most studs out and fit them after fitting head. It's been noted on here previously and where I first realised it, as I refitted my heads with the engine out of car.

I've used ARP's on anything from stock Renaults to 1000hp+ Toyo 6's & V8's (one at over 50psi boost) and never had a head or gasket or stud failure.

When I swapped to a 4.6 in my disco I did a test on a new set of TTY bols and the variation in release tension and stretch was scary. As little as 38lb retained tension and stretch length variation as well as stretch location variation.

[Bigbjorn]

Contradiction in terms?

Many thanks for solving that one for me.

They claim 800+ horsepower for a 3.4 litre turbocharged Indianapolis engine using methanol, 500 hp from a naturally aspirated 4.5 litre Trans Am 108 octane race gasoline engine. These are Stage 2 engines which use almost no standard production parts and Buick Motorsport pretty much warn against using standard production engines or parts in a high performance application.

Interestingly, their assembly and blueprinting manual has a chapter on balancing which includes a section on the firing order, balancing, and phasing of an even firing V12 produced by coupling two V6's together. There must have been a need for this information for Buick Motorsport to go to the trouble of producing this sort of information. I wonder who and where? A 9 litre turboed V12 could be handy.

[PhilipA]

Maybe it is just a missprint ( 6 instead of 8) as the 215 was the CID of the 3.5 V8 and it was known as the BOP215..

Maybe there are 215V6s also .
However if you google Buick 215 V6 everything comes up as V8, and an historical footnote is that the Buick V6 produced from 3/4 of the V8 AFAIK became the Holden 3.8.
Regards Philip A

[Bigbjorn]

Maybe it is just a missprint ( 6 instead of 8) as the 215 was the CID of the 3.5 V8 and it was known as the BOP215..

Maybe there are 215V6s also .
However if you google Buick 215 V6 everything comes up as V8, and an historical footnote is that the Buick V6 produced from 3/4 of the V8 AFAIK became the Holden 3.8.
Regards Philip A

The V6 was first produced in 1962 at 198 cubic inches. In later years it was produced in 225, 231, 252, 196, 181, 270 cubic inches, and 270 ci turbocharged in the Grand National front wheel drive rocketship in the 90's.

For some years four different displacements were in production simultaneously and up to 6200 per day were made. It came in front and rear wheel drive versions, carburetted and fuel injected, distributor and distributorless ignition, naturally aspirated and turbocharged, manual and auto transmissions.

By using a variety of production and/or after market components, the engine can be built in 151, 209, 244, 265, 272 cubic inch versions.