BHG. But why?

[siman]

Well just throwing it out there that I am LEARNING from a proffesional race car driver and builder, thats kind of a plus when making a suggestion. Given that alot of people have no clue what I actually do in the car realm here.

You guys might even see me on the road track

Anywho back on topic. I think it could of been a batch of bad gas and some high spirited drives that could of slowly degraded the condition of the HG itself.

I would not feel bad at all, I almost just like to think of it being a "known" thing that the engine will give out somehow sometime somewhere because you are pushing it closer to its limits.

-Jonathan Mann

 

[GrimJack]

I thought it was the Titian that had the evil rivet

Actually seems to be a bit of a problem for several manufacturers, I had to drill one out of my HKS gasket too. Likely wouldn't be a problem if I hadn't had the block and head skimmed, but as soon as you do, the sealing surface expands by enough that it's an issue.

 

[siman]

yeah I remember seeing those rivets. yikes!

I am out of here. I think we probably solved the problem and either way the motors going to be rebuilt.

Just another "my engine is FUBAR" thread :biglaugh:

just kidding around Jon (MDC). LOL

-Jonathan Mann

 

[Orion ZyGarian]

What exactly is the deal with the rivot then? Is it an unwanted extra part of the HG? Whats the deal?

Also, I am looking for the utmost maximum life out of my application. So far it seems the "stopper" type HG is the best. Does Cometic make a "stopper" type, or am I 'stuck' with HKS/GReddy?

Another thing...retorquing the headgasket after rebuild? Is that the process of loosening all of the studs and retorquing them again back to the correct amount? Or are you saying that after running the engine for a bit, the head will naturally become slightly "un-torqued" after rebuild? Please forgive me for such simple questions...I know all sorts of "advanced/complicated" stuff about MkIIIs, but there are so many "simple" things that I dont know.

Finally, using ARP's moly lube, what ft-lb rating should they be torqued to? Can we all agree on 81 ft lbs for proper setting? So many different ratings everywhere...81 ft lbs is what the sheet says and what seems to be right, but I'm asking the most knowledgable and experienced members of the MkIII community to be 100% certain.

 

[siman]

What exactly is the deal with the rivot then? Is it an unwanted extra part of the HG? Whats the deal?

It was a design/manufacturing flaw where the rivets were too tall and would not let the head compress all the way to make the seal

Also, I am looking for the utmost maximum life out of my application. So far it seems the "stopper" type HG is the best. Does Cometic make a "stopper" type, or am I 'stuck' with HKS/GReddy?

HKS/Greddy are the only two manufacturers that make the stopper type to my knowledge. If you want reliability or "life" out of your car, do not cut corners and try to save money. Cheap parts arent good and Good parts arent cheap

Another thing...retorquing the headgasket after rebuild? Is that the process of loosening all of the studs and retorquing them again back to the correct amount? Or are you saying that after running the engine for a bit, the head will naturally become slightly "un-torqued" after rebuild? Please forgive me for such simple questions...I know all sorts of "advanced/complicated" stuff about MkIIIs, but there are so many "simple" things that I dont know.

Yes you CAN do that, but its up in the air if its a good "practice" or not since everyone has their own opinion. I have no problem with the idea but have not excersized it myself on my own 7mgte.

Make sure that you loosen ONE BOLT and TIGHTEN ONE BOLT at a time, do not simply loosen them all then retorque them all, that breaks the seal of the head to the gasket completely! Just one by one. Take your time. Good technicques usually take the most time, and the most time taken ensures proper procedure execution!

Finally, using ARP's moly lube, what ft-lb rating should they be torqued to? Can we all agree on 81 ft lbs for proper setting? So many different ratings everywhere...81 ft lbs is what the sheet says and what seems to be right, but I'm asking the most knowledgable and experienced members of the MkIII community to be 100% certain.

81ft/lbs is if you are using 30 weight motor oil on the threads, 105ft/lbs if using ARP's own "Moly Lube" (which is my personal choice). Just do the full 105ft/lbs with the moly lube just so you can sleep peacfully and boost happily without having to worry if those studs will stretch or loosen under loads.

 

[GrimJack]

ARP moly lube torque is 81 foot pounds.

The rivet thing is a bit of an oversight from the gasket designers. They fitted the gasket on a bare stock block and head - and if we were all using un-cut blocks and heads, we likely wouldn't have any problems. However, as soon as you machine the surfaces, they get a bit wider in a few spots... and at least one of those spots happens to have a rivet in it. When you try to crush a rivet between two surfaces, you don't get a very good seal - or in some cases, you get a seal that works for a while, like we did on upgradedsupra's car.

Retorque - simple. Just use a breaker bar to crack the bolt back 1/4 turn, then retorque to the correct setting. Do this for each headbolt, in the same order as you would when installing the head. So, crack, retorque, crack, retorque, crack, etc.

 

[MDCmotorsports]

Retorque - simple. Just use a breaker bar to crack the bolt back 1/4 turn, then retorque to the correct setting. Do this for each headbolt, in the same order as you would when installing the head. So, crack, retorque, crack, retorque, crack, etc.

Grim:
Make sure you drain the coolant first! If you don't you'll get coolant into the cyls and run the risk of bending a rod.

 

[siman]

Grim:
Make sure you drain the coolant first! If you don't you'll get coolant into the cyls and run the risk of bending a rod.

Severe COMPRESSION like that would lead to severe DEPRESSION :rofl:


Grim: sorry for the typo. But I torqued mine to 100ft/lbs with the ARP lube LOL...Its still holding .....sitting in a storage facility..... :hsugh:

 

[GrimJack]

Grim: sorry for the typo. But I torqued mine to 100ft/lbs with the ARP lube LOL...Its still holding .....sitting in a storage facility..... :hsugh:

Despite appearances, I wasn't replying directly to you - I started the post, then had to go to a meeting, finished up the post when I returned.

 

[siman]

no problemo. I did not take it offensively :icon_razz

 

[Orion ZyGarian]

Well what should be done about the rivot problem?

Also, when should you retorque your head?

How many people running big power use cometics? I'm trying to justify buying a headgasket that has a higher "booboo rating" compared to shelling out the ass for a stopper type (which by all means I am most definetly ready to do)

Are HKS MHGs reusable? The car has one right now already though I dont count on using it again.

Thanks again, much appreciative to the MkIII fact database that is SM!

 

[johnathan1]

uh oh.... I cracked all of my studs, then retorqued... on a stock hg... has been fine though, so I am guessing that the decrease in torque wasn't enough (less than 5ft/lbs) to break the seal...since toyota torque was 58ft/lbs, and cracking them would put them between 70 and 75ft/lbs, right?

Also, if you did it one bolt/stud at a time, wouldn't it completely screw up the torque sequence, since the loosening and tightening sequences are opposite?

 

[aljordan]

Reg Reimer, an HKS master dealer, suggested that I find a greddy HG.

I will only run greddy gaskets in my motors for the above reason.

 

[Dirgle]

Finally, using ARP's moly lube, what ft-lb rating should they be torqued to? Can we all agree on 81 ft lbs for proper setting? So many different ratings everywhere...81 ft lbs is what the sheet says and what seems to be right, but I'm asking the most knowledgable and experienced members of the MkIII community to be 100% certain.

You should go by what the sheet that comes with your hardware states you should torque the studs/bolts down to. 81ft/lbs is fine for now but ARP may change their metal and their torque specs in the future, so make sure you read the sheet it comes with.

Now a little more information to chew on.

According to the sheet ARP sends with its studs. 81 ft/lbs with ARPs moly lube is 75% of the fasteners yield strength. This means that 108 ft/lbs is 100% of the fasteners yield strength(with ARP moly lube).

So if you torque past this point you will permanently stretch the stud. This is partially failed hardware and cannot continually and accurately provide the correct clamping force. Also you should not torque the bolts all the way down to 100% yield strength (108 ft/lbs), as this leaves no room for variations like the expansion of the aluminum head.

 

[GrimJack]

Well what should be done about the rivot problem?

Also, when should you retorque your head?

How many people running big power use cometics? I'm trying to justify buying a headgasket that has a higher "booboo rating" compared to shelling out the ass for a stopper type (which by all means I am most definetly ready to do)

Are HKS MHGs reusable? The car has one right now already though I dont count on using it again.

Thanks again, much appreciative to the MkIII fact database that is SM!

Rivets are easy - put the gasket on, put the head on top, and check to see if any of the rivets are on the mating surface - if they are, drill out the offending rivet. Or just drill them all out and use the front and rear pegs to align everything.

Retorque after the engine has been through a bunch of heat cycles.

Some MHGs are reusable, depends on what kind of shape the thing is in when you pull it out. Most people refuse to reuse them, though.

 

[MDCmotorsports]

90ft lbs with a new commetic FTW!

 

[jdub]

Finally found a spec sheet for the ARP head bolts...3p141592654 posted it in another thread. Explains where the 75 ft/lb torque spec value floating around comes from...it's for use for aluminum heads.

 

[MDCmotorsports]

See I knew I wasn't crazy.

 

[jdub]

See I knew I wasn't crazy.

We all knew you weren't...just took me a little time to prove it...LOL!
:biglaugh:

 

[bigaaron]

See I knew I wasn't crazy.

You still might be crazy :icon_bigg