MHG Torque

[MKIIITrbo89]

I know this question has been discussed probably to many times to count, but I thought I would just post this to see what other people have their MHG torqued to. I will be using arp studs and I contacted ARP and they said it should be torqued to 80 lbs. However, I'm on a quest for 500 Hp eventually and I have seen some people torque their MHG to 85 or 90. Would doing this hold better than 80 lbs. necessarily given the MHG would be installed correctly. Just wondering what people's thoughts were on the issue.

 

[GrimJack]

Did mine to 100. I've seen higher.

Of course, I've also seen 80 hold lots of power - 500 for sure - so pay your money and pick your poison.

 

[IJ.]

More isn't always better.

You may end up deforming the head around the bolt bosses I'd stick with ARP's recommendations.

 

[MKIIITrbo89]

OK thanks, I guess I'll stick with 80 then. Just wondering, Grim have you had any problems with yours being torqued to 100

 

[shaeff]

i've got mine torqued to 90ft lbs. ARP headstuds, and a Cometic MHG.

-shaeff

 

[IJ.]

MkIII: I'm not disagreeing with Grim 100% a lot of the guys have used 100 ft/lbs just for me I wouldn't as I know the internal structure of the head (Sawed one in half to check the port walls) and while we view a head as a big chunk of aluminium it's really honeycombed and thin/weak in a few places.

The other thing to consider is most 7M's have been run hot a few times in their life and as a result will be soft on the exhaust side so overtorquing may banana the head.

In extreme cases you can actually recess the washer as it sinks into the casting.

 

[Joel W.]

i gotta go with IJ here, any one who cuts a head in half just cuz hes curious..hahaha, got any piks of that, id like to see em...good info

 

[IJ.]

Here ya go>
(have a bunch more but they're much the same just different angles)

 

[Joel W.]

wow, thats an awsome cut.. not much structural material left inside once you look at it from that view..

 

[IJ.]

Yep it's a great illustration of my point!

Add into this as I said most heads are a bit soft by now it's really easy to deform them with too much torque.

On dinosaur motors (cast iron) You can get away with a LOT more clamp pressure right up until you pull the deck surface up around the bolt holes!

On our 7M's you need to be a little more delicate!

 

[GrimJack]

I haven't had any problems with mine... yet. I do know people who have run 125, but I don't have any information on the longevity of those engines, so it's not worth much.

IMO, as long as you go at least 72, you should be fine.