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Location:
Sydney
Registered:
May 2002
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BHG 7MGTE, ADVICE NEEDED!
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Fri, 12 July 2002 03:38
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Help! Ive finally got my MA70 on the road and had the pleasure of driving it around for the best part of 2 weeks when, despite my best efforts of re-torquing the head before i put the motor in,ive succumbed to the infamous BHG problem which has plagued 7M's since the day they were made. Oh well, at least when i put it back together, properly, i know i can safely run more boost. What i need to know is:
* What head gasket to run, and where to get it (im in sydney and would like something local). Ive been told to go a copper head gasket which is fine, but im not going to pull the bottom end out to 'O-ring' it. Will the copper gasket still be ok? The head will be machined & serviced before it goes on:
* Its a well known fact one of the biggest problems with 7Ms is the heads bolts. Where can i get some ARP head bolts & how much.
* Once ive got better head bolts & gasket on, what kind of boost can i safely run? I know any increase in boost shortens an engines life, and thats ok, as long as it doesnt terminate it.
Any advice is mucly appreciated. Cheers.
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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Location:
Adelaide
Registered:
June 2002
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Re: BHG 7MGTE, ADVICE NEEDED!
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Fri, 12 July 2002 05:41
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The ARP kit you are after is 240-280 from memory. (bought one once for the 5m in the hope they were the same-they weren't) You can get HKS gaskets for them-but I'm not sure how much. Having the block done too is crucial as david has already mentioned. As for how much boost you can safely run-it's a bit of a gamble. 7m's tend to blow easily-but then again the odd one will survive a fair bit (note I said 'odd one' as it is not very common though) Have a look on the fullboost website at the 500+rwkw 7m supra article-If they have managed (the workshop) to get the (stock)head gasket to hold 29 pounds-I suggest you talk to them first.
Sean
PS-unless you are planning to run a massive amount more than the standard boost it won't really affect the longevity of the motor-what affects that is more the way in which a faster car is driven-ie harder. Drive an engine with stanrd boost like that and it'll wear out at pretty much the same rate.
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Location:
Adelaide
Registered:
June 2002
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Re: BHG 7MGTE, ADVICE NEEDED!
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Fri, 12 July 2002 08:56
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7m's blowing easily?
Not if it's put together PROPERLY.
They can handle almost anything you can throw at them if you put it together properly. Stock HG can be used if not much boost is going to be used. But if you want lots of boost, ie 1 bar or more you really need a MHG. I don't think a copper HG is going to do you any good unless you o-ring the block. Just get a HK$ or similar MHG, stock head bolts will be fine if you torque them to 75ft/lbs. As long as the block and the head is decked properly to fit the MHG you'll be fine with whatever the stock turbo can throw at it.
If you mod the turbo or put a new one on the you would need arp bolts to torque it up some more, to around 85-90ft/lbs
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Location:
Lost in the K hole
Registered:
May 2002
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Re: BHG 7MGTE, ADVICE NEEDED!
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Fri, 12 July 2002 09:44
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not sure if torquing to 85/90 is a great idea. from what i understand, the head is designed to flex along the long axis when torqued, and this flex is given allowance in the cam shaft mountings. when way over torqued, you could flex the head beyond its design, and introduce loads to the camshafts and bearings.
could be wrong on this, but im sure i read it somewhere.
cheers
ed
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Location:
Adelaide
Registered:
June 2002
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Re: BHG 7MGTE, ADVICE NEEDED!
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Fri, 12 July 2002 11:06
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Maybe, I know peeps on the SOGI mailing list have used this torque before. No ill effects so far as i have heard.
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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Re: BHG 7MGTE, ADVICE NEEDED!
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Fri, 12 July 2002 13:27
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An friend of mine (mechanic) accidentally did the head bolts up to 80 on a couple with no ill consequence. That said, he now has taken to torquing them to 71-2 figure.
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Location:
Melbourne
Registered:
July 2002
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Re: BHG 7MGTE, ADVICE NEEDED!
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Fri, 12 July 2002 15:33
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Hi i'm using stock HG with ARP's for several months now with a hiflowed ct26@16 psi,..so far so good,this is the second stock HG and the other was MHG,...last two blew coz the block was corroded and i never saw it (bastard)make sure that the head has'nt been cooked,other wise its like torqueing into butter(very important),i've got a MHG and i'm not using it coz i have'nt found someone to prepare the surface's the way the should,strange motor hey! BHG's all around...in my opinion,good surface prep, ARP's,80 to 85ft/lbs and uncooked head/block is the way to go....may God be with us....cheers.
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Location:
Sydney
Registered:
May 2002
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Re: BHG 7MGTE, ADVICE NEEDED!
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Sat, 13 July 2002 00:09
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Does anyone know where i can get me a metal head gasket, HKS or similar? More importantly how much? Im hoping to run it at 15 pound (but then if the boost bug bites.........hmmmmmm.)so by the sounds of it a metal HG and ARP bolts torqued to 80 to 85ft/lbs and a machined & serviced head should do it. Thankfully i blew the current gasket 3 kms from home and limped it home without cooking it.
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Location:
Melbourne
Registered:
May 2002
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Re: BHG 7MGTE, ADVICE NEEDED!
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Sun, 14 July 2002 01:11
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you will also have todo the block surface aswell depending on the KM on the engine might be good to give it a freshen up, get the bores honed, new barings and rings.
Allan
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Location:
Melbourne
Registered:
July 2002
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Re: BHG 7MGTE, ADVICE NEEDED!
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Sun, 14 July 2002 02:10
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MHG have cost me anything from $380 to $550 depending on thickness,and up to 6 weeks to be delivered....where abouts are you!!....cheers.
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Location:
Sydney
Registered:
May 2002
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Re: BHG 7MGTE, ADVICE NEEDED!
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Sun, 14 July 2002 02:41
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Fark, 6 weeks, i cant wait that long. Ive been without it for two days now and im having boost withdrawals!!! Luckilly for me it seems my motor has had a rebuild in japan before it was imported. All bores have fresh cross hatching, (not even any carbon on the top of the bores where the rings dont go yet!), & the block surface has fresh machining marks. It appears when it was rebuilt that the head must of been dragged along the gasket on #6 as the metal insert was seveerly elongated to the point where it was already covering part of the water jacket. I dont know how it lasted me 2 weeks. As for another rebuild on the bottom end ill pass for the moment as the motor was as quiet as a mouse and used no oil (ie no smoke) for the two registered weeks, and belive me as is any kid with a new toy, it was used alot (1200kms). So at the moment ill just refresh the top end and go from there.
As for a gasket im not prepared to wait 6 weeks. Should i try a factory toyota gasket, arp bolts torqued to 80lbs, and my proposed 15 pounds boost? Do you guys think it will be sufficient? I know it wont be bullet proof, but is fairly reliable out of the question if it only cops the occasional thrash? Please let me know your thoughts. Thanks. Oh BTW Grande91, location is Sydney.
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Location:
Melbourne
Registered:
July 2002
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Re: BHG 7MGTE, ADVICE NEEDED!
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Sun, 14 July 2002 08:13
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You should be ok,stock HG,ARP's,75/85 torque...thats how mine is,and like i said,its been running for several months now with no probs,and i give it hell,on the road and at least twice a month on the drag strip @16 psi....good luck.
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Location:
North Sydney
Registered:
May 2002
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Re: BHG 7MGTE, ADVICE NEEDED!
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Wed, 17 July 2002 09:36
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Yup i second that,
Are you guys using the toyota coolant, youy guys with problems with head gaskets?
I know it's expensive but try and use the toyota red stuff cause the colour makes it go faster!! He he just joshin.
Apparently toyota developed it especially so the electrolosis doesn't occur like it used to on VN commodore heads where holden recalled them all and replaced the coolant to stop them corroding.
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