Changing BHG. Anything else?

[Sonyps307]

They sell a kit on eBay but I got mine from my auto parts store (pepboys) 30$ it came with 3 sizes and I just cut to fit. As for power yes I got some power back but my hoses were original so I think I had a leak.

[icey756]

Me and my friend didnt go with a MHG because we didnt shave the block. My question is did we make a mistake by no going with a metal one? I was reading that some ppl dont shave the block and other say that you absolutely have to get the head and block shaved. I was reading suprra_girls thread on steps to modifying your supra and i would love to do a lot of that stuff but idk if i should without a MHG. We did torque the headbolts down to 90psi though.

[907mge]

The stock hg is good to around 12psi from what i've heard, but don't hold me to it. But I believe the two reasons to get the head shaved are because the head is not flat enough or to make a smooth surface for the mhg since it needs to be as smooth as possible. So as long as you made sure to clean the surfaces and threads well then you should be fine with lower boost levels. But as far as your torque spec, I assume you mean ft.lbs.. Did you use arp head bolts , because that spec seems high even for them? I did 90lbs on my studs with the moly lube. Also did you follow the patten for tightening and do it in three passes?

[icey756]

yes. 3 passes of 30, 60, then 90. Arp head bolts. We already shaved the head when we put the new stock gasket on. Im just wondering if I would be able to do the stuff that suprra_girl has posted in her sticky thread on the stock gasket

[icey756]

Is it true that after 1000 miles i should retorque all the headbolts? i remember seeing something about it but i just dont see why i would need to if they are already at 90fp

[87hilux7mge]

it cant hurt to recheck after doing that big of a job. thermal expansion and vibrations can cause a small amount of loss, so checking them after a break in is a good check up.

[icey756]

damn it that sucks cause its such a bitch to do

[mirage83]

Don't recall if Arp headbolts require a retorque or not, but standard ones do, recommended after 5 or 6 thorough heatsoaks of the engine. Probably wouldn't hurt to check your Arp's anyway, just to make sure they were all torqued evenly the first time around. Also, make sure you only do one bolt at a time and in the proper order, and only crack it loose a little before re-torqueing it. You don't want to risk the HG shifting even a miniscule amount.

If I had caught your thread earlier I would have recommended replacing the heater union bolt and hoses on the back of the engine. The bolt tends to corrode and leak after a few decades, and the hose back there ages poorly as well. With the head off they aren't too bad to replace, but a cast iron bitch with everything in place.

[icey756]

yes replacing the hoses in back should have been something i thought of right away. Haha. I already blew a cooling hose for my turbo. The whole shit was spraying out onto my headers and smokin like crazy. Thought i blew my HG again. lol. I suppose i could retorque them. why do i have to loosen them a bit again? cant i just set it to 90fp and have at her in the proper order?

[mirage83]

Originally Posted by icey756

I suppose i could retorque them. why do i have to loosen them a bit again? cant i just set it to 90fp and have at her in the proper order?

I don't know all the reasoning behind it, just that all the better 7M mechanics whose opinions I trust (they generally know what they're talking about instead of just pulling figures and info out of the air) tend to recommend doing so. I think it may have something to do with the tensile characteristics of the bolts after they've been heat soaked a few times, but that's just a guess on my part.