Head RE+RE, tell me if I'm missing something

[radiod]

I'm about to embark on a full head swap on my car and I wanted to see if I'm forgetting anything. The plan is take off the head, bring old head and my nice new port'd and polished head to the machine shop, get them to do a valve & seat grind to matching things up nicely, swap over valvetrain etc., get the head prepped for an MHG, slap new head on and hopefully drive for more than a few months without having to do major work >_<.

Things I've got and am planning on doing:

0.051" Cometic MLS Head Gasket
Valve Springs
Fel-pro complete top end reseal gasket kit (includes everything from valve seals to thermostat housing gasket, pretty thorough kit)
Timing Belt
Plugs
Plug Wires
Thermostat
Upper rad hose
Turbo oil line gaskets (I have a VERY small leak on the return line that just haven't bothered fixing until now)

Is there anything else I should consider doing since the thing's going to be half torn apart already?

 

[Enraged]

are you prepping the block for the MHG?

you will need shims for the valves, but if you take all of the ones from both heads, you may not need to buy more.

are you running bigger cams? new springs are good, maybe upgrade to the BBC springs (I think SIP selling them as a set for the 7M).

 

[radiod]

Block's already prepped for the MHG, there's a blown up HKS one on there right now. Shims are all taken care of. The engine shop is going to be moving the valvetrain over and doing adjustments etc for me.

As for springs I'm going to be doing the Comp Cams 975 spring mod (Chev inner spring to give a higher seat pressure). I can't find the links right this second, but I know that stock seat pressures are 35lbs, 975 springs end up being 55lbs, Brian Crower springs are 57lbs. So there's no point in going to the Crower springs at this point.

At this point I've dismissed cams because for the price vs the performance I'd get out of them I don't think it's worth it at this point. The car is already running 330whp in it's current setup and I've got other issues (stupid fuel cut) that I need to put money into before I need to worry about valve lift.

 

[radiod]

I was doing a bunch of picking through the different sections today and got to the head gasket fitting threads. Completely oblivious to thinking about bore size, I had bought the Cometic 0.051" in 84mm, but I remembered the previous owner had put an HKS one after putting in overbore pistons. I took a look at HKS's website and ALL of their gaskets are 86mm bore...did I just screw myself over?

 

[David_Nguyen]

yep if it dont fit...dont make it fit...lol

 

[radiod]

Crysis averted! Talked to the previous owner (so glad I saved his number in my phone!) and he only did a 0.020" over bore, bringing the cylinder bore to 83.5mm if I'm not mistaken. Head gasket should work! Now the question is are my problems now due to the fact that he used an 86mm bore gasket on an 83.5mm bore cylinder...

Still, let me know if I'm missing anything! I feel like I'm talking to myself

 

[tsupranami]

I wouldn't think so. Most MHG's are sold in the standard 86mm, and so long as everything is flat, clean, smooth, and tight, all should work the same.

Maybe the previous owner didn't retorque? Maybe he didn't drill out the front MHG rivet? Maybe it ran lean? Many possibilities, but not enough info to determine cause.

Be sure to clean the deck spotless and retorque after a few heat cycles. ARP studs work better than bolts (oem or ARP).

Good luck!

 

[radiod]

Already have ARP studs in there, so that's taken care of. Most likely would have run lean if anything, as I've had fuel cut problems in the past. As for deck cleaning, I've done it a few times as an apprentice at GM, and none of them came back leaking, so I should be good . And yes, there are GM vehicles that use MLS gaskets standard.

 

[easternguy2005]

" get the head prepped for an MHG, slap new head on "

You're gasket thickness is directly related to the "prepping" to create the smooth surfaces and without knowing the compression it's a crapshot. Ask me how I know.....

 

[starscream5000]

Haven't seen this on here yet...

Have you hardness tested your new(er) head? This should be the first thing you do. If the head's too soft (annealed), then you've just wasted all of your time on that head.



For your sake, I hope the AL is still hard on your new head as it sounds like you've put a lot of work into it already.

 

[radiod]

Been away for the weekend so I couldn't follow up, sorry about that.

The local machine shop I took it too checked out the head through and through. I know that they did a pressure test on it for sure and it came out clean. Apparently they've done a fair number of 7M heads and this is one of the best ones they've seen in years (according to them). It came off a JDM 7MGTE with >20,000 miles on it, so I'm pretty confident in the integrity of the head.

One more week and I can start the work

 

[starscream5000]

Not to rain on your parade, but the head can and will aneal from just one BHG, regardless of how many miles are on it. As it's a JDM head per what you just said, you do not know it's history.

I suggest calling your machine shop and finding out exactly what they did to the head. I doubt they checked for hardness unless you specifically told them to. It's not a common practice.

 

[radiod]

I'll definitely keep that and mind and get it checked out then. Are there any signs that I myself can look for? I honestly hadn't heard of this happening until this point, is it a common problem?

 

[starscream5000]

On 7M's, YES.

They're notorious for BHG's. If it blows and overheats, the AL head probably got too soft, especially around #5 & #6 as this is where the majority of the BHG's occur. That part of the head also runs hotter than the rest of the head as well (EGR) and can aneal even without blowing the gasket. Have your machinist check for hardness around the back two cylinders, exhaust side mainly.

It's not something that most people have the hardware to check, so if you're not family with it (as you've stated), then you'll not be able to check for it yourself.

 

[radiod]

I went on google to just research some of this stuff a bit and holy smokes I find another Supramania thread! I just thought I'd post a link to it for reference sake for everyone else, because it's a VERY good writeup. Doesn't look like it's too old, but whatever, any reference is good.

http://www.supramania.com/forums/showthread.php?t=98915

So I will definitely get the hardness checked out on the new head, hope and pray that there's no issues :S.