Head teardown ?'s

[jmcboost]

My friend let me use his spare head to get it rebuilt and prep it for a MHG. I would also like to get a port and polish and oversized valves, so here are the questions :

1 . The head has been sitting for a couple of years, is this bad and if so, what should I look for?

2. When I tear down the head, I know I should mark everything and make sure I know where each cap and valve train goes, but do I need any special tools to tear it down, or can I just disassemble?

3. Should I check clearances before I teardown?

4. Does anyone have a list of the things to do when I take it to the shop?

5. Once I get the head finished, how long can I store it for and how should I store it.
This is my first time rebuilding and I don't want to miss anything. Thanks for the help.

 

[jmcboost]

Anybody?

 

[jmcboost]

Bissilissump !!

 

[IJ.]

Step 1: have them test it for hardness.

 

[GrimJack]

0. What IJ said.
1. No, don't worry about it.
2. You will need a special valve compressor tool. Everything else is pretty standard.
3. No, everything will be different when you put it back together anyway.
4. Not off the top of my head - write down what the shop suggests and post it here.
5. Put it on a sheet of corrugated cardboard, sealing side down, and store it as long as you like.

 

[jdub]

Read this thread:

http://www.supramania.com/forums/showthread.php?t=15003

 

[lagged]

0. What IJ said.
1. No, don't worry about it.
2. You will need a special valve compressor tool. Everything else is pretty standard.
3. No, everything will be different when you put it back together anyway.
4. Not off the top of my head - write down what the shop suggests and post it here.
5. Put it on a sheet of corrugated cardboard, sealing side down, and store it as long as you like.

without the cams installed, unless you like bent valves....

 

[IJ.]

If it fails a hardness test don't spend another cent on it.

 

[GrimJack]

If it fails a hardness test don't spend another cent on it.

Agreed 110%.

 

[jmcboost]

Thanks for the info. What's involved in the hardness test, and how much should I expect to pay?

 

[IJ.]

The hardness test is like 30 seconds all they need is an area on each side of the head surface clean of gasket to do it.

Most shops will do it free while you wait.

It's a graduated glass tube with a ball in it they sit on the head then let the ball fall and how high it rebounds indicates if the head is hard or soft.

Our heads have a bad habit of annealing if they've been overheated a few times and it will cost more than a new head to have it bought back to the correct temper!

 

[hotsup]

Step 1: have them test it for hardness.

You don't need to check hardness at all!! The aluminium structure doesn't change just because it has been sitting for sometime.
Get it crack tested first & then check the cyl block mating face for flatness & roughness, these 3 items are absolutely critical! When those 3 items are OK then go ahead with the build.

 

[jmcboost]

Ok, I will try to do both, Pressure test and Hardness test. As far as getting the surface as flat as possible, what do I need to ask them to make sure to do for a MHG. The shop says they have worked on 7MGTE's before, but I want to make sure they can do it to my standards. Thanks again for the help.

 

[GrimJack]

You don't need to check hardness at all!! The aluminium structure doesn't change just because it has been sitting for sometime.

No, but if the head was overheated on the car before it was pulled, it might not be hard enough anymore.

 

[IJ.]

You don't need to check hardness at all!! The aluminium structure doesn't change just because it has been sitting for sometime.
Get it crack tested first & then check the cyl block mating face for flatness & roughness, these 3 items are absolutely critical! When those 3 items are OK then go ahead with the build.

You need to ask "why" it's been stitting for a few years.....

Odds on being a 7M it came off a motor with a BHG and if it's been annealed it's useless so again a hardness test is the 1st step.....

Seriously I don't post just to make noise or increase my post count and anything spent on the head if it's soft is a total waste of money.

Only use for a soft head!

 

[figgie]

You need to ask "why" it's been stitting for a few years.....

Odds on being a 7M it came off a motor with a BHG and if it's been annealed it's useless so again a hardness test is the 1st step.....

Seriously I don't post just to make noise or increase my post count and anything spent on the head if it's soft is a total waste of money.

Only use for a soft head!

shhhsshh!!!

You know both me and you like typihng so no oen can read.. that what we live for!!

 

[IJ.]

LOL I understand that people have different ideas/experiances but there are certain basics when dealing with the 7M that will end up costing $$$ if ignored.

Unless you know the history of a head from day 1 you'd be a fool to take it on face value that it's still hard.

Spending $ on a soft head = pissing $$$ against a wall.

 

[hotsup]

To JMCBoost & IJ, I take back what I said about checking hardness. I found out from my engine building guru that indeed some cyl heads, after being cooked, can be effected by a degree of annealing. I have learnt something. Also some cyl heads are more susceptable to it than others. Please accept my humblest apology :icon_redf

 

[jmcboost]

^ No problem. The head has been sitting because it was swaped out for a JDM. The head was replaced from a BHG, so I know It has probably been through some not so ideal conditions. Thanks for the help. I am learning alot from this post. I am going to get the block checked before I go any further. What questions can I ask the shop to make sure they can prep this block for a MHG correctly? When I asked them about a hardness test, they acted like that was something they had never done before. Also I am confused on one thing, does milling take care of the head enough to use a MHG or is there another process that smooths the head more?

 

[Stretch]

Also make sure it's flat enough that when you et it cut it won't go too deep. I had a head cut and it was waay to warped to use. waste of money big time.
eric