7m going into machine shop What Do I need to know

[92TealSupra]

Alright. I have a '89 Supra, I am going to have the bottom end rebuilt.

I am goign to order Stock 7m-gte pistons, rings, bearings. I need to know a couple fo things.

What MHG should I buy, as in mm, brand? I am having the block decked, and the head resurfaced fro a MHG.

I also am using arp head studs, stock rods, and the crank is being micro polished. Is there anything I should let the machine shop know about what I need?

I want to make sure they do everything correctly.

Would ACL bearing be fine? I can get a set of pistons and bearing on ( Ebay ) for $132.00 for all, I know it's ebay, but it's not Ebay Piston or bearings, people are just using ebay to sell there products.
I don't like when people give me shit for buying off Ebay, I buy cooleeze product off there before and there STILL cooleeze, not ebay

Anyhow, I want this done correctly, is there anything I am missing that I may have over looked, I do know I have to have the timign belt cover on there for them to machine with the block!

Eathen.

 

[WhtMa71]

Make sure they can get the deck and head smooth enough for a MHG. You'll have to determine how much they take off the block/head to know how thick of a headgasket you'll need.

Will you be boring the engine oversized? If they're boring the cylinders make sure you have a timing belt tensioner installed and torqued to 36ft/lbs.

ACL bearings are fine but I would wait to order until your machine shop has inspected the crank to make sure it doesn't need to be cut. If it does, you'll have to get the correct size bearings.

 

[92TealSupra]

Make sure they can get the deck and head smooth enough for a MHG. You'll have to determine how much they take off the block/head to know how thick of a headgasket you'll need.

Will you be boring the engine oversized? If they're boring the cylinders make sure you have a timing belt tensioner installed and torqued to 36ft/lbs.

ACL bearings are fine but I would wait to order until your machine shop has inspected the crank to make sure it doesn't need to be cut. If it does, you'll have to get the correct size bearings.

I am not boring it, unless I have too. I will be inspecting the block in like 15 minutes once the head is off, I am taking off the head bolts right now. Why does the tensioner have to be torqued to 36 Ft'bs? Shouldn't I tighten all the bolts on the bottom timing cover as well as the tensioer?

 

[isnms]

edit: ah never mind, I see you already know that

 

[ForcedTorque]

Thanks for leaving the picture ISNMS. I have always been confused when reading about this, and have never searched enough about it to see that. One day I will be doing a motor, and that picture will stay in mind much better than words.

 

[isnms]

No problem... A pic is worth a thousand words

sorry I don't have anything else to add to Eathen's question.

 

[Moy]

I am not boring it, unless I have too. I will be inspecting the block in like 15 minutes once the head is off, I am taking off the head bolts right now. Why does the tensioner have to be torqued to 36 Ft'bs? Shouldn't I tighten all the bolts on the bottom timing cover as well as the tensioer?

I'd like to know as well. Why does the timing belt tensioner have to be on and torqued to spec, if the cylinders are going to be overbored?

 

[92TealSupra]

I'd like to know as well. Why does the timing belt tensioner have to be on and torqued to spec, if the cylinders are going to be overbored?

No no. When you deck the block, you need to have that lower cover on, otherwise when you place the head on the block that cover is taller then the block and the head gasket will not seat, and basically a epic fail.

Also what does " Lap " mean in words of milling? Do you lap a head? A block?

Also is there a certain amount of material the machine shop should take off or does it depend on the blocks condition?

I would like to add, my Head Gasket was about to blow, The water channel parts that are copper were severely bent, and one was melted it looked like.

Good Idea I decided I want to remove the motor.

 

[WhtMa71]

The machine shop will determine how much material to remove in order to make the surface good. Lapping is done after the surface is cut to make the surface smoother so your head gasket will seal. Sometimes this is not needed if the milling machine can do the job well enough.

Depending on how many miles are on your engine, it will probably have to be bored at least .020 over. After a while the cylinders will get funnel shaped and will have a ridge at the top of the bore where the piston rings don't touch. So an overbore will be necessary.

The tensioner needs to be torqued to spec before an overbore because it is directly connected to the no. 1 cylinder. When you torque it it distorts the cylinder wall enough to where the rings wont touch in about a coin-sized spot, that is, if you don't bore it with the tensioner installed. Ask IJ.

You should bring the block and crank to the machine shop before you order pistons or bearings. They'll inspect both, tell you if you need an overbore and if the crank needs to be cut and then you can order the proper sized pistons and bearings. Just make sure they don't bore the block until they have the pistons in their hands.

 

[92TealSupra]

The machine shop will determine how much material to remove in order to make the surface good. Lapping is done after the surface is cut to make the surface smoother so your head gasket will seal. Sometimes this is not needed if the milling machine can do the job well enough.

Depending on how many miles are on your engine, it will probably have to be bored at least .020 over. After a while the cylinders will get funnel shaped and will have a ridge at the top of the bore where the piston rings don't touch. So an overbore will be necessary.

The tensioner needs to be torqued to spec before an overbore because it is directly connected to the no. 1 cylinder. When you torque it it distorts the cylinder wall enough to where the rings wont touch in about a coin-sized spot, that is, if you don't bore it with the tensioner installed. Ask IJ.

You should bring the block and crank to the machine shop before you order pistons or bearings. They'll inspect both, tell you if you need an overbore and if the crank needs to be cut and then you can order the proper sized pistons and bearings. Just make sure they don't bore the block until they have the pistons in their hands.

Ahh Now I understand the theory behind the tensioer, thank you, I am going to make a list of what needs to be done.

Would having a head gasket more then the material taken off bad? it would low the compression, is this s bad idea?

So I will ask them how much was taken off and then I can add that together and go from there, I will get the numbers to determine what I need. I also won't order the pistons I will need. Should I do a .020 over even if I don't need it? it has 130,xxx miles on it on it.

I have already put all the bolts on the front timing cover on, I will torque the tensioer to 36 FT-lbs.

 

[WhtMa71]

At least .020 will probably have to be taken off. And if its bored 20 over, you can still have more room to go (up to .040 over) in case you break a piston or something happens with a ring.

The stock head gasket compressed is 1.37mm. So you will ask them what they take off the head and block and add it to 1.37. This is also assuming the block or head hasn't been machined before. It would still be a good idea to get both measured to be sure.
The block is measured from the crank saddle to the deck and is 198.5 mm and the head should be 116mm from deck to valve cover surface.

 

[ForcedTorque]

Also what does " Lap " mean in words of milling? Do you lap a head? A block?

They use a flat stone disc to lap both the head and the block to a certain RA value. I can't define RA, nor do I know the proper value you need, but somebody will chime in with the value, and you should ensure that your machine shop is capable of being that precise. As I understand it, domestics don't require theirs to be near as perfect. If you shop is not familiar with your motor, they may use what they know a Chevy 350 has no problem with.

Lapping is where they use the stone disc in a circular (laps) motion to get an even finish on the head or block.

 

[Crazybobmundo]

Hey dont mean to hi jack but if the engine has to be rebored does the headgasket have to be replaced with a bigger bore?

I used the search but no luck.

 

[Rennat]

yes it does... think about it logically for a minute... the HG bore is smaller than the bore of the cylinders and pistons then it will crash against the piston...

i belive all of the HKS ones are 86mm bore for this reason... and some cometic ones are 84 for the stockers, and 86 for the rest of them.

i ordered my bearings and MHG from titanmotorsports...
got the 1.4mm titan, and the clevite's...

just make sure its under a 40RA... which is how rough the surface is. If you can feel the ridges of the cutter in the head, you need to go to a new shop... and any shop who's worth their shit will know what an "RA spec" is...

and just my 2 cents, but if your just doing an "oem style" rebuild with a MHG and arp head studs or just little things like that, then you might not have to bore the cylinders over... get everything inspected before you start buying all of these parts "thinking" you'll need them..

 

[87tomanymods]

i would recomend having the machine shop get all the bearings and rings for you so there are all right size first time and no waranty issues with the machine work.

 

[92TealSupra]

yes it does... think about it logically for a minute... the HG bore is smaller than the bore of the cylinders and pistons then it will crash against the piston...

i belive all of the HKS ones are 86mm bore for this reason... and some cometic ones are 84 for the stockers, and 86 for the rest of them.

i ordered my bearings and MHG from titanmotorsports...
got the 1.4mm titan, and the clevite's...

just make sure its under a 40RA... which is how rough the surface is. If you can feel the ridges of the cutter in the head, you need to go to a new shop... and any shop who's worth their shit will know what an "RA spec" is...

and just my 2 cents, but if your just doing an "oem style" rebuild with a MHG and arp head studs or just little things like that, then you might not have to bore the cylinders over... get everything inspected before you start buying all of these parts "thinking" you'll need them..

Would 20RA we fine on the head + the block?

Also what is the exact Head height MM for the head and block, it was stated in a previous post on this thread, but are these numbers the real ones.

I am going to make a list of everything I need them to do, I want this done correctly!

Hopefully Ij. chimes in here too!

 

[IBoughtASupra]

I am glad someone asked this because I am buying a 7MGTE engine tomorrow, Friday April 3, and it is going to the machine shop.

Just help me out to make sure I got everything from this thread and fully understand it.

1) I am going to use Wiseco Pistons, .40 over, from Titan MotorSport. Using Stock Rods.

2) When giving them the block, leave the fron't timing cover on and make sure the tensioner is torqued to 36ft/lbs?

3) Having the crank machined with new rod and main bearing, any tips?

4) I am going to be using a metal head gasket. From what I have read, I should buy that at last. How do I know what thickness to get? I understand about have the block prepped from the headgasket, but how do I know what thickness after knowing the amount that was shaved off?

5) The head is going to be ported and polished, any tips? How hard are the valve seals to change? I have access to a world of tools.

The guys who I am getting this engine from said that the engine has lifter tap. I went to Toyota and a guy that has been working with Toyota's for twenty years said that he has never sold anything concering lifters and the 7MGTE does not have those problems.

I also read here,, what someone posted, that these engine don't lifters. WTF, who is right? Thanks.

 

[87tomanymods]

its a very direct sytem there are buckets and shims directly between the valve stem and cam lobe .many assume its hydralic and self adjusting ,but its not the shims come in different thicknesses .

 

[WhtMa71]

The real block and head thickness is what I posted... 198.5 and 116mm and the stock head gasket crushed is 1.37mm....

 

[black89t]

Would 20RA we fine on the head + the block?

Also what is the exact Head height MM for the head and block, it was stated in a previous post on this thread, but are these numbers the real ones.

I am going to make a list of everything I need them to do, I want this done correctly!

Hopefully Ij. chimes in here too!

yes. the lower the number the smoother it is. i think glass is like a 3 or 4 ra.