Block surface question???

[jkbmkiii]

What is the max material that can be taken off the block/ head surface?

I went to the shop that is doing the machine work and the surface of the block is pitted. I have been searching here but I have yet to find the specs iam looking for!

 

[p5150]

resurface it, then measure it. Get the appropriate thickness of head gasket. You will be fine.

 

[jkbmkiii]

resurface it, then measure it. Get the appropriate thickness of head gasket. You will be fine.

Thats what I told them but they seem to want a #, as far as how much is to much?

 

[IJ.]

-1mm/0.040" is about as far down as I'd take a 7M block.

 

[jkbmkiii]

Thanks IJ Thats what I needed!! The machine shop said " There is no way we need to take that much, but now we know!"

Thanks again!

 

[IJ.]

at 1mm you're getting very thin but .010" to .020" should be safe

 

[jkbmkiii]

The machine shop est is .010.. It is very hard to find anybody that works with the 7mgte, so I stole the guy around here that does a bunch of stuff for the turbo dsm guys, he was just unsure! all is taken care of thanks guys!

 

[jdub]

If you're using a MHG, also make sure they get the block deck surface to the correct RA spec

 

[p5150]

If you're using a MHG, also make sure they get the block deck surface to the correct RA spec

Riiiiiggght.....

 

[Nick M]

The actual spec is much lower. I suspect going below it contributes to excessive BHG's. Spec is .05mm, or .002"

 

[lagged]

Riiiiiggght.....

heh what i think he means is, the tool for measuring RA is $$$.

 

[IHI-RHC7]

MY machinest has an rA gauge...

 

[p5150]

What I mean is that you have a .01% chance of finding a machinist with the equipment to make it smooth enough. They all say they can, but 99.99% of them cannot and you wont know it until you go to pick it up.

 

[aljordan]

heh what i think he means is, the tool for measuring RA is $$$.

There is a set of blocks have have finishes on them. You can just match the finish with one of the blocks in the kit. I think the kit is only $40 or so. I thought about buying one... but ehh.

 

[jdub]

What I mean is that you have a .01% chance of finding a machinist with the equipment to make it smooth enough. They all say they can, but 99.99% of them cannot and you wont know it until you go to pick it up.

Not too sure where you got this statistic, but there are several machine shops in my general area (dozens in the Phoenix Metro area) with modern machines...getting to the RA spec is no problem at all. And if you want it really smooth, a machinist with a lapping table can make it like a mirror.

 

[p5150]

Not too sure where you got this statistic, but there are several machine shops in my general area (dozens in the Phoenix Metro area) with modern machines...getting to the RA spec is no problem at all. And if you want it really smooth, a machinist with a lapping table can make it like a mirror.

sorry bro - nothing personal but I dont believe it until I see it in person. Ive had at least 12 different machine shops in different parts of the country tell me that they could do it and it has never been true. The best RA ive seen is 50 microns - yes its smooth but not as smooth as hks wants. Ill bet some machine shops do have a lapping table though - thats the way to go.

 

[jdub]

sorry bro - nothing personal but I dont believe it until I see it in person. Ive had at least 12 different machine shops in different parts of the country tell me that they could do it and it has never been true. The best RA ive seen is 50 microns - yes its smooth but not as smooth as hks wants. Ill bet some machine shops do have a lapping table though - thats the way to go.

No offense taken...it's funny though cause I've personally seen two with the equipment that can do it and the RA meter to prove it. Both were in the 20-30 range.

 

[IHI-RHC7]

Same here, but it's rare. When I ask about lapping plates...
They laugh at me.

 

[IJ.]

The "Blocks" are meant to be used with an optical comparator and that's the part that costs big $$$ and very few shops have one as it's more a Tool Room tool.

Lapping tables are few and far between these days and you need to be careful if it's an old one as they do wear.

I bought a Lapping plate to do my block and while an expensive option it pays for itself in 1 BHG job so I'm not too concerned!

300mmx300xx Lapping plate!

 

[jdub]

I bought a Lapping plate to do my block and while an expensive option it pays for itself in 1 BHG job so I'm not too concerned!

300mmx300xx Lapping plate!

Ohhh...combine that with diamond paste and you got a mirror in no time!

I do like your toys Ian! :bigthumb: