MHG Question

[oldmansupra]

So I took my motor in to get resurfaced. Stock HG is 1.37 mm and the HKS one I want to install is 2.0 mm. I asked the machinist to take off 0.315 mm from the head and 0.315 mm from the block. He told me that I should take off LESS from the head and MORE from the block or it will cause detonation issues. I personally believe that to keep everything stock an equal amount should be removed. Any opinions?

 

[BrandonW]

you can just have the machine shop take off whatever is needed and get a different size mhg unless you already have that one

are you trying to use the stopper mhg?

 

[CT26smoker]

The machinist sounds like he also believes in whichcraft, UFOs, and the Maya Calendar prediction of the end of the world in 2012.
His statement makes no sence.

 

[oldmansupra]

Yeah i'm going to be using the HKS stopper MHG. I guess my question is should different amounts be taken from the head then the block? That's what he's telling me, however I believe an equal amount should be taken off.

 

[BrandonW]

it doesn't matter if different amounts are removed, just have what the total material was removed
if more is removed from the block and less from the head your still compensating with the hg

1) Stock HG = 1.37mm compressed

2) Stock head = 116mm deck to valve cover surface

3) Stock block = 198.5mm from deck to main bearing saddle

If 2 and 3 are less that amount needs to be added to 1 to retain the stock compression ratio and squish/quench.

 

[oldmansupra]

K awesome, just what I needed to know.

---------- Post added at 02:37 PM ---------- Previous post was at 02:36 PM ----------

My machinist also told me that if too much is removed from the head, it will cause detonation issues. This is the first time I've heard of that.

 

[ben1984j]

K awesome, just what I needed to know.

---------- Post added at 02:37 PM ---------- Previous post was at 02:36 PM ----------

My machinist also told me that if too much is removed from the head, it will cause detonation issues. This is the first time I've heard of that.

That's true, because removing material from the head or block raises compression, which increases the risk of detonation.

This is why you size a headgasket so that it makes up for the material removed. But you only want to remove the minimum amount of material (from both head and block) to achieve a flat, true surface on each. You don't pick a headgasket and then machine the head and block to match (your machinist should know this)...Instead, you take off no more material than is necessary, then use the amount of material removed to calculate your headgasket size based on the info BrandonW posted.