Milling the Stock Head

[Matt_E]

It's squish, not squash. :biggthumpup:

You will not decrease squish by cutting the dome. If anything, you'd increase it.
Generally, you measure squish and compression.
Then, run the numbers and mill the head to obtain desired compression while keeping squish reasonable.
After that, squish is checked again. If it's out of desired spec, it can be cut a bit larger without having a large effect on cranking compression.

 

[Rickster]

It's squish, not squash. :biggthumpup:

You will not decrease squish by cutting the dome. If anything, you'd increase it.
Generally, you measure squish and compression.
Then, run the numbers and mill the head to obtain desired compression while keeping squish reasonable.
After that, squish is checked again. If it's out of desired spec, it can be cut a bit larger without having a large effect on cranking compression.

What he said...

:biggthumpup:

 

[Idok]

One? Or are they breaking all the time? I am not really worried about one, but if it is common I will get the girdled head. A mod that takes a few hours of my time is always better than a $300 mod.

Rickster,
Can I run 93 with 190psi? I am not really looking to push my luck, 180psi would suit me fine.

pm skidaddy on that one....I dont think its worth it......

190 on pump gas = too much

 

[bit]

It's squish, not squash. :biggthumpup:

You will not decrease squish by cutting the dome. If anything, you'd increase it.
Generally, you measure squish and compression.
Then, run the numbers and mill the head to obtain desired compression while keeping squish reasonable.
After that, squish is checked again. If it's out of desired spec, it can be cut a bit larger without having a large effect on cranking compression.

I was referring to cutting down to the desired squish (sounds like wrong verb usage haha) and then cutting the chamber only to lower compression.

I guess I am looking for a relation for me to accurately predict both squish and combustion volume. When you are "running the numbers" are you using 0.010" = 12psi? Also by removing 0.010" front the head surface are you not also bringing the squish ring 0.010" closer? I understand they are not necessarily related, but I don't see how they are not related in this case. I guess I should be more worried about the compression, because it seems like I will not be removing enough material for the squish to be an issue.

 

[Matt_E]

Remove enough to get desired compression, then worry about squish.

 

[Gainera2582]

So if I have a stock head and gbpipe, do I really have to worry about the cylinder cracking if I don't increase my compression?

 

[Matt_E]

I'd say yes.