| Slant Six Forum https://slantsix.org/forum/ |
|
| Another milling question but this time asked in a different way https://slantsix.org/forum/viewtopic.php?t=68720 |
Page 1 of 1 |
| Author: | Tuckenoa [ Fri Aug 07, 2026 3:58 am ] |
| Post subject: | Another milling question but this time asked in a different way |
Ok so from what ive read here, these motors have a crazy amount of variation so instead of asking the usual questions how much can I mill off the head or how much can I take off the block? I’m gonna ask how do I tell how much I can take off the head and block? My goals are .140 of the block and .100 off the head. And im not sure what im supposed to measure to figure out what my max milling would be specifically for my engine. Thank you all! |
|
| Author: | Rick Covalt [ Fri Aug 07, 2026 4:53 am ] |
| Post subject: | Re: Another milling question but this time asked in a different way |
You have to decide what compression ration you want to end up at. Then CC the head and measure the piston depth down in the cylinder. Then put those numbers into a compression calculator and that will tell you where you are currently. Then change the inputs in the calculator to arrive at the desired compression ratio. If you get those measurements we can help you with "how much to cut it". Good luck! |
|
| Author: | hyper_pak [ Fri Aug 07, 2026 6:39 am ] |
| Post subject: | Re: Another milling question but this time asked in a different way |
Building a modified engine requires quite a few measurements. You need a machine shop that will help you along the way. On the engine I am building now I had this issue, among others. I measured the piston deck height with the stock pistons. When I had my block bored and new pistons installed, I measured a different deck height. I CC-ed my head and cut it down using the original stock piston deck height. I SHOULD have waited and used the correct new piston deck height. Now I have a different compression ratio than what I originally planned on running. Point is that building an engine requires careful planning and precision measurement. On a mild build you can use the generally accepted guidelines and advice. Good luck with your build. |
|
| Author: | Tuckenoa [ Fri Aug 07, 2026 7:05 am ] |
| Post subject: | Re: Another milling question but this time asked in a different way |
I guess my question wasn’t that clear but I’m wondering is what am I measuring to figure out what is the most I can take off of the deck and the head without going to thin like strength wise. Like i know with boring the motor you can sonic test. So yea what is the way to find the safe max amout of milling? I’m familiar with all the measurements and what they should be and what I want them to be and all that i am asking is I just don’t want to mill it too far and then have to get another block or head because I hit a water passage or something |
|
| Author: | Dart270 [ Fri Aug 07, 2026 7:39 am ] |
| Post subject: | Re: Another milling question but this time asked in a different way |
OK got it. I am not sure we know the limits, and it will depend on the block and head castings. Here's what I know: I have angle milled on a few heads up to 0.110" manifold side and 0.210" on the plug side. Never had problems with overheating or cracking/sealing. This means you should be able to do a traditional flat mill up to about 0.150" off the head. The block should be able to take about the same. FYI, I always use composite head gaskets and overtorque them to 85-100 ft-lbs. You could probably sonic test a block or head and see what the deck thicknesses are, but I've never done that. These things are thick and can take a lot... Lou |
|
| Author: | Tuckenoa [ Fri Aug 07, 2026 8:15 am ] |
| Post subject: | Re: Another milling question but this time asked in a different way |
Dart270- thank you for the info! |
|
| Page 1 of 1 | All times are UTC-07:00 |
| Powered by phpBB® Forum Software © phpBB Limited https://www.phpbb.com/ |
|