Jug deck milling depth

[Blackland Dan]

Hi guys. I need to decrease the deck height on my M5 jugs. Does someone have an idea how much I can safely take off? Thanks, Dan..

 

[MMfan]

What about the jug to crankcase gasket? what if you ran without it and just a little silicone? How much do you think you need to get taken off?

 

[Blackland Dan]

Hi Jason. It's kind of a long story, but, essentially, I'm about 1/4" below the deck with my pistons. I screwed up my math when I measured my new piston compression height. I've already removed the gasket. I have a 6"stroke with 4.80" bore and 4207 heads. My cranking compression is 150-160. I should be well over 200. Any thoughts on how to get the compression back up?
Thanks, Dan..

 

[Jeff Gravert]

Get another set of pistons.

 

[MMfan]

Wait for Lawrence Wilson or Glen(dieselbear) they may have a trick for you, I am sure they will be along in the next day or so. Or try them on facebook. Longer rods, new pistons, higher compression heads, block surfacing, something has to work.

 

[Captainhookerus]

Dan I don't know the best way but try it this way.Keep in mind that you need a 6 1/2 stroke crankshaft. I think this would be the best way out.
Ken

 

[mightymolinekid]

E-mail me and we need to talk because the pistons I'm using are 1/4" to tall lol!

 

[Blackland Dan]

mighty moline kid. email is on the way.

Kenneth, I like that idea and if a better one is not coming my way, I think that's what I'll do.

Jason, I'm .248 below the deck. I talked to Wendell Everett today to see if he knew how much I could shave off the top of the jug and he said he took off 1/8" one time with no problem. I measured the water chamber from the top and it was right about .350" thick. I talked to my machinist today and he said he can mill it for me. I'm thinking about taking .175" off. That will leave about 3/16". Do you think that will be enough. Moline kid above may have the answer. I'm waiting for him to contact me. Thanks to all for the help. Dan

 

[MMfan]

I would try to cc the head and figure what volume you have with the pistons below the deck. This will let you figure compression ratio. there are online calculators to help with this. It is possible that with decking the block and some from the heads you will get it right. The best answer is if the other guys pistons are right.

 

[Anonymous-0]

Mill the bottom of the blocks and/or the top of the crankcase.

 

[Jayberd]

Would a crank from a 625 work?
J

 

[shinnery]

I believe a 625 will be a liitle long and have a couple extra throws. An M-5 is a four cyl. engine tractor. Same engine for M602 and M670.
Bryce