gains from milling a head worth it
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gains from milling a head worth it

 
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gains from milling a head worth it - 9/27/2008 9:49:37 AM   
Landrew

 

Posts: 41
Joined: 9/5/2008
Status: offline 		 I have my head out on my 07 Rancher 420. I'm getting it bored as it got sunk and there is some piston/ring/cylinder wear. Since it was out I took the head over to the shop as well as the cylinder.  I was wondering if it is worth milling the head 10 to 20 thousands and increasing the compression? I know the timing will be retarded becasue of this.

Am I going to make gains with this or will the change in timing hold it back.
Post #: 1
RE: gains from milling a head worth it - 9/28/2008 9:30:40 AM   
kleinwild


Posts: 3538
Joined: 11/6/2006
From: Joaquin Texas
Status: offline 		Very large gains if done right!

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Post #: 2
RE: gains from milling a head worth it - 9/29/2008 1:07:09 PM   
Landrew

 

Posts: 41
Joined: 9/5/2008
Status: offline 		The shop doing it does a lot of the performance mods around here. What can I expect or what should I look for in doing it?

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Post #: 3
RE: gains from milling a head worth it - 9/29/2008 1:39:40 PM   
engie


Posts: 5174
Joined: 7/9/2006
From: Jackson/Starkville, MS
Status: offline 		The rancher engine is still a pushrod engine, correct?

You can achieve virtually unlimited compression out of doing this to a pushrod engine because the valves open straight up and down, whereas they come in at an "angle" on overhead cam engines.  It has nothing at all to do with timing on your engine, since you don't have overhead cams and thus no timing chain.  You'd just have to adjust your valves to work with the pushrods which will now essentially be "longer" in comparison to head height.  Worst case scenario, the pushrods may need to be shortened... 

Compression is essentially a linear gain.  If you have 10:1 compression and increase it to 12:1, and then match timing and fuel to it, you stand to gain 12/10, or 20% more power....

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Post #: 4
RE: gains from milling a head worth it - 9/29/2008 1:41:02 PM   
VT_Grizzly


Posts: 1019
Joined: 9/4/2001
From: VT
Status: offline 		To do this correctly - you should measure you piston to valve clearance.  In order to do this, you need to put some putty (form an auto store made for this application) on your piston and re-install everything torqued properly.  Turn the motor over and check how thick the putty is where the valve comes down near the piston.  Then you know how much you can shave without hitting a valve on the top of your piston.  When I bored mine out, I had them take off 10-15 thousanths, just to gain a little and have a clean head surface.  I don't think 10-20 thousanths would pose an issue, and it should gain a little compression. 

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Post #: 5
RE: gains from milling a head worth it - 9/29/2008 4:59:38 PM   
Landrew

 

Posts: 41
Joined: 9/5/2008
Status: offline 		Thanks for the help. I'll go ahead and get it done.

Cant wait to see how it runs after a new HMF pipe, Optimizer, porting and milling the head along with a 25 thou bore job.

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Post #: 6
RE: gains from milling a head worth it - 10/5/2008 11:57:31 PM   
longdude17


Posts: 454
Joined: 5/10/2007
From: fordoche--baton rouge--watson, Louisiana
Status: online 		i dont think the rancher 420 is a push rod engine.....

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Post #: 7
RE: gains from milling a head worth it - 10/6/2008 8:10:35 AM   
Landrew

 

Posts: 41
Joined: 9/5/2008
Status: offline 		It is. When I took it apart I was surprised to see pushrods on a vehicle from 2007. Sure makes it easy to do the cylinder as I dont have to worry about a timing chain etc. Though with the milled head the valves shoudl be re-adjusted.

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Post #: 8
RE: gains from milling a head worth it - 10/6/2008 7:50:13 PM   
toyazman76


Posts: 325
Joined: 2/12/2007
From: Port ST. Lucie Fl.
Status: offline 		Just a question. Why wouldn't you just go with a high compression piston?

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Post #: 9
RE: gains from milling a head worth it - 10/6/2008 11:01:53 PM   
Landrew

 

Posts: 41
Joined: 9/5/2008
Status: offline 		They dont make one. At least after a day or searching the web. I suppose Wiseco could custom make one for hundred of $ or more but that is to much for the return on investment.

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Post #: 10
RE: gains from milling a head worth it - 10/7/2008 7:51:59 PM   
longdude17


Posts: 454
Joined: 5/10/2007
From: fordoche--baton rouge--watson, Louisiana
Status: online 		well ill be danged....it is a push rod engine....i just looked at a parts fitche and man that is surprising! talk about making it easier to rebuild!

< Message edited by longdude17 -- 10/7/2008 7:58:07 PM >

_____________________________

05 kodiak 450 4x4 Camo....currently puking smoke...Up for trade
26" ITP Mudlites
homemade snorkels
CnC Machined Muffler Power tip
K&N air filter
12 point deer horns on the front rack
Lookin for a good Mechanic to rebuild

92 blue kawasaki bayou 220 (the blue beast)
UNI filter
Super Swampers
12 point deer horns strapped to front rack

08 Honda Rancher-Lil Red
Stick Stoppers and Basket Racks
27" ITP Mudlites
soon to come: PCIII, HMF, Springs

(in reply to Landrew)
Post #: 11
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