TheAMCForum.com Homepage
Forum Home Forum Home > The Garage > AMC V8 Engine Repair and Modifications
  New Posts New Posts RSS Feed - AMC 360 PISTONS
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Click for TheAMCForum Rules / Click for PDF version of Forum Rules
Your donations help keep this valuable resource free and growing. Thank you.

AMC 360 PISTONS

 Post Reply Post Reply Page  <1234>
Author
Message
SC397 View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Apr/30/2009
Location: Michigan
Status: Offline
Points: 2803
Post Options Post Options   Thanks (1) Thanks(1)   Quote SC397 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/21/2019 at 1:47pm
I use premium in all my AMC engines, even the ones with 8.5:1 compression ratio.  You might be able to run less than premium with 9.5:1 compression ratio but you will probably have to back the timing down.  You could also use the 1975 and later heads that would lower the compression some more.
Back to Top
LMM1996 View Drop Down
AMC Fan
AMC Fan
Avatar

Joined: Nov/03/2015
Location: Ohio
Status: Offline
Points: 31
Post Options Post Options   Thanks (1) Thanks(1)   Quote LMM1996 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/21/2019 at 2:17pm
When I bought my pistons we had some problems getting to the compression ratio that was advertised. We ended up going with the flat top version and the compression ratio ended up at 9.8:1. I think at the time Wiseco was advertising 10.5:1 for those with a 58cc chamber. One reason we were having problems was the combustion chambers actually measured 64cc instead of the 58cc they were supposed to be. Milling the heads down to 58cc brought it up to 9.8:1 which I was fine with. But I think the reason we didn't get over 10.0:1 like advertised is, and I could be wrong here, I think Wiseco calculated their compression with the piston at zero deck height. We just installed in the hole at the original spec so I think that is where the difference was. Another good thing about the Wiseco pistons is they have very generous valve reliefs. I think when PTV clearance was measured there was enough clearance for over .650" lift. I apologize for being a bit long winded, but I just wanted to share a couple things I found when building my engine. Hopefully somebody can use the info to help them choose when building their engine. 

Edited by LMM1996 - Feb/21/2019 at 2:19pm
Back to Top
SC397 View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Apr/30/2009
Location: Michigan
Status: Offline
Points: 2803
Post Options Post Options   Thanks (0) Thanks(0)   Quote SC397 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/21/2019 at 4:21pm
Yep, it looks like they are a little off in their calculations.

I just called them and the flat top pistons have a 8.6 cc valve relief which is not listed on their sheet.



Edited by SC397 - Feb/21/2019 at 4:38pm
Back to Top
PHAT69AMX View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jul/07/2007
Location: West Virginia
Status: Offline
Points: 3812
Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: Feb/21/2019 at 6:30pm
There are some AMC 360 with Wiseco Pistons
Compression Calcs also in the thread linked below.
Might it be that Wiseco "assumes" an "industry standard"
.010" Block Deck Mill and .010" Cylinder Head Mill ?

Edited by PHAT69AMX - Feb/21/2019 at 9:29pm
Back to Top
SC397 View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Apr/30/2009
Location: Michigan
Status: Offline
Points: 2803
Post Options Post Options   Thanks (1) Thanks(1)   Quote SC397 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/21/2019 at 7:19pm
.020" mill is not a standard.  It should be .010" at the most unless you tell the machinist otherwise.
I think that the Diamond Piston compression calculator is just more accurate than the Wiseco one.  Maybe they don't calculate the area of the head gasket.


Edited by SC397 - Feb/21/2019 at 7:21pm
Back to Top
WesternRed View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Aug/03/2010
Location: Australia
Status: Offline
Points: 3665
Post Options Post Options   Thanks (2) Thanks(2)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Feb/21/2019 at 7:43pm
Not sure why they chose 1.59" compression height as opposed to factory 1.60". Stock 360 pistons are nominally 0.012 down the bore anyway, so plenty of scope to deck the block. Giving up compression on an already low compression engine in this way is a bit counter productive.  Putting a slightly smaller dish on the piston on the other hand was a great idea, but they have given with one hand and taken away with the other.
I've finally given up drinking for good...........now I only drink for evil.
Back to Top
PHAT69AMX View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jul/07/2007
Location: West Virginia
Status: Offline
Points: 3812
Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: Feb/21/2019 at 9:28pm
Ok, yes, thanks SC397, using .010 milled from stock nominal 360 Block and 58cc heads with
Wiseco +.030 8.6cc 1.590 CH slugs & 4.27 x .043 Gasket comes up ~10.5 CR in my calculator
which does not include the small area above the Top Ring like the Diamond Calculator does.
Will edit previous post to .010

Red: ? might it be the 1.590 CH is -.010 from stock to "match" also milling the block .010 ?


Edited by PHAT69AMX - Feb/21/2019 at 9:58pm
Back to Top
Trader View Drop Down
AMC Addicted
AMC Addicted


Joined: May/15/2018
Location: North America
Status: Offline
Points: 796
Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Feb/22/2019 at 12:20am
OK, I do street builds only.
I have never seen a 360 or 401 that has needed the block milled.
Stone or float glass with paper and full contact (0.001" to 0.002") which any gasket and very tin coat of Hylomar takes care of. No leaks, ever!
Unless the engine has seen extreme use, who is milling and why??? ... Beyond custom performance modifications.
Never seen a cast head warped over 0.002", this does not need machining if you take off high spots (very little elbow grease, 10 to 15 minutes work).
A manufacturer of custom parts should be assuming stock. If not then they should be stating required modification.
My opinion.
  

Back to Top
69 ambassador 390 View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar

Joined: Nov/22/2009
Location: Peoria, AZ
Status: Offline
Points: 3384
Post Options Post Options   Thanks (1) Thanks(1)   Quote 69 ambassador 390 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/22/2019 at 12:56am
You should always mill to get the correct RMS surface for the specific gasket you are using.  Stoning can lead to too smooth of a surface and gasket issues.  MLS gasket require a different RMS than composite or steel shim gaskets.  You should always mill the decks even it is just to get the right surface.  .001-.003 is all that is needed if the surface is really still that good. 
Steve Brown

Algonac, Mi.

69 Ambassador sst 390

84 Grand Wagoneer

69 Cougar XR7

65 Fairlaine 500XL

79 F-350 Super Camper Special



Back to Top
oldguy View Drop Down
AMC Apprentice
AMC Apprentice


Joined: Nov/07/2011
Status: Offline
Points: 75
Post Options Post Options   Thanks (0) Thanks(0)   Quote oldguy Quote  Post ReplyReply Direct Link To This Post Posted: Feb/22/2019 at 1:47am
I have a set of wiseco .030 over pistons I bought but never used

Back to Top
 Post Reply Post Reply Page  <1234>
  Share Topic   

Forum Jump Forum Permissions View Drop Down



This page was generated in 0.063 seconds.
All content of this site Copyright © 2018 TheAMCForum unless otherwise noted, all rights reserved.
PROBLEMS LOGGING IN or REGISTERING:
If you have problems logging in or registering, then please contact a Moderator or