Max out of the hole

General engine tech -- Drag Racing to Circle Track

Moderator: Team

sccagt1racer
New Member
New Member
Posts: 32
Joined: Wed Jul 13, 2016 9:22 pm
Location:

Max out of the hole

Post by sccagt1racer »

I'm assembling a ls engine for a friend and from my calculations its going to be .012 -.015 out of the hole. I have a .051 head gasket right now and could go thicker if needed. How much is too much out and what is the min quench I'll be safe at. Ive been told .038 -.040. Its a ls6 with a wiesco forged piston. wiesco 6.125 rod and stock crank. Its going to see a max rpm of 7200 road race car.
User avatar
af2
Guru
Guru
Posts: 7014
Joined: Sun Jan 28, 2007 4:42 pm
Location: Grass Valley, CA :Northern Foothills

Re: Max out of the hole

Post by af2 »

Not advanced. You can get any thickness gasket you need. Get it assembled and figure from there.
GURU is only a name.
Adam
jed
HotPass
HotPass
Posts: 875
Joined: Tue Nov 18, 2008 4:18 pm
Location: Dallas

Re: Max out of the hole

Post by jed »

I have built several with the piston .012/.015 above the deck and used a .046 gasket with no
Reported problem.
Put it to get her and drive it like you stole it.
John
PackardV8
Guru
Guru
Posts: 7619
Joined: Sun Jul 30, 2006 2:03 pm
Location: Spokane, WA

Re: Max out of the hole

Post by PackardV8 »

Your combination should be OK.
Its going to see a max rpm of 7200 road race car.
Are you going to install the limiter chip and a locking tell-tale tach? Never believe a driver or a friend on a race track. They only shift when they're ahead.
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
Geoff2
Guru
Guru
Posts: 1980
Joined: Mon Nov 09, 2015 4:36 pm
Location: Australia

Re: Max out of the hole

Post by Geoff2 »

I am currently building an engine & have deliberately had the block decked so that the pistons are 0.010" out of the hole. 0.039"head gasket. Trying to cheat the octane fairy. Engine will be limited to 6000 rpm.
mag2555
Guru
Guru
Posts: 4585
Joined: Sun Sep 18, 2011 11:31 am
Location: Heading for a bang up with Andromeda as we all are.

Re: Max out of the hole

Post by mag2555 »

.015" out of the hole means it will grow to .020" when at normal temp, but if you have Aluminum heads concider it a wash!
You can cut a man's tongue from his mouth, but that does not mean he’s a liar, it just shows that you fear the truth he might speak about you!
houser45
Pro
Pro
Posts: 279
Joined: Thu Apr 24, 2014 10:05 pm
Location:

Re: Max out of the hole

Post by houser45 »

Leave it with the .051”
CGT
Guru
Guru
Posts: 2063
Joined: Sun May 10, 2009 12:29 pm
Location:

Re: Max out of the hole

Post by CGT »

sccagt1racer wrote: Wed May 16, 2018 6:34 pm I'm assembling a ls engine for a friend and from my calculations its going to be .012 -.015 out of the hole. I have a .051 head gasket right now and could go thicker if needed. How much is too much out and what is the min quench I'll be safe at. Ive been told .038 -.040. Its a ls6 with a wiesco forged piston. wiesco 6.125 rod and stock crank. Its going to see a max rpm of 7200 road race car.
Aluminum block? I have done quite a few that were .006 to .008 above deck and used a .036 cometic..aluminum head, aluminum block LS. Your clearances above will be fine, even if its iron.
Rick360
Guru
Guru
Posts: 1104
Joined: Sun Oct 03, 2004 9:55 pm
Location: Missouri

Re: Max out of the hole

Post by Rick360 »

mag2555 wrote: Thu May 17, 2018 1:03 pm .015" out of the hole means it will grow to .020" when at normal temp, but if you have Aluminum heads concider it a wash!
Wow, I gotta see the math on that. :-k

Rick
User avatar
af2
Guru
Guru
Posts: 7014
Joined: Sun Jan 28, 2007 4:42 pm
Location: Grass Valley, CA :Northern Foothills

Re: Max out of the hole

Post by af2 »

Rick360 wrote: Thu May 17, 2018 3:52 pm
mag2555 wrote: Thu May 17, 2018 1:03 pm .015" out of the hole means it will grow to .020" when at normal temp, but if you have Aluminum heads concider it a wash!
Wow, I gotta see the math on that. :-k

Rick
Ya me too. On a typical blown Brad we see .014" growing from hot to cold. HMM If the piston was out it will stay out!
GURU is only a name.
Adam
RCJ
Expert
Expert
Posts: 802
Joined: Wed Jul 25, 2007 6:15 am
Location: Oklahoma

Re: Max out of the hole

Post by RCJ »

I've run 100s of laps with a motor that is .027 out of the hole with a.070 cometic gasket..040 is what shoot for.
User avatar
af2
Guru
Guru
Posts: 7014
Joined: Sun Jan 28, 2007 4:42 pm
Location: Grass Valley, CA :Northern Foothills

Re: Max out of the hole

Post by af2 »

RCJ wrote: Thu May 17, 2018 4:56 pm I've run 100s of laps with a motor that is .027 out of the hole with a.070 cometic gasket..040 is what shoot for.
Re working a 489 that is using a .061" Felpro and will get the same one at .039" total clearance using Aluminum heads now.
GURU is only a name.
Adam
pamotorman
Guru
Guru
Posts: 2802
Joined: Thu Mar 06, 2014 11:55 pm
Location:

Re: Max out of the hole

Post by pamotorman »

sccagt1racer wrote: Wed May 16, 2018 6:34 pm I'm assembling a ls engine for a friend and from my calculations its going to be .012 -.015 out of the hole. I have a .051 head gasket right now and could go thicker if needed. How much is too much out and what is the min quench I'll be safe at. Ive been told .038 -.040. Its a ls6 with a wiesco forged piston. wiesco 6.125 rod and stock crank. Its going to see a max rpm of 7200 road race car.
the aluminum block will grow .005 so you will be .005 less than room temp measurement
User avatar
MadBill
Guru
Guru
Posts: 15024
Joined: Tue Nov 15, 2005 10:41 am
Location: The Great White North

Re: Max out of the hole

Post by MadBill »

There have been a number of S/T threads on ideal piston/head clearance and 0.040" seems to be well-accepted as a good target for iron blocks with steel rods. Most feel ten thous 'too much' is way better than five thous too little, but there are numerous builders that are prepared to fly much closer to the sun; down to 0.030" and even a tad less. :shock:
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.
xanadu
Pro
Pro
Posts: 372
Joined: Thu Aug 28, 2008 5:41 am
Location: Brisbane Australia

Re: Max out of the hole

Post by xanadu »

Closest ive gone is .028" on an iron headed ford 351C. Im still scared when i think about it.
Post Reply