sbc 383 head gasket q's and quench q's - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 09-15-2010, 08:46 PM
Registered User
 
Join Date: Sep 2010
Location: Tustin CA
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
sbc 383 head gasket q's and quench q's

Hey hotrodders! im putting together a sbc 383 with aluminum afr heads but im running into some issues. my piston is .021 in the hole and my standard fel pro 1003 with a compressed thickness of .041 will yield a horrible .062 quench! i plan on using my AFR 180s with 75cc but i can change them for a set of 65cc. regardless, do you think i should run a fel pro 1094 which will give me a .036 quench, mr gasket 1130g which will give me a .041 quench or the jegs brand #555-210044 which gives me 0.045 quench? heres a chart from jegs

http://www.jegs.com/SizeCharts/JEGSHeadGaskets.html

Thanks, Mark
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 09-15-2010, 09:05 PM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 12,246
Wiki Edits: 326

Thanks: 602
Thanked 767 Times in 657 Posts
Quote:
Originally Posted by Chevystr383
Hey hotrodders! im putting together a sbc 383 with aluminum afr heads but im running into some issues. my piston is .021 in the hole and my standard fel pro 1003 with a compressed thickness of .041 will yield a horrible .062 quench! i plan on using my AFR 180s with 75cc but i can change them for a set of 65cc. regardless, do you think i should run a fel pro 1094 which will give me a .036 quench, mr gasket 1130g which will give me a .041 quench or the jegs brand #555-210044 which gives me 0.045 quench? heres a chart from jegs
http://www.jegs.com/SizeCharts/JEGSHeadGaskets.html
Thanks, Mark
Mark, what I would do is to use the head gasket that is recommended by the head manufacturer, a Fel-Pro 1003 or AFR 6800, which is probably also a Fel-Pro 1003 repackaged.
The problem is with fretting of the aluminum head with the wrong gasket. Just cut the block decks even with the piston crown for a zero deck and use the head gasket compressed thickness for the squish dimension.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 09-15-2010, 09:22 PM
Registered User
 
Join Date: Sep 2010
Location: Tustin CA
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
i wish i can but the block has all been assembled and the block was only decked 0.004, my bad. what other options do i have?
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 09-15-2010, 09:40 PM
ericnova72's Avatar
More for Less Racer
 
Join Date: Jan 2007
Location: S.W. Lower Michigan
Age: 47
Posts: 7,662
Wiki Edits: 0

Thanks: 10
Thanked 148 Times in 136 Posts
Quote:
Originally Posted by Chevystr383
i wish i can but the block has all been assembled and the block was only decked 0.004, my bad. what other options do i have?
Take it back apart and do it right, deck the block more. Anything else will be a quench or reliabilty compromise, right now you will just be out a couple gaskets and some time.

No "Easy Button" here.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 09-17-2010, 08:15 AM
Registered User
 
Join Date: Sep 2010
Location: Tustin CA
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
so i took every apart. How much should i take of the block, 0.021? I'm using a probe forged flat top with 2 valve relief which adds up to be 4cc. My question is if i zero deck the block will i have piston to valve clearance issues with my comp roller Xr276HR cam? (224 duration@0.050w/503 lift intake, 230 duration@0.050w/510 exhaust)
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 09-17-2010, 09:44 AM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 595 Times in 545 Posts
Quote:
Originally Posted by Chevystr383
so i took every apart. How much should i take of the block, 0.021?
This will depend on what gasket you want to use. If the gasket is 0.039"-0.041", you'll want to cut it to zero- which will be 0.021" off the block decks if the measurements you took are accurate- and were checked on both banks, front and rear cylinders.

Quote:
I'm using a probe forged flat top with 2 valve relief which adds up to be 4cc. My question is if i zero deck the block will i have piston to valve clearance issues with my comp roller Xr276HR cam? (224 duration@0.050w/503 lift intake, 230 duration@0.050w/510 exhaust)
I doubt it- BUT it still has to be verified.

If you did the actual measurements w/the previous build up, you can use the new dimensions to see on paper if there's an obvious issue or not. But this is not a replacement for actually measuring things.

If you didn't physically measure the P to V clearance before, you have to now. If it's insufficient, the valve reliefs will need to be deepened, a lower ratio rocker arm used or a different lift cam used. Deepening the reliefs will also affect the CR a bit.

All that said, there's a very good chance there will be NO problems w/the P to V.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 09-17-2010, 01:26 PM
Registered User
 
Join Date: Sep 2010
Location: Tustin CA
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
My machinist measured that the piston was .021 in the hole in cyl 1 and 8. Im using 1.5 ration stainless fuller roller rockers. i dont need any more lift because the gain in lift is only 4cfm of intake and 2cfm exhaust when using the afr 180s. So in the general i should take .021 front and back and the intake manifold pad.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 09-17-2010, 02:29 PM
Registered User
 
Last photo:
Join Date: Apr 2007
Location: Seattle, Wa
Posts: 6,437
Wiki Edits: 0

Thanks: 3
Thanked 331 Times in 288 Posts
Quote:
Originally Posted by Chevystr383
Hey hotrodders! im putting together a sbc 383 with aluminum afr heads but im running into some issues. my piston is .021 in the hole and my standard fel pro 1003 with a compressed thickness of .041 will yield a horrible .062 quench! i plan on using my AFR 180s with 75cc but i can change them for a set of 65cc. regardless, do you think i should run a fel pro 1094 which will give me a .036 quench, mr gasket 1130g which will give me a .041 quench or the jegs brand #555-210044 which gives me 0.045 quench? heres a chart from jegs

http://www.jegs.com/SizeCharts/JEGSHeadGaskets.html

Thanks, Mark
GM 10105117 has stainless steel faces on both sides and the 14096405 has stainless steel on one side and graphite on the other. They both have a compressed thickness of .028, pick one.

These are thin multi-layered gaskets which work the shear problem between aluminum heads and cast iron blocks that results in fretting and brinneling of the aluminum. The .028 with your .025 deck will give .053 which isn't too trashy.

Aluminum heads are more tolerant of compression ratio than iron which gives some easing of the constant pursuit of .040 inch. Actually .062 isn't a disaster unless mixed with a circular dish piston. These type pistons reduce the closing surface area to damn little of nothing and the dish adds another .050 to .080 depending on part number to the squish/quench distance. These are really bad in that regard, circular dish pistons should be avoided like the plague. There is nothing you can do to generate anything like amount of squish/quench needed with these things.

I don't use Mr Gasket's gaskets.

Bogie
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 09-17-2010, 06:10 PM
Registered User
 
Join Date: Sep 2010
Location: Tustin CA
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
hey bogie im using a flat top piston probe part #P3831F-030, do you think a .041 quench would be awesome or leave it at .062.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 09-17-2010, 06:48 PM
Registered User
 
Last photo:
Join Date: Apr 2007
Location: Seattle, Wa
Posts: 6,437
Wiki Edits: 0

Thanks: 3
Thanked 331 Times in 288 Posts
Quote:
Originally Posted by Chevystr383
hey bogie im using a flat top piston probe part #P3831F-030, do you think a .041 quench would be awesome or leave it at .062.
Dot forty one would let you push the SCR which in turn is a bit more power and mileage, but with aluminum you could do .062 and probably not see the difference. Aluminum sucks the head out faster than cast iron, which is what the quench part of squish/quench is all about (detonation resistance) so I doubt you'd have any problems. After-all at this point with the pistons in and the heads selected things are what they are and I think your in a good situation no matter which thickness gasket you use. With aluminum heads I'm as much concerned about fretting as anything else as this can lead to gasket failure especially between the paired exhaust cylinders. So to minimize the fretting and brinnelling you want a multi-layered gasket that will put a stable face against the aluminum and take the shear moments inside the gasket so head isn't constantly rubbing the gasket face. Now you can't totally eliminate this but you can make it better with most any multi-layered gasket. GM on the L98 and ZZ4 actually use a pretty thick gasket at about .053 to .058 compressed, so that with .025 in the hole makes .078 to .083. To me this demonstrates that the factory is more worried about fretting and brinnelling than detonation.

Bogie
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 09-17-2010, 08:35 PM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 595 Times in 545 Posts
I would think there's no good reason for not using as near to 0.040" quench as possible- in that it will increase turbulence more so than a wider quench distance. I mean, if you can, you might as well, IMO.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 09-17-2010, 10:17 PM
Registered User
 
Join Date: Sep 2010
Location: Tustin CA
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
so should i stick with my .062 or should i go to the .041, my head gaskets are the fel pro 1003 which is designed for aluminum heads
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 09-17-2010, 10:27 PM
ericnova72's Avatar
More for Less Racer
 
Join Date: Jan 2007
Location: S.W. Lower Michigan
Age: 47
Posts: 7,662
Wiki Edits: 0

Thanks: 10
Thanked 148 Times in 136 Posts
Since you have it apart, I'd follow thru and deck it. No sense cutting corners. There is added power(no matter how small it is) and reduced octane sensitivity in having tight quench. I personally just couldn't live with more than .050", .062" is way too much for me, I prefer .035"-.040"ish. A good flat deck surface is a big benefit too.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 09-17-2010, 10:43 PM
Registered User
 
Join Date: Sep 2010
Location: Tustin CA
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
yeah i figured that also. 062 just sounds too much but old bogie puts up a good debate. i honestly want the absolute best out of the motor, thats why i went with a flat pistons thinking i would get awesome quench right out the box
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 09-17-2010, 11:05 PM
ericnova72's Avatar
More for Less Racer
 
Join Date: Jan 2007
Location: S.W. Lower Michigan
Age: 47
Posts: 7,662
Wiki Edits: 0

Thanks: 10
Thanked 148 Times in 136 Posts
As far as the SBC goes, it takes a decked block or an .015" gasket to get tight quench, just the way it works out with the pistons that are available. Would be nice if piston companies would offer the piston with a .015" taller height to eliminate the need to take more than a skim cut off the block, but you have to order custom to get them that way. Off the shelf models all match GM blueprint dimension, or are shorter.

Bogie is correct, if you aren't trying to push the limits of compression ratio and pump gas the .062" quench will likely never matter. Have you actually done the math to figure your compression ratio??

Your cam is small enough I would be very surprised if more decking caused a piston to valve problem with Probe pistons, if you decide to go ahead and deck it..
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -6. The time now is 06:49 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.