406 engine questions. - 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 11-15-2012, 08:21 PM
Registered User
 
Join Date: Nov 2012
Posts: 26
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
406 engine questions.

Just bought a fresh 406(so i thought)
Ok the casting numbers says its q 4 bolt but it has 2 bolt caps.is this good?
Also has new h400p cp30 pistons.well it has a small rap(sounds like a wrist pin)
And i saw that they also ground the piston skirts to clear the crank.whats going on with this motor?

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 11-15-2012, 08:26 PM
vinniekq2's Avatar
Registered User
 
Join Date: Jun 2012
Location: BC,Canada
Age: 56
Posts: 8,084
Wiki Edits: 0

Thanks: 322
Thanked 784 Times in 750 Posts
poor match of parts and not put together correctly. pull it down,dont bandage a big disaster
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 11-15-2012, 08:27 PM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 12,950
Wiki Edits: 326

Thanks: 761
Thanked 1,013 Times in 849 Posts
Quote:
Originally Posted by 95chevy406 View Post
Just bought a fresh 406(so i thought)
Ok the casting numbers says its q 4 bolt but it has 2 bolt caps.is this good?
Also has new h400p cp30 pistons.well it has a small rap(sounds like a wrist pin)
And i saw that they also ground the piston skirts to clear the crank.whats going on with this motor?
As a young man, I used to buy complete motors until I learned that every seller is a liar. Never again. I want it used up and ready for a rebuild or in pieces. Either one is fine, because the cost is commensurate with the value of the hunk(s).
Your noise could be anything, from a skirt hitting a counterweight to a cracked piston to a loose pin to a counterweight hitting the end of the dipstick to one of the rods hitting the cam to................
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 11-15-2012, 08:39 PM
Registered User
 
Join Date: Nov 2012
Posts: 26
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The guy said it ran good with no noises.the pistons only had very litle cabone on them.guessing less then 30 min run time.is it good to use 2 bolt caps on a 4 bolt block.the sound was coming from the # 1 or 2 piston.my cam is only a .435 .465 lift.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 11-15-2012, 08:41 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 597 Times in 546 Posts
Are you saying the block is drilled for 4 bolts but now has 2 bolt caps? If that's the deal the caps won't be registered in the block recesses the way they should be. This would leave them largely unsupported and I would think this would be an invitation to have the caps moving laterally, aka cap walk.

Last edited by cobalt327; 11-15-2012 at 08:48 PM.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 11-15-2012, 08:48 PM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 12,950
Wiki Edits: 326

Thanks: 761
Thanked 1,013 Times in 849 Posts
Quote:
Originally Posted by 95chevy406 View Post
The guy said it ran good with no noises.the pistons only had very litle cabone on them.guessing less then 30 min run time.is it good to use 2 bolt caps on a 4 bolt block.the sound was coming from the # 1 or 2 piston.my cam is only a .435 .465 lift.
What do you think the guy is gonna say when he's trying to extract money from your wallet??????? He's gonna lie through his teeth. TRUST NOBODY.
When the 400 blocks were produced, some were manufactured with 2-bolt mains and others were produced with 4-bolt mains. Of course the hot rodders immediately grabbed the 4-bolt blocks because they thought they would be stronger than the 2-bolt blocks. But hold on there, gasoline breath, it was discovered that the webbing in the 4-bolt blocks was not sufficient to prevent pulling the whole shebang out of the crankcase and runnin' over the crank. Oddly, the 2-bolt blocks were stronger and have been used ever since as the block of choice when building a 400. If your block is an original 4-bolt block and has been built using 2-bolt caps, it's still a 4-bolt block with weak webbing above the crank.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 11-15-2012, 08:54 PM
Registered User
 
Join Date: Nov 2012
Posts: 26
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Never took the cqps off to see if it is a 4 bolt but the casting number says it is and yes it has 2 bolt caps.
3951511=70-73 sbc 400 4 bolt main b&g body
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 11-15-2012, 09:16 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 597 Times in 546 Posts
Quote:
Originally Posted by cobalt327 View Post
Are you saying the block is drilled for 4 bolts but now has 2 bolt caps? If that's the deal the caps won't be registered in the block recesses the way they should be. This would leave them largely unsupported and I would think this would be an invitation to have the caps moving laterally, aka cap walk.
Having said that, I cannot remember if the 2 bolt caps are as wide as 4 bolt caps. Too late to go out to the shop to look right now.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 11-15-2012, 09:31 PM
1Gary's Avatar
Registered User
 

Last journal entry: 383 dyno sym
Last photo:
Join Date: Oct 2010
Location: Roch,NY
Age: 67
Posts: 1,538
Wiki Edits: 0

Thanks: 201
Thanked 156 Times in 142 Posts
Techinspector1 is right about resellers that are private sellers.There are plenty of honest shops building quality engines like ours that suffer from situations like yours. Those honest shops are nothing without you guys trust.We do really need that.

Just to I.D. what you have or don't have,it sounds like a total teardown.That would be my suggestion.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 11-15-2012, 09:42 PM
Registered User
 
Last photo:
Join Date: Jan 2011
Location: Hopewell, Va
Age: 62
Posts: 1,206
Wiki Edits: 0

Thanks: 0
Thanked 117 Times in 113 Posts
406 engine questions.

Mount the motor on an engine stand. Flip it over to remove the oil pan. Unbolt one of the main bearing caps to see if has 4 holes or two holes under the cap. If it has 4 holes find the guy who sold it to you and get your money back. Tell him you will take him to court if he doesn't want to give the money back.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 11-16-2012, 12:53 PM
Registered User
 
Join Date: Nov 2012
Posts: 26
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Got it all torn down.it is a 2 bolt block.stock crank turned .010 on rods and mains.pistons and rods all look good and pins move freely..main bearings have alittle grooving and one rod bearing lock was ground off.the kotor also had low oil pressure at idle after warmed up.less then 5 psi.still not sure what the rapping noise was.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 11-16-2012, 04:39 PM
Registered User
 
Join Date: Nov 2012
Posts: 26
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
And on all the big ends of the rods there are little cross hairs like they were honed out so i think they were sized.im hoping it was either a bad bearing set or dry start up.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 11-16-2012, 04:49 PM
vinniekq2's Avatar
Registered User
 
Join Date: Jun 2012
Location: BC,Canada
Age: 56
Posts: 8,084
Wiki Edits: 0

Thanks: 322
Thanked 784 Times in 750 Posts
measure all the parts while its apart,,balance?
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 11-16-2012, 04:52 PM
Registered User
 
Join Date: Nov 2012
Posts: 26
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Im gonna have the crank and rods checked.
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 11-16-2012, 08:42 PM
Registered User
 
Last photo:
Join Date: Jan 2011
Location: Hopewell, Va
Age: 62
Posts: 1,206
Wiki Edits: 0

Thanks: 0
Thanked 117 Times in 113 Posts
Quote:
Originally Posted by 95chevy406 View Post
Got it all torn down.it is a 2 bolt block.stock crank turned .010 on rods and mains.pistons and rods all look good and pins move freely..main bearings have alittle grooving and one rod bearing lock was ground off.the kotor also had low oil pressure at idle after warmed up.less then 5 psi.still not sure what the rapping noise was.
Check the rod that the bearing lock was wore off, look at the crank journal where that bearing fit also to see if it spun any. Like was said the crank and rods need to go to the machine shop to be measured.
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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Going EFI on 406 SBC questions LanceM Engine 2 01-29-2011 11:12 AM
406 sbc questions brians407sbc Engine 3 07-15-2010 05:40 PM
406 sbc, build questions manchildau65 Engine 59 04-03-2010 06:59 PM
406 rebuild questions... ddhens Engine 4 11-10-2007 11:03 PM
406 sbc questions tiresmoke55 Engine 13 04-26-2007 10:50 AM


All times are GMT -6. The time now is 12:45 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.