3935438 Casting 4 Bolt Main - What is your opinion? - Team Camaro Tech
Engine General Engine Discussion.

 
LinkBack Thread Tools Display Modes
post #1 of 4 (permalink) Old Oct 27th, 18, 11:54 AM Thread Starter
Gold Lifetime Member
Brett
 
Join Date: Mar 2016
Location: Austin, Texas
Posts: 932
Garage
3935439 Casting 4 Bolt Main - What is your opinion?

I found a freshly machined 3935439 casting 4-bolt main 427 block bored out to a 496. The seller says the deck was machined so there are no stamping left. New cam/crank bearings. with bearing caps and studs with nuts. Seller wants $600. Does this sound worth investigating for a purchase? I could go look at it tomorrow and inspect for quality. Maybe offer an amount less ($500 cash). What do you all think? Can this be a two piece rear seal or a one piece rear seal?

Brett......

1969 SS 396 X66 - RS Conversion - TKO600 - 3.73 Posi - Paint Code 71-LeMans Blue

Last edited by Brettallen59; Oct 27th, 18 at 01:22 PM. Reason: typo
Brettallen59 is online now  
Sponsored Links
Advertisement
 
post #2 of 4 (permalink) Old Oct 27th, 18, 12:26 PM
Senior Tech
Dave
 
Join Date: Dec 2005
Location: Tampa, Florida
Posts: 4,586
Re: 3935438 Casting 4 Bolt Main - What is your opinion?

3935439 would make it a 1968-'69 427 Mark IV two piece rear main seal block. To make it a four bolt block; four bolt main caps were added (which can be done by any machinist after the fact), and oil cooler provisions were machined into the block for Corvette applications.

Those cooler line holes will look like this if the pipe plugs were removed for cleaning the block:



Is worth a premium? In my opinion no.

Final honing (sizing the bore) is done to match the pistons, not having custom pistons turned down to fit your existing block. So a bare block over bored already is useless without eight to ten (two spares in case you drp a valve or two) new pistons to fill those bored holes.

Big Dave
Larger Dave is offline  
post #3 of 4 (permalink) Old Oct 27th, 18, 01:11 PM Thread Starter
Gold Lifetime Member
Brett
 
Join Date: Mar 2016
Location: Austin, Texas
Posts: 932
Garage
Re: 3935438 Casting 4 Bolt Main - What is your opinion?

Ooopps Dave, I was wrong. It IS a 9. 3935439 casting number. Sorry for the typo. So these did not come as a 4-bolt? That is good info, although it looks okay in the pic as a decent upgrade. I'm sorry I misunderstood. I now see this block was available as both a 2-bolt and a 4-bolt block.

Brett.....




1969 SS 396 X66 - RS Conversion - TKO600 - 3.73 Posi - Paint Code 71-LeMans Blue

Last edited by Brettallen59; Oct 27th, 18 at 01:33 PM.
Brettallen59 is online now  
 
post #4 of 4 (permalink) Old Oct 27th, 18, 01:23 PM
Senior Tech
Dave
 
Join Date: Dec 2005
Location: Tampa, Florida
Posts: 4,586
Re: 3935438 Casting 4 Bolt Main - What is your opinion?

All of the blocks were cast the same. Whether it got four bolt main caps or two bolt main caps was determined by a work order given to the machinist that converted the raw casting int a finished block. Two or four was a mater of what cap they put on the block. Two bolts were cheaper so Chevy made more of them.

Big Dave
Larger Dave is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
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.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



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

 
For the best viewing experience please update your browser to Google Chrome