3914638 is it a 307? - Team Camaro Tech
Engine General Engine Discussion.

 
LinkBack Thread Tools Display Modes
post #1 of 14 (permalink) Old Apr 27th, 09, 04:07 PM Thread Starter
Senior Tech
mark
 
Join Date: Feb 2009
Location: N.Y.
Posts: 510
3914638 is it a 307?

Hi guys this is my first post on this site and I have to say that the info here has been very helpful! The problem I am having is the confusion over the casting number 3914638.The guy I bought it from swore it was a 68 327 truck motor but after tearing it down I found forged domes in it with the stamp std on the top which indicates standard bore.Well with the cylinders being in good shape i gave it a good honing job and got a set of 327 standard 4.00 pistons and they do not fit.Was wondering if anyone had this problem and if so what did you do.Thanks
mark191 is offline  
Sponsored Links
Advertisement
 
post #2 of 14 (permalink) Old Apr 27th, 09, 04:28 PM
Gold Lifetime Member
Harry
 
dawg's Avatar
 
Join Date: Mar 2004
Location: Colebrook CT.
Posts: 3,988
Re: 3914638 is it a 307?

thats a 307 cu inch motor
but you can bore to fit I assume

Dawgs 69
434 stroker
US Navy retired
http://www.northeastf-bodyassn.com/
dawg is offline  
post #3 of 14 (permalink) Old Apr 27th, 09, 05:13 PM Thread Starter
Senior Tech
mark
 
Join Date: Feb 2009
Location: N.Y.
Posts: 510
Re: 3914638 is it a 307?

I dont understand how half the sites list it as a 327 and the others list it as a 307.
mark191 is offline  
post #4 of 14 (permalink) Old Apr 27th, 09, 05:58 PM
Moderator
 
Join Date: Aug 1998
Location: Waldorf Md. USA
Posts: 3,243
Re: 3914638 is it a 307?

Mark,

My engine builders software and Mortec both show it as a 307. Which "site" says it is otherwise ??

Got to ask .... why would you buy a set of pistons without measuring the bore first ?

Bill Koustenis
Owner
Advanced Automotive Machine
Waldorf Md
1971 Chevelle "Heavy Chevy" original owner

Enginerepairshop.com
BillK is offline  
post #5 of 14 (permalink) Old Apr 27th, 09, 06:14 PM Thread Starter
Senior Tech
mark
 
Join Date: Feb 2009
Location: N.Y.
Posts: 510
Re: 3914638 is it a 307?

chevrolet car club is one site that lists it as a 327 2 bolt truck.And as for measuring the bore it was stupidity.But pretty sure i can just bore to size because the stroke is the same for 307 or 327
mark191 is offline  
post #6 of 14 (permalink) Old Apr 27th, 09, 06:39 PM
Gold Lifetime Member
Jeff
 
yellow69RS's Avatar
 
Join Date: Jul 2007
Location: Aurora, IL
Posts: 4,610
Send a message via Yahoo to yellow69RS
Re: 3914638 is it a 307?

I'm sure a machinist should be saying this but I wouldn't try to bore that block .125.
307 is 3.875 bore and 327 is 4.000
Jeff
yellow69RS is offline  
post #7 of 14 (permalink) Old Apr 28th, 09, 05:40 AM
Gold Lifetime Member
Harry
 
dawg's Avatar
 
Join Date: Mar 2004
Location: Colebrook CT.
Posts: 3,988
Re: 3914638 is it a 307?

look for a suffix code on the block to find out if in fact its a 307 or 327 but you already tried a 4" piston and it didnt fit so you have a 307

Dawgs 69
434 stroker
US Navy retired
http://www.northeastf-bodyassn.com/
dawg is offline  
post #8 of 14 (permalink) Old Apr 28th, 09, 04:39 PM
Banned
 
Join Date: Apr 2000
Location: Columbia, MO USA
Posts: 21,341
Re: 3914638 is it a 307?

I'd sonic check it and bore away if it's OK..

pdq67
pdq67 is offline  
post #9 of 14 (permalink) Old Apr 28th, 09, 06:24 PM
Senior Tech
Patrick
 
Join Date: Jun 2005
Location: Quitman Georgia
Posts: 2,519
Re: 3914638 is it a 307?

Quote:
Originally Posted by yellow69RS View Post
I'm sure a machinist should be saying this but I wouldn't try to bore that block .125.
307 is 3.875 bore and 327 is 4.000
Jeff
This is true! You must get new pistons.

69RS/SS,383,10:1cr,4.10,60ft1.6sec,1/8-7.6sec@88mph,1/4-12.1@110mph,Vicjr,RPMheads,750dp, Proform main body, cam,246*-250*@.050,.510,522,1.6rr,700r4,3200stall
383 IS SOLD!
Building a 489BBC
http://s90.photobucket.com/albums/k264/pnewell44/
speedfreek is offline  
post #10 of 14 (permalink) Old Apr 28th, 09, 06:37 PM
Senior Tech
 
Join Date: Apr 2005
Posts: 318
Re: 3914638 is it a 307?

Had a unit in here some time ago for a build, block #3914638. Most definitely a "stock" 327" (4.000" bore) core!

I do show a casting #3914636 as a 307"?

Thanks, Gary in N.Y.

P.S. Make certain the posted numbers are correct, some of these early casting's are difficult to read, especially while they're still somewhat dirty.
GOSFAST is offline  
post #11 of 14 (permalink) Old Apr 29th, 09, 03:53 PM Thread Starter
Senior Tech
mark
 
Join Date: Feb 2009
Location: N.Y.
Posts: 510
Re: 3914638 is it a 307?

Quote:
Originally Posted by pdq67 View Post
I'd sonic check it and bore away if it's OK..

pdq67
what is sonic checking? thanks
mark191 is offline  
post #12 of 14 (permalink) Old Apr 29th, 09, 04:49 PM
Banned
 
Join Date: Apr 2000
Location: Columbia, MO USA
Posts: 21,341
Smile Re: 3914638 is it a 307?

A sonic checking device is like a sonar gun that can measure part thicknesses once it's calibrated in.

You hold it's transducer, (i.e., sending head), tight against the part, (cylinder wall in this case ), a sonic wave goes out, returns and then it is converted electronically into thousandth's of inches or whatever...

A good Machine Shop should have one, imho.. It can tell you if the cylinders are thick enough before boring to bore an 1/8" over. As well as check for thinner rust spots and even sand cast pinholes and such.

The one I've seen is like the size of an old hand-held transistor radio w/ a transducer and cord on it. Nor much bigger than a dwell meter as I recall??

And if it won't bore an 1/8" over, heck, bore her a 1/16" over and turn her into a highly HOPPED UP 292 and go big engine hunting!!

pdq67
pdq67 is offline  
post #13 of 14 (permalink) Old Apr 29th, 09, 05:11 PM
Gold Lifetime Member
John
 
Vintage 68's Avatar
 
Join Date: Mar 2002
Location: Moraga,Ca.,USA
Posts: 13,704
Wink Re: 3914638 is it a 307?

Quote:
Originally Posted by GOSFAST View Post
Had a unit in here some time ago for a build, block #3914638. Most definitely a "stock" 327" (4.000" bore) core!

I do show a casting #3914636 as a 307"?
...

The confusion comes from the fact that GM used the 3914638 casting for some 307's - just underbored* it to 3.90"...
I've tore apart a 'DF' coded 307 a couple years back with a 638 block.
It is more common to find 307's using the 3914635 or 636 blocks though

As stated, bore it to fit your pistons you ordered and be done with it.
It will take a 4.0" bore, I've never run into a problem boring one to standard oversizes yet.



* = vs. a 4.0" bore for a 327 or 350 - don't start hate mail...

1968 Convertible
Some trucks
Other V8 things - some of which float
Other V6 things - none of which float
Oh yeah, and 1 "Straight-Six" ...

If a man says something in the garage - and his wife can't hear him - is he still wrong !!!
Vintage 68 is offline  
post #14 of 14 (permalink) Old Apr 29th, 09, 05:52 PM
Banned
 
Join Date: Apr 2000
Location: Columbia, MO USA
Posts: 21,341
Re: 3914638 is it a 307?

And I'm figuring most "round bottom" 283's will bore to .155" over just like a .030" 302" engine block!

BUT I would sonic check 1st!!

pdq67
pdq67 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









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.



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