305 vrs. 307 sbc - 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 06-26-2008, 02:45 AM
Member
 
Last photo:
Join Date: Feb 2002
Location: Agua Dulce Calif.
Posts: 328
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
305 vrs. 307 sbc

My 72 el Camino is using oil like the Valdez in Alaska. It was a no history 350 motor from someones 67 nova was good for several years, I still have the maybe original 307 that was
in the truck when I got it
and I have the chance to get another 76 el Camino 305 for the motor,to swap into my 72. Is one with the 305 versus the 307
better then the other. Fuel economy is now an issue not when I first put the 35o in a few years back. Your thoughts thanks Ed

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 06-26-2008, 05:58 AM
RippinRon's Avatar
Member
 
Last photo:
Join Date: Jun 2004
Location: Thornbury, Ontario
Age: 34
Posts: 948
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
I'd say the 307 is better due to the larger bore diameter. There will be less valve shrouding than the 305.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 06-26-2008, 07:31 AM
Deuce's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Choosing a trailer
Last journal entry: Jan 13 2013
Last photo:
Join Date: Aug 2002
Location: Deuceland USA
Age: 66
Posts: 5,657
Wiki Edits: 6

Thanks: 0
Thanked 9 Times in 9 Posts
I prefer the 305 ... for it's longer stroke. It has the same stroke as a 350 ...
I believe that the stroke makes more torque and torque is useful in moving a street geared, small cubic inch equipped vehicle.

Not much difference either way IMHO ...
__________________


"I won't be wronged . I won't be insulted, and I won't be laid a hand on. "







Last edited by Deuce; 06-26-2008 at 12:41 PM.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 06-26-2008, 07:47 AM
schnitz's Avatar
Member
 
Last wiki edit: Building a new shop
Last journal entry: Christmas 2008 came early!!!
Last photo:
Join Date: Jan 2004
Location: Wausau, Wisconsin, in a house...
Age: 40
Posts: 1,163
Wiki Edits: 54

Thanks: 8
Thanked 1 Time in 1 Post
This thread has near-perfect timing for me. I have both in my garage now (the '69 307 has approx. 30,000 miles, and the '78 305 has 161,000), and I've been debating the same thing for quite some time. One of these two will end up with a fairly mild refresh in the not to distant future. Only because I'm flat sick of pushing a 4500lb car on and of my trailer. So, please let the info/opinions/feedback flow....



In a while, Chet.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 06-26-2008, 07:58 AM
Member
 
Last photo:
Join Date: Jun 2007
Location: murfreesboro tn.
Posts: 731
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
305 vrs. 307 sbc

the 307 will need hardened valve seats running unleaded gas
unless it has been done already .
more power than the 305 ,being you might be hauling stuff .
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 06-26-2008, 08:07 AM
schnitz's Avatar
Member
 
Last wiki edit: Building a new shop
Last journal entry: Christmas 2008 came early!!!
Last photo:
Join Date: Jan 2004
Location: Wausau, Wisconsin, in a house...
Age: 40
Posts: 1,163
Wiki Edits: 54

Thanks: 8
Thanked 1 Time in 1 Post
Quote:
Originally Posted by burnt olds
the 307 will need hardened valve seats running unleaded gas
unless it has been done already .
more power than the 305 ,being you might be hauling stuff .
For mine, I was thinking about just doing a head swap from a 305 since it is otherwise unmolested. Most of the used 305 heads seem pretty reasonably priced in my area, so I figured they'd be a decent option, and might be for the O.P. as well.

For fuel milage, I'm thinking that the two should be dang close to the same. Any better thoughts than my semi-uneducated best guess?


In a while, Chet.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 06-26-2008, 09:27 AM
killerformula's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Carburetor
Last journal entry: Clean up
Last photo:
Join Date: Oct 2003
Location: Northeast
Age: 34
Posts: 3,486
Wiki Edits: 3

Thanks: 13
Thanked 27 Times in 18 Posts
I've always been under the impression that a 307 is actually quite a decent, underrated small-cube performance motor whereas a 305 was more of the economy work-horse. It would be slightly easier to get power out of the 307.

Torque will depend on what choices you make with the carb/intake/heads/valves and will be pretty much the same on either motor if built similarly.

K
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 06-26-2008, 09:47 AM
schnitz's Avatar
Member
 
Last wiki edit: Building a new shop
Last journal entry: Christmas 2008 came early!!!
Last photo:
Join Date: Jan 2004
Location: Wausau, Wisconsin, in a house...
Age: 40
Posts: 1,163
Wiki Edits: 54

Thanks: 8
Thanked 1 Time in 1 Post
Quote:
Originally Posted by killerformula
Torque will depend on what choices you make with the carb/intake/heads/valves and will be pretty much the same on either motor if built similarly.

K
That sounds about right to me as well (which adds the complexity to the decision...).


In a while, Chet.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 06-26-2008, 10:46 AM
Registered User
 
Join Date: Jun 2008
Location: NorCal
Posts: 6
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by schnitz
This thread has near-perfect timing for me. I have both in my garage now (the '69 307 has approx. 30,000 miles, and the '78 305 has 161,000), and I've been debating the same thing for quite some time. One of these two will end up with a fairly mild refresh in the not to distant future. Only because I'm flat sick of pushing a 4500lb car on and of my trailer. So, please let the info/opinions/feedback flow....



In a while, Chet.
That 'no mileage' 307 would be a straight drop in at my house... why mess with something that fresh?
If unleaded burns a valve, then vortec/manifold or performance 305 heads could be swapped on.

Ben
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 06-26-2008, 11:58 AM
DoubleVision's Avatar
Not Considered a Senior Member
 
Last photo:
Join Date: Oct 2002
Location: Heart Of Dixie
Age: 40
Posts: 10,658
Wiki Edits: 0

Thanks: 15
Thanked 60 Times in 57 Posts
I would take the 305 heads and swap them over to the 307, I would also add a small rv cam to the 307 while I was at it. The stock cam in the 307 has a history of going flat. The 305 heads on the 307 would put the compression around 9.5:1, the small valves coupled up with a small rv grind cam along with a double roller timing set would give it all the torque you need.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 06-26-2008, 12:19 PM
sbchevfreak's Avatar
Licenced Automotive Technician
 
Last photo:
Join Date: Feb 2004
Location: Land of big Easter eggs, Alberta
Age: 35
Posts: 1,609
Wiki Edits: 0

Thanks: 13
Thanked 9 Times in 9 Posts
Quote:
Originally Posted by DoubleVision
I would take the 305 heads and swap them over to the 307, I would also add a small rv cam to the 307 while I was at it. The stock cam in the 307 has a history of going flat. The 305 heads on the 307 would put the compression around 9.5:1, the small valves coupled up with a small rv grind cam along with a double roller timing set would give it all the torque you need.

X2. I have run an almost exact combo like that, and it was very satisfactory. I had several people argue that a 307 could never pull tlike that, and It must be a , lol.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 06-26-2008, 12:50 PM
Deuce's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Choosing a trailer
Last journal entry: Jan 13 2013
Last photo:
Join Date: Aug 2002
Location: Deuceland USA
Age: 66
Posts: 5,657
Wiki Edits: 6

Thanks: 0
Thanked 9 Times in 9 Posts
A 307 has the same stroke as a 327 ...
A 305 has the same stroke as a 350 ...

Which makes more torque ??

That is WHY the 305 would make more torque than a 307. Every thing else equal. Chevrolet already had the 307 ... when they came out with the 305 ... Chevrolet engineers decided that a 305 was a BETTER design for moving low compression equipped vehicles ... on todays watered down gasoline. Who am I to say they were wrong ??

Factor in the miles and the wear on your 305 VS the lower mile 307 ... if you just want to install a engine and go ... no question ... the lower mile 307 would be my choice. BUT ... both rebuilt and ready to install for another 100 thousand miles ... the 305
__________________


"I won't be wronged . I won't be insulted, and I won't be laid a hand on. "






Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 06-26-2008, 01:00 PM
killerformula's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Carburetor
Last journal entry: Clean up
Last photo:
Join Date: Oct 2003
Location: Northeast
Age: 34
Posts: 3,486
Wiki Edits: 3

Thanks: 13
Thanked 27 Times in 18 Posts
Quote:
Originally Posted by Deuce
A 307 has the same stroke as a 327 ...
A 305 has the same stroke as a 350 ...

Which makes more torque ??

That is WHY the 305 would make more torque than a 307. Every thing else equal. Chevrolet already had the 307 ... when they came out with the 305 ... Chevrolet engineers decided that a 305 was a BETTER design for moving low compression equipped vehicles ... on todays watered down gasoline. Who am I to say they were wrong ??

Factor in the miles and the wear on your 305 VS the lower mile 307 ... if you just want to install a engine and go ... no question ... the lower mile 307 would be my choice. BUT ... both rebuilt and ready to install for another 100 thousand miles ... the 305
I guess you have to assume that a longer stroke=more torque. I think that's a generally held assumption but I'm not sure if its true? For example, an oldsmobile 350 and a chevy 350 have the same cubes, but the olds motor has a shorter stroke and a bigger bore, yet its generally known that an olds motor, all else being equal, will out-torque a chevy motor. Another example is the buick and olds 455 motors, both with varying bore/stroke ratios, but very similar torque ratings (again, when all other things are equal/similar). That's generally why I think it has more to do with the length of the intake runners/valves...

K
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 06-26-2008, 01:17 PM
31 five window
 

Last journal entry: Master cylinder
Last photo:
Join Date: Oct 2007
Location: louisiana
Age: 57
Posts: 1,578
Wiki Edits: 0

Thanks: 1
Thanked 15 Times in 15 Posts
I have to go with Deuce on this one. The longer stroke means more torque. The comparison to the Olds or Pontiac 350,I believe the main difference is due to the better heads not the stroke.IMHO.
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 06-26-2008, 01:28 PM
MrPhotographer06's Avatar
Army Strong
 
Last wiki edit: How to remove a VW Type I body
Last journal entry: well once again
Last photo:
Join Date: Jan 2007
Location: Fort Bragg,SC
Age: 22
Posts: 631
Wiki Edits: 1

Thanks: 0
Thanked 0 Times in 0 Posts
I go with deuce too.. you have more options in my opinion with more stroke
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:
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
307 sbc compression ratio's? C.W Engine 6 06-16-2007 05:37 AM
305 heads on a Chevy 307 75Guy Engine 6 04-30-2007 10:58 PM
307 to 305 engine/ transmission swap pjd Engine 6 08-19-2005 10:47 PM
Conversion of SBC 307 to 350! Houman SS '70 Engine 22 04-09-2005 01:09 PM


All times are GMT -6. The time now is 02:55 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.