305 head on 350 - 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 10-20-2005, 11:52 AM
Member
 
Last photo:
Join Date: Feb 2004
Location: Louisiana
Posts: 205
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
305 head on 350

I've been in the tech area alot lately at a local track. They have a pretty much strictly stock class there. The rule says must run an open chamber heads. One of the gray areas has been a 305 head on a 350. This is what the track says. The 305 chamber fits the cylinder on a 305, but on a 350 it overlaps the cylinder, and makes it a closed chamber. Is that so? I know a double humped head is a closed chamber head, but some of the guys being dq'd say that the 305 head isn't a closed chamber head, but rather a small chambered head. The track says that's the case on a 305, but it becomes a closed chamber on a 350. The track also says a 350 head such as a 487 won't run good at all on a 305. Is that so? Also some of the guys that run 350's are alledging that the some of the guys running blocks with a 305 number on them and a 305 head could be boring them out to 350. Now I know that the catings in those 2 blocks are different and the cylinder walls would be too thin, but some of them are claming that some of the 305 blocks can be bored out to a 350. Is this true?

I've seen things like this before. 78-86 GM passenger cars with a metric frame are supposed to be automatic, a no disc brakes on the back. That's what most people say anyway. Well, my friend has a 78 Monte Carlo that come stock with a standard tranny in it. The Floorboard is prepared for it and everything. My neighbor has a Buick Grand National, and it has stock disc brakes on it. By the way, that's a V6, and it will fly. Could possibly an early 305 have been just a smaller bored 350?
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 10-20-2005, 12:04 PM
BOBCRMAN@aol.com's Avatar
Member
 
Last photo:
Join Date: May 2002
Location: Holly, michigan
Posts: 7,951
Wiki Edits: 0

Thanks: 13
Thanked 218 Times in 207 Posts
A 305 head on a 350 is just a smaller combustion chamber. These heads will raise your compression ratio at the expense of more quench area, smaller valves and smaller port "Windows". A 350 head on a 305 will lower your already low compression ratio and you won't be able to pull a fat girl off a tricycle.

NO WAY can a 305 be bored to 4" 350 bore. You may possibly come across a mis-cast block no. ( I've seen quite a few oddities ) but no big bore jobs on 305 blocks.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 09-08-2006, 06:15 AM
runn141's Avatar
SB S10
 
Last photo:
Join Date: Sep 2006
Location:
Posts: 1,252
Wiki Edits: 0

Thanks: 17
Thanked 13 Times in 13 Posts
no chevrolet motor i know of can be bored more than .060 except the 283's. 305 had 2 high compression heads #416 and #601 both 1.84 1.50 valves. #601 had 53cc chambers but the #416 had 58cc and an intake flow of a 350 head. i took a set of #416 heads, had the intake valve seat cut to 1.94 from 1.84 and done a gasket match port job and bowl blended it. i put them on a 358 it gave it 11.3 to 1 compression. believe it or not i could retard the timing and have no detonation on pump gas. and i know for sure because i kept a close on the plugs.but the #416 is a better chamber design for a 350, i think.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 10-15-2006, 09:00 PM
Registered User
 
Join Date: Oct 2006
Location: Anchorage
Posts: 15
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
#416 heads, huh, what would be the full casting number on these heads. i have put 305 heads on my 350, just looking to up the compression ratio. i was just wondering if i had a good set of 305 heads???????
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 10-15-2006, 09:18 PM
sbchevfreak's Avatar
Licenced Automotive Technician
 
Last photo:
Join Date: Feb 2004
Location: Land of big Easter eggs, Alberta
Age: 34
Posts: 1,604
Wiki Edits: 0

Thanks: 8
Thanked 9 Times in 9 Posts
Quote:
The 305 chamber fits the cylinder on a 305, but on a 350 it overlaps the cylinder, and makes it a closed chamber.
An open chamber head is an open chamber head. The way it fits the bore has nothing to do with the chamber design. .

Quote:
but some of the guys being dq'd say that the 305 head isn't a closed chamber head, but rather a small chambered head. The track says that's the case on a 305, but it becomes a closed chamber on a 350.

Once again, this is incorrect information. The 305 head IS an open chamber head. It is an open chamber head on a 305, and I could bolt it on a 400 SBC, and it would STILL be an open chamber head. What it does it boost the CR of the 350, the same way a closed chamber 350 head would. It simply does this by having a smaller chamber volume, while remaining open. I'd suggest having a good look at the rulebook for that track/class. If there is a rule specifically for the 305 head on a 350, you cannot argue. If there is not, and it simply states that you must run a stock, open chamber GM head, the 305 heads should pass tech
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
350 to 305 swap 78Z Engine 10 02-06-2005 01:42 AM
305 or 350? Miserlou57 Engine 4 02-05-2005 08:13 PM
305 head on 350 Houman SS '70 Engine 11 02-02-2005 05:51 AM
Distributor Question - 1985 305 and 1975 350 Fragzem Electrical 3 10-28-2003 10:07 PM
305 vortec heads on a 350 tonylsg Engine 13 09-21-2003 05:54 PM


All times are GMT -6. The time now is 08:21 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.