reworking 350 heads - 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 11-04-2008, 12:28 AM
Registered User
 
Join Date: Nov 2008
Location: new zealand
Posts: 4
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
reworking 350 heads

what can people tell me about reworking standard 350 heads. can do a lot of work myself on them and just want to tid up some standard heads to get the most out of mild 350 woring in 3000 to 3500rpm range and topped out at 4500rpm. was thinking of just tidying up ports for better flow with high performance vavle springs and installing screw in rocker studs for roller rockers etc. fuel economy and good mid range torque are the main criteria. got pop top pistons so don't want to go smaller in chambers and bump compression up.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 11-04-2008, 05:22 AM
Henry Highrise's Avatar
Lost in the 60's
 
Last wiki edit: Removing stuck fasteners Last photo:
Join Date: Dec 2001
Location: Dixieland
Age: 69
Posts: 15,189
Wiki Edits: 4

Thanks: 0
Thanked 10 Times in 9 Posts
Moving to the Engine forum
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 11-04-2008, 08:31 AM
Registered User
 
Join Date: Jul 2008
Location: NC
Age: 33
Posts: 240
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Well, personally, I wouldn't do very much to them... the only thing I would do is do a little pocket porting below the valve seat and shape up the material around the guides... other than that... as long as the guides and seats look check out ok then I would call it a day. If the seats are wide or the guides have too much play when a valve is inserted then have a shop do a 3 angle and put in some guides. Stock springs will work for a cam that's 'all in' by 4500. Besides, that's probably close to where a stock GM 350 signs off anyways, (maybe more like 4,000).

Screw in studs are only necessary if you are turning some rpm consistently or you have open spring pressures surpassing the 300lb marker. You don't need them just because you are going to run roller rockers.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 11-04-2008, 08:51 AM
DaSouthWon's Avatar
I put up the tools against$300
 
Last photo:
Join Date: Apr 2006
Location: Memphis,Tennessee
Age: 35
Posts: 683
Wiki Edits: 0

Thanks: 0
Thanked 3 Times in 3 Posts
If you've never ported heads before, do your research before you start grinding on them. I would just look in the ports for excess casting flash and large rough spots and try to remove that. To smooth or to much widening of the port can be bad and hurt performance if your not sure of what your doing, especially on the intake side.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 11-04-2008, 10:00 AM
Registered User
 
Last photo:
Join Date: Apr 2007
Location: Seattle, Wa
Posts: 6,656
Wiki Edits: 0

Thanks: 3
Thanked 399 Times in 346 Posts
Quote:
Originally Posted by 350boatie
what can people tell me about reworking standard 350 heads. can do a lot of work myself on them and just want to tid up some standard heads to get the most out of mild 350 woring in 3000 to 3500rpm range and topped out at 4500rpm. was thinking of just tidying up ports for better flow with high performance vavle springs and installing screw in rocker studs for roller rockers etc. fuel economy and good mid range torque are the main criteria. got pop top pistons so don't want to go smaller in chambers and bump compression up.
There are many good books on the subject, one I recommend is "How to Build & Modify Chevrolet Small-Block V-8 Cylinder Heads" by David Vizard. This will lay a very good foundation for understanding the Chevy head and what does and does not work with them.

Bogie
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 11-05-2008, 01:01 AM
Registered User
 
Join Date: Nov 2008
Location: new zealand
Posts: 4
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
350 heads.

thanks for comments. think i'm on right track with things. need to change rocker studs as standard ones are too small to fit the roller rockers i have so may as well use what i already have. anyone got ideas on best castings for this application. while not high revving engine will be working hard as they do in boats with constant revs for long periods. so heads that are prone to cracking not a good choice. reading a lot on here about all different types and getting a bit confused what might work. weight not an issue just good solid reliability keeping in mind i want to stick with 76cc chambers to keep compression ratio under control.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 11-05-2008, 01:17 AM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 12,526
Wiki Edits: 326

Thanks: 684
Thanked 869 Times in 739 Posts
"487" 3973487, OR 3973487X. The regular casting was found on the 1971-1972 350 LT-1 engines, had 1.94/1.50" valves, 76CC combustion chambers, DO have accessory holes, intake port volume should be 161CC's, exhaust port volume should be 65CC's. The 487X had 2.02/1.60" valves.

"441" 3932441. This head was found on the 1969-1970 350 engines (255hp 350), it was a decent flowing large chamber head. It had 1.94/1.50" valves, 76CC combustion chambers, DO have accessory holes, intake port volume should be 161CC's, exhaust port volume should be 61CC's. Not to be confused with 3923441, which was a 1.72/1.50" valve, 327 truck head.

http://cgi.ebay.com.au/BRAND-NEW-CHE...1%7C240%3A1318

Last edited by techinspector1; 11-05-2008 at 01:41 AM.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 11-05-2008, 06:53 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,456
Wiki Edits: 0

Thanks: 2
Thanked 322 Times in 319 Posts
Change the pistons. Dome pistons is a bad bad choice for a boat motor.
New hyper flat top or dished pistons are not expensive. under $100/set
This opens the door to using a real performance cylinder head. (64ish cc chamber)
Stock L-31 vortecs work great on boats. Thats why Mercury marine Mercruiser 350 motors use them. Take a clue.

Its cheaper to do it correctly now, then do it over later.
Dome pistons are not going to work in a boat motor.
Use them in something else, or sell them.

Follow the piston makers recomendation for ring end gap for marine use ( larger)
cold block water temp and hot pistons need larger ring gaps.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 11-05-2008, 07:01 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 28
Posts: 8,609
Wiki Edits: 0

Thanks: 15
Thanked 273 Times in 255 Posts
If you're looking to max out at 4500 RPM's and good milage, you may want to actually add some material, you can use a variety of methods, usually welding or epoxy to do it, by filling in the voids and smoothing out the turns you'll increase air velocity and this is very important for low end.

I ported out a set of Vortec's that I'm using for a max torque engine, but I removed as little as possible as opposed to a max hp engine where you want to increase the volume a little more for upper RPM range.

Just try to keep the runner as small as possible with smooth turns and as few of turns as possible.
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
305 vortec heads vs 350 vortec rimracers Engine 6 04-02-2007 08:41 PM
olds #5 head johann Engine 1 07-30-2006 10:05 PM
Questions about chevy 350 heads. rayzorsharp Engine 11 04-27-2006 07:36 AM
350 Different heads Nobodyknows Engine 2 04-13-2006 07:03 PM
350 heads babygene41042 Engine 2 06-08-2004 08:10 PM


All times are GMT -6. The time now is 08:23 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.