milling gm 350 290 hp.. 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 02-12-2009, 09:06 PM
Registered User
 
Last photo:
Join Date: Jan 2009
Location: Vancouver Island
Posts: 88
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
milling gm 350 290 hp.. heads

Hi guys.. I have a 4 bolt 1976 350.. And just picked up these heads for next to nothing only 3500 miles..He got some vortecs..anyway the heads are the gm crate motor 350 290 horse heads..194/150...76cc.. How much can be milled of these to get a little higher CR..( Motor will not be raced just saturday night stuff)
Whats the general rule to max milling, to where the other components need to be changed..ie push rods ect ... How far can i go..I guess some where in the 9cr is a nice number.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 02-12-2009, 09:33 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,444
Wiki Edits: 0

Thanks: 2
Thanked 320 Times in 317 Posts
Physicaly, you can flat mill them down to the edge of the intake valve seat.
Approx .060" iff the heads will get you there. Generally you'll end up with 69-70 cc chambers after carving off .060". (approx) If you combine this .060" flat mill with a thin .015" shim head gasket it s not too bad.
You can reduce the chamber volume even more by $$$angle milling$$$ the heads. Again, the intake valve seat edge is the limit. You can get the chambers down to around 64cc +/-. This angle milling is $$$more involved and costs more money to do$$$.
The intake face on the heads and head bolt holes spot face needs to be corrected too. more time=more money.
This is why I like to start with a small combustion chamber head (305HO or other) for these low budget hop ups.
Less total finished cost.
You still have a poor flowing cylinder head but if you fully port them they are not too bad. A little pocket port job is not going to cut it. You need to get serious with the porting to get airflow and power. Plan on getting dirty if you really want to make some power.
You can drill and roll pin the stock rocker studs.
Its cheaper to swap pistons or start with a small chamber head than getting all carried away with $$$ angle milling $$$ on a budget build up.
You could even use your good 1.94x 1.50 valves in a reworked #416 head and sell/or trade your bare 76cc crate motor head castings.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 02-12-2009, 10:35 PM
Registered User
 
Last photo:
Join Date: Jan 2009
Location: Vancouver Island
Posts: 88
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
hmmm paid 125 buck and came with the stock cast intake aswell..all like new...I guess they will sit..But you say i could use the valves in other heads.. never thought of that..
not a total loss anyway.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 02-12-2009, 10:45 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,444
Wiki Edits: 0

Thanks: 2
Thanked 320 Times in 317 Posts
Quote:
Originally Posted by candrive55
hmmm paid 125 buck and came with the stock cast intake aswell..all like new...I guess they will sit..But you say i could use the valves in other heads.. never thought of that..
not a total loss anyway.
If the heads are in as good shape as you say they are then yes you can probabily rob the valves to put in another head with a small combustion chamber and sell/trade the bare castings to someone rebuilding a truck motor that wants a low cr.
You could also tear down your motor and swap the pistons for 3.5CC .150" dome "claimer" pistons with just a honing and new rings and bearings if the bore are still decent. Could even get the block decked. Then the 76cc heads (with lots of porting) are usable.
You want 10:1 to 10.3:1 and net .038"-.040" quench for a "cheapy saturday night bad boy".

Does your motor have dished pistons now?

Last edited by F-BIRD'88; 02-12-2009 at 10:54 PM.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 02-12-2009, 11:06 PM
Registered User
 
Last photo:
Join Date: Jan 2009
Location: Vancouver Island
Posts: 88
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
getting some great info and ideas from ya here..To be honest with ya i picked up this 350 block about 6 years ago and cant remember what the pistons are. But dont think there dished..
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 02-12-2009, 11:16 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,444
Wiki Edits: 0

Thanks: 2
Thanked 320 Times in 317 Posts
stock bore claimer pistons

Whats this for , a Camaro or Malibu cheap street bad boy?
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 02-13-2009, 12:27 AM
Registered User
 
Last photo:
Join Date: Jan 2009
Location: Vancouver Island
Posts: 88
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Got my eye on a 1960 pontiac two door with a six in it.. Plan is to go roller block with vortecs..Having doughts on that tho price and all..but just couldnt pass on these heads.. ..But getting the parts together for the engine now..
Thanks..
Funny ..The little woman goes whats those for i say a car motor..She sez..What car....To funny
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 02-13-2009, 12:30 AM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,444
Wiki Edits: 0

Thanks: 2
Thanked 320 Times in 317 Posts
Your new Poncho

All pimped out

Last edited by F-BIRD'88; 02-13-2009 at 12:36 AM.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 02-13-2009, 12:32 AM
SSedan64's Avatar
Registered User
 
Last photo:
Join Date: Dec 2007
Location: Macon, GA.
Age: 50
Posts: 6,016
Wiki Edits: 0

Thanks: 0
Thanked 46 Times in 46 Posts
Funny ..The little woman goes whats those for i say a car motor..She sez..What car....To funny[/QUOTE]

Whoops! Let the cat out out the bag.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 02-13-2009, 11:23 AM
Registered User
 
Last photo:
Join Date: Apr 2007
Location: Seattle, Wa
Posts: 6,654
Wiki Edits: 0

Thanks: 3
Thanked 398 Times in 345 Posts
Quote:
Originally Posted by candrive55
Hi guys.. I have a 4 bolt 1976 350.. And just picked up these heads for next to nothing only 3500 miles..He got some vortecs..anyway the heads are the gm crate motor 350 290 horse heads..194/150...76cc.. How much can be milled of these to get a little higher CR..( Motor will not be raced just saturday night stuff)
Whats the general rule to max milling, to where the other components need to be changed..ie push rods ect ... How far can i go..I guess some where in the 9cr is a nice number.
There's a reason why why these heads were cheap and the guy you got them from bought Vortecs.

The big chamber heads are boat anchor candidates, you can fix them to some extent, but the money you spent for them and the money you'll spend trying to make a silk purse out of a sows ear would have been better spent on a set of Vortecs.

If the heads you bought are 1976 production or newer only about .030 is safe to mill. Check their casting number against MorTec's list for a rough idea of their year of manufacture.

Bogie
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
Heads AMCFREEK Engine 2 01-25-2009 10:46 PM
350 w/305 Hi Po 601 Heads RoyLeoGracie Engine 17 11-25-2008 10:28 PM
What will my HP and torque be with the patriot heads eatonde Hotrodding Basics 11 11-21-2008 09:03 AM
DEBATE: Which heads are better?....Chevy 350, Pontiac 350, Olds 350 or Plymouth 350. Steve-0321 Hotrodding Basics 21 11-26-2007 12:44 AM
283 heads on 350 70 nova Engine 5 11-09-2005 08:26 AM


All times are GMT -6. The time now is 04:39 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.