Factory chevy 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 Advertise
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 02-24-2007, 11:34 AM
Registered User
 
Join Date: Feb 2007
Location: Hermitage, Pa
Age: 54
Posts: 131
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Factory chevy heads

I have a question regarding factory small block heads, I am trying to make 400hp out of a 350(2 bolt main) and am wondering if factory open chamber heads will support this based on flow. The is a low buck engine for a street strip car not a daily driver. I have tried to find flow numbers for the open chamber heads and have found some info particularly on the 882s this http://racingfeed.com/downloads/chevy_flow_data.pdf has numbers that include the 882 and my dd dyno program also has some numbers which suggest they will support 400 hp is this believable? I have three sets of open chamber heads, early 882s(1.94/1.5), 993s(1.94/1.5), and 493s(1.94/1.6) and am trying to decide which to use. I know the best answer is to go with vortecs but I already have an intake vortecs seem to go for $400 used and I heard they are limited on lift(machining cost) and I already have the others(all of which would need rebuilt). So my question is will the factory open chamber heads support 400 hp and which ones of the three I have would be the best choice?

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 02-25-2007, 01:01 AM
curtis73's Avatar
Hates: Liver. Loves: Diesel
 
Last wiki edit: How to find cheap parts
Last journal entry: Found an LQ9 today
Join Date: Dec 2005
Location: Carlisle, PA
Age: 46
Posts: 5,572
Wiki Edits: 16

Thanks: 32
Thanked 75 Times in 62 Posts
Or use Vortecs and flat tops. As cast they are more than capable of 400 hp. For the money you'd spend on all that F-bird recommends you could have three sets of vortecs. That saves a lot of money for the intake of your choice.

Heck for that matter, the amount of money you'd spend modifying older heads to get that much power, you could probably buy a complete 350-hp vortec engine from Ebay.

Vortecs flow over 230 cfm as-cast. Why spend crazy money modifying old-school heads? No offense, but you can buy vortecs, higher-lift springs and retainers, and the intake to go with it for LOTS cheaper than you can make a set of 305 heads flow like that.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 02-25-2007, 05:43 PM
curtis73's Avatar
Hates: Liver. Loves: Diesel
 
Last wiki edit: How to find cheap parts
Last journal entry: Found an LQ9 today
Join Date: Dec 2005
Location: Carlisle, PA
Age: 46
Posts: 5,572
Wiki Edits: 16

Thanks: 32
Thanked 75 Times in 62 Posts
Quote:
Originally Posted by F-BIRD'88
I do the 305 head hop up with new valves, springs, seals shims and all machine work nesssessaryfor hi perf use and a quick flow test for $440 (Can) all tax inc. .
Hey, that's cheap. You should charge more for that. That's pretty easily $1000US worth of work and parts. I take back what I said
Reply With Quote Quick reply to this message
 
  #4 (permalink)  
Old 02-25-2007, 09:23 PM
Registered User
 
Join Date: Feb 2007
Location: Hermitage, Pa
Age: 54
Posts: 131
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I do like the idea of using the 305 heads but I want to go over what I would need to do in a little more depth so I get it done and can accurately price it out in our area. I need to port the heads how extensively the picture you show is great is that it or do the runners need modified is epoxy used? At what lift are you getting 230cfm? Studs need pinned (I can do this) along with deshrouding the valves, machine shop increases the valve size for both valves and does a valve job(three angle?) exhaust valve edge taken off? Is this all the machine shop needs to do assuming the guides are ok? Ill look for that casting this week to see whats available. I will compare the costs with the vortecs the vortec prices Ive seen for stock vortecs is around $400 and require machining for lifts exceeding 470 is this correct?
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 02-26-2007, 07:13 AM
Member
 
Join Date: Sep 2006
Location: NORTHEAST
Age: 60
Posts: 1,680
Wiki Edits: 0

Thanks: 3
Thanked 64 Times in 58 Posts
Quote:
Originally Posted by F-BIRD'88
I do the 305 head hop up with new valves, springs, seals shims and all machine work nesssessaryfor hi perf use and a quick flow test for $440 (Can) all tax inc.
I port them, deshroud the chambers for large valves and modify the rocker studs at home.
I clean and assemble them myself at home after machining.
Done it many times. I have vortec heads Have done more than 1 set of these also. I know how much it costs to buy and get them ready to use.
they do work well. The ported large valve 305 head route is cheaper by far. They work very well also. My ported 305 heads flow more than stock vortec heads do out of the box.
You can do it too.
Note: stock vortec heads flow 228cfm in and 153ex
have flow tested more than 1 set.

What are you using for equipment at your HOME to do this type of work??

We have done quite a few engines using the Vortec heads with a good valve job a 79 degree bowl hawg and cut for 59CC's and have seen 432 horse and 468 on the torque and its only a 355.

On our SBC circle track engines 11:01 Ford flat tappet cam and HP 600 we have seen nubers up to 515 and 488 on the torque.

The 305 head does not have a fast burn chamber or raised intake and exhaust ports.

And if the 305 heads were that good ALL the shops i deal with would be using them. HMMMMMMMMMMMM

I really doubt you have the proper equipment at home for doing seat and guide work and cutting the decks. Maybe a die grinder at best!!!
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 02-26-2007, 01:51 PM
Registered User
 
Join Date: Feb 2007
Location: Hermitage, Pa
Age: 54
Posts: 131
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
What Vortec head is the one to have are there differences, what is a decent price for the vortecs. What needs to be done to them to run .500 lift are the stock rockers sufficient for 400 hp is the stock valve size sufficient? I guess in short I am asking what would need to be done to them to support 400 hp in a 355 pump gas engine?
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 02-26-2007, 02:15 PM
curtis73's Avatar
Hates: Liver. Loves: Diesel
 
Last wiki edit: How to find cheap parts
Last journal entry: Found an LQ9 today
Join Date: Dec 2005
Location: Carlisle, PA
Age: 46
Posts: 5,572
Wiki Edits: 16

Thanks: 32
Thanked 75 Times in 62 Posts
They'll do it in stock form. They're good for about .470" lift as-is, but its tough to find aftermarket cams under .470" and its tougher to make 400 hp with a .470" cam.

The good news is, if you're using an aftermarket cam you'll probably be needing upgraded springs anyway. There is a VERY common package available from multiple sources that allows for .550" lift without any machine work.

Flat top pistons should give you between 10 and 10.5:1 depending on your valve reliefs and compression height. That's fine for pump gas with the fast burning vortec chambers. A cam that is about 224/234 on a 110 LSA should put you squarely at 400+ hp at about 5500 rpm and 450-ish tq at 3500 rpm. Small tube headers, air gap intake, 600 cfm carb, and that will be one heck of a runner.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 02-26-2007, 02:22 PM
curtis73's Avatar
Hates: Liver. Loves: Diesel
 
Last wiki edit: How to find cheap parts
Last journal entry: Found an LQ9 today
Join Date: Dec 2005
Location: Carlisle, PA
Age: 46
Posts: 5,572
Wiki Edits: 16

Thanks: 32
Thanked 75 Times in 62 Posts
Oh.. forgot the other question...

Pretty much any casting is as good as the next. Some say that the "hecho in Mexico" heads aren't as good, but I've yet to see definitive proof of that. One of the reasons vortecs flow so well is an extra 30-degree back cut at the valves and other rumors are floating around that the 906 casting lacks that back cut. Others report that they simply have different exhaust valve seats that aren't cut the same and they hurt flow. I have two sets of 906s that have the extra back cut, but they have both been rebuilt so who knows how they were originally configured. At any rate, they all flow better than any old-style heads and they're only different by a few cfm. For a 400-hp engine, any will do just fine.

Some good tech here: http://www.chevymania.com/tech/vortec.htm
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 02-26-2007, 02:58 PM
King of my Man-cave.
 
Join Date: Nov 2003
Location: Michigan
Age: 61
Posts: 2,896
Wiki Edits: 0

Thanks: 6
Thanked 19 Times in 16 Posts
Quote:
Originally Posted by curtis73
Hey, that's cheap. You should charge more for that. That's pretty easily $1000US worth of work and parts. I take back what I said
Talk and pretty pictures are cheap. So is some people's labor. It's the price of finding out that one guy's great deal is someone else's reality check that is priceless.. Anybody doing THAT much work to a set of highly shrouded, small port heads and claiming THAT much power out of them lives in a very optimistic world. As was stated by one who should know, if those heads were capable of that kind of modification with reasonable expense (for the machinist as well as the end user), there would be a lot more performance shops turning them out like hotcakes.

But they aren't........




tom
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 02-26-2007, 04:20 PM
Member
 
Join Date: Sep 2006
Location: NORTHEAST
Age: 60
Posts: 1,680
Wiki Edits: 0

Thanks: 3
Thanked 64 Times in 58 Posts
Quote:
Originally Posted by machine shop tom
Talk and pretty pictures are cheap. So is some people's labor. It's the price of finding out that one guy's great deal is someone else's reality check that is priceless.. Anybody doing THAT much work to a set of highly shrouded, small port heads and claiming THAT much power out of them lives in a very optimistic world. As was stated by one who should know, if those heads were capable of that kind of modification with reasonable expense (for the machinist as well as the end user), there would be a lot more performance shops turning them out like hotcakes.

But they aren't........




tom
Tom

I see you read right through this guy at least I try to post factual info here and not try to mislead every body,
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 02-26-2007, 04:31 PM
Member
 
Join Date: Sep 2006
Location: NORTHEAST
Age: 60
Posts: 1,680
Wiki Edits: 0

Thanks: 3
Thanked 64 Times in 58 Posts
Quote:
Originally Posted by F-BIRD'88
I do the 305 head hop up with new valves, springs, seals shims and all machine work nesssessaryfor hi perf use and a quick flow test for $440 (Can) all tax inc.
I port them, deshroud the chambers for large valves and modify the rocker studs at home.
I clean and assemble them myself at home after machining.
Done it many times. I have vortec heads Have done more than 1 set of these also. I know how much it costs to buy and get them ready to use.
they do work well. The ported large valve 305 head route is cheaper by far. They work very well also. My ported 305 heads flow more than stock vortec heads do out of the box.
You can do it too.
Note: stock vortec heads flow 228cfm in and 153ex
have flow tested more than 1 set.
F-BIRD'88

If your going to blow smoke up my ***** you better build a bigger fire then that. LOL
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 02-26-2007, 04:31 PM
cool rockin daddy's Avatar
Member
 
Join Date: Aug 2003
Location: wherever cool cars are
Posts: 1,533
Wiki Edits: 0

Thanks: 0
Thanked 4 Times in 4 Posts
Seems to me that taking a stock pair of Vortecs and adding the beehive springs will give you the lift capacity you want at a fraction of the price of porting out 305 heads. 400 HP easy. If manifold is a concern, pick up some used Dart SS heads.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 02-26-2007, 06:44 PM
NAIRB's Avatar
Hotrodders.com Moderator
 
Join Date: Sep 2002
Location: cimarron, ks
Posts: 1,642
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
The only time you should use a stock type 305 head is if class rules require them. There are some 305 classes out there, and if that's what was required, that is what I would run.

I've done a bunch of these things, and to make them decent heads takes an incredible amount of work. A set of stock vortec heads will blow them away.

Hand porting old iron heads is not something you want to do for a living if you want to live very long. It's too easy to get good stuff, out of the box. Been there, done that, bought the T-shirt, gave it away.


Nairb
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 02-26-2007, 06:56 PM
NAIRB's Avatar
Hotrodders.com Moderator
 
Join Date: Sep 2002
Location: cimarron, ks
Posts: 1,642
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
Quote:
I have a question regarding factory small block heads, I am trying to make 400hp out of a 350(2 bolt main) and am wondering if factory open chamber heads will support this based on flow. The is a low buck engine for a street strip car not a daily driver. I have tried to find flow numbers for the open chamber heads and have found some info particularly on the 882s this http://racingfeed.com/downloads/chevy_flow_data.pdf has numbers that include the 882 and my dd dyno program also has some numbers which suggest they will support 400 hp is this believable? I have three sets of open chamber heads, early 882s(1.94/1.5), 993s(1.94/1.5), and 493s(1.94/1.6) and am trying to decide which to use. I know the best answer is to go with vortecs but I already have an intake vortecs seem to go for $400 used and I heard they are limited on lift(machining cost) and I already have the others(all of which would need rebuilt). So my question is will the factory open chamber heads support 400 hp and which ones of the three I have would be the best choice?
You could get close to 400 ponies with a good set of open chamber heads. The early, big port heads like the 441's or 487 heads flow enough air, but their big, slow burning combustion chamber will lose 20 ponies over a good compact chamber like the early double hump heads had. A good set of early double hump heads would be better, but they are getting scarce and usually need too much work to justify using them. With matching components, enough cam, and compression ratio, I would think 375 horsepower on 441s or 487s would be very doable.
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 02-26-2007, 08:41 PM
Registered User
 
Join Date: Feb 2007
Location: Hermitage, Pa
Age: 54
Posts: 131
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Ive done a bit more research on the open chamber heads originally my flow data came from dd dyno and I believed it was supported by a car craft article where the numbers were nearly the same(same source?) Ive read the Lingerfelter book where he stated the 993 heads flow better then the 882s I read the Vizard book on head porting he supplied actual flow data on the stock 993s using Vizard numbers with my pump gas combo the best HP I get through dd dyno is 335, I believe the Car Craft data is flawed or they tested a really good stock 882 head. With Vizards porting the 993 flow is dramatically increased and according to dd dyno will support 400 hp. After reading the book I dont believe he likes the open chamber heads.. So combined with some of the feedback the open chamber heads are going back on the shelf. My choices now are either going to be the vortecs or the 305 head. Comparing the two with machining cost in my area I cannot do the 305 heads for $450 it would be more like $650+ so even with the purchase of a vortec manifold the costs would be close and I would not have to spend all the time porting. I think the vortecs are the way to go for me. If anyone has a good set of vortecs they want to sell pm me. Thank to all for the info the search begins .
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:
Insurance
Please select your insurance company (Optional)

Log-in



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
SBC 350 superiority rebuttle...was:POWERED BY CHEVY, WRITTEN ON A FORD, (from 'Engine Oldsmolac911 Hotrodders' Lounge 49 01-12-2011 10:00 PM
AFR or Vortec heads? Cam? rodent Engine 18 06-08-2010 03:50 PM
Chevy #193 heads....Your thoughts.. 8843astro Engine 12 05-10-2009 11:56 PM
Chevy Small Block Heads druss32 Engine 17 05-10-2006 08:35 PM
best factory sbc heads onebad98z Engine 15 04-07-2005 12:17 AM


All times are GMT -6. The time now is 09:10 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.