Opinions/hp estimate on this 350 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> Hotrodding Basics
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 02-21-2005, 06:51 PM
Member
 
Last photo:
Join Date: Feb 2005
Location: North Dakota
Age: 42
Posts: 85
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Opinions/hp estimate on this 350 sbc?

Hi all.

Ive been wrenching on a street stock, dirt track car for a buddy for a few years now and have just been talked into doing the engine work on top of chassis and carb setup recently.

With that being said, the last time I tore into an engine was shop class in highschool 15 years ago. A few weeks ago we picked up a used 350 sbc for the car and upon inspection I noticed the camshaft to dist gears were tore up pretty bad. I ordered a new cam from speedwaymotors 238/244 dur @.050 cam lift, 298/300 deg adv dur, 106 deg lobe centerline, .502/.516 gross valve lift and a set of antipumpup lifters. Put everything back together after double and triple checking my work since its been so long since ive done anything like this and after installing the engine it started right up to my own amazement
Beings we are rule limited this engine runs about a 9.5:1 cr, holley 2 bbl 500cfm carb sitting ontop of a stock 4 bbl manifold with a 1 inch adapter plate, 991 heads with 1.94/1.5 valves and some flat milling done to them.

Normal revs this engine will be used at are 3000 to 6500. Does anyone have an opinion on the setup or estimate on what kind of hp/trq this thing will put out? Any input would be greatly appreciated as Im getting in over my head on this and Im sure it will continue to the point of where I'll be doing complete engine rebuilds and will be spending much time in these forums as I already have been just reading through thread after thread

Seriously tho what ya think of the setup?
Thx in advance
Mike

Last edited by kane583; 02-21-2005 at 10:45 PM.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 02-21-2005, 06:56 PM
lluciano77's Avatar
Short changed on common sense
 
Last photo:
Join Date: Jun 2003
Location: california
Age: 36
Posts: 3,548
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
If you ever need more carb you can get one of the Holley 6425 650 CFM 2 barrel carbs. They are on Ebay every once in a while. I got one for $100. I ended up trading it for a set of heads.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 02-21-2005, 07:00 PM
Member
 
Last photo:
Join Date: Feb 2005
Location: North Dakota
Age: 42
Posts: 85
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Wish I could but rules limit us to 500cfm
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 02-21-2005, 07:08 PM
bracketeer's Avatar
489 Lemans
 

Last journal entry: Street Legal
Last photo:
Join Date: Dec 2004
Location: Courtenay, BC, CehNehDeh
Age: 55
Posts: 2,139
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Hp

3998991....72-73...307/350......75cc chambers

Heads and carb are too small for that cam in my opinion.
With a .477 cam with that combo-280 HP.
If that cam works-maybe 325 HP.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 02-21-2005, 07:11 PM
Member
 
Last photo:
Join Date: Feb 2005
Location: North Dakota
Age: 42
Posts: 85
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Funny you should mention that. The cam i pulled out of it was about a .480 lift from what I could tell with a mic. I was going to put something of the same size in but the driver wanted more bump so I gave him what he wanted
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 02-21-2005, 07:31 PM
Member
 
Join Date: Dec 2004
Location: Madison, WI
Posts: 1,885
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Bracketeer is pretty close to what I would expect for a restricted motor like that. about 300.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 02-21-2005, 07:46 PM
Member
 
Last photo:
Join Date: Feb 2005
Location: North Dakota
Age: 42
Posts: 85
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
GM may use any production head with a maximum intake valve diameter of 1.94, maximum exhaust valve diameter will be 1.60. No angle plug heads allowed on Chevy. The only after market head allowed on GM is the
Dart S/R No._s 4351, 4361. 1.94 intake and 1.50 exhaust. No “bow tie” or vortex heads allowed


So is there a gm head better then the 991 heads that fit those rules that I might try or possibly are either of those dart heads worth the money?
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 02-22-2005, 06:34 AM
NXS's Avatar
NXS NXS is offline
wind & fire = guides to power
 
Last photo:
Join Date: Nov 2004
Location: Oklahoma
Posts: 1,534
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Funny rules. No vortecs but aftermarket heads allowed?

How about porting? Sounds like the heads should be ported and some 1.6 ex valves installed. Probably some 1.6 rockers too.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 02-22-2005, 01:30 PM
Member
 
Last photo:
Join Date: Feb 2005
Location: North Dakota
Age: 42
Posts: 85
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
No head work is allowed other then milling and stock rockers only.
The rules can drive a guy crazy sometimes
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 02-26-2005, 09:27 PM
Member
 
Last photo:
Join Date: Oct 2003
Location: Tri-Cities, TN
Posts: 726
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
2 barrels are fun. They seperate the boys from the men. Camshaft is critical on thiese engines. Most of the time you need to run a reverse split cam. . .more duration on the intake side. This way you can pack more air and fuel in the cylinder and add dynamic compression to the engine to "fool" the engine into thinking it has more compression. It is not uncommon for a stock cylinder headed 358 2 barrel engine to exceed 400 HP with a flat tappet cam and a legal 500 cfm 2 barrel. One of my customers had a Vortec headed engine that was 468HP.

If you have no lift limits then you need to run like a 1.7 on the intake a 1.5 on exhaust. Most over lift the intake but my arguement is you are limited on what the intake can pack in the cylinder, so if you are starving the engine due to the carb, why do you think you need to crutch the exhaust.

Chris
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 02-27-2005, 01:34 AM
E.T. divided by $ spent= Speed
 
Last photo:
Join Date: May 2002
Location: NYS america's unwiped butt
Age: 34
Posts: 1,858
Wiki Edits: 0

Thanks: 0
Thanked 5 Times in 5 Posts
Double humps(corvette fuelies) are what most stock cars guys use.If ya go w/ them though please find a set thats allready modded to some degree(screw in studs milled etc..),as original unmolested ones are hard to find now and worth $$ to collectors.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 02-27-2005, 09:26 AM
Member
 
Last photo:
Join Date: Oct 2003
Location: Tri-Cities, TN
Posts: 726
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
If you want to make power with a 2 barrel engine that is limited to stock castings, you want the 906 Vortec head.

Chris
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 02-27-2005, 10:38 AM
NXS's Avatar
NXS NXS is offline
wind & fire = guides to power
 
Last photo:
Join Date: Nov 2004
Location: Oklahoma
Posts: 1,534
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
He can't run Vortecs.

Your compression(or your buddies) is way down running the 75cc head. The best way to make power for free/cheap is compression. The heads need to be milled. You need to run a steel shim headgasket. You need solid core wires and Non-resistor plugs, AC44. If you are using a 2-4 adapter plate smooth it and match to the intake. Pull the choke flapper out of the carb.
Getting into the realm of cheating they make a 1.6 ratio stock looking rocker. But the compression. That needs to be as high as possible. The steel shim headgaskets will do wonders if you are replacing the HGs anyway.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 02-27-2005, 11:00 AM
Member
 
Last photo:
Join Date: Feb 2005
Location: North Dakota
Age: 42
Posts: 85
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
This is some good stuff, exactly what ive been looking for! The block has already been decked and heads have been straight milled to the point that if any more were taken off I think the pistons would hit the spark plugs Hg are .015 steel shim. Ive already removed all the uneeded parts off the carb such as choke. The adaptor plate we are using is factory ground to fit the larger bores on the 4bbl manifold so thats covered too. Solid core wires and non resistor spark plugs never crossed my mind tho, would it really make a noticeable difference or is that just a weak link that needs fixing? As far as changing rockers to get more lift I'll have to check into that to see if I can get by with it. Im concerned tho that I may not have enough valve to piston clearance. I guess the only way to find out is to buy more tools
Lastly I need to check on the double hump heads but Im sure they arent legal as well since they are 202 on the intake correct? Or am I wrong?


Mike
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 02-27-2005, 11:06 AM
NXS's Avatar
NXS NXS is offline
wind & fire = guides to power
 
Last photo:
Join Date: Nov 2004
Location: Oklahoma
Posts: 1,534
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
You can run a larger gap and therefore a larger initial flame front meaning less total timing needed. The double hump heads were mostly 1.94 valve as far as i know. Where did Bracketeer get your heads casting # from?
Reply With Quote Quick reply to this message

Recent Hotrodding Basics 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
Why not a 350 sbc? bowtieorbust Engine 29 09-05-2008 09:43 AM
Late model 350 SBC Question Smoker113 Engine 3 02-19-2005 10:12 PM
nitrous on my 350 sbc? Trav Engine 16 10-25-2003 10:32 AM
olds 350 trans on a sbc Blob Transmission - Rearend 4 10-18-2003 02:24 PM
350 SBC...specific years? 78SilverShark Engine 2 10-14-2003 07:20 PM


All times are GMT -6. The time now is 03:22 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.