Carb selection advice: SBC Mild cam - 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 04-20-2013, 08:41 PM
PorsChev
 
Last photo:
Join Date: Oct 2004
Location: Modesto, Cali
Age: 27
Posts: 62
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Carb selection advice: SBC Mild cam

Here are the specs

350 SBC 4 bolt main
.040 overbore
76CC heads from 74-80
9 to 1 compression
Performer RPM intake manifold
Hugger headers
manual trani

Currently I have a 600cc holley single pumper 4 brl that seems to run OK, but just doesnt have the power or response that I am looking for. I used to have a throttle body fuel injection setup (Holley) that made substantially more power and torque and performed flawlessly until the ECU died and I had to go back to carbs.
I have had the carbs dyno tuned a couple of times in the past by a very good tuner extremely familar with holleys and I am not happy with them, The power breaks up substantially in the upper rpm's and the torque down low is just not what it should be (half what it should be..). The latest dyno a year ago was 235rwhp and 295rwtq (Power valve changed and some other stuff, still broke up in top end and just felt sloppy). The same dyno 4 years prior was 245rwhp and 275rwtq with about 25% drivetrain loss. When fuel injection was used it had 50more hp and 100 more tq to my butt dyno which has been very accurate to date

Im looking for a carb that will let me tune it better and fit my performance needs better.

I do road racing very occasionally but mostly mountain runs and drift days in the car, but it is 90% a street car.

I was thinking a holley 670 street avenger, can anyone confirm this would be good?

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 04-20-2013, 08:51 PM
Registered User
 
Join Date: Jun 2012
Posts: 123
Wiki Edits: 0

Thanks: 0
Thanked 7 Times in 7 Posts
what kind of car, weight, gearing, max rpm, fuel type.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 04-20-2013, 09:21 PM
PorsChev
 
Last photo:
Join Date: Oct 2004
Location: Modesto, Cali
Age: 27
Posts: 62
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
73 Porsche 914, 2300lbs, close ratio 4 speed, 6500 max rpm, CA 91 octane.



Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 04-20-2013, 09:45 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,028
Wiki Edits: 0

Thanks: 3
Thanked 358 Times in 354 Posts
Get a 750 double pumper.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 04-20-2013, 09:46 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,028
Wiki Edits: 0

Thanks: 3
Thanked 358 Times in 354 Posts
get some high performance cylinder heads that actually flow air and you might make some horsepower.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 04-20-2013, 10:05 PM
PorsChev
 
Last photo:
Join Date: Oct 2004
Location: Modesto, Cali
Age: 27
Posts: 62
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
750? Really? That seams like a lot of carb.

I dont really think I need better heads, The power level I had with the fuel injection (650cc TBI) was plenty, Im just trying to get to that power level and close to the drivability with carbs.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 04-20-2013, 10:37 PM
Registered User
 
Join Date: Jun 2012
Posts: 123
Wiki Edits: 0

Thanks: 0
Thanked 7 Times in 7 Posts
holley 390 with vacuum secondaries
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 04-20-2013, 11:07 PM
PorsChev
 
Last photo:
Join Date: Oct 2004
Location: Modesto, Cali
Age: 27
Posts: 62
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
390? Your joking right?
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 04-21-2013, 12:27 AM
Proud LOSER
 
Last photo:
Join Date: Mar 2008
Location: Ottawa
Posts: 1,799
Wiki Edits: 0

Thanks: 54
Thanked 249 Times in 216 Posts
Quote:
Originally Posted by Andyrew View Post
750? Really? That seams like a lot of carb.

I dont really think I need better heads, The power level I had with the fuel injection (650cc TBI) was plenty, Im just trying to get to that power level and close to the drivability with carbs.
2300# curb weight, manual trans, a set of decent alum heads and a 750dp would make for a seriously fun street car.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 04-21-2013, 12:57 AM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 12,860
Wiki Edits: 326

Thanks: 750
Thanked 971 Times in 819 Posts
Nobody has asked about the cam yet??????? The SCR is 9.0:1. If you using a big cam with that SCR, there's the problem.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 04-21-2013, 01:01 AM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,028
Wiki Edits: 0

Thanks: 3
Thanked 358 Times in 354 Posts
Quote:
Originally Posted by Andyrew View Post
750? Really? That seams like a lot of carb.

I dont really think I need better heads, The power level I had with the fuel injection (650cc TBI) was plenty, Im just trying to get to that power level and close to the drivability with carbs.
ya a 750 is just right. anything smaller on any high perf 350 is too small.
The engine does not care what you think or about BS carb size selection rules.

Buy a 750cfm double pumper carb. The avenger carbs are crap.
Buy a used/rebuildable not fuared 650-700-750or 800cfm holley double pump carb and upgrade it to 750HP carb status with a Proform or Holley

HP 750 carb body kit.

4777 thru 4780 list numbers all can be upgraded with the proform HP 750 body kit. No you got a rockin 750HP carb thatr you can tune. for ta fraction of a new crap avenger carb.

Ditch those old smog era 200 horse heads. What are they 882's?

If you are not going to do it right and get/build a 750 HP carb just keep and fine tune the 600carb.

Last edited by F-BIRD'88; 04-21-2013 at 01:08 AM.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 04-21-2013, 01:06 AM
PorsChev
 
Last photo:
Join Date: Oct 2004
Location: Modesto, Cali
Age: 27
Posts: 62
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Tech inspector, Mild cam. Here are the details on it. If I remember it was an RV style cam. (We tried to eliminate low end torque, trani does not fair well with high torque)

It's an Elgin "Pro Stock" Cam
These are the specs on the box.
DURN DUR. @ .050 CAM LIFT Valve Lift Lobe Centers
IN Ex IN Ex IN Ex IN Ex IN Ex
291 291 218 218 0.303 0.303 0.455 0.455 105 115
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 04-21-2013, 01:09 AM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,028
Wiki Edits: 0

Thanks: 3
Thanked 358 Times in 354 Posts
We tried to eliminate torque

You certianly avoided horsepower.... This engine has neither.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 04-21-2013, 01:16 AM
PorsChev
 
Last photo:
Join Date: Oct 2004
Location: Modesto, Cali
Age: 27
Posts: 62
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by F-BIRD'88 View Post
Ditch those old smog era 200 horse heads. What are they 882's?
Yup 882's.

We've already had the 600 tuned to what the local tuners can do with all new parts, 4 hours of dyno work, and really I havent noticed enough difference to justify any more work at $100 an hour, Even they said its as much as they can do on that carb as its sacrifice this direction or sacrifice that direction.. So its time to move on to new hardware..

I'll look at the option you presented me, I appreciate the breakout
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 04-21-2013, 02:02 AM
PorsChev
 
Last photo:
Join Date: Oct 2004
Location: Modesto, Cali
Age: 27
Posts: 62
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
So this is what I would be looking at if I went the Proform route? Note the carb donor is a mech secondary whereas the proform is vacuum.

http://www.summitracing.com/parts/pro-67101c/overview/

Holley 700 Double Pumper Carburetor | eBay
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
Need Help With Carb & Cam Selection budgetbuilder Engine 24 11-06-2009 06:22 AM
sbc 350 choosing cam mild build quickchevy95 Engine 12 11-07-2008 06:28 PM
mild sbc build help, cam help callmejavier Engine 20 04-16-2008 06:56 PM
cam,and carb selection. motorhead454 Engine 27 03-20-2008 10:16 PM
HELP cam, intake and carb selection? sniper4570 Engine 5 01-15-2002 08:16 PM


All times are GMT -6. The time now is 08:03 PM.


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.