L31 Vortec Conversion to Carb. - 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 07-25-2010, 12:14 PM
Rodding & Camping-Love It !!
 
Last photo:
Join Date: Jul 2010
Location: South Western Ct.
Age: 71
Posts: 13
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
L31 Vortec Conversion to Carb.

To convert an L31 Vortec to carburetor is it as simple as the correct intake w/carb. & distributor w/vac adv ? IF so what would be the base line timing for start up?

Thanks

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 07-25-2010, 12:29 PM
Rodding & Camping-Love It !!
 
Last photo:
Join Date: Jul 2010
Location: South Western Ct.
Age: 71
Posts: 13
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I also just read this in the archives "if you have a roller cam that you will need to change out the distributor drive gear or you'll wreck stuff." Is this correct? The L31 has a roller cam. Sometimes you wonder IF maybe we read to much????

Thanks
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 07-25-2010, 12:51 PM
Sinister's Avatar
Registered User
 
Last photo:
Join Date: Aug 2007
Location: Los Angeles, CA.
Posts: 221
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
You'll need a melonized distributor gear. You'll have to figure out a fuel pump as well.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 07-25-2010, 12:55 PM
Rodding & Camping-Love It !!
 
Last photo:
Join Date: Jul 2010
Location: South Western Ct.
Age: 71
Posts: 13
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts

Well I guess I'm REALLY going to show my age or lack of knowledge at this point!!! Im clueless as to what a Melonized Gear is. Can you bring me up to speed??
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 07-25-2010, 12:55 PM
406cu.in. of tire smokin' fun
 

Last journal entry: 406 Build Thread
Last photo:
Join Date: Jun 2008
Location: Tacoma, WA
Posts: 232
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
You already have the correct distributor gear, but I would replace it with a new one anyway as cheap insurance. I found out the hard way and got to rebuild the engine a second time. Saving $40 cost me about $800.

The fuel pump should work fine, but you'll need a regulator and will need to wire it so it comes on with the ignition.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 07-25-2010, 01:01 PM
Rodding & Camping-Love It !!
 
Last photo:
Join Date: Jul 2010
Location: South Western Ct.
Age: 71
Posts: 13
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The Dist. that I have is a "New" Crossfire HEI so would I assume that the gear would be OK? I know its new as I just bought it as a back up for the 33 Chevy.

I also "plan" on pulling the in tank pump and going with the original block mount pump or a good electric frame mount pump. First I must determine if there is a fuel pump lobe on the cam!!!! I've been lead to believe that some ZZ4 cams do not have a fuel pump lobe????
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 07-25-2010, 01:10 PM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 12,587
Wiki Edits: 326

Thanks: 699
Thanked 884 Times in 751 Posts
Quote:
Originally Posted by Ct Street Rod
To convert an L31 Vortec to carburetor is it as simple as the correct intake w/carb. & distributor w/vac adv ? IF so what would be the base line timing for start up? Thanks
Yep, pretty much. You'll need an electric fuel pump and filter and make sure not to exceed the pressure limit of the carburetor you'll be using. 5 1/2 lbs max for a Quadrajet, AFB or Performer. 6 1/2 lbs max for a Holley. This is not a case like EFI, where more pressure could make more horsepower. With a carb, you have to limit the pressure into the bowl to prevent over-powering the needle/seat and blowing raw fuel into the intake manifold. Set the float(s) properly and limit the pressure. Electric pumps work best when the push, not pull, so mounting the pump/filter back at the tank/cell is a good idea. That is also a good place to mount a regulator. Use one that will dump excess fuel back into the tank/cell rather than a deadhead regulator that will heat the fuel and wear out the pump quicker.

The blurb about distributor gears probably should have been worded differently, like....."Insure that the material that the distributor drive gear is made from is compatible with the material the camshaft drive gear is made from". The camshaft drive gear is normally part of the casting of the camshaft, so you would want to touch base with the tech at the cam grinder to find out what they like for distributor drive gear material compatibility with that particular camshaft.

With L31 heads, I would start at 34 degrees initial + mechanical, all in by 2800. More cam will want more initial ignition timing, so increase the initial and limit the mechanical to get to your 34. Once the motor is running, you can try rocking the timing back and forth a couple of degrees, but the L31 chambers are very efficient and should work best around 34.

The following is quoted from www.gnetworks.com and says it best about the ignition timing with a larger cam.....
"INITIAL TIMING
The chief function of initial timing is to provide a clean idle
and crisp throttle response. One of the best guides to
determine the initial ignition timing of V8 engines can be
found in the Barry Grant, Inc. catalog or at their website
under the Demon Carburetor Guide. Typically, they recommend 10- to 12-degrees of initial timing when
the duration of the camshaft is less than 220-degrees @ 0.050 of valve lift; 14- to 16-degrees of initial
timing with a camshaft duration of less than 240-degrees @ 0.050; and 18- to 20-degrees of initial timing
when the camshaft duration is less than 260-degrees @ 0.050 of valve lift."

Last edited by techinspector1; 07-25-2010 at 01:22 PM.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 07-25-2010, 01:12 PM
Sinister's Avatar
Registered User
 
Last photo:
Join Date: Aug 2007
Location: Los Angeles, CA.
Posts: 221
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
In addition to the fuel pump lobe, the block might not be machined for a mechanical fuel pump. As for the distributor gear: http://www.summitracing.com/parts/ACF-10456413/
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 07-25-2010, 01:19 PM
Rodding & Camping-Love It !!
 
Last photo:
Join Date: Jul 2010
Location: South Western Ct.
Age: 71
Posts: 13
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The block is machined, it does not have a pump rod as of now. Plan on putting a rod in and hand turn the motor over to see if it pumps.

Thanks to all you guys for sharing your knowledge. Any firearms questions
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 07-25-2010, 04:30 PM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 12,587
Wiki Edits: 326

Thanks: 699
Thanked 884 Times in 751 Posts
............Never mind. Unrelated to the subject.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 07-25-2010, 06:21 PM
Rodding & Camping-Love It !!
 
Last photo:
Join Date: Jul 2010
Location: South Western Ct.
Age: 71
Posts: 13
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I hesitated to add that at the end BUT I am grateful to you guys for sharing your expertise and was throwing that out as a gesture for my expertise. I really should have said to send PM.
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
98 350 vortec conversion 98Disco1 Electrical 3 01-17-2010 05:58 PM
1997 5.7 Vortec Conversion 71ChevySWB Engine 2 01-14-2003 07:42 PM
Vortec Conversion For Small Block Chevy M-1-4 Engine 3 11-20-2002 05:51 PM
TBI conversion to Carb Seon Engine 0 10-15-2002 03:20 PM
4.3L vortec conversion fightingcody Engine 3 05-18-2002 09:41 PM


All times are GMT -6. The time now is 04:38 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.