L31 Vortecs on a 305 block - 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 10-10-2008, 02:36 AM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 12,898
Wiki Edits: 326

Thanks: 751
Thanked 985 Times in 831 Posts
L31 Vortecs on a 305 block

Need some guidance from you motorheads who have done this (or tried it or know someone who tried it). Putting parts ideas together for a friend who is bucks-down. He has a 305 short block that needs bored. I was thinking a 0.030" overbore and some cast flattop pistons with valve reliefs (5cc's) and a zero piston deck height with 0.040" gasket and 62cc chambers (cut the heads 0.012") would put the static compression ratio at 9.35:1, which should work great on pump gas with the proper cam and tight squish.

I played with this on the DynoSim and came up with a marine cam that seems to work the best. Comp 12-318-4, ordered with 0.440" lift to work with stock L31's. I know some of you will say that the Vortecs will take more lift than that, but I'm just working it on the low side for the software dyno run.

RPM TQ HP VE BMEP
2000 325 124 73.4 157.8
2500 330 157 75.7 160.5
3000 353 201 81.2 171.4
3500 379 252 87.2 184.1
4000 393 300 92.1 191.2
4500 396 339 95.2 192.4
5000 386 367 95.8 187.4
5500 360 377 93.1 174.9
6000 319 364 87.7 154.9

Question is now, will the L31's bolt onto the 305 without something kissin' something? I'm wonderin' too, about shrouding the valves with that tiny little bore. I don't think the software takes that into consideration. Don't know for sure. I went through a search and saw the Car Craft build with L31's, but I'm not sure I would trust their word. Would rather hear from some of you guys. Already thought about the "shelf" between the head and block. Also talked to my buddy about a 350 block to no avail.

    Advertisement

Last edited by techinspector1; 10-10-2008 at 02:55 AM.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 10-10-2008, 06:49 AM
GMC boogie's Avatar
Member
 
Last photo:
Join Date: Nov 2004
Location: Louisiana
Age: 49
Posts: 628
Wiki Edits: 0

Thanks: 1
Thanked 20 Times in 20 Posts
http://www.popularhotrodding.com/eng...cks/index.html

Here is another article by popular hot rodding. They don't say how close the intake valve is to the cylinder wall but...it's gotta be close.

I would personally keep looking for a 350 block since he needs a bore job on the 305.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 10-10-2008, 08:05 AM
curtis73's Avatar
Hates: Liver. Loves: Diesel
 
Last wiki edit: How to find cheap parts
Last journal entry: 1999-2001: Getting it on the road
Last photo:
Join Date: Dec 2005
Location: Pittsburgh, PA
Age: 40
Posts: 5,128
Wiki Edits: 16

Thanks: 0
Thanked 2 Times in 2 Posts
For the cost of the machine work and parts on the 305 you could buy three running 350s.

I know... bucks down... but that doesn't hold water on the 305/350 debate. If he's bucks down, seriously have him buy a running 350 shortblock, a set of vortec heads, and a used ebay intake and carb. He'll have 300 hp potential out of the box, and spend less than the machine work, parts, and heads on a 305. I have two 350s that I got for free, and one complete vortec marine engine used one season I got for $50 with a blown head gasket. I replaced the head gasket and it was like brand new. For the 305 you propose you're looking at tanking, cam bearings, boring and honing, blueprinting the crank centerline and decking the block, shaving the heads, and more tanking. That is serious money at a machine shop. Heck, for $1200 he can buy a reman 350 vortec longblock with no core charge, which is a lot less then you'll spend on buying heads and all that machine work.... and then you'll be left with a lot of work in a 305 that has very little value.

The Vortecs will work on the 305, but I might reconsider the benefits. Firstly, I've been told that you should shoot for a .040" overbore to prevent valves from contacting cylinder walls, and secondly; the major benefit to the Vortecs is their flow which will be seriously hampered by the tiny bores.

If he's truly bucks-down, then a completely blueprinted and customized 305 is NOT the cheap way to get things done. If he want's to buck the system and try to make a performer out of a redheaded stepchild with a blatant disregard for physics, then the 305 is his *****
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
the history of chevy v8's savman1 Hotrodders' Lounge 43 03-02-2012 06:57 PM
Who thinks I can squeeze more out of this 305? :D Gokussj5okazu Engine 16 08-18-2007 05:51 PM
305 crank in a 350 block 455c-10 Engine 5 05-17-2005 10:55 AM
305 small block chevy hp. stickshift Engine 18 04-08-2005 10:47 AM
1986 305 chevy vs. 1987 305 chevy new style small block mtinsley Engine 2 08-22-2003 11:55 AM


All times are GMT -6. The time now is 11:09 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.