Some 4-71 GMC installation questions - 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 01-21-2005, 03:37 AM
Neophyte's Avatar
I'm not superstitious
 

Last journal entry: Release catch for trunk lid pt.5
Last photo:
Join Date: May 2004
Location: Johannesburg, South Africa
Age: 44
Posts: 261
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Some 4-71 GMC installation questions

I can get hold of a 4-71 GMC blower for a decent price. In my part of the world they are quite scarce 2nd hand. I haven't gone and checked it out yet but what I do know is that I'll need to have pulleys made for it and I'll need a manifold. The guys selling is upgrading to a 6-71.

The engine I want to put it on is a 350 SBC TBI motor, .020 over with flat-tops and a Crane cam 272/282. Can't remember the .050 duration off-hand though.

To use the blower I thought of getting heads from a 400 SBC due to bigger chambers and ports. This way I hope to lower the c/r enough to use a max of 6lbs boost. I'll then most probably also use a carb or two instead of the TBI. I do however have an aftermarket programmable ECU if I decide to stay with injection.

My questions are as follows:
1. What is the minimum approximate width of the drive belt?
2. Does the belt have to be toothed or can it be ribbed (like on a serpentine belt)?
3. What kind of drive ratio must I use to get the 5-6 lbs of boost?
4. Will the cam I've got be enough?

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 01-21-2005, 06:33 AM
BOBCRMAN@aol.com's Avatar
Member
 
Last photo:
Join Date: May 2002
Location: Holly, michigan
Posts: 8,115
Wiki Edits: 0

Thanks: 25
Thanked 266 Times in 249 Posts
The only years that 400 heads had bigger chambers are the 70-71 with the 1.60 exhaust. After that Chevrolet just used the 350 production head with steam holes drilled in them. Ports are more or less all the same.

Way back when we used to drivethese things with three V-belts so a serpentine type belt of an inch or so should be usable if you are going for six lbs boost.

As for pulley ratios and availability. Try someone in the business like Dyers.

A blower motor isn't all that picky about camshaft. All you need to do is vary the boost and the fuel/air mix gets packed in there!
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 01-21-2005, 03:58 PM
Member
 
Join Date: Nov 2004
Location: rio de janeiro
Posts: 224
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Hey SA. Keep the fuel injection system.The best aftermarket recurving is made right in your country.Look for Unichip from Dastek. Paulo
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 01-21-2005, 09:55 PM
Neophyte's Avatar
I'm not superstitious
 

Last journal entry: Release catch for trunk lid pt.5
Last photo:
Join Date: May 2004
Location: Johannesburg, South Africa
Age: 44
Posts: 261
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
BOBCRMAN, Thanks. I'll definitely need better head than the TBI ones I've got now. I'll have to see what I can't scratch out under the bushes over here...lol. If that the case with the belt I'm gonna see if the standard serp belt will fit as I'm not gonna be using the p/steering pump. Does Dyers have some web-site?

Paulo, I actually bought the engine for my 53 Chevy without the original ecu. When the V8 shops import them that unfortunately doesn't come with from the states. I actually bought a setup called Mr. Turbo which is quite adjustable. And I can adjust myself from my laptop if I want.

Last edited by Neophyte; 01-21-2005 at 10:03 PM.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 01-21-2005, 10:07 PM
BOBCRMAN@aol.com's Avatar
Member
 
Last photo:
Join Date: May 2002
Location: Holly, michigan
Posts: 8,115
Wiki Edits: 0

Thanks: 25
Thanked 266 Times in 249 Posts
TRY www.dyersblowers.com
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 01-21-2005, 10:09 PM
Neophyte's Avatar
I'm not superstitious
 

Last journal entry: Release catch for trunk lid pt.5
Last photo:
Join Date: May 2004
Location: Johannesburg, South Africa
Age: 44
Posts: 261
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Cool, thanks!
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 01-24-2005, 02:04 PM
Neophyte's Avatar
I'm not superstitious
 

Last journal entry: Release catch for trunk lid pt.5
Last photo:
Join Date: May 2004
Location: Johannesburg, South Africa
Age: 44
Posts: 261
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
BOBCRMAN,

I don't suppose the standard serpentine belt of 9/16" would be enough or could it?
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 01-24-2005, 02:24 PM
BOBCRMAN@aol.com's Avatar
Member
 
Last photo:
Join Date: May 2002
Location: Holly, michigan
Posts: 8,115
Wiki Edits: 0

Thanks: 25
Thanked 266 Times in 249 Posts
I would go at least an inch wide. Try some of the truck type belts and pulleys.
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



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