TBI assistance needed - 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 05-22-2006, 07:05 PM
Registered User
 
Join Date: May 2006
Location: tallahassee, florida
Posts: 6
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
TBI assistance needed

Currently have a 91 Chevy truck with a 350 TBI motor that went south. Picked up an older 350 (manufactured in 83-85). Is it possible to use the older motor with the TBI setup so that I do not have to go with a carb and change the wiring harness and such. The older 350 is very clean and had very few hours on it. I do not want to switch to a carb and know I will most likely have to switch to another intake manifold. Will the Holley 300-49 be a possible solution? I would think there is an aftermarket inatke manifold for such a conversion.

I am not a mechanic and was told to bore the holes on the TBI intake out some to allow for the 4 center holes in the TBI intake to fit. I tried this and learned very quickly that this would not work. I had a vacuum leak and had trouble timing the engine. The engine runs and sounds strong but I now know this is not the solution. The older motor is in the truck and I am trying to find someone who has gone through the same thing.

Could my other option be taking the heads off my 91 TBI 350 motor and have them reworked? Would they fit on the older block and could I then use the complete TBI setup? I have been playing with this problem for the last month or so and need some real help. THANKS....

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 05-22-2006, 07:13 PM
Member
 

Last journal entry: JB's 37 Pickup
Last photo:
Join Date: Oct 2002
Location: Smoky Mountains
Age: 76
Posts: 2,358
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
You may be giving up too quick on your base plate modification. I have seen some of these "wallowed out" holes really butchered and were sealed up and made leak proof by filling with lots of RTV before installing bolt with a washer. Don't start it for 24 hours so the glob of RTV has a chance to cure. An alternative before you butchered the base plate was to use the heads off your old motor but it would require the same glob of RTV now.

Trees
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 05-22-2006, 08:42 PM
dh79's Avatar
Member
 
Last photo:
Join Date: Dec 2002
Location: Vancouver, BC
Posts: 301
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
There are adapter plates to allow the tbi unit to be bolted to a carb manifold. Summit (and I'm sure jegs too) sells them. That would allow you to bolt the throttle body to the older style manifold but you'll still have to adapt any manifold mounted sensors required for the fuel injection.
__________________
81 Grand Prix, 355, 700r4, 8.5" 4.10
64 Oldsmobile Jetstar, all original
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 05-23-2006, 08:18 PM
Registered User
 
Join Date: May 2006
Location: tallahassee, florida
Posts: 6
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
TBI Assistance

Quote:
Originally Posted by trees
You may be giving up too quick on your base plate modification. I have seen some of these "wallowed out" holes really butchered and were sealed up and made leak proof by filling with lots of RTV before installing bolt with a washer. Don't start it for 24 hours so the glob of RTV has a chance to cure. An alternative before you butchered the base plate was to use the heads off your old motor but it would require the same glob of RTV now.

Trees
I appreciate the feedback. I do not believe the holes have been butchered that badly (if at all). I waited several days after putting on the intake before I put the rest of the TBI setup on and put the motor in. After starting the engine, I sprayed carb cleaner around the walloed out holes to try and locate any leak but could find nothing. I really believe I might have another leak somewhere that I can not find. Since asking last night I have done some additional research where others say what I have done should work. Do you have any further suggestions for me? This is a really nice truck and it is driving me crazy because I am really stuck. Thanks again.......
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 05-23-2006, 09:24 PM
NorthStar's Avatar
Member
 
Last photo:
Join Date: Feb 2003
Location: Minnesota
Age: 51
Posts: 847
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I would swap the late model heads to the early block.

Allows you to use TBI intake manifold, accessory bolts holes will be correct, braces for plug wires have something to bolt onto, centerbolt valve covers can go back on.


Be sure that older motor doesnt have flattop pistons if they are combined with newer heads compression will be too high.

Use the head bolts with 1/2" heads or there might be a exhaust manifold clearance issue.

Be sure to use the correct intake manifold gaskets.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 05-24-2006, 11:11 AM
Hippie's Avatar
Analog man in a digital world.
 

Last journal entry: HEI comparison.
Last photo:
Join Date: May 2003
Posts: 2,255
Wiki Edits: 0

Thanks: 3
Thanked 5 Times in 5 Posts
Quote:
Originally Posted by Greg Latvala
I would swap the late model heads to the early block.

Allows you to use TBI intake manifold, accessory bolts holes will be correct, braces for plug wires have something to bolt onto, centerbolt valve covers can go back on.


Be sure that older motor doesnt have flattop pistons if they are combined with newer heads compression will be too high.

Use the head bolts with 1/2" heads or there might be a exhaust manifold clearance issue.

Be sure to use the correct intake manifold gaskets.
I second that.
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:
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
Tbi Mods NAIRB Engine 8 05-03-2005 07:50 AM
TBI "High Idle Problem": conoverbandit Engine 9 02-08-2004 12:49 PM
TBI Questions on a 93' Chevy FS 350 IWANTMOREHP Engine 1 01-04-2004 02:42 PM
350 TBI suggestions needed crshrmn3 Engine 5 12-06-2003 11:28 AM
350 GM Goodwrench Caprice engine in 3rd Gen TBI F-Body? wrmason3 Engine 2 09-14-2002 08:01 PM


All times are GMT -6. The time now is 04:56 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.