The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1988 - 1998 GMT400 Chevy & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 04-24-2021, 12:40 PM   #1
papsoldblue72
Registered User
 
papsoldblue72's Avatar
 
Join Date: Apr 2008
Location: Somerset, Kentucky
Posts: 232
91 old school swap

I have a 91 1500 Silverado with a 4.3, and 5 speed manual. I'm wanting to swap in a 350 and keep the 5 speed trans. Is it possible to use the existing flywheel, water pump, pullies, and engine mounts? Please help....
__________________


It's been a long time coming... It's time to get it done..
papsoldblue72 is offline   Reply With Quote
Old 04-24-2021, 01:00 PM   #2
Palf70Step
State of Confusion!

 
Palf70Step's Avatar
 
Join Date: Jul 2002
Location: Gulfport, MS USA
Posts: 42,671
Re: 91 old school swap

V6 engine mounts are different and pretty sure the 350 will not fit sitting that far back. Far as the rest of the stuff it should all work. Make sure you use all the accessories as the serpentine belt rotates reversed of the normal V-belt setup. I know the trans will work, I am not positive if the flywheel and clutch are the same or not. Pretty sure it will work, but the clutch is smaller diameter for the V6 vice the V8.
__________________
Bill

1981 GMC High Sierra SWB Stepside

Member of Louisiana Classic Truck Club (LCTC)
Board Vendors
Bill's Gallery
Life isn't tied with a bow, but it's still a gift.
Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God!
It's scary when you start making the same noises as your coffee maker.
Palf70Step is offline   Reply With Quote
Old 04-24-2021, 03:40 PM   #3
1976gmc20
Registered User
 
Join Date: May 2015
Location: Montana
Posts: 3,496
Re: 91 old school swap

Man if you're going to go to that much work, try to find yourself an NV4500 and throw away that lightweight 5 speed which is what I'm pretty sure that you have.
__________________
Current/past Chevy/GMC trucks:
1958 Chevy C-60; 1965 GMC C-50; 1965 Chevy C-10; 1971 Chevy K-10; 1973 Chevy K-20; 1976 GMC C-20; 1977 Chevy C-10 Suburban; 1980 Chevy K-10; 1989 Chevy K1500; 1991 GMC V1500 Suburban; 2016 Chevy K2500 HD

Other vehicles: 1988 Jeep XJ; 2011 Toyota 4Runner
1976gmc20 is offline   Reply With Quote
Old 04-25-2021, 10:07 PM   #4
papsoldblue72
Registered User
 
papsoldblue72's Avatar
 
Join Date: Apr 2008
Location: Somerset, Kentucky
Posts: 232
Re: 91 old school swap

Quote:
Originally Posted by Palf70Step View Post
Far as the rest of the stuff it should all work. Make sure you use all the accessories as the serpentine belt rotates reversed of the normal V-belt setup.
Okay the main thing I'm wondering is the water pump going to bolt to my old school 350.. I've heard the mounts are different, but where can I get the right ones??
__________________


It's been a long time coming... It's time to get it done..
papsoldblue72 is offline   Reply With Quote
Old 04-25-2021, 10:10 PM   #5
papsoldblue72
Registered User
 
papsoldblue72's Avatar
 
Join Date: Apr 2008
Location: Somerset, Kentucky
Posts: 232
Re: 91 old school swap

Quote:
Originally Posted by 1976gmc20 View Post
Man if you're going to go to that much work, try to find yourself an NV4500 and throw away that lightweight 5 speed which is what I'm pretty sure that you have.
Sorry dude just using what I have.... Plus I'm not going to beat on it too much right now...
__________________


It's been a long time coming... It's time to get it done..
papsoldblue72 is offline   Reply With Quote
Old 04-29-2021, 05:37 AM   #6
Tx Firefighter
Watch out for your cornhole !
 
Tx Firefighter's Avatar
 
Join Date: Jun 2003
Location: Azle, Texas
Posts: 14,126
Re: 91 old school swap

I've done this swap a few times.

V8 mounts will bolt to your existing crossmember once you remove the V6 frame mounts. Then the engine will bolt to the trans and no driveline mods will be needed. The existing flywheel, clutch, bellhousing bolts and starter will bolt onto the 350 as long as it's a one piece rear main seal engine (newer than 87). If your V8 is a 2 piece rear main seal engine you will need to change the flywheel to match.

To do it right you'll need the proper V8 fan shroud.

The lower (crankshaft) pulley will need to be swapped for the proper V8 one as the V6 harmonic balancer is thinner than the V8 one so the V6 pulley is deeper dished to compensate for the skinnier balancer. Everything else on the front of the engine is a straight bolt on to the V8.

You can reuse the existing V6 ECM and wiring harness as long as you install the proper 350 PROM chip into the computer. All of the plugs on the V8 will be the same as the V6. You will need to slightly pull the wiring harness further forward into the engine compartment to reach all proper locations on the V8 but you won't need to mod it.
__________________
Kevin -

You can find me working on something or the other on Instagram, link below...
My Instagram
Tx Firefighter is offline   Reply With Quote
Old 04-29-2021, 06:02 AM   #7
papsoldblue72
Registered User
 
papsoldblue72's Avatar
 
Join Date: Apr 2008
Location: Somerset, Kentucky
Posts: 232
Re: 91 old school swap

Quote:
Originally Posted by Tx Firefighter View Post
I've done this swap a few times..
Thanks for the info... Guess I'll need to find some stuff... lol
__________________


It's been a long time coming... It's time to get it done..
papsoldblue72 is offline   Reply With Quote
Old 05-04-2021, 11:47 AM   #8
LT7A
Registered User
 
Join Date: Oct 2015
Location: Seattle, WA
Posts: 1,790
Re: 91 old school swap

Wow, good info TXFF. And paps, if you've got an NV3500, I don't think you need to worry, as long as you're not hammering on it. I looked into those as a lower cost alternative for a 5-speed, and they will handle a reasonable amount of torque.
LT7A is online now   Reply With Quote
Reply

Bookmarks

Tags
350, engine, manual transmission, swap

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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

Forum Jump


All times are GMT -4. The time now is 12:00 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Copyright 1997-2020 67-72chevytrucks.com