bigger engine?

[unreconstructed1]

how are ya'll doing? I just bought a 67 GMC that needs ALOT of work. over the next few months I'll be repairing the entire bottom edge of the cab and bed alot of surface rust and a few more problems. my question is, my truck has a straight 6 in it with a 3 on the tree. what kind of work will be involved in putting a 350 in it? i figured ill have to relocate the motor mounts back toward the firewall some, but am i gonna have to change the front end? the current crossframe looks too narrow to be able to move the motor mounts back far enough to put a 350 in. just wondering

[Americanrider]

from Western Washington.

We need a little more info on your truck, 2wd or 4wd?

Heres the deal for these trucks,
250 six, motor mounts in rear location
292 six, motor mount offest from each other
283 or any SBC's, Motor mounts in rear location for 4x4's because of front driveshaft issues. Motor mounts in forward location for 2wd Small blocks.

In the frame rails the are 2 set of holes [where the towers & mounts bolt up to the frame] forward and rear. Your 6 banger should be mounted in the rear set unless you have a 292 in there or it's a 4x4.

To stick in a SBC you'll need a set of V8 towers and a V-8 fan shroud. What tranny are you planning to use?

Post some pics, tell us your plans and stick around.... It's fun here and we will help keep you motivated and on the right track.

[bryanw1968]

I think you will find you will need to move the motor mounts UP instead of back. If I remember correctly the I250 has staggered mounts and the I292 has mounts straight accross. I have my 350 sitting on the rear mounts and it is WAY too far back. I would put a V8 on the front mounts if I were to do it again. I believe the reason do use the rear mounts is because the trans hooks right up to it.

[shifty]

Originally Posted by unreconstructed1

how are ya'll doing? I just bought a 67 GMC that needs ALOT of work. over the next few months I'll be repairing the entire bottom edge of the cab and bed alot of surface rust and a few more problems. my question is, my truck has a straight 6 in it with a 3 on the tree. what kind of work will be involved in putting a 350 in it? i figured ill have to relocate the motor mounts back toward the firewall some, but am i gonna have to change the front end? the current crossframe looks too narrow to be able to move the motor mounts back far enough to put a 350 in. just wondering

Motor mounts have diff't position.
You'll need to cut and drill out the old tranny xmember and put in a new one.

I had your setup (3sp/6cyl) and I have a ton of pictures of the removal process and reinstall - click on the link in my signature below for a huge chunk of pictures, and the other link shows my buildup to put an LS1 in my truck (EFI ~350 SBC, basically).

I also have a spare, completely rebuild stock auto tranny crossmember with new hardware that is a direct bolt-in for your truck if you're interested. It's an easy bolt-in to take care of when the cab is off, or if you want to replace your old, rotten cab mounts (there are four of 'em).

Looks like you're just up the road. If you're anywhere near Chattanooga, I can probably meet you nearby on my next trip up or something (may not be for a couple months).

Keep in touch. I'll be happy to answer questions if I can, or refer you off to someone else who can.

Welcome to the forum.