1968 gmc 2500 w/351 v6

[iggybob44]

Im trying to get a little info on a truck i owned some years back...Its a 1968 GMC 2500 Custom Camper and it had a 351 V6 in it. Ive still got the owners manual for the 1968 1500-3500 series and they list both the 305 and 351 V6 engines,but i have never seen any other references to the 351 being an option for the light duty's. Was this an oddball special order truck,or was the 305 truly the only V6 offered in these trucks,and a Previous owner swapped in the 351?

[Jtrux]

Originally Posted by iggybob44

Im trying to get a little info on a truck i owned some years back...Its a 1968 GMC 2500 Custom Camper and it had a 351 V6 in it. Ive still got the owners manual for the 1968 1500-3500 series and they list both the 305 and 351 V6 engines,but i have never seen any other references to the 351 being an option for the light duty's. Was this an oddball special order truck,or was the 305 truly the only V6 offered in these trucks,and a Previous owner swapped in the 351?

I remember a 68 GMC my dad had years ago and it had a 351 as well, maybe a custom order thing.

[factorystock]

The 351 first became an option for pickups in 1966. By 1969 it was no longer used in pickups, GMC realized the light duty pickup buyer wanted the better all around performance of larger V8's. The 351 was still used in larger trucks to 1974. Was common to see 351's in 66-68 GMC pickups.

[1969 GMC]

the engine was listed on the spid, too. one of my ex coworkers had one that had been sitting for almost 20 years, and I've seen a few on this board as well.

[Bob B.]

Installing the 351 in pickups was GMC's idea to keep up with the 352 and 390 Ford, 383 Dodge, and the 327 and 396 Chevys. The pickups got a special version of the 'big truck' 351 called the 351E. This version had the large port and valve 'Magnum' heads used on the 410M and 478M V-6's. 351E's also used a special Stromberg carburetor and exhaust manifolds. The 351E might not have been quite as fast as the Big Blocks, but they can pull HARD!

[67_C-30]

I have one in my dump truck, and it is a beast. I have another one disassembled, and I took pics of the differences between the Magnum heads and the standard heads, and there is a LOT of difference. The intake ports are good bit bigger, and the exhaust ports are a lot bigger. The Magnum intake is totally different and will not work on std heads. The intake valve is also bigger on the Magnum. Here's comparison shots.



The Magnum head is on the bottom.



The Magnum head is on the right.




The Magnum intake is on the right.



The Magnum valves are on the bottom.

[iggybob44]

thanks for all that info,and i agree it wasnt fast in the way some of the V8's were,but it did have pulling power! At the time i owned it,i was living in a town built on a hillside,and this truck pulled the hills very easily in drive,it typically didnt need to drop down to second gear to maintain speed.

[TP from Cntl PA]

The V-6's were the closest a gas engine ever came to having the low end of a diesel.

I got a 305 in a '69 3500 and loaded it is a beast, she'd roll over any big block I've ever run in a pickup on a hill! Never seen a engine that you only had to downshift because the clutch would slip..........It would lug down and keep on going. Amazing.