Carlarena1

My new to me shop truck (99 GMC K2500 Suburban 350 motor) sent a rod straight through the oil pan after the first 1000ish miles... Good thing i got it for free. Frame and body wise the truck is worth fixing, but good quality junk yard Vortec 350s are getting harder to find, and more expensive for sure. I have an 88 350 TBI motor that runs good, could i take it down to the block and bolt on the Vortec stuff? Are the blocks the same, or will i run into fitment problems? It sure would save me a boat load of cash if i could use what i already have. Thanks in advance guys! hope everyone had a great Easter!

66_Jetstar

The vortec engines have a crank sensor that the early engines dont have. The crank will have a pin wheel at the balancer and the block uses a plastic timing cover with a sensor hole.

Edit- looks the plastic cover will swap between the blocks, but it does not use all the bolt holes. You'll need the cover and the timing set with a pin wheel. You should also swap the roller cam as well.

Lonnies Performance

The early engines did not have provisions for factory roller cams.
Typically, the first year for roller cams was 87 in cars & 95 for truck engines.

Depending on the casting, you may not have the hold down bosses and/or the required machining to use factory roller lifters.
For these engines you will need aftermarket link bar roller lifters.

Here is the info I saved concerning casting numbers, which may/may not be all inclusive.
For 350 flat tappet blocks without provisions for the OEM roller look for casting number 10054727, 14079287, 14088548, and 14101148. Be careful of 14101148 as there is a roller block 14011148.

350 blocks that are roller provisioned, even if currently using a flat tappet cam look for 10243880, 14011148, 14088526, and 14093638 all of which can be 2 or 4 bolt blocks. The 880 carries across the 1995/1996 divide being used as a flat tappet cam engine in 1995 becoming the L31, Vortec with roller cam in 1996 up thru 2002 production.

Also, if going with an aftermarket cam, the Vortec heads are lift limited to around .420-.425" lift, dependent on valve seal type, unless you mill the guides down.

66_Jetstar

I assume you're planning on using the 88 shortblock and swapping the vortec top end?

You should look into the chamber sizes, the vortec heads I think have considerably smaller chambers than the earlier normal SBC stuff.

The 88 block will be cast with the roller bosses, but you'll have to drill and tap the holes.

Carlarena1

Thanks for the replies guys, It sounds like its a bit more work then i am able to do at the moment. Ill just find myself a complete vortec 350 and go from there.

Carlarena1

Junk yards are asking crazy money for hi milage junk, so I'm reconsidering attempting this. I really don't have anything to loose as the running tbi motor is in a truck that will never move again. I had read that i could run vortec heads with the stock 88 factory flat lifter cam. Does that sound correct? I would prefer to leave it flat tappet style, and not have to drill or tap the block. They say to use self aligning rocker arms, but aren't the stock vortec rocker arms self aligning? Also which push rods would i use? Its difficult, because most of the info i find is people trying use vortec heads with their TBI system, not much on transplanting an older bottom end into a vortec... Thanks again for helping me with this crazy project guys.

66_Jetstar

I'd check chamber sizes before going all in. Older SBC heads had huge chambers while the vortecs were smaller. You might run into a huge jump in compression.

Beyond that, you're looking at a head/intake swap along with a timing set. This is no big deal. The TBI cams suck, a swap would be well worth the effort, you'll have the heads and timing cover off anyway..