89 350 TBI head question

[Gamikatsu]

I have a 89 GMC jimmy, and i'm ready to replace heads and a cam. i believe i have a cam picked out... but am ready to do heads. what heads are a "direct" replacement.. L98, vortec, ETC. i would like to currently use the stock intake manifold... with a 50MM bored TBI unit from ebay. about to order the TB, but want to do heads first.

 

[woody80z28]

Casting #193 LO5 heads are what should be factory equipment for you. They are commonly referred to as "TBI" or "Swirl Port" heads, but beware there are a few casting numbers for them (#187 305, #810 HD 350, etc) that are not your original equipment. Those heads as well as L98s and some other stuff from that era will work with your intake though. Vortecs will not work without another intake, but they are a better flowing head than any of the older stuff. I just converted mine this summer.

 

[Gamikatsu]

ok... what intake did you use? i'm thinking of using a edelbrock spread bore 4 barrel dual plane manifold, cuz i can get one for like 35 dollars... and a 4bbl to tbi adapter... what is the best adapters out thier?

 

[woody80z28]

That's exactly what I'm running. I used a TransDapt adapter.

Beware, you will need the tune the engine for Vortec heads. I went with a little more cam along with the heads & intake and the stock tune sucked.

 

[Gamikatsu]

ok, well any chance you have the casting #'s or years of the motor your heads came off?

 

[woody80z28]

Vortec #062 (#906 is the same) 96-98 350 truck engines (L31). Be careful with used Vortec heads, they are crack prone. I bought a new pair after I got 2 cracked pairs in the junkyard.