[jkelly334]

i own a 1997 chevy z71 pickup with a 5.7 liter vortec 350 engine. I recently owned a 400sbc engine that has been bored .030 with flat 4 valve reliefs. wondering if i could use the short block in my truck and still use the factory fuel delivery system,which is throttlebody injected.if so what would be a nice performance camshaft? Thanks.

[ericnova72]

A 400 with flat top pistons and 64cc heads(which the Vortec heads are) will put compression ratio over 11.25-1, way too high for pump gas. Your stock TBI and computer won't like the additional 50 cubes either, you will need a custom computer chip or a chip reflash to even make it work.

[Rickracer]

Trust me on this, the regular TBI system is NOT Vortec friendly. We replaced a 95 TBI 305 with a Marine Vortec long block, used a Vortec dual plane intake, and a Holley TBI adapter, (just like the Projection one), and it took bigger injectors, a custom burned chip (twice), and still only ran barely acceptable @ idle. Now out on the road, it ran GOOD, plenty of power, much better fuel mileage than the 305 ever got, but at idle, it would stall, or almost stall, randomly, and all too frequently. We put a Holley 600 carb on it and it ran GREAT, but the 4L60E trans didn't work, so I had to switch it back. It's possible that an adjustable regulator and more fuel pressure may have cured it, or at least made it better, but the owner, my old boss, traded it off when the trans went bad. Not saying you won't be able to make it work, but be prepared for some tuning issues.

[SSedan64]

I thought the 97 Vortec engine used Multi Port injection, not TBI?

[Adam65]

'97 aint TBI (not stock anyway)

My 406 w/ vortec heads, comp XE268 cam, 9.2:1, with 454 TBI and 17-18# fuel pressure (needed additional inline pump) ran great. Performer RPM intake and adapter plate-ran fine. On the edge of needing higher stall converter than the GM police car converter (couple hundred rpm over stock). Custom chip with EGR turned off. Very torquey thru middle rpms-great hi-po pickup engine. Very mild lope @ idle.

'93 1500 truck.

[Rickracer]

Originally Posted by SSedan64

I thought the 97 Vortec engine used Multi Port injection, not TBI?

You are exactly correct sir, I didn't even think about that. The one I was referring to was a 95. 97 would be Multi-port. I know Vortecs work very well with mild bigger cube motors, but with 4 v.r. flat tops, I agree with ericnova72, it would probably have too much compression. Being a 97, (OBDII), you should be able to do your own programming though.

[SSedan64]

Yep, much easier with MPI. Would definitely need 14-18cc D-Dish pistons.
With the 4VR pistons Cr would be about 11.7Cr, w/0 Deck & .040" gasket.
With 14cc Dish = 10.6Cr
18cc = 10.15
20cc = 10.00

[jkelly334]

Thank for the correction. It is Multi-port Injection. So would it work with dish top 20cc pistons and programmer

[Rickracer]

Be sure it's the D-shaped dish though, that way, you keep the squish and quench,

[FastOrange]

Originally Posted by SSedan64

I thought the 97 Vortec engine used Multi Port injection, not TBI?

not quite MPFI, but CSFI, still it will not like the new engine.