im building a 355 with large valve pocket ported l69 heads
valves have been unshrouded, .40 gasket,1.6 rockers
im an old shade tree big block rev tuner and know nothing about tbi
the 89 camaro has a 34? 9 bolt
i would like to use my l69 intake and 454 gm tbi adapter
what would be the best cam and what mods will need to be done to the ecm

 

Are you saying that the rear gear is 3.42, 9 bolt?
Are you going to use roller lifters in that 355? The LT-1 cam seems popular.
The trick to getting a tbi set up running good is getting the air to flow around the injectors, a manifold that'll keep the air/fuel charge moving fast (large plenums & ports slow it down), & a cam that makes good vacuum for the map sensor. The ability to adjust the fuel pressure helps alot too.
When a tbi is set up good, it'll run like a big 2 barrel engine w/out the cold start hassels.

 

thanks
I have a 96 lt1 cam
Ill push the pin in give it a try
should i use the TB off the 454

 

Your springs handle over .500 of lift right?

 

If you're talking about a REAL FACTORY L69 intake that was designed to work with a Qjet carb, you can't adapt a TBI of any sort onto it. It's got 4 holes at the carb flange designed to match up ONLY with the throttle bores of a QJet. Nothing else adapts onto it very well.

Even on the 454 TBI engines of the late 80s/early 90s, while they used a 'Qjet-style intake' with a TBI on top, it was an intake that had two big "kidney bean shaped" openings on the carb flange (plus a very odd looking adapter on top to mate the TBI to the intake). They NEVER used a 4-hole-flange QJet intake with TBI.

If you want to run TBI on top, you can choose either the small block throttle body or the big block throttle body, but either choice will require the use of a different intake than you have now. You need big open plenum holes that you can put an adapter on top of.

 

This one works w/ a q-jet intake, it moves the tbi back over the secodarys.

 

On BOATS and other MARINE engines they did. I even have a factory non heated big block TBI to square bore TBI adapter from a boat.

I would actually suggest an edelbrock victor junior 2bbl with a 2bbl carb - TBI adapter and a big block TBI unit. The manifold will need some grinding in the plenum area to fit the throttle blades, but it works very well.