TBI cam selection

[Scott Conner]

Ok so I'm hoping this is in the right place, but what is the biggest cam that a stock tbi and computer can handle? My truck has a gm 300 hp crate motor and the cam grind is different than a stock tbi engine. My problem is that the truck always seems to run a tad rich and you can smell it at the tail pipe I have replaced the plugs, wires, cap, rotor, ignition module. Cleaned and reset the IAC, checked the pressure regulator and spring. Now the PO who put the motor in had twisted the braided fuel line and it has a kink in it and the only other issue is that the egr valve is disconnected but any vacuum lines to it have been capped off

 

[someotherguy]

Without custom tuning you're toast. The TBI control system can't deal with anything much different than the stock engine parameters, including cam, heads, etc. A few people get away with the Melling MTC1 as that's the commonly recommended upgrade cam for a TBI, but beyond that, you're tuning just for it to run right - and also tuning to get any advantage out of your upgrades.

Running rich...the TBI is totally dependent on the MAP sensor signal and any drop in vacuum thanks to an aggressive cam grind, and you're instantly losing.

Richard

 

[beardeddummy]

Time for a carbermerator

 

[daturbosix]

Time for a carbermerator

x2

 

[Scott Conner]

x2

That's what I'm thinking so o need a lower psi pump,hei and intake, also I wonder just how useless 1st gear in a lm56 would be with 4.10s or should I bother with that rear and hard launches, cuz from what I read that transmission has some weak gears

 

[Scott Conner]

Without custom tuning you're toast. The TBI control system can't deal with anything much different than the stock engine parameters, including cam, heads, etc. A few people get away with the Melling MTC1 as that's the commonly recommended upgrade cam for a TBI, but beyond that, you're tuning just for it to run right - and also tuning to get any advantage out of your upgrades.

Running rich...the TBI is totally dependent on the MAP sensor signal and any drop in vacuum thanks to an aggressive cam grind, and you're instantly losing.

Richard

That's about where I was thinking I would be on that, these tbis are very particular when it comes to vacuum and cam profile and fuel pressure for that matter, so carby time it is anybody got an intake and hei dizzy ?

 

[Scott Conner]

Well I'm getting set for that carbemerator swap gonna get a pro billet hei from whites because it's full loaded with msd stuff and ready to drop in for 60 bucks, got some friends who have intakes and I may have sourced a set of vortec heads for the cheap. And I got an almost new edlebrock 650 carb,I have all new fire sleeved braided AN line for my fuel from filter to carb all I need is the adapter to go from 14x1.5 mm to AN-6. Is there a low psi pump I can put in my sending unit so I can just drop it in and go? I have a new sending unit already and I have a fuel pump door in my bed already too.

 

[slowburb]

If you depend on your truck you should really be looking at a better distributor than that Chinese marvel of engineering you talked about. I don't mean to be funny. The best tool to fix one when it breaks is a tow truck.

 

[KRS1]

Unsure if your truck has a roller or flat tappet, but Harris performance has some suggested "TBI friendly" cam sizes

http://tbichips.com/?page_id=73