another 400 sbc and tbi question

[55Willy]

what about running a stock 79 400 with a 350 tbi set up?

what is limiting it from functioning properly?

I just want reliability,

 

[1985_K5_Silverado]

It could be that the 350 injectors aren't delivering enough fuel for an engine that has ~16% more displacement. It could be that the cam profile of that originally carbureted '79 engine's camshaft isn't quite compatible with the stock TBI computer. That's just two possibilities.

 

[Thunder]

As said not enough fuel, Cam is wrong.
All you need is a good chip burned an an adjustable fuel pressure regulator to make it run right.
I would also go with a Bored GM 600 CFM Tb and 68 LBhr injectors with an adjustable fuel pressure regulator. So you can get the most out of the 400
To make it work right with a bigger TB or with the stock one.
You will need a new chip for the computer. The stock chip is programed for the needs of a 350. It cant compensate for the fuel needs of a 400 espically with a cam designed for a Carb.You Should have a computer frendly cam.
Call these guys and talk to Ed:http://www.fastchip.com . They know their stuff and They prolly have a chip in stock that will work with a stock SBC 400. Cost ya around $300.

 

[fatbob]

I'm working on that right now, and hopefully will have the anwser soon. But for now, my theory is that already be functioning properly and reliable at lower rpms. I had mine running for a couple days, and was happy enough with the preformance, but I had a rod knocking so I had to tear it back down. I DID put in a TBI cam & stock TBI heads with the stock injectors and stock ECM, and I do think I could get even more out of it with bigger injectors and tweaking the chip. But it already had more power than the old 350, and I dont think youll need more fuel untill you start getting the rpm's up there.
It's not clear if you have an engine with problems, or if its just a project you are thinking about.

 

[55Willy]

project I'm thinking of. before I was gonna do y dart heads and a huge cam but I'm leaving the 400 stock.