carb vs tbi

[scottberry]

I replaced a bad 5.0 L Mercruiser with a 5.7 L with a little more power. Since the original engine was a vortec with the TBI, I decided to build a vortec motor to keep from replacing everything. The engine shop put an upgraded cam and some other little items to give me a little more HP.

I can't seem to get it tuned right as it runs a little rich at low RPM's and idle. I have played with the timing a few times but can't seem to get it right.

I was considering swapping out the TBI with a new intake and carb. Can anyone share the pros and cons. Also besides the fuole pump pressure, what else to I need to consider when making the swap.

 

[towman818181]

Re: carb vs tbi

extra sensors will be needed for the tbi to work properly

 

[gadget73]

Re: carb vs tbi

If you changed from a 305 to a 350 with a cam, you'll either need to have the TBI computer re-programmed to handle the changed engine, or get a computer for a 350. The non-stock cam throws a wrench in the works though, since there is probably not going to be any computer on the shelf that just happens to be exactly what you need. Not sure how flexible the Merc EFI stuff is, but on a car what you'd do at this point is have the thing tuned, whch alters the fuel and timing curve to match the new motor's needs.

 

[scottberry]

Re: carb vs tbi

I also have a funny whistleing noise when I throttle down. I replace the IAC last season but it still whistles. Is this common on a TBI?

I guess I will need the cam and engine specs to get the ECM re-programmed, correct?

 

[maxxman04]

Re: carb vs tbi

yes you will need all that info for Mark. he's great tho.