New engine not satisfying.

[TBI355]

OK guys and gals, heres the issue, I put a new 355 in my truck that I bought from a local engine builder, added Flowtech shortys, and true dual 2 1/2 exhaust. the engine idles smoothly and with no load it revs nicely. Timing is set to 8 degrees btdc. I run at least 93 octane ALWAYS! When the engine went in it got new cap & rotor, Bosch premium wires, new sensors. Im not sure what the cam specs are but the man that built it said it's one step better than stock. I have noticed that the torque comes on a little later than the old motor, but when I stand on it, it down shifts, and it seems to fall on its face for a second, then gradually gains power. My old clapped out 350 had instant power to 4500, while this one will rev to 5000 plus. It has refurbished TBI heads. I have bounced it off the rev limiter with the new motor, while I never hit it with the old motor in the 2 years I had the truck. Is this a cam problem or the fact that the o2 sensor is just hanging there because the exhaust shop diddnt weld a bung for it. Also note the engine doesnt seem to have the power thru the RPM range that the old motor had, even though it seems to be running well. Is this a fuel issue, due to the o2 being left out? Thanks in advance.

 

[FastOrange]

hook up the o2

 

[454SSguy]

sounds like it's dumping fuel. 02 sensor might be culprit.

 

[DRAGGIN95]

Yes absolutely hook up your 02 sensor. If I were you I would try to find out the specs on the cam, and also find out why the timing is set to 8 degree's BTDC instead of 0 degree's like is called for on a TBI motor, I have ran them at zero in a mild tbi 355 myself with no problem's.

 

[darren250r]

Yep, timing and O2 sensor are the obvious places to start.

 

[Tempted]

I've been running 6-8* advanced for a very long time, no issues. Make sure the timing was set properly. Not 8* while the electronic advance was still attached.

 

[Just2Sweet]

I've been running 6-8* advanced for a very long time, no issues. Make sure the timing was set properly. Not 8* while the electronic advance was still attached.

Yep, my '92 Camaro with a TBI 305 has run 6-8* advanced for the past decade without a single problem

 

[DRAGGIN95]

Yeah but imagine how much power he's loosing running 8 degree's retarded instead of zero much less advanced!

 

[TBI355]

It is 8* advanced, I'll get the o2 hooked up and let yall know if it helped. Thanks for the input.

 

[TBI355]

It is 8* advanced, I'll get the o2 hooked up and let yall know if it helped. Thanks for the input.