Need help/advices with 350 TBI engine mods

[Dom94burb]

Hi guys,
I live close by Montreal in Québec, Canada, and I just cannot find somebody that knows/works on TBI mechanics... Any references? Anybody??

My daily driver is a 94 suburban K1500 with a 350 TBI and .373 differential ratio. I do 99.5% highway/street use and the trucks is on the road pretty much every day.

The truck is in a very good shape for its age so I decided to do some improvements. I had the engine completely rebuilt from the pan to the intake manifold a few months ago. It was always felling ''breathless'' when pulling trailers, or as soon as the wind would pick-up a bit to strong on the highway, so I asked the shop who rebuilt the engine some advice on mods to do to help it pick-up some hp's and torque.

They installed a Melling MTC1 camshaft (see below specs), flat top pistons, double timming chain, and Flowtech shorty headers at my demand as want to switch the original exaust system to a full free flow exaust.

MTC-1 [email protected] Valve lift Lobe center Lobe separation
INT 204 .420 107
EXH 214 .443 117 112

Now after doing all those mods and having the engine fully rebuilt, it got ''a bit'' more ''humf'' then before, but nothing really noticeable. Somebody told me to increase the advanced timming, wich I did following the proper technique (by-pass and reset computer), got it to 7 degree max, more than that it started ''pinking''. It made a very good difference but caused the idle to giggle when engaged in drive and stopped (exemple stopped at a red light) and it is quite annoying...

I have also noticed that it runs Very well in the morning when it is cold (lots of power!) but as soon as it gets to 180 degree, it feels like it is running too lean...

I have been trying to find a place or a mechanics that knows it's ways around this type of mechanic but didn't find anything yet. I just want somebody to tell me what is going wrong and what to do to get it top shape. If it needs a tune, I need somebody to be able to tune it! If it needs complementary modifications, I need someone to be able to telll me wich and/or be able to do it.

I just feels like nobody wants to work on this type of truck and I don't get why, it is a very simple mechanic...

Any help/advices are welcome!

Thanks ahead,

Dom

 

[thz71]

It's just a small block chevy. No mechanic should have a problem working on it. Imo

 

[Dom94burb]

I will assume you mean no mechanic shouldn't have any problem working on a "small block chevy", or that you are just being sarcastic...

On another note, I have realised this morning that the idle does not "giggle" as I previously assumed, the engine is missing but not regularly, just enough to make the idle go up to compensate, wich make it feels like it goes up and down.

My oil pressure is also super high all the time, almost at max on the guage, even with 5w30 oil. The shop that rebuilt the engine originaly told me to run it with diesel engine oil as it is supposed to be better than regular gasoline engine oil... I did not liked the sound it was making when cold so after 12000km I have just switched it back to regular 5w30. Don't know if the high oil pressure could be an issue...