350 ho crate motor

[GlenMacNeil]

Have a 1989 c1500, had a 305 tbi. Bought a new crate motor 350 ho base motor and was told it would give me my 300hp with a throttle body setup. When I picked up my motor I was told that the idle was not right, now 2.5 months later it still does not idle correctly. Have been told everything from that motor is not set up for tbi, or ho motors don't idle correctly. This is from the GM dealership who installed the motor. Am now 1.5 weeks into waiting for a Mem Card? to be delivered from Texas, which apparently take 3-4 weeks to deliver to Canada. Anyone have any ideas as to why the idle is off?

 

[slowburb]

Where is the timing set? Do you have any vacuum leaks? What is the idle rpm?

 

[GlenMacNeil]

I have no idea about the idle set, it was a GM dealership and mechanics who did the install are they not the experts? Apparently not, that's why I posed the question. No vacuum leaks. No tach, guessing 700-800 rpm when idle is right, 100 when is stutters.

 

[DRAGGIN95]

Any deviation from stock really needs a custom chip on a TBI truck especially if you expect to see any power gains over stock, with the specs of the engine etc programmed to match, it also really needs a bigger throttle body and injectors to ever reach 300hp, such as the aftermarket holley or a 454ss throttle body, this used to be a popular swap, but I don't see it much anymore.

 

[GlenMacNeil]

They did not swap out the throttle body only put in 350 tbi injectors as I was told and sold.

 

[90halfton]

I thought the 305's and 350's used the same injectors? I could be wrong.

 

[GlenMacNeil]

thats interesting as they charged me $450 for two new "350" injectors?

 

[sewlow]

Whereabouts are you in Canada?

 

[DRAGGIN95]

The 4.3, 305, and 350 all use different injectors, but I still don't see the stock 350 injectors and throttle body ever supporting 300hp, but you can upgrade to a set up that will.

 

[GlenMacNeil]

I am in Nanaimo BC. I bought and installed gm part #19210007 330hp engine, based solely on the fact that I was promised a 300+ motor. Am I wrong? This motor idles worse than my 25year old 305. As for horsepower I suppose the best thing is to dyno it and then have them explain?