computer switch over - The 1947 - Present Chevrolet & GMC Truck Message Board Network

biglou55 · 02-25-2003, 01:50 PM

Hello people I am over on the 67/72 board what i would like to find out is on my 90 k1500 i am taking out the defunct 305 and putting in a goodwrench 350 my 22 year old know it all son say,s i have to change the ecm because of different pulse rates to the tbi i told him he was full of it. Could you knowledgable people please settle this dispute for us. thank,s in advance biglou55

red450ih · 02-26-2003, 06:51 PM

I'm pretty sure the ECM is the same, but the injectors ARE not. The 305 has a 51 lb/hr where the 350 has/NEEDS a 61 lb/hr injector. Everything else is a bolt on.

Keith

68_c10_on20s · 02-27-2003, 09:50 AM

ill have to agree with the guy on top of me but i might have a question about the chip but you could prob get a whole computer from a wrecked one for cheap,and you might could even go with bigger injectors for some more h/p,i gota 94 ext cab witha 350 has 200,000 miles on it gonna get me gm motor when i blow this one cant beat that price huh,,,,good luck,Steve

biglou55 · 02-27-2003, 11:03 AM

I have the ecm from the donor truck. I am also using tbi setup from the donor. so i shouldn,t have to change the ecm. I have heard this engine run. what should i listen for after it is running that will tell me that i have to change the ecm.

*Piston* · 02-27-2003, 11:15 AM

Yes the fuel curve is the same for 305 vs. 350.
Injectors I believe are different but will work in the 350. Might be a good idea to check with the parts store on this, they aren't a big deal to change out. The Fuel pump, sensors and ecm are the same. You'll be able to swap the 305 w/350 without having to change a thing. Make sure your 350 comes with the balancer. Everything else will interchange.
We get alot of the older trucks (88+) that want the 305 swapped out with a crate 350, been done many times.

73stepside · 02-27-2003, 11:24 PM

you will have to change the knock sensor and knock sensor module. the ones for the 305 are too sensitive for the 350 and will set the ses light off. some guys say to change the chip to a 350 chip for the spark curve but i believe they are both the same. i would also change the injectors too. the 305 are barely enough for that motor let alone they have to support a 350. other than that everything else will swap over. hope this helps.

biglou55 · 02-28-2003, 08:22 AM

I am using everything that is on the 350 the tbi is the 350 one . the only thing that is from 305 is the exhaust manifold. I just need to know if the ecm is diff. I have the 350 ecm. I would just like to tell my son that the old man knows a thing or two. THANK,S GUY,S

red450ih · 02-28-2003, 11:32 AM

The ECM's have the same GM part number. Plug in and go.

Keith

biglou55 · 02-28-2003, 03:44 PM

:p Thank,s for your help guy,s HAPPY TRUCKING.

02-25-2003, 01:50 PM	#1
biglou55 Senior Member Join Date: Sep 2002 Location: Greenfield Mass. Posts: 551	computer switch over Hello people I am over on the 67/72 board what i would like to find out is on my 90 k1500 i am taking out the defunct 305 and putting in a goodwrench 350 my 22 year old know it all son say,s i have to change the ecm because of different pulse rates to the tbi i told him he was full of it. Could you knowledgable people please settle this dispute for us. thank,s in advance biglou55 __________________ Certifiably crazy person

02-26-2003, 06:51 PM	#2
red450ih Registered User Join Date: Mar 2001 Location: Nashville, Tennessee Posts: 225	I'm pretty sure the ECM is the same, but the injectors ARE not. The 305 has a 51 lb/hr where the 350 has/NEEDS a 61 lb/hr injector. Everything else is a bolt on. Keith __________________ GMC

02-27-2003, 09:50 AM	#3
68_c10_on20s Registered User Join Date: Aug 2002 Location: Waxahachie TX Posts: 773	350 ill have to agree with the guy on top of me but i might have a question about the chip but you could prob get a whole computer from a wrecked one for cheap,and you might could even go with bigger injectors for some more h/p,i gota 94 ext cab witha 350 has 200,000 miles on it gonna get me gm motor when i blow this one cant beat that price huh,,,,good luck,Steve

02-27-2003, 11:03 AM	#4
biglou55 Senior Member Join Date: Sep 2002 Location: Greenfield Mass. Posts: 551	I have the ecm from the donor truck. I am also using tbi setup from the donor. so i shouldn,t have to change the ecm. I have heard this engine run. what should i listen for after it is running that will tell me that i have to change the ecm. __________________ Certifiably crazy person

02-27-2003, 11:15 AM	#5
Piston Account Suspended Join Date: Oct 2002 Location: Olathe, KS Posts: 2,301	Yes the fuel curve is the same for 305 vs. 350. Injectors I believe are different but will work in the 350. Might be a good idea to check with the parts store on this, they aren't a big deal to change out. The Fuel pump, sensors and ecm are the same. You'll be able to swap the 305 w/350 without having to change a thing. Make sure your 350 comes with the balancer. Everything else will interchange. We get alot of the older trucks (88+) that want the 305 swapped out with a crate 350, been done many times. Last edited by Piston; 02-27-2003 at 11:17 AM.

02-27-2003, 11:24 PM	#6
73stepside Registered User Join Date: Feb 2002 Location: Moore OK 73160 Posts: 974	you will have to change the knock sensor and knock sensor module. the ones for the 305 are too sensitive for the 350 and will set the ses light off. some guys say to change the chip to a 350 chip for the spark curve but i believe they are both the same. i would also change the injectors too. the 305 are barely enough for that motor let alone they have to support a 350. other than that everything else will swap over. hope this helps. __________________ 04 GMC Sierra RCSS 70 CST LWB 04 HD Sportster 1200 Custom Last edited by 73stepside; 02-27-2003 at 11:27 PM.

02-28-2003, 08:22 AM	#7
biglou55 Senior Member Join Date: Sep 2002 Location: Greenfield Mass. Posts: 551	I am using everything that is on the 350 the tbi is the 350 one . the only thing that is from 305 is the exhaust manifold. I just need to know if the ecm is diff. I have the 350 ecm. I would just like to tell my son that the old man knows a thing or two. THANK,S GUY,S __________________ Certifiably crazy person

02-28-2003, 11:32 AM	#8
red450ih Registered User Join Date: Mar 2001 Location: Nashville, Tennessee Posts: 225	The ECM's have the same GM part number. Plug in and go. Keith __________________ GMC

02-28-2003, 03:44 PM	#9
biglou55 Senior Member Join Date: Sep 2002 Location: Greenfield Mass. Posts: 551	:p Thank,s for your help guy,s HAPPY TRUCKING. __________________ Certifiably crazy person



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.