new 350 TBI - The 1947 - Present Chevrolet & GMC Truck Message Board Network

pimperout · 09-29-2007, 02:11 AM

i bought a 350 a few weeks ago and me and a buddy put it in my truck (87 4x4 TBI). We swapped out a 305 with a rolled bearing in it for the 350 and i was wondering what all needs to be changed to make it just like a factory 350. I have heard knock sensors, injectors, 350 computer chip, and some ECS module or somthing, i was just wondering if any of you guys could let me know what exactly has to be changed the motor is currently running perfactly fine i just want it to have the proper amount of power out put is all thanks for any replies

Hoods69BadBowTie · 09-29-2007, 04:02 AM

So the motor u put in is carbed or? I m not exactly sure what you are asking.

pimperout · 09-29-2007, 01:58 PM

sorry its a TBI, we wired up the 350 exactly the same as the 305. But the 305 had less fuel flow and what not so i was wondering what all has to be changed as far as the computer/injectors go to make it run just like a factory 350 TBI

Morgsie · 09-29-2007, 07:17 PM

Injectors, ECU and knock sensor need to be changed to the 350 ones.

**texassquarebodies** · 09-29-2007, 07:54 PM

Just stab it in and see how it goes. Buddy of mine did this same swap about 6 months ago no problems!!!
Your injectors are the same, if it came from a truck. Easy swap.... if any problems change the computer ,,,,, should be ok

Tony

Texas Square Bodies
73-87 used truck parts

Russell · 09-29-2007, 08:34 PM

As mentioned above you'll need to get ahold of a set of 350 injectors, a 350 knock sensor, ESC module, and a 350 prom.

The prom is located inside the engine computer behind the glove box. Just take the two screws out of the cover, pop it off, and replace the two chips inside. Make sure that you put the two chips in properly with the right orientation or you'll have problems.

350 knock sensor threads in directly where the old one was, and uses the same connector. You are best off buying a brand new one from GM, as they begin to loose their sensitivity with time, and most of the aftermarket units from Napa or whatever are junk. Make sure you install the new one by hand, and not with a power tool of some sort, the force of an impact or something will most likely wreck it.

ESC module is located just to the left of the throttlebody as the big square / flat module. These are tuned to the specific frequencies of the knock sensor output vs engine displacement, so make sure you get the right one unless you want to chase your tail looking for ignition issues or a code 42. Again, best off buying new from GM, as they can be tough to identify from different vehicles in the wrecking yard, and like usual, the aftermarket units suck.

350 injectors can be found on any TBI 350 engine from either a truck or a car and changing them out is pretty easy. Before you install your new gasket and stuff, run the engine for a couple minutes with the new injectors and use a timing light to see where the fuel spray is hitting the side of the throttle body bores. You want it to be hitting the side right above the butterfly valves on the baseplate to get your best atomization. Quite often they hit the valves making big droplets that are hard to burn, so it may help you a bunch to install an injector pod spacer. Be careful when you re-tighten the pod as it is fragile, and you can bust the rear foot off really easy.

TBI units also benefit a bunch from a throttlebody spacer between the TBI unit and the intake, just like a carb. Open air elements help a ton with airflow capabilities too

If you want a couple other quick / free power-gains for TBI engines, check out the Ultimate TBI articles at http://www.thirdgen.org/technical-articles

PhilaTruck · 09-29-2007, 08:56 PM

Just a word of caution when handling computer equipment:

Make sure you are grounded when you touch the chip. (Touch something metal before and during, if possible. Do not touch the gold contacts.

I don't know how touchy these PROMs are, but desktop components can be finicky.

Russell · 09-30-2007, 12:11 AM

These proms are pretty durable, but it ist still a good idea to ground yourself out. A static arc will damage one, but it has to be pretty significant.

PhilaTruck · 09-30-2007, 11:18 AM

Ever get shocked sliding off the seat of your truck when you touch the handle?

I do every winter. Sometimes I think it'd be enough to kill a cat.

krue · 09-30-2007, 11:34 AM

Thanks for the links Russell.

pimperout · 10-04-2007, 02:53 PM

awsome thanks so much guys you really helped clear the air for me

09-29-2007, 02:11 AM	#1
pimperout Registered User Join Date: Sep 2006 Location: Bow Island, AB, Canada Posts: 166	new 350 TBI i bought a 350 a few weeks ago and me and a buddy put it in my truck (87 4x4 TBI). We swapped out a 305 with a rolled bearing in it for the 350 and i was wondering what all needs to be changed to make it just like a factory 350. I have heard knock sensors, injectors, 350 computer chip, and some ECS module or somthing, i was just wondering if any of you guys could let me know what exactly has to be changed the motor is currently running perfactly fine i just want it to have the proper amount of power out put is all thanks for any replies __________________ ________________________ 68 chev K20 being converted to a cummins powered 70 GMC 4x4 09 jacked up mega cab (daily driver) 53 chev (someday project) 70 GMC (parts) 71 GMC (parts)

09-29-2007, 04:02 AM	#2
Hoods69BadBowTie Chevys Kick A$$ Join Date: Jan 2005 Location: Zootown, MT Posts: 12,699	Re: new 350 TBI So the motor u put in is carbed or? I m not exactly sure what you are asking. __________________ HOODS is what I answer too -'79, '77, '88 Pickup Sold, '85 Camaro, '83 T/A, '81,'83,'90 K5 Blazer All Sold -'79 3/4 ton "Big Yellow Bananna" Lifted 4spd. 39.5 TSL Swampers, The money Pit -'86 K5 Blazer Silverado 6.2 4" lift 35"s -'95 Ext. Cab Shorty 4" Tuff Country rolling 35" M/T's -'83 Monte Carlo T-Tops. 126,500 Original Miles -LATER I would rather push a Chevy then drive a ford!!

09-29-2007, 01:58 PM	#3
pimperout Registered User Join Date: Sep 2006 Location: Bow Island, AB, Canada Posts: 166	Re: new 350 TBI sorry its a TBI, we wired up the 350 exactly the same as the 305. But the 305 had less fuel flow and what not so i was wondering what all has to be changed as far as the computer/injectors go to make it run just like a factory 350 TBI __________________ ________________________ 68 chev K20 being converted to a cummins powered 70 GMC 4x4 09 jacked up mega cab (daily driver) 53 chev (someday project) 70 GMC (parts) 71 GMC (parts)

09-29-2007, 07:17 PM	#4
Morgsie Registered User Join Date: Apr 2005 Location: BC, Canada Posts: 122	Re: new 350 TBI Injectors, ECU and knock sensor need to be changed to the 350 ones.

09-29-2007, 07:54 PM	#5
texassquarebodies Truck Nut Join Date: Jun 2007 Location: Wills Point, Texas Posts: 407	Re: new 350 TBI Just stab it in and see how it goes. Buddy of mine did this same swap about 6 months ago no problems!!! Your injectors are the same, if it came from a truck. Easy swap.... if any problems change the computer ,,,,, should be ok Tony Texas Square Bodies 73-87 used truck parts

09-29-2007, 08:34 PM	#6
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	Re: new 350 TBI As mentioned above you'll need to get ahold of a set of 350 injectors, a 350 knock sensor, ESC module, and a 350 prom. The prom is located inside the engine computer behind the glove box. Just take the two screws out of the cover, pop it off, and replace the two chips inside. Make sure that you put the two chips in properly with the right orientation or you'll have problems. 350 knock sensor threads in directly where the old one was, and uses the same connector. You are best off buying a brand new one from GM, as they begin to loose their sensitivity with time, and most of the aftermarket units from Napa or whatever are junk. Make sure you install the new one by hand, and not with a power tool of some sort, the force of an impact or something will most likely wreck it. ESC module is located just to the left of the throttlebody as the big square / flat module. These are tuned to the specific frequencies of the knock sensor output vs engine displacement, so make sure you get the right one unless you want to chase your tail looking for ignition issues or a code 42. Again, best off buying new from GM, as they can be tough to identify from different vehicles in the wrecking yard, and like usual, the aftermarket units suck. 350 injectors can be found on any TBI 350 engine from either a truck or a car and changing them out is pretty easy. Before you install your new gasket and stuff, run the engine for a couple minutes with the new injectors and use a timing light to see where the fuel spray is hitting the side of the throttle body bores. You want it to be hitting the side right above the butterfly valves on the baseplate to get your best atomization. Quite often they hit the valves making big droplets that are hard to burn, so it may help you a bunch to install an injector pod spacer. Be careful when you re-tighten the pod as it is fragile, and you can bust the rear foot off really easy. TBI units also benefit a bunch from a throttlebody spacer between the TBI unit and the intake, just like a carb. Open air elements help a ton with airflow capabilities too If you want a couple other quick / free power-gains for TBI engines, check out the Ultimate TBI articles at http://www.thirdgen.org/technical-articles __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

09-29-2007, 08:56 PM	#7
PhilaTruck Right on the line, baby! Join Date: Oct 2003 Location: Phila, PA 19130 Posts: 1,486	Re: new 350 TBI Just a word of caution when handling computer equipment: Make sure you are grounded when you touch the chip. (Touch something metal before and during, if possible. Do not touch the gold contacts. I don't know how touchy these PROMs are, but desktop components can be finicky. __________________ 83 GMC 406 th400/3.73 Eaton Truetrac posi, headers, x pipe, & racePros. Tubular control arms, lowering rear springs, caltracs. Still ugly, but getting built right, although slowly Click and scroll down for site vendors! Subscribe here!

09-30-2007, 12:11 AM	#8
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	Re: new 350 TBI These proms are pretty durable, but it ist still a good idea to ground yourself out. A static arc will damage one, but it has to be pretty significant. __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

09-30-2007, 11:18 AM	#9
PhilaTruck Right on the line, baby! Join Date: Oct 2003 Location: Phila, PA 19130 Posts: 1,486	Re: new 350 TBI Ever get shocked sliding off the seat of your truck when you touch the handle? I do every winter. Sometimes I think it'd be enough to kill a cat. __________________ 83 GMC 406 th400/3.73 Eaton Truetrac posi, headers, x pipe, & racePros. Tubular control arms, lowering rear springs, caltracs. Still ugly, but getting built right, although slowly Click and scroll down for site vendors! Subscribe here!

09-30-2007, 11:34 AM	#10
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,448	Re: new 350 TBI Thanks for the links Russell. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

10-04-2007, 02:53 PM	#11
pimperout Registered User Join Date: Sep 2006 Location: Bow Island, AB, Canada Posts: 166	Re: new 350 TBI awsome thanks so much guys you really helped clear the air for me __________________ ________________________ 68 chev K20 being converted to a cummins powered 70 GMC 4x4 09 jacked up mega cab (daily driver) 53 chev (someday project) 70 GMC (parts) 71 GMC (parts)



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