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Old 02-03-2005, 07:10 PM
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350 to 305 swap

Hello

Here is my problem... I had a 350 throttle body and i swapped it out for a 305 the same, I started it, and it runs OK but it seem to be over fueling, I swapped the computer form the 350 for the computer that came with the 305 I had to also swap out the throttle body to match my linkage, 350 throttle body on the 305 Could this be the problem. Or do i need to put the chip out of the 350 computer into the 305 computer? Any help would be helpfull..

Cheer's Jim

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Old 02-03-2005, 07:25 PM
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sensors

if you put a 350 throttle body on a 305 then most likely you need to change the throttle position sensor. im not certain on this they might be the same. but check that out. and if you put the 350 computer in the 305 then you probably were gettin mixed signals from the computer input. the 350 requires more fuel then the 305 so it was drowning it out. that explains your "over fueling" problem. check out the sensors and let me know what happens.

PS - what year are we talkin about here?
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Old 02-03-2005, 07:44 PM
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Ya i never thought about the throttle position senser the 305 was out of a 1988 and the 350 was in my 1994..I will try that tomorrow and let you know....


Thanx Jim
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Old 02-04-2005, 10:10 AM
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Did you change the knock sensor? the 350 and 305 have different bore sizes, the knock sensor goes by frequencey`s, different bore sizes give a different frequencey, so a 305 knock sensor is in order. The 350 also used bigger injectors.
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Old 02-05-2005, 11:41 AM
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Hello Everyone

I have some interseting info here I swapped out the 350 for a 305. When i did the swapp i changed out the throttle body from the 350 onto the 305, I also swapped the whole computer and this is was what was causing my over fueling problem. So i thought i would change the computer back to the origional one for my 350 and this seemed to clear up all my problem's, All the guages now work and no more check engine light or anything. So I have a 305 engine with the 350 computer and a 350 throttle body running like a charm.

I find this amazing but it seem to be working fine, Just thought i would post my results for all. Maybe this will help someone else in the future.....

Thanx for all the help guys...

Cheer's Jim
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Old 02-05-2005, 07:58 PM
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change the injectors to 305 ones.
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Old 02-05-2005, 09:00 PM
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TBI

305 and 350s both use the same size injector
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Old 02-05-2005, 09:12 PM
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305s use a 40lb injector while 350s use a 55lb.
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Old 02-05-2005, 09:35 PM
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I will try changing the injectors to the 305 ones and see if it makes any difference. But it is running like a top right now with the 350 injectors. But i am going to try it and see if it makes any difference... Just for fun >>>


Cheer's Jim
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Old 02-05-2005, 09:44 PM
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if the chips are compatable, swap to the 305 one when you change injectors. is the transmission a 700r or 4l60e?
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Old 02-06-2005, 02:42 AM
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The transmission has bull low 1,2,3,and overdrive, and will pull a train if needed..


The 305 came out of a automatic, So will this make a difference with the computer chips? Would it not be looking for shift signals and such? I think the computer out of the 1988 is no good for my 1994 because it is not from a manual transmission...Am i correct?


Cheer's Jim
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