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305/350 swap..NEW question

T

thewestwon

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I'm going to be swapping out my fuel injected 305 for a freshly rebuilt 350 in a week or so. I have no idea the specifics of GMs TBI system in 87, but would it be possible to use the injection from the 305 on the 350? (I didn't know if the truck's computer would take care of the difference?) Or, will i have to switch to a carburetor/buy a 350 injection system?

Thanks for the help.
 
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Assuming the 350 is rebuilt back to stock specs, You will need the 350 injectors, and swap the ecm prom for one from a truck equipped with a 350. If its not rebuilt stock, (cam change), then you will most likely need a custom tune.
 
Swap Questions

I have searched the site and not reached any definite conclusions so...: I have decided to switch from the tbi (in the 305) to a carb (in the 350) for simplicity and the fact that the 350 won't be a permanent engine change. I have a sending unit for a carbed '87. Exactly what else will I need parts/specialized tools wise to do the swap (assuming there are no major problems). Also, what are some potential problems or shortcuts you guys that have done similar jobs have run into?

Thanks
 
I think that going to a carb is a huge step backwards put it on with the TBI stuff and see how it runs. I bet it will run just fine.

I have swapped 350s into camaros with the TBI that orginally had 305s and not a single problem
 
I convert cars from carb to EFI, not the other way round. :D I wont own a carbed vehicle now.

Definitely a step or two backwards. Bolt it in there and try it. worst case you convert to carb afterwords if it runs like crap. It will be no harder to convert after the fact.

Besides, a chip and 350 injectors will get you all set up.

Rufus
 
Alright well assuming I decide to keep the tbi setup or get a new one to match the 350s specs, what all will I need to do the swap (parts/special tools/etc..)?
 
An EFI engine swap is no different than a normal carb engine swap. Basic hand tools and a cherry picker.

The 87 305 EFI system will work for the 350 with only 2 exceptions.

1. The Injectors in the throttle body are different. The 350 uses a larger injector. you can swap injectors from a 350 or what most people do is swap the entire throttle body. Either one will get the job done.

2. The chip in your computer will need to be tuned to match the cam that you have in the 350. As mentioned previously brian at www.tbichips.com will be able to hook you up with a proper tune if you have the cam specs.

That is it. The rest of the EFI system just bolts up to the 350 and the 350 will bolt right up to your truck. no need to over complicate it.

Rufus
 
Alright. I guess I wasn't sure if I'd need anything for the actual swap (I had read something mentioning a new flex plate - things like that)
 
I am sure someone will chime in here if I am incorrect but as long as the engine is 95 and down where will be no need to change the flex plate.

The 305/350 use the same flex plate. The 96 and newer engines changed the balance method and would require the matching flex plate.

Do you know what year the new 350 motor came out of? I am fairly certain it will be a bolt in affair.


Rufus
 
Yep, should be good to go! Swap all the dress from your 87 over to it. It should all fit with the exception of the valve covers and oil pan. Depending on what heads you have you will either need the "center bolt" valve covers or the "perimeter bolt" covers to match the heads you will be using. The oil pan is different from the one piece rear main seal and the older 2 piece main seal. Just use the appropriate one. That should be it!
 
You will also need a 350 knock sensor and ESC module. The 305 stuff wont work.
If you havent had the engine totally built yet get a mild computer frendly installed cam so you dont have to get custom chip burned.
What you need:
55 lb hr injectors. Simple swap. 305 TB and 350 Tb are the same. Just neeed 350 injectors.
Chip from a similar 350 truck. Must match the trans you have.
ESC module and knock sensor from a 350 truck.

The cam in the engine you are having built must be computer frendly ot you will need a chip burned to work with the cam.
If you are on a budget a Melling MTC1 cam will work ok with stock TBI, It is a pretty common cam to use in rebuilds for both TBI and carb engines
 
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