305 to 350
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Joined: Mar 2009
Posts: 92
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From: Pensacola FL
Car: 1978 Trans am
Engine: 6.6 400
Transmission: TH350
Axle/Gears: Good question
305 to 350
Hi, i tend to read more than post and finally made an account a couple months ago, however im really wanting to get rid of my 305 and put in a 350. i was wondering if there was a thread somewhere that had a nice walkthrough for this?
i figure this is probably the most common swap so i was just looking to see how much would need to be put in at this time.
EDIT:
i have a 1984 trans am, its the 15th anniversary edition with automatic overdrive, 3.73 rear, and its got the 305 with the 4barrel HO carb. any help or just a link to the thread that covers this would be great.
i would just like to press on the pedal and be thrown back in my seat even more every time. also a healthy move up the horsepower chart would be nice too.
thanks
-alex
i figure this is probably the most common swap so i was just looking to see how much would need to be put in at this time.
EDIT:
i have a 1984 trans am, its the 15th anniversary edition with automatic overdrive, 3.73 rear, and its got the 305 with the 4barrel HO carb. any help or just a link to the thread that covers this would be great.
i would just like to press on the pedal and be thrown back in my seat even more every time. also a healthy move up the horsepower chart would be nice too.
thanks
-alex
Last edited by 79_T/A_guy; Jun 28, 2009 at 02:53 AM.
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From: 51°N 114°W, 3500'
Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
Re: 305 to 350
Externally, they're identical engines. Dropping in the 350 is no different than pulling and reinstalling the 305.
Thread Starter
Junior Member
Joined: Mar 2009
Posts: 92
Likes: 0
From: Pensacola FL
Car: 1978 Trans am
Engine: 6.6 400
Transmission: TH350
Axle/Gears: Good question
Re: 305 to 350
thats nice to hear, however will all bolt on's from a 305 fit a 350, ie distributer, intake manifold, carb, alternator, that stuff.
also my 305 is buried inside my engine compartment, and im curious if there is just alot of junk on it i dont really need. as i would liket to clean it up under the hood as much as possible.
here is a pic of my engine:

here is where i would like to go with it:
https://www.thirdgen.org/forums/albu...pictureid=4477
not really the same parts but less clutter. i could careless about emission's, and smog gear. just as long as i can drive the car, and the motor wont over heat id be happy. just simple and nothing unneeded, i guess.
also my 305 is buried inside my engine compartment, and im curious if there is just alot of junk on it i dont really need. as i would liket to clean it up under the hood as much as possible.
here is a pic of my engine:

here is where i would like to go with it:
https://www.thirdgen.org/forums/albu...pictureid=4477
not really the same parts but less clutter. i could careless about emission's, and smog gear. just as long as i can drive the car, and the motor wont over heat id be happy. just simple and nothing unneeded, i guess.
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Joined: Jul 1999
Posts: 17,271
Likes: 171
From: 51°N 114°W, 3500'
Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
Re: 305 to 350
Externally all the SBC engines use the same parts. They all have the same bolt patterns so parts can easily be mixed and matched.
An aftermarket intake manifold isn't for a 305, it's for a SBC because it will fit all of them etc.
An aftermarket intake manifold isn't for a 305, it's for a SBC because it will fit all of them etc.
Thread Starter
Junior Member
Joined: Mar 2009
Posts: 92
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From: Pensacola FL
Car: 1978 Trans am
Engine: 6.6 400
Transmission: TH350
Axle/Gears: Good question
Re: 305 to 350
ok, i was looking to put an edelbrock performer intake manifold, and edelbroke performer 650cfm carb on my 305 for now as my carb is running rich and is just needing to be replaced or rebuilt. with that said i as hoping that you would say that as i wont be able to get this 350 project done for a year or two, simply as i wont have the money.
now i seriously may sound stupid but i need to ask we are talking about pontiac 350's not chevy 350's? im assuming pontiac as i would have to change the bellhousing if im not mistaken, and would like to keep the car all pontiac.
lastly having a 350 bored and stroked to a 383 wont be a problem, and a 650cfm carb should be able to handle this assuming its got a mild rebuild and mild cam. by mild cam i mean something a bit meaner than a stock cam but not a pro-stock cam by anymeans.
now i seriously may sound stupid but i need to ask we are talking about pontiac 350's not chevy 350's? im assuming pontiac as i would have to change the bellhousing if im not mistaken, and would like to keep the car all pontiac.
lastly having a 350 bored and stroked to a 383 wont be a problem, and a 650cfm carb should be able to handle this assuming its got a mild rebuild and mild cam. by mild cam i mean something a bit meaner than a stock cam but not a pro-stock cam by anymeans.
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Joined: Jul 2001
Posts: 4,461
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From: BFE, MD
Car: 13 Ram 1500/ 78 Formy
Engine: 5.7 / 7.4
Transmission: 6sp / TH350
Axle/Gears: 3.55 posi / 3.23
Re: 305 to 350
the last true Pontiac v8 was the 301. when the 3rd gens came out the v8's were corperate, a.k.a chevy.
To keep, errr, convert your ride back to Poncho power read/peruse the sticky up top on swapping in the mill.
383s are killer engines, for the correct cfm needed there is a formula you can use to determine it.
To keep, errr, convert your ride back to Poncho power read/peruse the sticky up top on swapping in the mill.
383s are killer engines, for the correct cfm needed there is a formula you can use to determine it.
Thread Starter
Junior Member
Joined: Mar 2009
Posts: 92
Likes: 0
From: Pensacola FL
Car: 1978 Trans am
Engine: 6.6 400
Transmission: TH350
Axle/Gears: Good question
Re: 305 to 350
so if i understand correctly a chevy 350 would bolt up to my 84's 700R4 no problem? so technically i am running a chevy 305 i guess.
really i just want something that will be an easy, well as easy a an engine swap can be swap from a 305 to a 350/383. ill take a closer look at the stickies and try and find that formula. anyways though thanks to the both of you for all the info.
really i just want something that will be an easy, well as easy a an engine swap can be swap from a 305 to a 350/383. ill take a closer look at the stickies and try and find that formula. anyways though thanks to the both of you for all the info.
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Joined: Jul 1999
Posts: 17,271
Likes: 171
From: 51°N 114°W, 3500'
Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
Re: 305 to 350
If you want to use a Pontiac engine, that's an entirely different story. Pontiac and Chev are completely different engines and are no different than trying to use Chev parts on a Ford.
Buick, Old, Pontiac and Caddy use a specific bellhousing pattern. SBC and BBC have they're own bellhousing pattern. Although a few of the older transmissions came with a dual bolt pattern, late model transmissions such as the 700R4 only use the Chev pattern. The only way to use a Pontiac engine is to use a transmission with the BOP bellhousing pattern.
Buick, Old, Pontiac and Caddy use a specific bellhousing pattern. SBC and BBC have they're own bellhousing pattern. Although a few of the older transmissions came with a dual bolt pattern, late model transmissions such as the 700R4 only use the Chev pattern. The only way to use a Pontiac engine is to use a transmission with the BOP bellhousing pattern.
Junior Member
Joined: Apr 2009
Posts: 53
Likes: 0
From: Minnesota
Car: 1982 Trans Am
Engine: 350 Chevy
Transmission: T5
Axle/Gears: Stock
Re: 305 to 350
As far as cleaning it up under the hood, it all depends on what you are going to use, or what works. If its not working or whatever, throw it out unless your going to replace it. Here is under my 82, its not pretty, but as you can see there is not very much under the hood. I got the car with no air conditioner or anything in it already so alot of crap is missing. Got the car as a roller and put a 350 in it..
And like they said, the third gens v8s are all chevy motors. Any small block chevy will bolt right up to your car i do believe.
Anyways here are some pics.
EDIT: If your putting another engine in, your most likely not going to throw all that junk back on the new engine. As you can see my engine has none of the emmission stuff on it anymore. Just the basic stuff to make it run i guess.

And like they said, the third gens v8s are all chevy motors. Any small block chevy will bolt right up to your car i do believe.
Anyways here are some pics.
EDIT: If your putting another engine in, your most likely not going to throw all that junk back on the new engine. As you can see my engine has none of the emmission stuff on it anymore. Just the basic stuff to make it run i guess.

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From: Mid-State North Carolina
Car: 83 Z28
Engine: Comp Controled 350 w/ carb
Transmission: 5 Speed
Re: 305 to 350
I did the swap on my 83 Z with a T-5. There are a few things U need to know to start with. SBC are the same except for the rear main seal. 85 back have 2 piece and 86 up have one. Makes difference in what flexplate U need. Older 350's (77 models I know) have the dipstick on drivers side. It will work if U run headers but if U reuse U're manifolds it gets in the way. All the other parts (intake, carb, front accessories) bolt back up and work fine, I am even running the 305 ECM with comp controled dist and carb.
Junior Member
Joined: Apr 2009
Posts: 53
Likes: 0
From: Minnesota
Car: 1982 Trans Am
Engine: 350 Chevy
Transmission: T5
Axle/Gears: Stock
Re: 305 to 350
Hmm.. I actually dont have a dip stick on my motor yet, i need to get one. But it looked like it would fit on mine. I did not look at it real close tho so i may be wrong. Or maybe my manifolds arent even the third gen ones.
Thread Starter
Junior Member
Joined: Mar 2009
Posts: 92
Likes: 0
From: Pensacola FL
Car: 1978 Trans am
Engine: 6.6 400
Transmission: TH350
Axle/Gears: Good question
Re: 305 to 350
well if it came with a "chevy" motor than i guess it wont be so bad putting a chevy 350 in it. but i want to make sure,
if i buy a running chevy 350 preferably close to 1977 i should be able to put it in without a ton of complications?
i will probably end up buying a 350 block and build the motor over time to a 383 and put that in when its done but i dont want to build a 383 to find out in the end it wont fit in my firebird. i have a couple older chevy's but they will have to wait till i get the firebird done.
if i buy a running chevy 350 preferably close to 1977 i should be able to put it in without a ton of complications?
i will probably end up buying a 350 block and build the motor over time to a 383 and put that in when its done but i dont want to build a 383 to find out in the end it wont fit in my firebird. i have a couple older chevy's but they will have to wait till i get the firebird done.
Junior Member
Joined: Apr 2009
Posts: 53
Likes: 0
From: Minnesota
Car: 1982 Trans Am
Engine: 350 Chevy
Transmission: T5
Axle/Gears: Stock
Re: 305 to 350
well if it came with a "chevy" motor than i guess it wont be so bad putting a chevy 350 in it. but i want to make sure,
if i buy a running chevy 350 preferably close to 1977 i should be able to put it in without a ton of complications?
i will probably end up buying a 350 block and build the motor over time to a 383 and put that in when its done but i dont want to build a 383 to find out in the end it wont fit in my firebird. i have a couple older chevy's but they will have to wait till i get the firebird done.
if i buy a running chevy 350 preferably close to 1977 i should be able to put it in without a ton of complications?
i will probably end up buying a 350 block and build the motor over time to a 383 and put that in when its done but i dont want to build a 383 to find out in the end it wont fit in my firebird. i have a couple older chevy's but they will have to wait till i get the firebird done.
Thread Starter
Junior Member
Joined: Mar 2009
Posts: 92
Likes: 0
From: Pensacola FL
Car: 1978 Trans am
Engine: 6.6 400
Transmission: TH350
Axle/Gears: Good question
Re: 305 to 350
great, i dont want AC, or heat, or anything i dont need. i just want the car to drive and idle, and not leave me stranded
Junior Member
Joined: Apr 2009
Posts: 53
Likes: 0
From: Minnesota
Car: 1982 Trans Am
Engine: 350 Chevy
Transmission: T5
Axle/Gears: Stock
Thread Starter
Junior Member
Joined: Mar 2009
Posts: 92
Likes: 0
From: Pensacola FL
Car: 1978 Trans am
Engine: 6.6 400
Transmission: TH350
Axle/Gears: Good question
Re: 305 to 350
well i think they are worthless, they arent hooked up. i guess they were bypassed from what the previous owner said to add horsepower. this was done back in 1989 or 1990 so they have been sitting unused for almost 20 years. tomorrow i am going to try and pull apart some of the junk so ill post some pictures asking whether or not i can remove something as i dont want to pull something vital that i wouldnt know is vital.
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