305-350 swap

[85silverbeast]

My friend wrecked his 1994 chevy silverado 3/4 ton truck with a 350 engine in it runs good. Heres the story he'll sell it to me for $100.00 I was thinking what do I need to swap into my 1985 chevy silverado, my engine is not that good it smokes a little should I just rebuild the 305? Any help or suggestions would be highly appreciated.

[bitchin85]

first off, it all depends if your going to leave it tbi, or swap it to carbed.. the easiest thing to do is use an in-line fuel pump, and your old intake and carb on the motor out of the 94 and everything will bolt right it. plan b is to convert it to tbi and youd need a new gas tank, wiring harness, all the computer cran and so on

[85silverbeast]

I plan to swap my 650 cfm edelbrock carb and edelbrock intake manifold. What do you mean inline fuel pump? Will I have to use my 305s multiple belt system or can I use the serpentine setup from the 350.

[bitchin85]

on tbi motors, they did not have the block cast for a mechanical fuel pump.(the pump was in the tank on them), so youll have to get an electric in-line fuel pump for it. and since your going barbed, pretty much everything bolts right up. and yes you can use the serp set up off the tbi motor. or you could keep your v.belt setup.. thats up to you but they will both work

[mongoose]

Originally Posted by *****in85

on tbi motors, they did not have the block cast for a mechanical fuel pump.(the pump was in the tank on them), so youll have to get an electric in-line fuel pump for it. and since your going barbed, pretty much everything bolts right up. and yes you can use the serp set up off the tbi motor. or you could keep your v.belt setup.. thats up to you but they will both work

some do some dont... it;s really best to check...

[mongoose]

i've had lots of tbi motors come with mounts and holes to run a mech. pump...


you can't just generalize, you actually have to look at it to see if you can..

[85silverbeast]

I dont mind buying and hooking up an inline pump I talked to one of the guys at the parts store and said its not difficult at all to hook it up. A friend of mine is now telling me that this engine might not work that the intake is different that it would only work if it was a 93 and under.I doubt that his correct but I tought Ill ask you guys to get the parts I need before I start the swap.

[85silverbeast]

Thanks for your quick replies *****in85 I appreciate it. Where can I pick up one of this elecric inline fuel pumps? Any specific brand or any pump will do? And how do I hook it up?

[thrtsxchambers]

I recently picked up a inline electric fuel pump from advance for about $40. Mine is feeding a 500 carb on a 305, not sure if it pumps enough for a 350 you may have to check into that so the price may be different.

[bitchin85]

No problem.. And any auto parts store should have one. You need one with I believe 7-9 psi but I'm not 100 percent.. And in just hooks into your main suply live to your carb somewhere and hook the wires to your ignition and away you go

[85silverbeast]

Do you think carquest or any of these chains stores carry this pumps? Where and how do you hook up the pump though?

[85silverbeast]

Thanks for all your help ima go pick up the 350 tonight i just cant pass it up for a 100 bucks thanks for all your help this is definitely the best truck forum!

[bitchin85]

That is a real good deal as long as it don't knocw or smoke and is low mileage.. Good luck to you

[bitchin85]

it may be 4-7 psi but any universal in line pump will do

[85silverbeast]

Thanks bro I just called a local store here and highest rated universal pump is 7 psi the clerk said it should work. Im going to freshen up the 350 anyways new gaskets and seals and see if theres anything wrong before the install.

[ruffrida2005]

my mechanical pump I got for my 350 is between 6-9PSI. You should also look at summit or jegs. You may find a better pump. But they are very easy to hook up. I would recommend that you run the pump off a relay system. you can pick that up at any chain auto store or online.

[78 Chevyrado]

It'll be fine. edelbrocks are supposed to run at 5.5psi or 6psi max.

If that's a vortec engine, you will have to get a vortec style intake. vortec-carb intake manifolds are available.

[bitchin85]

Originally Posted by 78 Chevyrado

It'll be fine. edelbrocks are supposed to run at 5.5psi or 6psi max.

If that's a vortec engine, you will have to get a vortec style intake. vortec-carb intake manifolds are available.

its out of a 94. chevy ran tbi till 95 then started using vortecs in 96.

[85silverbeast]

*****in85 is correct 96 and up are vortec engines i heard they have more horsepower about 225 because of the roller cam setup they have. What are the benefits or advantage of running the electric in line fuel pump off a relay?

[Jonboy]

Instead of jacking with an inline fuel pump and all, if you are going to go through the 350, put in a cam with an eccentric for a mechanical fuel pump and run that. The block is stil the same, and has a boss cast in for the fuel pump.

[bitchin85]

Originally Posted by Jonboy

Instead of jacking with an inline fuel pump and all, if you are going to go through the 350, put in a cam with an eccentric for a mechanical fuel pump and run that. The block is stil the same, and has a boss cast in for the fuel pump.

the tbi motors do have the block off plate for a mechanical fuel pump but if you take it off, under the plate is just casting.. you cant bolt a fuel pump up to it

[Slonaker]

I don't think your intake will work on that engine (but I'm not positive...) because the bolts are at a different angle.. Some people make them work by modifying the intake, though. I have one at home that has been modified that way. If it doesn't work, you can buy the right carb intake from Edelbrock and others or find instructions online for modifying yours.

The later engine has a one piece rear main seal and your old one is a two piece. The two engines use different flexplates. If both trucks have the same trans, make sure you get the flexplate (assuming it is an automatic) off the old truck. If you have to buy one, an '86 or '87 engine has the one piece rear main, and a flexplate for one of them should fit the new engine. I had to buy a flexplate for an '85 pickup when I switched my '86 from a 305 to a 350 with a one pice rear main seal.

Another possible issue would be exhaust manifolds. Some 350s and 305s had different bolt spacing. I don't know if your will be an issue or not. The crate 350 I bought was drilled for both, so I didn't have a problem.

I don't mean to discourage you. I just want you to know what you could be up against.

Slonaker

[bitchin85]

your intake will workjust fine. if it were a 96 or newer (vortec) then youd need a special intake. carbed and tbi will bolt right up with each other. and with the exhaust, there is a seventh bolt hole all the way in the front that one of the heads may not have but you should be fine. but for your fuel pump, take the block off plate off and check it out. if its machined out, then you can go either way. i just know some were and some werent.. but your intake will work fine

[MR .T]

the middle bolts on the intake in the newer heads go straight down. "Swirl port heads" are what the 95 will have and they do suck, the older heads have the middle bolts on an angle. the old intake wont bolt on without modification. Id get some older heads from another engine or use the 305 heads if they are still good.

[mongoose]

they dont go straight down.... but they are not as much of an angle..

you can widen the middle holes out some to get it to work... i've even seen some people leave them out.. i don't know how well that worked though, OR.. you can get the proper intake for them..

there are stock gm intakes that run a 4 barrel, and have the holes drilled properly for the early 90's heads.