Wanna replace my 2.8 v6 with a 305 v8 but wonfering if i hve to change anything besides mounts exhuast fuel pump and trans

 

With an '85 you will not have much wiring or elec. to worry about.

The main things to address will be...
V8 engine
engine mounts
V8 transmission
V8 exhaust
Fuel
Spark
V8 rad. as the V6 IIRC has the in and outs flipped around on the rad. vs the V8.

Fuel.. You have a few options
1) use the stock in tank elec. pump, add a mallory $100 reg on the supply line and turn pressure to what you need. That pump will not support 275 HP or more really
2) Replace with in tank elec pump that can support more power, and add the reg. as well
3) remove pump out of tank, replace with a length of hard line the same length as pump, then use a block mounted fuel pump.
4) Same as above but replace whole pickup/sender with an early third gen V8 carb'ed sender.

Spark is easy. Use a common large cap, coil in cap HEI dist. and you can use fab up your stock 6 cyl coil 12 volt wire to plug into the HEI and work

If you have factory gauges, the tach will not read right on a V8, oil pressure, water temp, etc will all work fine if you use the correct sending units in your new V8 engine and look at a wiring diagram and find which stock underhood wire went to each sender/gauge and hook the same wire onto the sender on V8 engine.

It's really a very simple swap.

When you get ready to do the swap, you might want to get with me about parts. As we found out we are only about 6-7 hours away from each other.

I buy and part out third gen F bodies, plus I build performance engines. So I may have a lot of the parts you will need.

Heck in fact I got a few right now that may peak your interest. Can't/won't ship these but I have a running 305 V8 out of a '85 Z28 , I got a vortec 350 that I was told ran, but never heard it do so. I have the heads pulled off it now. So I'm going to finish pulling it apart and sell as separate parts...Bare block, rods/pistons, crank, roller lifter setup, heads.
I got the factory '85 z28 Y pipe, exhaust manifolds, aftermarket cat deleted, flowmaster exhaust system, etc and I will be getting more part cars coming in

 

Really don't need that costly regulator, just a y-block with a 3/8 inlet, a 3/8 outlet, and a 5/16 outlet. The return being smaller forces gas to the carb, but I ran a 350 with a QJet this way, no regulator at all, and it drove fine for many months.

 

Then what happened???

diante24, what year is your car?

 

Then I got a better job in another state, so I pulled my 350 and sold that third-gen.

 

Itd a 1985

 

Okay, '85. That means the radiator will have the inlet/outlet flipped vs. the V8 radiator like Night rider said.

The fuel pump will be fine, you'll just need a regulator (or cosmick's system) if the 305 has a carb. If you get a factory EFI 305, that system will have a regulator (assuming you get all the EFI parts).

 

Mines fuel injected can i reuse my harness for the components needed on the v8 motor

 

I only need a flowmaster muffler for my exhaust due to how my exhuast made not trying to change much unless you have the whole exhuast system

 

I have a full system Exhaust manifolds, Y pipe, intermittent pipe, over rear axle pipe, flowmaster muffler, 2 tailpipes out of the flowmaster

 

All the exhaust systems route the same, especially after the cat(s). The difference is in the pipe size.
A single 2.25" is a choke on even an LG4 / LO3, and while a single 2.5" is better, there's no harm running a 3" on the mildest of 305s.
So check what size you have.

 

2.5 pipe

 

how for all of it i wanna try and get it from you

 

pipes and all that you have for sale

 

Are you local to me and can pick items up?, if so I can do $275 for the complete exhaust system with exhaust manifolds, Y pipe, flowmaster cat back system.