I have the 305 TBI in a pickup. It is a sick hog with 153,000miles on it. I have 3 options I am considering, what are your opinions on them???
1- I have fresh 468 big block 2pc rear seal.
2- I have fresh 383 small block 2 pc rear seal
3 Could buy new 305 crate engine and some simple mods?? like cam, rockers, headers, I have 492 heads sitting around.
I will be towing most of the time I use the truck and don't really care about mpg.
What are the pro's and con's? All I know is that if bore changes I need to change some sensors and the injectors won't be big enough for the 383 or a highly modified 305 or 350.

 

Since you don't care about MPG throw in the big block and carb it, be sure to do headers and duals because its a mandatory thing for being cool

 

I know you say MPG isn't that important, but just how much are you willing to go with that? 7 - 11 MPG? If so, 468, and use off the shelf 454SS TBI parts, have a chip burnt if you don't want to do it yourself, and leave it at that.

If the idea of as little as 7 MPG doesn't seem that great anymore (175 miles per complete 25 gallon tank), go with the 383. Much simpler and will tow better than the 305 would have.

This question is really about you - how far are you willing to go with the MPG?

 

i'm all for big blocks in a truck. Nothing like the pulling power of a big block.

 

Next question, if I hooked up a mech fuel pump to the same fuel line that the electric pump is on will it pull fuel? I was told I couldn't use the electric fuel pump on a carb with out bypass style pressure regulator which would require a return line. It'd be simple if I could just use the existing fuel line through a mech pump.

 

If I were in your situation, I would build a 400 Small Block! The power and torque of a big block in a small block package. It's just easier that way. Then use some good heads, a carbed intake with a carb-tbi adapter, 454 injectors and tune the ECM. Keep your fuel mileage and make power!

I am thinking

.030" Bored 400 Block
Stock 3.75" stroke crank
Upgrade to 5.7" Rods
Go to the correct piston in a slight dish or reliefs
Go with some Dart Iron Eagle 180 CC heads(72 CC and drill the steam holes)
Go with a mild cam such as the L82 cam or a similar one. (218-224* duration intake, 224-230* duration, 112+ lobe seperation, as much lift as possible)
Keep the stock Exhaust manifolds with a High Flow Cat and a Low restriction exhaust system.
Perform the ultimate TBI mods and put the 454 injectors in the 305 injector pod.
Edlebrock Performer or Performer RPM intake
Holley Projection-Carb manifold adapter
Get a knock sensor for 350 or 454

The result is in the neighborhood of 325 FWHP and 450 ft/lbs of torque by 4,500 if tuned right. That is plenty for towing!

 

I'd say that would be a good idea, but he already has two perfectly fine motors for the job and said he didn't care about mileage. It'd be cheaper and easier to use what he has than to start with a fresh block.