Currently I have a 305 tbi motor that i switched to carb on. Just wondering what kind of power gains there would be? My friend has a l98 out ofa 91 Z with 103,000 miles. j/w if any of you had done it?

 

I don't have the particular combination you're talking about (many have done it). But, in general, you're adding 45 cubic inches of displacement, going from low-flow/high-velocity intake ports (intended for good torque and fuel economy, not power) to decent flowing ports, and a really lame cam (also intended for good torque and fuel economy) to a decent cam.

Just putting the L98 under your induction would be a pretty substantial boost. But, unless you do something about the exhaust (assuming you still have the stock exhaust system), its potential will still be severely limited. Gutting the cat doesn't help a whole lot - you need headers, backed up by high-flow y-pipe, cat, and cat-back.

 

Well, I am in the process of changing to carb on my L98. I wont be able to go to the track until march. Thats when they open. I am also adding hedman Lt headers, and 3.73 gears.

I would like to see somemore feed back also.

 

Have fun getting the longtubes in there. It looks pretty tight. I had my motor out when i installed mine so that was easier that way. TPI is a good system. It would be easier for you to use your carb and everything. This way you wouldnt have to deal with the wiring.

 

305 Carbed from TPI here...Im seeing a big power gain on the highend, it doesnt jump quite as hard as it did with the TPI ((running Posi 3.73)) Gear. However on the top end im noticing a huge gain in power. My only problem is, the damn thing loves drinking gas.

 

I did this swap last year. I have hard a hard time getting the carb adjusted however it runs pretty good. The torque is incredible but the car isnt super fast. It will smoke the tires thru first however it could use some internal mods.
I also was told that the cam is designed to go with the TPI unit so it stops making power at 5k. I let the car shift on its own since the upper RPM's are empty.
read my sig for my mods.

 

it runs like a carbed engine....cuz thats what it is....

 

Explain.... Are you saying carbed cars cant run well?

 

My combo runs very smooth, however I know that I will need to either invest in a new cam / heads combo or a new Long block.
Anyway the car does runs very smooth. I just recommend making the hard effort up front to remove the intake fuel pump and install a mechanical.