ok i might have asked about this before but not sure.i have a 92 Z28 with a wore out 305 TPI motor.i have a rebuilt 75 350 motor with mild cam like a 440/440 lift,0.30 over with 10.1 compression.i have a spare 305 TPI motor sitting around with the whole upper end.i want to redo the 305 heads and put them on the 350 and have the same 10.1 compression.i know i need a flywheel for the 75 motor but what else will i need?can i do anything to my intake to get more RPMs out of it?like maybe port and polishing it?what prom can i use in the ECM?the car needs a motor because it has 147000 miles on it and has major blow by.i know the rings r wore out and smokes out the tailpipe under hard throddle.soi hope somebody has done this and can help me out.

 

Yes you can put that motor is your car and it will work. the only thing is that the 305 heads on the 350 will raise the comp ratio alot more than 10:1. the intake should fit without any issues as long as the spare 305 that you have has the same heads that you want to put on the 350. 85-86 intake base are the same 87-up are the same. so if your intake is 87 up then you will need 87 up heads and vice versa. you can also take the flywheel off of the 305 and bolt it up, they should be the same. as for the ecm, you will need to get a 350 prom, and also you will need bigger injectors. think 305 has 19#/hr and the 350 has 22#/hr. also someone can probably correct me, but you will also need to get a knock sensor and esc module for the 350 as they are different.

 

i know the compression will rise.i have a set of 305 heads on the 350 now but are from 81-85 year range.thats how i got 10.1 compression.i believe that there is a plug in the block on the side by the starter for a knock sensor.so i should be good there.i was thinking that i needed a prom make for what i would be running.what ESC module u talking about?the spare motor i have is from a 91 camaro,so i know they would work.another thing i was thinking about doing was using the heads already on my 350 and just having the intake re drilled to work with the 81-85 heads.i know the flywheels are different because the 75 block is a 2 piece rear main where my 92 motor is a 1 piece.just need to find a good one for that older block.i did forget about the injectors.now there is more money i would have to put out for that.damn.lol.just trying to figure out what all i need before i do any of this.

 

I did this with an 82 350 in my 87 Firebird. It will run without having to change the PROM, just a 350 PROM has slightly better tuning for your engine. The 305 injectors will be fine too, would just need to bump the fuel pressure from 42 to 46psi to run without spark knocking. The PROM is programmed to the injectors for fuel mapping. If you need an 85-86 tpi manifold, I have 2 of them. I would trade you as long as you provide the shipping cost for both. I have used the ESC from the 305 system without any problems and the knock sensor would need to be from the TPI engine (they have different part numbers, but work the same way). If you are just going to get it running again, PM me with questions. I have done this swap and had no problems with 305 parts used on a 350 engine with a cam.