So I'm looking into swapping a vortec 350 out of a 98 pickup. I found the truck being parted and the guy only wants a couple hundred for the motor with 105k on the clock. I would like to put it into my 85 Firebird and replace my wheezy old 305. I don't really need or want any performance upgrades yet, accept maybe an LT1 cam, some valve springs and the longtube Hedmans I currently have on my 305.

My question is, will everything from my transmission bolt up to it? Flex plate torque converter so on. I have yet to decide if I'm gonna go through the work of keeping it EFI or just carburetor.

This is also off topic, but what is so good about the Borg Warner 9 bolt. My car has an open diff one.

 

Everything from your transmission will bolt up. The only thing that won't bolt on from your old engine is the intake manifold.

Edit - your flex plate won't bolt on either if your engine has a 2 piece rear main seal, so try and get the one with the engine.

 

The flexplate on the Vortec may be 168 tooth, which will require the truck starter if that's the case. Simple enough to get an '86-up 3rd gen V8 flexplate and keep the 3rd gen starter - makes it easier for header clearance should you decide to go that route in the future.

Some minor details such as the cam sensor and front damper will have to be addressed. And you'll need a Vortec spreadbore intake manifold. And you should get a 350 knock sensor and module. And the LG4 exhaust will absolutely choke the 350. But, it's still a good swap option.

 

Shouldn't be a knock sensor on an 85 LG4.

 

Thanks for the input. Ive already adressed exhaust issues with some 1 & 5/8 primary longtubes with 2 & 1/4 dual exhaust dumped at the rear axle.

 

Yep, there is.

That's the year the LG4 got the L69's & LB9's CR.

 

Single 2-1/4" is still too small. Are you talking duals? If so, 2-1/4" duals will be fine.

 

Yeah, duels. And yes I'm sure it has a knock sensor. It's on the passenger side of the block. I won't be using it though, as the previous owner clipped and removed a lot of the electronic bits. Everything electronic had been disconnected and is missing from the carb when I got the car. Its drive-able and It still gets 21 or 22 mpg on the freeway, and it detonates above 4500 rpm when pulling, and mid throttle response sucks below 2k rpm. Thinking about getting a summit brand non CCC Qjet and vacuum advance HEI + protronics module for the new motor. I know the CCC stuff can work great. But I don't think I could get it all working right again.

 

A Canadian non-ccc '85 LG4 would not have a knock sensor correct?

 

That I don't know. I had an '84 full size van, U.S. version, non-CC q-jet, that had a knock sensor.

 

Well, I guess if there's no ecm there can't be a knock sensor

 

There can be if it has an EST module, but there's no knock sensors on LG4s with Canadian emissions.