Olds 350 Question List

[J.Rod22]

Whats up everybody, I have a 307 olds with 200-4r trans and I plan to swap the engine out for a 350 olds but I have some questions about this swap. Im kind of a noob when it comes to cars but Im trying to learn so I can build up my car. So instead of searching everywhere for all my questions I decided to just make this post and ask all my questions once and for all. This might also help other noobs out there who may be afraid to ask and look like a noob lol.

1. What is the difference between running the olds 350 with the computer and running it without the computer? Which is better?

2. To run the olds 350 without the computer exactly which year distributor will I need and what carb. can I use?

3. If I decided to run it without the computer I hear that I will need a lockup convertor kit. What exactly is a lockup convertor kit and what does it do? How do I install it?

4. If I decided to go with another trans will I still need to get a lockup convertor kit?

5. Will my stock rearend hold up to that engine?

These are all the questions I cant think of for now. I would appreciate it if you guys can help me with these questions. Feel free to pick a question to answer or if you know all the answers then answer all of them :lol: . Hopefully after this I will know all I need to know lol. Thanks again

 

[Blake442]

If your 350 is stock, or close to it, you can run it on the computer just fine.
If properly tuned, you shouldn't notice much of a difference, if any at all, between computer controlled and not.
I personally would do without it unless you have vehicle inspections where you live.

Look for around '74-'79 for the carb and distributor.
Make sure the distributor is an HEI unit and not a points set-up.

The torque converter lock-up locks and unlocks the torque converter at highway speeds (3rd & 4th gear) and helps slightly drop the engine rpm and usually yields one or two mpg.

You will only need the lock-up kit if you're using a trans with a lock-up converter.
The TH-350C is the lock-up version. You can eliminate the feature by putting a non-locking converter in and it will be fine.

 

[81X11]

Hey sharp car! I also have a white Cutty and in the future plan to do this 307 to 350 or 403 swap myself. From what I've read the easiest option is to re-use your intake, so the computer and everything else still works. The 200R4 trans will hold up ok to the 350 and 403 as long as you are not dogging on it a lot.

One upgrade to budget for is new exhaust manifolds and a new exhaust system. The 307 system is terribly restrictive. Also your rear end gears are most likely very tall for economy, which kills your performance. I'd plan to change those too. You may even want to try that first if your 307 is running well. From what I've read going with a lower rear axle ratio and upgraded exhaust really helps these cars.

I'll be watching this thread to see what others have to say.

Again sharp car and good luck!

-Mike

 

[Black Sheep]

The TH-350C is the lock-up version. You can eliminate the feature by putting a non-locking converter in and it will be fine.

Input shaft splines are different between the th350C and the th350. Convertors won't interchange. Just disconnect the electrical plug for the lock-up on the side of the trans if you don't want the lock-up feature.

 

[J.Rod22]

So will my sensors from the 307 screw into the 350 so I can use the 307 harness?

 

[FE3X CLONE]

So will my sensors from the 307 screw into the 350 so I can use the 307 harness?

You'll probably want to get an A4 manifold off an earlier 307 (non-roller engine) to use on the 350. That will make the swap much less problematic if your trying to keep the computer.

Personally, if you don't have to deal with emissions or inspections, just unhook the wiring harness and tuck it up along side the passenger fender. Then get a '74-'79 Q-jet and HEI as mentioned above. Bolt on and go.

The other issue with keeping the computer is your going to need a place for the O2 sensor. You won't be using the exhaust manifolds from the 307 so you'll need to have the 350 manifolds modified (drill/tap or weld bung) for the O2 sensor.

 

[megaladon6]

keep the trans, you'll be much happier with the OD. however, it may need some upgrades to survive the extra torque and a lead foot. the good news is that there are some good companies out there that build relatively inexpensive performance units--around $1300. i'd keep the stocker in there till it has issues though--some were really built right and last.

check out bowtie overdrives for the simplest and cheapest lockup converter system.

the rear will survive for a bit, but plan on getting an 8.5in in the future.

do NOT get a 74-79 q-jet. you want one from the 80's so that the throttle bracket geometry is correct for the transmission TV cable. the 80's also had an adjustable part throttle screw, which is nice for tuning.

 

[J.Rod22]

So will my sensors from the 307 screw into the 350 so I can use the 307 harness?

You'll probably want to get an A4 manifold off an earlier 307 (non-roller engine) to use on the 350. That will make the swap much less problematic if your trying to keep the computer.

Personally, if you don't have to deal with emissions or inspections, just unhook the wiring harness and tuck it up along side the passenger fender. Then get a '74-'79 Q-jet and HEI as mentioned above. Bolt on and go.

The other issue with keeping the computer is your going to need a place for the O2 sensor. You won't be using the exhaust manifolds from the 307 so you'll need to have the 350 manifolds modified (drill/tap or weld bung) for the O2 sensor.

Oh ok. I really would rather go without the computer so the engine compartment will look cleaner and less clutter. But the only thing that has me intimidated is the thing about the trans lock up.

 

[FE3X CLONE]

do NOT get a 74-79 q-jet. you want one from the 80's so that the throttle bracket geometry is correct for the transmission TV cable. the 80's also had an adjustable part throttle screw, which is nice for tuning.

How do you do that if your not running the computer? The '80's model carbs were CCC controlled. Unless you maybe get one off a truck.

The TV bracketry will be fine. The key is using an aftermarket adjustable TV cable. Of course they make special adapters as well now but I've never had a problem with just using the aftermarket cable and adjusting it properly.

 

[FE3X CLONE]

Oh ok. I really would rather go without the computer so the engine compartment will look cleaner and less clutter. But the only thing that has me intimidated is the thing about the trans lock up.

It's not hard at all. If you buy a lockup control kit they'll come with the instructions.

http://www.bmracing.com/bmracing/instal ... 540-04.pdf

My brother used the B&M kit on his '81. But I don't remember us having to mess with the valve body.