67 Firebird

72 ventura

New member
3
0
1
Getting ready to replace the original 3.8 overhead cam motor / automatic with a 350 with Muncie four speed . What headaches can I expect? Anyone done this ?
 

melsg5

Staff member
SUSTAINING MEMBER
20,803
161
63
I assume you mean a Pontiac 350?
Look in a Firebird aftermarket parts catalog such from Ames Performance to see motor mounts and brackets differences if any. Same for the transmission.
 

cammerjeff

Active member
622
27
28
Belleville MI
When replacing the original Pontiac OHC-6 with a Pontiac 350, there are a few issues you will have. And as your FB is a 1967 model you will have 1 more thing to consider, the 67 Firebirds with the OHC-6 used a throttle rod not a cable that attaches the gas pedal to the carb. So it will have to be replaced with a cable. I do not know how it attaches to the gas pedal compared to what you have. The other issues are as follows.

1 - Fuel Line placement, the OHC-6 cars have the fuel pump mounted on the passenger side - the V-8 cars have it on the drivers side.
2 - Battery placement - See above same applies as it does to the starter
3 - Motor Mounts and subframe plates are different
4 - Different Radiator may be needed, but as you are going to a manual trans it simplifies it as you do not need a transmission cooler (that your stock radiator would not have if you still have the 2-speed ST-300 Transmission, they were air cooled)
5- Transmission crossmember for the manual trans cars is different
6 - Fuel Line Size - if the OHC-6 is a 1bbl model the fuel line will be to small to feed a performance V8's needs.

Thats off the top of my head, I am sure there are a few things I am forgetting.
 
G

G-943498

When replacing the original Pontiac OHC-6 with a Pontiac 350, there are a few issues you will have. And as your FB is a 1967 model you will have 1 more thing to consider, the 67 Firebirds with the OHC-6 used a throttle rod not a cable that attaches the gas pedal to the carb. So it will have to be replaced with a cable. I do not know how it attaches to the gas pedal compared to what you have. The other issues are as follows.

1 - Fuel Line placement, the OHC-6 cars have the fuel pump mounted on the passenger side - the V-8 cars have it on the drivers side.
2 - Battery placement - See above same applies as it does to the starter
3 - Motor Mounts and subframe plates are different
4 - Different Radiator may be needed, but as you are going to a manual trans it simplifies it as you do not need a transmission cooler (that your stock radiator would not have if you still have the 2-speed ST-300 Transmission, they were air cooled)
5- Transmission crossmember for the manual trans cars is different
6 - Fuel Line Size - if the OHC-6 is a 1bbl model the fuel line will be to small to feed a performance V8's needs.

Thats off the top of my head, I am sure there are a few things I am forgetting.
Thank you that is good information just what I was looking for .
 
Last edited by a moderator:
Top