Hey guys/gals I'm new to the forum. I've swapped my 350 for a 455 and had nothing but problems. Firstly, the vibration shakes the bolts from my torque converter. Secondly, the engine sits too high in the cradle as I had to use the 350 motor mounts and the shaft from my carb poked a hole straight through my hood

I have an assembly manual for the Cutlass and it states that a 455 sits lower in the cradle due to the increased deck height.

Has anybody else made this swap and encountered similar problems?

 

Welcome. This is a frequent question.

The 455 sits "higher" because it IS taller - by about 1.5". That's normal and Olds even used notched valve covers on the 67-72 big block A-body cars to clear the brake booster and HVAC box because of this. The motor mounts must match the frame mounts, not the block, so your use of the "350" mounts is correct (Anchor P/N 2261 or equivalent to be exact). The crank centerline on your 455 is currently in exactly the same place as was the 350. It cannot be lower, as the oil pan would hit the crossmember. The factory used different motor and frame mounts for the big block cars in the 1969-72 model years not because of the block size but because the motor mounts on these cars were stronger and larger, requiring different frame mounts. These mounts did NOT change the engine location, they simply made more room for the larger mounts. You're current setup is both correct for the swap and the best you will get. Reference this thread for more motor mount info:

https://classicoldsmobile.com/forums...tion-list.html

 

Then why the vibration and hood clearance problems?

 

Perhaps we need to know more about this 455.

How did it run before you put it in this car?

- Eric

 

Tired 350, ran okay but needed rebuild. I was just hot to get a big block swapped in. Problems started at onset of swap. I was told the 455 came out of a 73 Delta 88.

 

So you never actually ran this 455 in a car before you put it in this car...?

- Eric

 

Joe,

So is it possible that my frame mounts sit further up the cradle causing my motor to be 1.5" too high? This would explain a lot since the manual shows the frame mounts to be lower on the frame (in the cradle).

 

Eric,

Nope.

 

Hmmmmmmmm...

- Eric

 

I got the 455 block from a friend of mine (passed on now). Also gave me a matching set of C-Heads to go with it. It idles fine and revs fine. The problem comes when I get up to 60 and above ...vibrates like a pair of barber's clippers. Eventually shakes out the bolts where the torque converter mounts to the flywheel.

 

Sounds like something is out of balance. Driveshaft maybe? Flex plate?

Larry

 

The vibration has nothing to do with the motor mounts. Have you tried getting the car going fast enough to vibrate, then shifting into neutral and coasting while the engine returns to idle? If the vibration continues, it is not engine related. Is the vibration speed related, or engine RPM related? In other words, will the vibration happen at a lower speed if you have the trans in second and run the engine at a higher RPM? Also, what flexplate is on the 455, the one from the 350 or some other one that it came with? The 350 and 455 use the same flexplate. Did you keep the original TH350 or swap to a TH400?

As for hood clearance, tell us what intake, carb, air cleaner, and body you have. Also, it is not possible to mount the frame mounts "higher". Either you have the original 350 frame mounts, which require Anchor 2261 motor mounts, or you have the big block frame mounts, which require 2328 motor mounts. If you incorrectly used 2328 motor mounts with the 350 frame mounts (which is difficult to do, by the way, as the bolt holes won't line up), you will see about 2" of clearance between the oil pan and the crossmember. If so, that's your problem. If the clearance is closer to 3/4", then the mounts are correct. It is not physically possible to use the 2261 motor mounts with the big block frame mounts, as the oil pan will hit the crossmember.

Again, please read the other thread I posted above and scroll down until you get to the photos of the different frame mounts, so you can identify exactly what you have.

Also, please give us all the info you can on the swap. Did you personally do it? Did you take the 350 out yourself? Did you at any time remove the frame mounts from the crossmember?