[fastboy143]

I have this 73 Bonneville parts car/engine donor.
1. The 73 455 has different motor mounts than the 65. Is there an easy solution or do I have to have them fabricated?

2. The rear brakes on the 65 are lame, missing a strut bar on one side and have worn out/leaky cylinder on the other side. THe 73 has a recent brake job on all four. Can I bolt everything from the backing plate outward from the 73 onto the 65? I know the lug pattern is the same, but what of the axle tube ends?

Thanks for any help.

Barry

[Stuart]

I'm pretty sure the newer engine will bolt in the older car, as long as you use the early style motor mounts. I'm also pretty sure the newer car's brakes will not bolt on to the older car - 1971 and newer big Pontiacs don't share very many chassis parts with 1970 and older cars.

[66bonne]

I have a 73 455 in my 65 Catalina - dropped right in.

[fastboy143]

66 Bonne: that's what I thought, but the motor mounts look different? I unbolted 1 long nut and bolt on each side of the 73. That bolt goes through a bushing, which is mounted on the sides of the block. I don't have the motor completely out yet, but it seems different than what ws on the 389. That motor (and those mounts) is gone, sold to fund the purchase of the 73.

I guess I'll get a good look once I get that last converter bolt out.

Stuart, thanks for the reply. I was hoping to use some of the new brake hardware on the old 65 rear brakes. They are weak. Excited about both going and stopping, since I just did a scarebird conversion on the front brakes.

Thanks for both replies (so far).
PS: 66Bonne, your car has been an inspiration for a while now. Your strip numbers are my goal, we both know that about 235 wide tires is it for this chassis.

[fastboy143]

66bonne, what gears do you run in your 65?

[jku72]

The motor mounts are different, and mount in a slightly different location. Luckily, the 455 has bolt holes for the old style as well as the new style motor mounts.

[66bonne]

jku72 is dead on right about the motor mounts.
Fastboy143: Like yourself we have a 3:42 posi in the rear. We [my son and I] run Mickey Thompson ET Streets 235/60R15s. We had to roll back the inner fender wheel well openings to get the tires to fit and they are still a bit on the tight side. The rear axle assembly is anchored with hard polyurethane bushings which REALLY help keep the rear straight when launching.
Thanks for asking, Jim

[fastboy143]

Gotcha: old style motor mounts. Dialing parts house now.
I won't expect mid 12's too soon. This 455 is getting fresh 6x-4's, an 068, a quadrajet tune, and long branch manifolds into 2.25" with an H-pipe. Nothing fancy just yet, but I hope to get close to 14 with this mild, 90% street combo.

[66bonne]

fastboy143: that sounds like a nice combo for your 455. Depending on rear tires I think you'll easily be in the 14s and the 13s are not out of the question.