new guy here helping out a friend with a '68 convert. and a 455

[chopperimpala]

I plan on being on here a lot as I have a '57 olds Fiesta wagon, and need lots of advice, BUT first I am trying to help out a friend!... here is the scenerio: He has (that I am working on) a 68 Cutlass convertible, and a 455 / turbo 400, out of a '75 olds 4 door. the frame (motor mount) pads from the '68 are GONE!! He has the motor mounts and frame pads from the '75!! The pads themselves DO NOT line up with ANY frame mounting holes on the '68, (to small) but I have the motor, with the mounts, and the frame pads attached and have set the motor and tranny in the engine "bay" on the '68. Well the problem is, the motor tilts to the rear pretty bad BUT it fits in with NO clearance problems anywhere, such as, distributor, exh. manifolds, valve cover to brake booster, etc. MY only concern is the drastic tilt of the motor!!! do I need to replace the original motor mount from the '75, with '68 mounts (none in town, would have to --special-- order them)??? there isn't much room that I see, that would drop the front of that motor down that much?!?!?ANY HELP would be greatly appreciated, ALSO did a '68 even have this motor tranny combo??? He got a GREAT deal on all this but I am starting to see why....(the aggrivation of this install)... thanks KEN

[joe_padavano]

The only 68 A-body with a 455 was the Hurst/Olds, but the 400 offered in the 442 that year was externally identical. In 68, all the Olds A-body cars used the same motor and frame mounts, so any 350 mounts will work as well. Be careful, because the big block mounts changed in 1969 and many vendors incorrectly list the 69-72 rubber motor mounts as 68 mounts. In reality, the 64-69 small block and 65-68 big block motor and frame mounts are all identical, so you can use any of those and be correct.

In fact, so long as you use motor and frame mounts as a matched set, you can use any 64-72 A-body mounts and the 455 will fit just like stock. There are three different motor/frame mount configurations - the early mounts I noted above, the 69-72 big block mounts, and the 70-72 small block mounts. All three configurations will put the block and the crank centerline in exactly the same place when used as a matched set, but due to dimensional differences you can't mix (for example) a 69 big block rubber motor mount with a 68 frame mount.

As for the trans, is it a long tail housing or short tail housing TH400? The A-body cars use the short configuration, though I've heard of people who used the long trans and had a custom driveshaft made. It isn't easy to change the tail housing as the output shaft also needs to be changed, which requires the trans to come apart.

You really want to get the engine at the proper level, since having it misaligned will cause problems with things like fan shroud clearance, carb float level, u-joint alignment, linkages, and exhaust system.

[gmoney]

Ken, I have done this swap on a 69 and a 72 cutlass. Here are some other lessons learned. The exhaust systems do not mix, match or interchange. I had to go all new from manifolds on. The front springs need to be repalce for the weight differance. the radiator needs to be a four core or the beast will run hot. The trans mount needs to be for the turbo 400 not the same as the turbo 350. The first car I shortened the drive shaft but kept braking U joints. The second time around we put a short shaft on the trans with much better results. You will also have to change the input spline on the shaft if going from a turbo350 to a 400. Good Luck, Mike.

[chopperimpala]

thanks guys, I got the correct rubber motor mounts, but my problem now are the "frame pads" ( the mounts that are bolted to the frame crossmember, on which the rubber motor mounts bolt to.) 3 out of 3 different styles have the front of the motor to high!! I have the orig. radiator that came with the motor, and I have exh. manifolds that "seem" to clear everything, and the driveshaft will have to be custom made. I am gonna hit the pick and pull this weekend, to look for a pair of shorter frame mounting pads. AGAIN, thanks for the help!!! Ken

[Guest imported_Julian]

for what its worth...If you use 350 frame mount pads and 350 motor mounts it will fit just fine. As far as a 4 core radiator.. I swapped my 350 out in my 71 for a 455 18 yrs ago and to this day have NEVER ran hot...and yes I do have a full guage package (rally pack)..I am sure that a 4 core radiator is the best way to go but I have never had ANY problems with mine and I also coupled it up with a turbo 350 with B&M shift kit....Glenn knows this car. is my 71 rag-top...

[chopperimpala]

Well shes in!!! after hours in the wrecking yard and pick and pull, I found that the frame pads from a chevelle were the closet I could find!!! I found NO '68 cutlass' to compare, BUT by measuring with a set of dial calipers (belive me it wasn't easy!!) I came up with them. I had to drill 2 new holes in the frame, but welded up the 2 I didn't use, and it worked!!! When it is done I'll take some pics if anyone is interested...Ken