[81bird455]

I have a 81 trans am that started out life as a 301 turbo,when i bought car 3 years ago it came with a chevy 350 and a converter plate matched to a bpo th400.since tranny has sprung a leak and engine has lost compression,im going to rebuild th400 and match it to 70 olds 455 4 bl.i know this has been done hundreds of times,i just cant seem to find anyone who knows which motor mounts and brackets i need.HELP!!.

[81bird455]

I have a 81 trans am that started out life as a 301 turbo,when i bought car 3 years ago it came with a chevy 350 and a converter plate matched to a bpo th400.since tranny has sprung a leak and engine has lost compression,im going to rebuild th400 and match it to 70 olds 455 4 bl.i know this has been done hundreds of times,i just cant seem to find anyone who knows which motor mounts and brackets i need.HELP!!.

[ErikW]

You need the mounts and brackets from a 403 T/A.

[bigger=better]

so the buick will interchange with the olds?

[mike nixon]

the 403 mounts should work.

you may have to modify the a/c box to fit as the 455 is wider than the 403 that came in these cars. i know this has to be done for g bodies but am not sure on the f series.

buick mounts are not the same as olds or pontiac.

welcome to the forums.

mike

mike

[gregl316]

I just finished the swap. I put a 455 Olds in my 81 Turbo. What a pain but worth it. I bought the mounts from National Parts Depot to put an Olds in a Pontiac. They are the same as the Olds 403 mounts if you can find them. Then I just bought new frame rail mounts for the 301 and it works great. But... it is a little deaper then just motor mounts. Write me if you want the whole run down.

[Colin]

I think using the 403 mounts will cause a 455 to sit higher.The 455 has a taller deck than the 403(makes it wider and taller overall).It will work fine though, but may cause hood clearance issues, depending on the breather you use.Joe Mondello sells mounts that allows the 455 to be at the same highth as the 403.Shouldnt really matter though unless you plan to use a factory shaker scoop.

[Jaggs79transam]

The 403 mount are what you need I am doing this swap right now in a 79 ta.

Colin you are right to an extent, If you use the 403 mounts you must use the 403 frame mounts also. If you use a 403 motor mount with a 455 frame mount the motor will sit like 1 and 1/2 inch low and an 1 1/2 too high if you reverse that order 455 motor 403 frame.

This comes from actually changing them 6 times to get the motor in the car LOL.

[Formula428]

The BBO is 1.3 inches taller and wider than the SBO on each side. Mike, I don't think that the a/c box has to be modified even on a G-body; I've seen this done with stock boxes. If you weren't planning on running a/c, you could try to track down a non-a/c box for a cleaner look.

[79SE]

Hey Jaggs79Transam, are you using your shaker mounted to the engine? I am in the process of converting my 403 to a 455 Olds. Having the motor built now and trying to collect as much data as possible from those that have done the swap to avoid problems down the line.Thanks.

[Jaggs79transam]

Yes I am, I did however change the carbs out from the 403 to the 455 the heater box MUST BE MODIFIED before you try this swap. I also ran into power steering pump problems. The Pump hits the steering box (I just fabricated a new bracket and raised it up 5 inches)

73 cutlass parts work well here.
Jaggs79transam@yahoo.com if you need anything else

[79SE]

When you say that the heater box must be modified, are you referring to the A/c box or is there a wider box for non-a/c cars? What did you do to modify the heater box?

[Jaggs79transam]

The box that covers you heater core I dont really know the proper name lol I just know I modified mine to get the motor in.

Oh headers are here installing them in an hour

[Jaggs79transam]

Sorry forgot the mod i did
Cut the case out and bought a fiberglass body kit for a car then simply patched where I put the dip in the cover (It's not a very big modification)

[mike nixon]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Formula428:
The BBO is 1.3 inches taller and wider than the SBO on each side. Mike, I don't think that the a/c box has to be modified even on a G-body; I've seen this done with stock boxes. If you weren't planning on running a/c, you could try to track down a non-a/c box for a cleaner look. <HR></BLOCKQUOTE>

in my 81 diesel g/p i used the diesel mounts and also installed the a/c in the car. the box has to be modified, no way around it in this application [ 73 455 olds th400].

the pontiac, buick and chevy bolt right in.

if you have a non a/c setup for one of these cars contact me as i need the underdash parts for a current project.

mike

[Badbird69]

Having done a few G-body A/C to Non-A/C conversions, I can tell you that it is quite involved, but the end result is a nice factory installed look. The dash must come out as all the wiring, cables, venting, etc. are different. Even the inside of the glove box door must be changed and don't forget the panel under the steering column that holds the left and right vent levers. Your best bet is to go junkyarding to find a Non-A/C car and get EVERYTHING from under the hood and under the dash. Also, the vent levers and under-column panels are model specific, e.g. Cutlass, Regal, Malibu, Gran Prix are not interchangeable. Your most likely candidates will be 1978-1980 vintage as most 1981 and later cars had A/C. Happy hunting!

[mike nixon]

when you're out yarding and find one of these let me know. there are none in this area for a g/p and haven't been for the past 10 yrs. i worked in a gm dealer from 85-95 and never saw a g/p with out a/c. that's why i've put the word out here.

the conversion procedure isn't tough if parts are available.

mike

[Badbird69]

Mike,

I found one last summer in a yard about 60 miles out of town that was complete. It was also delightfully equipped with manual steering and brakes. I'll try to trek on up there in the next few weeks. If they haven't crushed it yet, I'll extract the goods.

Dick

[Badbird69]

Mike,

AS long as I wasn't going to Norwalk, I went junkyarding instead. (hey, its a nice break from the office) The yard that had the G/P had crushed up 1900 cars since I was there last, but miraculously had kept that one because it is a poplular body style for a particular class of roundy-rounders up there. I got everything you need for the A/C to non-A/C change-over. Also grabbed the manual steering box & column and the complete manual brakes set-up. This was a '79 V6 stick car with no frills. Let me know what you need.

Dick

[mike nixon]

dick, i dropped you a line today.

mike