[MO Olds]

Hi - I have just joined this site after not much luck on TA Country (it had crashed a couple times and all content has been lost lately). I have read a ton of posts on swapping an Olds 455 in place of the 403 on this site prior to joining but have some questions still. I also wanted to start a build thread for my '79 TA as this is an OLDSMOBILE 455 and not a Pontiac...maybe its a Heavy Duty instead of Super Duty!

First, is anyone still around that performed this in the past? Sadly, some of the people i emailed are no longer with us. If so, any pictures available? My main concern is the A/C box. Consensus is that 50% say no modifications and 50% say you need too. Thought a picture would help. The notched valve cover from a Cutlass/442 may be a good option.

Here is summary plan so far:
- Use 403 motor and block mounts
- Use the 455 alternator bracket instead of 403
- Use the 403 Power Steering bracket instead of 455
- If using headers, ones for a '73 - '77 Cutlass with the 455 are most compatible to the TA frame.
- Do not use tall valve covers
- Oldsmobile has 3 different water pump lengths; use the water pump for a 403 onto the 455 or at least one the same length as a 403

Ancient posts that I've been using for some info:

http://forums.maxperformanceinc.com/...13#post2409313

and

https://forums.maxperformanceinc.com...d.php?t=396696

[MO Olds]

The motor is lone gone hence the 455 but here is a pic of the TA from a long time ago. Shaker clearance issues will not be a problem with the giant hole in the hood!

[Trevor78]

Water pump will depend on the combination of brackets and pulleys. 403 brackets generally won't work, or other SBO as they use both head and intake or head and water pump plate to mount.

[MO Olds]

Originally Posted by Trevor78

Water pump will depend on the combination of brackets and pulleys. 403 brackets generally won't work, or other SBO as they use both head and intake or head and water pump plate to mount.

Thank you.I should have said make sure water pump length is same; the longer version for the 455 and 403 if you have A/C since part numbers are interchangeable.

I've spent a lot of time at ClassicOldsmobile forum for great Olds info but they are light on Trans Am knowledge. I know later on there is issues with factory A/C brackets bolting to Edelbrock performer intake but that will come later.

[Big Bear]

Did the 455 Olds install on a one year old 1980 TA. Had no a/c box clearance problem. Used the 403 engine mounts to bolt it in. Engine was from 73 Toronado complete with a/c compressor. Headers were from 70 442 but needed some mods. One pipe was close to the floor at the gas pedel and use to get a little warm on the heel. The car was a turbo 301 that had a fire. Modified the hood into a cowl induction. The shop that got the car after me found a hood and shaker that fit well. The intake was the original Toronado low rize. They also got the a/c working with the Toro compressor.

[MO Olds]

Originally Posted by Big Bear

Did the 455 Olds install on a one year old 1980 TA. Had no a/c box clearance problem. Used the 403 engine mounts to bolt it in. Engine was from 73 Toronado complete with a/c compressor. Headers were from 70 442 but needed some mods. One pipe was close to the floor at the gas pedel and use to get a little warm on the heel. The car was a turbo 301 that had a fire. Modified the hood into a cowl induction. The shop that got the car after me found a hood and shaker that fit well. The intake was the original Toronado low rize. They also got the a/c working with the Toro compressor.

Big Bear I can't believe it. You would think people are still around or would be able to find at least a picture of the 455 swap but the internet has lost so much of the history. You are the only person I've encountered on the entire web in over a year. Very much appreciate you providing input and experience! Also extremely happy to hear the AC suitcase/box won't be an issue. I may opt for notched valve covers to help but was dreading cutting into the case itself for room as I've read to believe. Nothing like first hand experience!

[Trevor78]

I've saved several pics of 455 Olds swaps but they don't show much, or the info or fit since many forum threads have disappeared. Still more chance than finding a week old post on fbook. 265/350/403 Olds in Firebird only used the long WP, AC or not, they changed pulleys instead. The extra length allowed more combinations of accessories and smog, without changing individual engines each time.

[MO Olds]

Originally Posted by Trevor78

I've saved several pics of 455 Olds swaps but they don't show much, or the info or fit since many forum threads have disappeared. Still more chance than finding a week old post on fbook. 265/350/403 Olds in Firebird only used the long WP, AC or not, they changed pulleys instead. The extra length allowed more combinations of accessories and smog, without changing individual engines each time.

Thanks for the clarification! I have seen some in the G body forum, I know different model but same years, with a 455 swap and showed some good pics.

[MO Olds]

I think the battery and speakers are shot but definitely cool! Hope to post engine pics soon when the rebuild is complete as well as installation. Big thanks to Grand73Am for helping with engine paint choices!

[Trevor78]

What are the engine paint choices?

Of course my previous post should say 260, not 265, wrong obscure engine!

[MO Olds]

Originally Posted by Trevor78

What are the engine paint choices?

Of course my previous post should say 260, not 265, wrong obscure engine!

Ha. Somehow I read 260 anyway...

Going with GM Corporate Blue. However, the official PPG code is 15159 but may go with code 16513 which is a little greener and was color matched to a set of 403 valve covers of the time period. I plan to bring those codes to the paint mixers and see which one I like best side by side.

[Trevor78]

No worries, be aware that they generally go greenish with heat discoloration so an already greenish blue may end up more than intended after some time. A few guys have used Chrysler green as a decent match for 45yr old GM Corporate blue, and it was. But then it discolours...

[8453johng]

That original battery is worth some money. Very rare to see working or not (probably not).

I have a battery topper identical to your original battery over a Walmart battery on my 80 TA pace car.

Very cool do not trash the battery you never see the original battery ever.

[MO Olds]

Originally Posted by 8453johng

That original battery is worth some money. Very rare to see working or not (probably not).

I have a battery topper identical to your original battery over a Walmart battery on my 80 TA pace car.

Very cool do not trash the battery you never see the original battery ever.

Really....steak dinner money or White Castle type of money? ha. Maybe I will drain it and use it for display. I haven't had a chance to throw on a volt meter (99% sure no charge) but might be interesting to see!