[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!

[Jay S]

268 is the advertised duration at .006” tappet, and the 218 is the duration at .050” tappet lift on the 268 cam. Catelog descriptions in compcam’s listings are often for 350 cid engines. The cam you picked out will act more like 10:1 in your 9:1 455, it will be fine on 93 with fairly cold spark plugs.

Our 76 455 has J heads. If you ground off those A.I.R. boss’s and install 2.07 intake valves they won’t be much different than any of the other common big valve 455 heads. The exhaust ports don’t flow well on a Olds, especially with the A.I.R. boss’s.. The intake ports flow pretty well though, even a J isn’t to bad, will flow a little less. I’ll be interested to see how you get along with that cam, it is going to have a ton of low end tq.

[MO Olds]

Originally Posted by Jay S

268 is the advertised duration at .006” tappet, and the 218 is the duration at .050” tappet lift on the 268 cam. Catelog descriptions in compcam’s listings are often for 350 cid engines. The cam you picked out will act more like 10:1 in your 9:1 455, it will be fine on 93 with fairly cold spark plugs.

Our 76 455 has J heads. If you ground off those A.I.R. boss’s and install 2.07 intake valves they won’t be much different than any of the other common big valve 455 heads. The exhaust ports don’t flow well on a Olds, especially with the A.I.R. boss’s.. The intake ports flow pretty well though, even a J isn’t to bad, will flow a little less. I’ll be interested to see how you get along with that cam, it is going to have a ton of low end tq.

I researched a ton about the cam and not sure how I missed that. I thought it was a safe choice compared to stock below. Will let you know how it goes and thanks for feedback!
Stock camshaft:
Exhaust Advertised Duration (Deg): 296 Degree
Exhaust Duration At 0.050 Inch Lift (Deg): 208 Degree
Intake Advertised Duration (Deg): 274 Degree
Intake Duration At 0.050 Inch Lift (Deg): 196 Degree

Yes the Olds community all focus on which heads are best; especially now Edelbrock offers new aluminum. Like you said, there is not a whole lot of difference between them all unless you are racing.

Any of your Olds in an F-body?

[Jay S]

My only F body is as 77 Trans Am with a Pontiac engine. I have seen them done though, usually on 403 power f bodies. IRC, you can’t run too tall of a valve cover or the 455 will hit the power boost, stock should clear OK, not a ton of extra room. Same thing goes on the A/C cars on opposite side. If I recall correct, engine mounts should be the same between the 403 and the 455. Water pumps interchange, so you can use which ever length water pump matches the accessories and pulley you find. The pulley’s all inner change. The 455 has a taller block deck, and the brackets that bolt to the heads are unique to 455s. Most of the differences are in the A/C mounts and alternator.

The factory Olds cams were rated at 0 lift duration, it made them look bigger than they actually were.

You have probably figured out who is the aftermarket support for Olds engines. Rocket racing and Mondello performance both carry a lot of Olds parts.

[Shoehornguy]

Hello new to the forums. I have only joined to help another guy out. He reached out to me via my craigslist ad for a 403 and th350 I am selling. Anyhow he had some questions about the 455 swap. I am going to add some pictures here of the 455 I put into an 80 TA.. The biggest thing modified was the set of cheapo ebay headers. Had to add one inch to one of the runners and move one a little back. The modification was only on the passenger side. The header was hitting the lower control arm mount. His specific question was about the Alternator bracket and what I used. I have not put the hood on the car yet. But the alternator is lower than the top radiator hose. I used the 403 Alternator bracket as well as the power steering bracket. Some pictures below. I can attempt to put the hood on the car tomorrow to see if it has fitment issues. I might end up having to change the location to the passenger side like an olds 442.

Also I used the 403 water pump and bought some aftermarket aluminum pullies to get everything to line up. If I can find the items I purchased I will add them to the list of stuff I installed.

[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.

[Trevor78]

The hose looks due for replacement anyway. If you have the same type again to suit the 'vertical' water neck you can take an inch out of the height at the water neck, bringing it down closer to alternator height and sitting behind it.

[MO Olds]

Agree with above. The alternator bracket needs to come from a different car/Olds motor other than a 403 TA. Still unsure of what Power Steering pump bracket to use.

A pic and link below for reference
https://www.78ta.com/HTAF/index.php?topic=3288.15.

[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]

Just the more common Olds brackets then, some may have to come from a big-block Olds or modified for the attachment changes between narrow and wide decks.

[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.