Author Topic: Final Olds 403 (Read 5800 times)

olds403 · « **on:** February 12, 2022, 10:40:22 PM »

All

I lied....I am doing one more. This will be a maxed out 403. It will go in my brother’s Trans am.
The computer dyno says 550Hp for all you haters. You know my LS Olds did 509hp on gas. Video posted and have the print outs. One nasty motor

This will be one sick 403. 330 custom crank, Molinar rods, Racetec custom pistons, Wilson custom RPMintake, Wilson Throttle body and AEM ignition. There is only one 403 in existence that I know that has made more HP than this last one will make. For all the haters since 1985......Video will be posted. the OLDS403

Wallington · « **Reply #1 on:** February 12, 2022, 11:06:14 PM »

Awesome.....one problem, you can't give your brother a better 403! So....2nd last ever!

Not familiar with the Wilson items. Will he be using a drop-base of sorts, stock air cleaner base, fixed shaker?

Sent you an email as well about 200-4R....probably in junk folder!

5th T/A · « **Reply #2 on:** February 13, 2022, 08:32:19 AM »

Olds 403,

I am not a doubter or hater. Back in the early 70’s I had a few friends with 442’s that were built and ran very well. But never got any dyno numbers. Impressive dyno numbers on your latest build, I would imagine it has tons of torque too. If you can please post the dyno sheet.

Thanks for sharing!

olds403 · « **Reply #3 on:** February 13, 2022, 09:57:11 AM »

Everyone hates the 403. Just like the 301 haters. All jokes aside.
Waiting on cometics head gaskets. Then dyno.
Wilson modified the Rpm intake for fuel rails and hogged out the middle. using their throttle body on AEM computer.
The rpm is 2inches taller. The wilson body is about like a qjet height
Will use a 400/455 pontiac air cleaner and a 400/455 shaker ring on a shaker body.
That is the trick to make it work. I do have two custom drops that works too - pro-touring Fbody made them for me
Not a coil on plug motor. Using the computer for fuel control and msd box for ignition.

https://www.wilsonmanifolds.com/collections/4-barrel/products/4150-throttle-body-1287-cfm

pg79ta · « **Reply #4 on:** March 10, 2022, 05:07:34 PM »

I know it’s an old thread but ….. I have a 403 . Now stroker 424 330 crank , halo girdle 10.6 -1 . Rpm intake . Roller cam 528 lift 233/238 duration 7a heads ported and reworked bb size ports . Harland sharp rockers balanced . Etc without going nuts best guess for how car is now waiting for spring

« **Reply #4 on:** March 10, 2022, 05:07:34 PM »

olds403 · « **Reply #5 on:** March 18, 2022, 02:58:46 PM »

Sounds like a well built one
This is the 403 with the Edelbrock ported heads.

https://flic.kr/p/2n9kamR

olds403 · « **Reply #6 on:** March 29, 2022, 08:38:22 PM »

The first dyno pull was 475HP/485tq. Carb and Chinese HEI. The Intake is the choke point and being a Trans Am already pushing it running a RPM intake. Victor is out of the question so be it......

Next pull is on EFI will be with 1000cfm Wilson Throttle body and Holley Dual Sync on AEM ECU.
Not as much as computer dyno said, but still have more tuning to do. Not much more we could have done to it considering compression is 10:25:1 and needs to be streetable.

b_hill_86 · « **Reply #7 on:** March 30, 2022, 07:20:43 AM »

Nice! I’m glad to see the capability of a 403. Too many people rag on them and I feel like they’ve never had one and just regurgitate what they read on the internet.

ryeguy2006a · « **Reply #8 on:** March 30, 2022, 12:05:05 PM »

What heads are you using @olds403

olds403 · « **Reply #9 on:** April 02, 2022, 10:43:29 PM »

The heads are edelbrock rpm gen1. They were hand ported and have the flow sheets from champion racing.
It ran on the ECU today which was super cool to see an Olds run with port injection and ignition/fuel mapped from a laptop.

olds403 · « **Reply #10 on:** April 02, 2022, 10:59:26 PM »

Picture

olds403 · « **Reply #11 on:** April 17, 2022, 09:37:27 AM »

Done

Did 490Hp/488 Tq. There might be more in it with more tuning, but probably this will be it.
Not much more we could have done with this one and still run on pump gas.

b_hill_86 · « **Reply #12 on:** April 17, 2022, 01:08:43 PM »

That’s awesome!

olds403 · « **Reply #13 on:** April 17, 2022, 07:23:45 PM »

Thanks as nothing here is a secret. Everything can be bought. The heads had larger valves and port work but hey - not a LS. Not bad for 403.

Wallington · « **Reply #14 on:** April 17, 2022, 08:38:17 PM »

Nice figures. It's interesting how decent torque on these engines is fairly consistent while the HP can still vary greatly. My mild 403 had only slightly less tq but massively less hp!

« **Reply #14 on:** April 17, 2022, 08:38:17 PM »

b_hill_86 · « **Reply #15 on:** April 17, 2022, 09:18:15 PM »

Quote from: olds403 on April 17, 2022, 07:23:45 PM

Thanks as nothing here is a secret. Everything can be bought. The heads had larger valves and port work but hey - not a LS. Not bad for 403.

I just appreciate the fact that you built yours and posted the results. As a person who is new-ish to these engines I appreciate first hand knowledge, experience, and success with whatever it may be but especially engine setups. More so with what is considered the step-child of engines sometimes (no offense meant, honestly) I feel like now-a-days a vast majority, through no intentional ill-will of their own, regurgitate info they see online as fact which isn’t always true.

Quadrajunk = not true

557 block- limitations yes; junk - no

403/boat anchor = junk; not true

Even 301 = junk not true as demonstrated by 301 garage.

490hp and 488 torque is plenty respectable and more than my 400 Pontiac is making so HELL YEA

Plenty of people would be more than happy with that I’m sure. Maybe self included.

olds403 · « **Reply #16 on:** April 18, 2022, 05:32:09 PM »

Questions just reach out. Done ✔️

This is the other one with the stroker crank based off an LS.

http://www.transamcountry.com/community/index.php?topic=83645.0

olds403 · « **Reply #17 on:** April 20, 2022, 04:02:24 PM »

Done 495HP. With air cleaner and was a HOT pull.
No more motors planned. Time to enjoy

The videos are here

https://youtu.be/9ydnF1_-VwY

https://youtu.be/W_FELuYad50

scarebird · « **Reply #18 on:** April 20, 2022, 08:06:22 PM »

I had a beater '78 Riviera powered by a 403/TH350 combo; even with 150k+ miles it ran great. When it got scrapped I wish I hung on to the 403 - I think it would have made a nice replacement motor for the 425 in my 442.

We did not have the internet then so the common lore was that the 403 was "Ho": no visible means of support.

Never heard of the bottom end being blown out of one though...

PsychoCidWS6 · « **Reply #19 on:** November 17, 2024, 02:56:49 PM »

Hello olds403!

My goodness it's good to see you enjoying, I was on TAC ~20 years ago. Couldn't remember my handle, 79PsychoCidWS6 maybe.

All of your 403 building insights helped me greatly. My engine has been together for years but the car was never put back together. Working on that now.

It will take some months yet but we'll see a ~375-400hp plant hit the streets again hopefully by summer. Need to rewire and rehose the rest of the car and get the Qjet built.

Please forgive me off topic run, just very excited to see you in action and having fun with it.

Car and build look amazing, congrats!

- Cid

PS - Scarebird - I blew out the bottom end of my original mildly built 403 going 130mph having just swapped in 3.23 gears for the original 2.73. The rod shot out the block. The piston stayed at home. And despite that she still turned over and turned on the next day. Beastly!

« **Reply #19 on:** November 17, 2024, 02:56:49 PM »

News:

Author Topic: Final Olds 403 (Read 5800 times)