Olds 307 to Olds 403 engine swap info please?

Hi all. Not wagon related, but I know many have done this swap on 80's GM full size wagons.

The 307 in my 88 Cutlass has finally put in it's notice. I have almost no oil pressure, am getting a lower-end knock, and do not want to deal with oil pumps and bearings on a 307.

I know there are a lot threads about this swap, but can someone give me the complete "parts list" for this swap?

My car is an '88 Cutlass Supreme Classic, stock 307 and 200R4 transmission, floor shift car. I've got the opportunity to buy a '77 403 out of a full size Buick. It runs great and has low miles.

I'm on a super tight budget for this swap right now. This came at a bad time. I don't plan to hop up the 403, but I do plan to re-seal it, install a new oil pump, timing chain and gears, water pump, then clean it up and paint it, and will detail the engine compartment while it's out. I just want it to look good and be reliable.

My stock 200R4 is a weak link here, and I know it. I want to retain the overdrive, and the trans shifts fine now, so I'm going to cross my fingers. I don't plan to hot-rod around in this car, it's just a cruiser, so hopefully the little transmission will hold up for a while.

I want to retain my CCC so I can keep my Cruise Control and TCC in the transmission working, but I know the VIn 9 307 intake won't work on the 403. If I get an early 80's 307 intake, can I use my current carburetor and will everything else bolt up?

I've read all the pulley's and mounts off the front of the 307 will work fine on the 403. How about the 307 flywheel and starter? Also what do I do about the exhast manifolds? Anyone know if the Cutlass exhaust pipes will bolt up to the 403 manifolds? the 307 manifolds are tiny, the 403's look larger. I am planning to add cat-back dual exhaust after doing this swap, but for now it's going to have the single. Will it bolt up?

I really want to gather all the needed parts together so I can do the swap over a weekend with some help from my friends.

Any tips or a list of parts to grab are much appreciated!

Please help me bring my pretty little Cutlass back to life!

-Mike

 

The 403 is an Olds engine so my bet is it bolts up. I have never worked with a 403 so I can't address this with accuracy. Done 455 swaps but never a 403. But most Olds engines were very much the same. I'll bet it drops in. I think you have answered most of your own questions regarding the transfer of the 88 stuff onto the 77.

 

Here's some info from wikipedia.....

403
The 455 "big block" Olds V8 was replaced in 1977 with the 403 cu in (6.6 L) "small block" V8. It used a wide 4.351 in (110.5 mm) bore, the largest ever used in a small-block V8, with the Olds small-block standard deck and 3.385 in (86.0 mm) stroke. The bore was so wide that the cylinder walls were "siamesed" (similar to another GM 400 CID small block engine) — there was no space for coolant flow between the cylinders. This sometimes led to overheating problems. Some very early 403s were painted metallic blue like the 455, but most were painted GM Corporate Blue.
The Olds 403 was used by Buick and Pontiac in addition to Oldsmobile. The engine was only produced through 1979. Output was 185 hp (138 kW) and 320 lb·ft (430 N·m).



Applications:

• 1977 Buick Century Estate
• 1977–1979 Buick Riviera
• 1977–1979 Buick Electra
• 1977–1979 Buick Estate Wagon
• 1977–1979 Buick LeSabre
• 1977 Oldsmobile Cutlass
• 1977 Oldsmobile Vista Cruiser
• 1977 Pontiac Bonneville
• 1977–1978 Oldsmobile Delta 88
• 1977–1978 Oldsmobile Toronado
• 1977–1979 Oldsmobile 98
• 1977–1979 Oldsmobile Custom Cruiser
• 1977–1979 Pontiac Trans Am
• 1977 Pontiac Grand Prix available with California Emissions Only
• 1977–1978 GMC Motorhome

The Olds engines should all swap. As I said above they are very much the same. I believe they all have the same stroke. I know that when I built 445's and put them in my 307 wagons you could hardly tell the difference when you looked under the hood. The 455 is like an inch and a half wider but bolts right up with very little problem. The parts from your 307, if you want it to drive like the 307, should all transfer. I don't KNOW this but would bet on it.

 

I think I got a deal worked out on that 403....fingers are crossed, it sounds pretty good!

 

Good luck. Hope it's a good engine.

 

Well I bought an engine....actually it kinda fell in my lap. One of my buddies that has a restoration shop got in a 71 Cutlass Supreme with a good running Olds 350 in it. He's going to do a 455 swap in it, and had no use for the 350.
Made the deal this weekend. Ran the numbers and it's the original 71 "Rocket 350" with #7 heads, which came from the factory with unleaded-friendly hardened valve seats.
It's been "updated" with an Edelbrock intake, electronic ignition, and an aftermarket carb, plus the usual "Pep Boys" dress up stuff. It's filthy, and I can't tell if it's ever been rebuilt, but it runs great, no smoke or noises, good compression, and has good power. Should be quite a step up from my gutless 307.
He wants to keep the carb and distributor, but I get everything else. Will be pulling it this week, and then I'm going to bring it home and put it on my engine stand, stare at it, and decide the next steps.
Progress!


-Mike

 

Perfect. Great engine for your car. You are lucky...Olds 350's are getting hard to find.

 

I was all set to buy that 403 when this car showed up right in my backyard. I'm going to replace the timing chain and gears, all the gaskets, give it a once-over and make it pretty, and then plan to drop it in the Cutlass this fall.

Fun stuff!

-Mike

 

Well.....as long as it's sitting there....you COULD slide a mild cam in there and strap on a good intake & carb.......

 

It has a dirty Edelbrock Performer 350 intake on it, and I'm getting that with the deal. I have no idea what cam is in it now, or if it's ever been apart.

I will have to find a carb and distributor for it. Also will have to sort out the exhaust. Fun-Fun.

First order of business is getting it home and getting it cleaned up. Will go from there!

-Mike

 

Went and took another look at the engine at lunch. It has an Edelbrock 1406 on it now, but I could not see any numbers on the distributor.
Took some pics, but it was really BRIGHT and hot out there, so there is a lot of glare.

The engine is pretty leaky, it for sure will need new gaskets at least. Check out the oil on the top of the water pump housing?
Lots of cleaning to do!!

 

If it has a Performer carb & intake...it may have a Performer cam as a package. Could have heads too. Can you ask the previous owner?
EDIT:
Forgot...if there's oil around the water pump...check the timing cover for oil leaks.

 

He bought it as it sits. Has not been into it, so don't know if it's ever been apart. Did a compression test and it's good. Runs fine, he just wants a 455, so the 350 is coming out.

We'll see!

-Mike

 

Well here is the latest update on the Cutlass project.

This is the last year the Olds has to pass emissions tests, and the inspection is out tomorrow. I fired the Cutlass up last night at 9pm...after sitting since the end of June, all it took was three pumps on the gas, and the 307 came right to life. It sounded fine too, amazing it's shot. On the gauge cold it has 60psi oil pressure.

After sitting under the carport for a month it was dusty, so I drove to the car wash and sprayed the dust off. The car wash is about 2 miles away. Car ran fine, a/c blowing ice cubes and engine seemed fine, but when I got to the wash the oil pressure was below 30.

I sprayed the car off and wiped it down....it's SUCH a good looking old car, I just love it and can't wait to get it really "alive" again.

After the car wash, I drove to my mechanic buddie's house that's going to get it inspected for me. The plan is to inspect it cold, before it loses pressure and starts knocking. ANYWAY his house is about 5 miles from the car wash. Driving over I watched the oil pressure gauge slowly drop closer and closer to the red mark. Came to a stop a about a block from his house and the gauge dropped to nothing....doh. I pulled up in front of his house and opened the door to hear the lower-end tapping away. Oh well...

It should be inspected tomorrow, and once the new sticker is on the window, it's time to start pulling it apart.

-Mike

 

Oh, and after much discussion here, on the Cutlass forum, and with some of my old techs, here is the engine swap plan..

I get the 71 Olds 350 this coming Friday. It comes home and gets put on the engine stand, gets cleaned, gets all new gaskets, a new front seal, gets a new timing chain, water pump, and a general once-over. We're also going to put in new valve stem seals, as it puffed just a bit of smoke when I started it in the 72 Cutlass last week after it sat for almost a month. And yes I am going to "bling" it a little with a fresh coat of gold paint and some chrome valve covers.

The engine has an Edelbrock Performer intake on it, and it's the EGR model with all the ports for the emissions controls. After going back and forth about this A LOT, I've decided to keep the car original and keep the computer.

Here is the method to my madness. To get rid of the computer, I'd have to get a new carb, new disributor, modify the transmission for the electronic lockup, modify the a/c system, modify the cruise control, and remove all that wiring without damaging the stuff I want to re-use.

If I keep it original, all I have to do is find some 1980-85 307 iron exhaust manifolds which have the larger ports and the 02 sensor ports. That's it. Everything else will bolt up as-is. ALL the vacuum lines have just been replaced, and the car has no check engine light on now. In other words, the hardest part of the swap will be remembering where all the vaccum lines go.

So that's where I am now. I'm rounding up new gaskets and such, and have to go get some new exhaust manifolds.

Will post pics as the project progresses.

-Mike