'77-78's and 403's

[MrEarl]

Just a thread to talk about and give thoughts and opinions of the Olds 403's in the '77 and '78  Rivieras. I know there aren't a lot of those years out there and would be curious to know how many came with that particular engine. Anybody here done any performance upgrades to theirs?  Askin for a friend 😄

[Seafoam65]

The Olds 403 is a great engine! I have a 79 Trans Am Firebird with the 403 with automatic transmission and a 2:73 rear axle with posi.

In '79, if you got the 4 speed trans you got the 400 Pontiac V-8 rated at 220 horsepower and a 3:23 posi rear axle. The 403 was rated at 185 horsepower.

Prior to owning the 79 T/A I have now, I owned a 79 400 4 speed T/A for many years. All the car magazines both back in 79 and today imply that

the 403 is a slug. The problem is they never had a test done where they pitted the two engines against each other in a drag race, nor did they ever drag

test a 403 car. Not only does the 403 have 3 more cubes than the Pontiac v-8, it has WAY more torque than the 400. I took my stock 400 four speed to the track many times and the best it could do was 15.95 in the quarter mile. Later when I bought my 403 car, I took it to the track expecting mid 16's. With the 2:73 axle

it runs 15.40's all day long! Add to this the fact that the 403 gets way better gas mileage than the 400 Pontiac mill. The 403 doesn't need any performance mods.....

it hauls ass in stock form. I tried several times to get High Performance Pontiac magazine to do a drag test between my car and a stock 400 4 speed T/A. They never would agree to do it because I think they were afraid of what they might find out about the 400 Pontiac motor. They were afraid that the results would not fit the narrative. As if all this wasn't enough, the  Pontiac 400 was not available in California because it

would not pass their emission standards like the 403 easily did! 

Edited September 24, 2019 by Seafoam65 (see edit history)

[NC1968Riviera]

The 77 Riv below was at the ROA Annual Meet in Gettysburg this year. It belongs to a ROA member from Texas.

I think it has the 403 and 4 wheel disc brakes. It is a beautiful car!

 

[RivNut]

Lamar,

 

The 350, 403, and 455 all have the same exterior dimensions.  Go all out and find a 455 for your  purposes.  Check out the "Mondello Oldsmobile" website.  Call them and tell them what you're looking for.

[joe_padavano]

58 minutes ago, RivNut said:

Lamar,

 

The 350, 403, and 455 all have the same exterior dimensions.  Go all out and find a 455 for your  purposes.  Check out the "Mondello Oldsmobile" website.  Call them and tell them what you're looking for.

 

Sorry, but that is incorrect. The Olds small block (260, 307, 330, 350, and 403) has a 9.33" deck height. The Olds big block (400, 425, and 455) has a 10.625" deck height. The intake manifold on a 455 olds is about 1.5" wider than on a 403, and the entire motor is equally wider (and taller). Yes, a 455 will bolt in place of a 403, but they are not the same exterior dimensions.

Edited September 24, 2019 by joe_padavano (see edit history)

[telriv]

ALSO, since the 455 has a higher deck height the T/A hood scoop is taller & makes the hood bulge with closing.

[70rivme]

Awesome engine! Put a set of #5 heads from a 350 on it and it will move out really well. Just my experience.

[MrEarl]

1 hour ago, RivNut said:

Lamar,

 

The 350, 403, and 455 all have the same exterior dimensions.  Go all out and find a 455 for your  purposes.  Check out the "Mondello Oldsmobile" website.  Call them and tell them what you're looking for.

 

I've looked at a 455 swap as well as an LS swap, both including mating transmissions. If comparing costs to my current plans of just doing a performance upgrade to the top end of my existing 403, the 455 swap would likely run about 2-3x the cost and the LS about 3-4x the cost. In addition, while the 455 would bolt up, it would be tight. I even found a great deal on a rebuilt complete 455 and T200 4R transmission but guess where it was.... California, mightn't you know.  I've spent the last few months over on the ClassicOldsmobile forum and have gained a healthy respect for the 403, as well as learned a great deal especially in regard to the do's and don'ts of such a build. There are some unbelievably knowledgeable folks there who have been extra helpful and quick to answer my questions and point me in the right direction, with @joe_padavano being one of the most helpful.

So I know what I want to do and am lining up someone to do the work. I just wanted to post here on the Buick forum to hear what y'alls experiences might have been with the engines and any builds, especially any possible post build problems.

[MrEarl]

7 minutes ago, 70rivme said:

Awesome engine! Put a set of #5 heads from a 350 on it and it will move out really well. Just my experience.

 

5's are hard to find, 6, 7's and 7a's are very close flow wise and I have a set of 6's lined up. Thanks!

[joe_padavano]

46 minutes ago, telriv said:

ALSO, since the 455 has a higher deck height the T/A hood scoop is taller & makes the hood bulge with closing.

 

What does that have to do with a Riviera?

 

[RivNut]

2 hours ago, joe_padavano said:

 

Sorry, but that is incorrect. The Olds small block (260, 307, 330, 350, and 403) has a 9.33" deck height. The Olds big block (400, 425, and 455) has a 10.625" deck height. The intake manifold on a 455 olds is about 1.5" wider than on a 403, and the entire motor is equally wider (and taller). Yes, a 455 will bolt in place of a 403, but they are not the same exterior dimensions.

Thanks,  I knew there were some things in common.  Apparently I didn't know about the deck height.  I was just aware they they could be R&R without a hassle.

Ed

Edited September 24, 2019 by RivNut (see edit history)

[MrEarl]

1 hour ago, telriv said:

ALSO, since the 455 has a higher deck height the T/A hood scoop is taller & makes the hood bulge with closing.

 

Hey Tom, the subject vehicle here is my '79 wagon which I failed to mention.

[RivNut]

I think that Mr. Earl, knowing that some Rivieras came with a 403 Olds engine, wanted the opinions of owners of those Rivieras to give their opinions of the engine.  His Estate wagon has an Olds engine in it and he's looking for more power.

[Seafoam65]

One thing you want to watch out for when you assemble the engine is the funky giant metal pie pan intake manifold gasket.

If you don't put a bead of silicone around each water  coolant passageway on either side of the metal gasket, you will get coolant in your oil

or an external coolant leak or both. Ask me how I know! Also, only use the Fel Pro rubber valve cover gaskets, not the cork ones or you will have leaking valve cover gaskets two years later. Again, ask me how I know!

[joe_padavano]

9 minutes ago, Seafoam65 said:

One thing you want to watch out for when you assemble the engine is the funky giant metal pie pan intake manifold gasket.

If you don't put a bead of silicone around each water  coolant passageway on either side of the metal gasket, you will get coolant in your oil

 

As directed in the Chassis Service Manual. This is especially important if there is any pitting from corrosion around those ports. I've this to be more common now as these parts are half a century old.

I'll add that the rubber end seals are worthless. I throw them away and build up a bead of RTV on the end walls of the block. Permatex Ultra is the best I've found for this and for the bead around the water ports.

[1965rivgs]

1 hour ago, joe_padavano said:

 

As directed in the Chassis Service Manual. This is especially important if there is any pitting from corrosion around those ports. I've this to be more common now as these parts are half a century old.

I'll add that the rubber end seals are worthless. I throw them away and build up a bead of RTV on the end walls of the block. Permatex Ultra is the best I've found for this and for the bead around the water ports.

That manifold gasket is a PITA...I use "The Right Stuff" and have been very staisfied with it.

Tom Mooney

[1965rivgs]

9 hours ago, MrEarl said:

Just a thread to talk about and give thoughts and opinions of the Olds 403's in the '77 and '78  Rivieras. I know there aren't a lot of those years out there and would be curious to know how many came with that particular engine. Anybody here done any performance upgrades to theirs?  Askin for a friend 😄

Hi Lamar,

  I had a 403 in a `77 Olds 98 coupe with big miles and I didnt have any problems with the motor except an intake gasket leak and if I recall correctly I had to replace some rocker arm hardware due to tick, tick, tick.....

Tom Mooney

[joe_padavano]

54 minutes ago, 1965rivgs said:

That manifold gasket is a PITA...

 

Not really. There are four locating bosses, one in each corner, that fit into holes in the cylinder heads. These locate the gasket correctly and also "snap" it into place so it doesn't move as you set the intake down. I dry fit the gasket first to ensure those four bosses are in the right place. There was a batch of FelPro gaskets a few years ago that had one of the bosses located incorrectly - I saw this first hand. Other than that, no issues in over 40 years of using them. The bigger problem is the weight of the factory iron intake, especially on the big block. My back is getting too old to lean over the fender trying to lower that into place! 😮

 

The last time, I actually used my engine hoist for the intake.

 

 

[1965rivgs]

15 minutes ago, joe_padavano said:

 

Not really. There are four locating bosses, one in each corner, that fit into holes in the cylinder heads. These locate the gasket correctly and also "snap" it into place so it doesn't move as you set the intake down. I dry fit the gasket first to ensure those four bosses are in the right place. There was a batch of FelPro gaskets a few years ago that had one of the bosses located incorrectly - I saw this first hand. Other than that, no issues in over 40 years of using them. The bigger problem is the weight of the factory iron intake, especially on the big block. My back is getting too old to lean over the fender trying to lower that into place! 😮

 

The last time, I actually used my engine hoist for the intake.

 

 

  Yes, except for the reasons you listed which make it a PITA and the fact more than a handful of them I did in my 40 year career as a tech DID dislodge and make a mess due to the one piece design of the gasket and the difficulty of placing the heavy manifold, its a piece of cake....🙄

Tom Mooney

[telriv]

For the valve covers. For years I used various gaskets. After 2-3 years they started to leak.  As a last resort I used Permatex Ultra or the Right Stuff

RTV & NEVER had a leakage problem again on ANY olds engine.

 

Tom T.

[Lesabre T-type Chris]

I have been the proud owner of a 1977 Buick Riviera with the Olds 403 for the last 3 years.  Growing up, my parents had several Buicks including a 1977 Buick LeSabre 4-door that I was really fond of as a kid.  As a teenager I drove it until getting a 1985 Buick LeSabre 4-door Limited Collector's Edition.  The '77 LeSabre had the Pontiac 301 V-8 and the '85 had the Olds 307 V-8.  I always wanted a 2-door version of those Lesabres with the Buick ralleye wheels and a bigger V-8--I finally found it in my Riviera as it is based on the GM B-body.  At first I was disappointed to have the 403 because I really wanted a Buick motor.  Over time, though, I have grown to appreciate the 403 a lot.  It really is smooth and quiet.  The 403 in stock form isn't a drag racer but it can get up and go much better than the 301 and 307 motors.  From my experience it is because of the higher torque that the 403 has vs. those other engines.  GM should never have put an engine smaller than 350 ci. in the B-bodies in the 70's and 80's because of their weight.

 

I, too, have been doing a lot of research on the 403 and have found that it has a lot of potential.  I am in the process of making plans to add some performance capabilities to it.  Recently, I took the plunge and had a true dual exhaust installed.  That has made a difference in performance for sure.  The engine can definitely breath better and is more 'eager' to squeal the tires.  These cars came with 2.41 gears in the rear standard (highway gears) and that hurts them off the line.  The next project for my Riviera will be to change the gears and add positraction to the rear end.  Likely 3.23 or so.  Long-term, I am planning to have the 403 rebuilt with smaller chamber heads to increase the compression ratio as well as a cam that is a little more aggressive (but not too wild).  From the factory, the 403's have some deficiencies with windowed main webs and siamesed cylinders as well as some other small flaws.  That is all corrected pretty easily if you have an experienced Olds engine shop/builder as corrections to rectify these issues are readily known.

 

I'll post a couple pics of her...

 

Chris

 

[Lesabre T-type Chris]

 

[Lesabre T-type Chris]

[J3Studio]

Draft, draft, draft text:

 

"The Riviera was undoubtedly a long way from its unique 1963 status. Along with the platform change, the fifth generation also lost its Buick engines. The new Riviera had only Oldsmobile-sourced power options, both of which were smaller and less powerful than 7.4 liter/455 ci V8 from prior years.

 

[… 1977]

 

The standard powertrain for 1977 was the Oldsmobile-built L77 155 bhp 5.7 liter/350 ci V8 with a four-barrel carburetor mated with a Turbo Hydra-matic three-speed automatic transmission. EPA fuel economy ratings for this combination were 15 city/22 highway by the standards of the day—about a 23% improvement over 1976. The Oldsmobile-built L80 185 bhp 6.6 liter/403 ci V8 with a four-barrel carburetor was available for $65 and dropped mileage ratings slightly to 15 city/21 highway. Both the L77 and L80 were available in California-specific versions, which, unlike the Federal versions, gave no rear axle ratio options. The L80 was also available in an “Altitude” version—sold in the Denver area and adding another $22.

 

[… 1978]

 

The standard powertrain continued to be the L77 155 bhp 5.7 liter/350 ci V8 with a four-barrel carburetor paired with a Turbo Hydra-matic three-speed automatic transmission. EPA fuel economy ratings for this combination were 15 city/22 highway by the standards of the day. The L80 185 bhp 6.6 liter/403 ci with a four-barrel carburetor was available for $65 and was rated at 14 city/20 highway."

 

 

 

[MrEarl]

Interesting MPG figures. Here’s the original sticker out of my Estate Wagon  

I would LOVE to get the 13 as shown, maybe someday. 

 

 

 

 

[J3Studio]

1 minute ago, MrEarl said:

Interesting MPG figures. Here’s the original sticker out of my Estate Wagon  

I would LOVE to get the 13 as shown, maybe someday.

 

 

Love the sticker! The ratings I quoted are from the original EPA guides. I find that many of the pre-1985 ratings are … hopeful.

[J3Studio]

On 9/24/2019 at 12:12 PM, NC1968Riviera said:

The 77 Riv below was at the ROA Annual Meet in Gettysburg this year. It belongs to a ROA member from Texas.

I think it has the 403 and 4 wheel disc brakes. It is a beautiful car!

 

Looking to see if it a) had a sticker and b) if I took a picture of it. It definitely had the four-wheel disc brakes:

 

Edited September 29, 2019 by J3Studio (see edit history)