1969 428 Catalina convertible

[mjs5678]

New here with a couple questions. I bought a 1969 Catalina convertible 428 with allegedly under 60K original miles. It does have original paint confirmed with a digital paint thickness gauge. The car came with the window sticker and protect-o-plate and is all matching without any modifications other than electronic points and after market coil.

My questions are, how unusual is this car and would I be foolish to slightly modify it with front disc brakes and a560229 limited slip diff. and gear and eventually big valve heads? Nothing that couldn't be changed back to stock.

[Ben M.]

It's unusual solely because it's in great shape and 52+ years old. That alone makes it "rare" nowadays. As far as modifications, adding disc brakes and a posi rear or doing some minor motor mods will NEVER result in lowering the value of the car if you use factory style components and keep the factory stance. If you go full airbags, 4" drop, big wheels, or turbo LSx, you'll lose some value, gain some other regarding trying to sell it.

At this point I would drive it and do the disc brakes and better rear end at a minimum just because those things don't hurt value and make the car safer and more fun to drive. Anyone who complains about those mods when you go to sell the car wasn't interested in buying it anyways.

[Stuart]

Welcome to the site, and nice car. I don't know how many were equipped with a 428, but there were only 5,436 Catalina convertibles built out of a total of 212,851 Catalinas of all body styles in 1969, so they weren't common by any means. I agree the changes you would like to make won't detract from its value.

[67GP428]

Welcome aboard Mate! I'm a Big Fan of the 1969 styling over the 68 and 70 Pontiacs. I feel that would be nice upgrades for your car and wouldn't hurt the resale at all. Post some more pictures and info on your car. Have you gotten the PHS yet?

[mjs5678]

I will have to send for the PHS docs. The car was sold in Indianapolis September of 1968. The gentleman I bought it from was the second owner said he got it from his friend. I do know he put less than 5K on the car in the 25 years he had it.

The interior and dash are both in great shape with no cracks or tears, barely any wear! I can tell the timing chain is worn by the way it runs but that will be corrected very soon. Drove it 190 miles home in the rain the day I bought it, first rain it has seen in many years according to the previous owner.

[stevep]

I would do the discs and posi and not worry about it.
A 1969 428 Catalina is a rare car

[Mark Simiele]

Neat car and nice to see a survivor like that still out there in such well preserved cosmetic and mechanical condition. . Good luck with it and enjoy it as you wish. None of those changes you want to do are going to affect anything.

[J GLASGO]

What a cool car!! If you ever get tired of it, call me. 330 6186583 John

[OCMDGTO]

Wow very nice ride! Amazing that the original paint looks that good

[mjs5678]

I was very skeptical when the previous owner insisted the paint was original it just looked too good! There are no swirl marks or even micro scratches in the paint. I have only had the car for just over 8 weeks and haven't even washed it yet, it is dirty in my pics!

Here's a pic of the window sticker and protect-o-plate.

[camerjeff]

Very Nice Ride! I agree with disc front brakes, posi and some engine tuning and enjoy the drive!

[will slow gto]

Sweet Catalina convertible with some nice options. Agreed that adding disc brakes will do nothing but increase value and your enjoyment. Can you confirm that it has the #46 heads? If it has 16 or 62 you already have the large valve heads.

[mjs5678]

I will check the head casting #, installing a new timing chain in a few weeks.

[scottydl]

Beautiful! Body style is almost identical to my 69 Executive coupe, and the story is remarkably similar... mine is almost all original, and I bought it from the 2nd owner who was a friend of the 1st. I've frequently wished mine were a convertible with a 428 also. ;)

[trophy421]

Wow! That car is awesome and rare. Doesn't need a thing except timing chain IMO.

[Diego]

Per the GM Heritage Center, 114 Catalina convertibles were built with the L79 428.

[hawkins69]

Very cool 69, crazy so few were made. My mother drove a 69 2 dr hardtop Catalina Ventura 428 in the late 80s. Probably not near as rare as your convertible

[scottydl]

Per the GM Heritage Center, 114 Catalina convertibles were built with the L79 428.

Where is this info found? I've like to look up my '69 Executive hardtop coupe, 400 2bbl.

[mjs5678]

Wow! I knew it was a cool car when I found it. Had no idea it was that unusual!

[Diego]

Where is this info found? I've like to look up my '69 Executive hardtop coupe, 400 2bbl.

They have a matrix that someone made a long time ago (it's not the Fred Simmonds ones from '89), but they're incomplete. The numbers came from somewhere, but those documents are MIA. That being said, 2,793 were built among all Executives.

[scottydl]

That being said, 2,793 were built among all Executives.

I'd be curious to know the breakdown on 4dr vs 2dr, engine options, etc. but that option may not be available.

Where is the current matrix located?

[Diego]

In a file full of 1969 stuff.

Very little is available in the matix for the big cars. The actual production sheets that exist for some years are non-existent for the 1969s, although I suspect they existed when Fred Simmons did his thing 30+ years ago.

[mjs5678]

My daughter found this posi carrier from a Facebook post. The owner told me about totaling a 68 Ventura when he was 18. Though it had 2.90 gears and sent pictures of a sludge coverd carrier! Went to look at it yesterday was almost 50 miles away. Had rubber gloves on when he pulled it out of the bucket. Started cleaning the ring gear and found 41 12 did a little math on the phone and was very happy to see 3.416 come up! Cleaning it up in kerosene now, looking better already.

[J GLASGO]

Nice

[mjs5678]

Everything is coming together better than I ever dreamed. Looking forward to getting the car up to you John!

[north]

Neat car, never knew the regular 428 was so rare on those cars. Black is an uncommon color on Cat’s back then too! Sweet, keep her nice and original!!

[mjs5678]

Only adding a limited slip with a 3.42 gear and front disc brakes. Rebuilding the suspension and replacing the radiator. Just want a nice driver!

[north]

3.42 will really energize that car. Honestly the 3.42 probably had more to do with an HO feeling stronger than the 428/360 than any actual engine differences.

Disc brake set up for those cars are a bear to find. Best bet is parts cars or even cheap drivers that can be scavenged. In fairness though the big car drum brakes are stout, lots of surface area, not like the junky little A-F body drums. That being said though they will still let you down on a hard long stop so discs are the way to go if you can find a set.

My big cars are a mix of disc and drum cars. So what you need are the following...
Discs, calipers, splash shield etc of course
The big dual diaphragm booster, delay valve and the right HD master (master is available from Cardone still)
The proportional valve on the frame is the same disc or drum but the brake line that runs the crossmember is different.

The spindles are the same so no need to open up the suspension.

[mjs5678]

I think I have all my parts together! Taking the car up to Glasgo Auto Performance on Thursday. Really been enjoying driving the car so much.

The thought of not having a car for 3 or 4 weeks was too much to bear! I am picking up a 67 Grand Prix convertible Saturday!! It's another clean original low mileage car. But that's another thread for next week!

[north]

Here is my Cat. Nicely preserved rust free car. Red guts. Sweet driving car but the 428 was not factory installed. Done right though with a complete stock 69 Bonnie 428-360. Paint looks good in pics but it’s one of those thick early 80’s enamel shoots, cracking like an old cue ball!

One of these days I’ll get it in a paint booth!

[mjs5678]

Very nice! Love the power antenna.

[mjs5678]

Took the car to its first show last weekend, had a great time and met a lot of wonderful people!

[mjs5678]

Last August on a 90 degree day I had a detonation problem! Tore the engine down and found #7 piston with a broken ring land. Number matching block will soon become a 461CID with KRE cylinder heads.

[mr67gp]

Wow-bummer. But it sounds like the block was not damaged beyond repair?

Why the switch to KRE heads? Not knocking them (pun intended :D ), but for a driver application you won't likely notice the advantages they afford. A large chunk of change that could go to suspension upgrades?

Thanks for the update. Cool, unique car.

[mjs5678]

Block wasn't damaged at all, really doesn't have much wear. Just want to build a dependable street engine that has a little more power than it had. The small valve heads #46 I believe are holding the engine back from it's potential . I want an engine that will run on pump gas, 93 octane and from my understanding the aluminum heads will help. I already have a set of long branch exhaust manifolds. So I think the engine with a relatively mild cam should be very streetable with a 85cc combustion chamber, 9.5 CR? While still keeping loads of torque?

I want my Cat to compare to my 68 SS427 Impala I owned when I was 19! I believe the engine I have in mind will do just that!

When I was 19 I owned a SS427 Impala and a 59 vette, red with a white cove!

[mjs5678]

BTW, I have gone through the suspension completely. just want to replace the top eventually. Put a 2100 rpm stall converter in last summer before my "problem". The car is a joy to drive! Converter may haye contributed to my current issue! Really woke it up from a stop!! But I believe the hot day lead to the demise of the piston!

[mjs5678]

Dropped the engine and parts off in Tennessee two weeks ago to a fellow Toyota technician that builds Pontiac engines! I haven't done line work in 7 years. Hope to have it back and installed in August. Looking forward to having a couple more ponies under the hood.

[will slow gto]

That piston is a bummer, glad to hear the block made it out relatively unscathed. Your car is otherwise so original so I probably would have went with some #96 heads to lower compression and increase valve size but it sounds like you’re really enjoying putting your foot in it so the KREs will fit the bill nicely. Your car sure looked great in that earlier snowfield pic among mostly GTOs.

[David Brown]

I had the same detonation problems with my 70 Bonneville. 1970 weas the only year of the high compression 455, and it did not like 93 octane fuel. I monkeyed around with octane boosters and timing for a couple years. Then I got a 6X heads with large exhaust valves, street ported and enlarged bowls to lower compression my Jim Butler. That corrected the pinging.

[mjs5678]

David, I have always admired your Bonneville beautiful car! I hope I am building a pump gas friendly engine. Saving all my original parts if anyone in the future wants to restore it to factory stock!

[mjs5678]

David have always admired your Bonneville, beautiful car! I hope I am building a pump gas friendly engine. I am keeping all the original parts if anyone in the future wants to put it back to stock.

[mjs5678]

Engine is finally back home! Still have all the original parts and a nice pump gas friendly numbers matching block engine! Working on getting an original set of long branch manifolds ceramic coated to install with the new engine. Hope to have everything together to cruise next spring!

[mgarblik]

Your engine looks very good. I have followed this thread from the start. If you were to paint the heads, intake and water pump Pontiac blue, 90% of the people looking under your hood in the future would have no idea the engine wasn't the stock 428. Only the angle plugs would be an immediate give away. Especially if you grind off the Kauffman name. Love your car!!

[ck67goat]

Nice car. I stripped a 69 428 HO Bonneville Convert a while back. I believe I might still have the original discs and calipers somewhere. I also have the HO exhaust manifolds and a few other items such as taillights, front grilles, etc. Feel free to PM me if anything needed.