1969 Pontiac 2+2 427/390 Convertible Barn find - But this one a 4-speed

Howmac · Guru

1969 Pontiac 2+2 427/390 Convertible Barn find - But this one a 4-speed

seventy2plus2 · Canadian Poncho Superstar!

I've got one of the long trans rods if you need one. I bought it hoping to someday make the reverse lockout functional in my 70 Parisienne, but upon hearing how tough the other stuff is to attain I've abandoned the idea.

davepl · Poncho Master!

I need a second eye but I think I have everything - here are my two pics, let me know if this covers it. I've got the two rods on the transmission and then this short third rod with a spring loose.

7_40 AM 1_15_2018 - Bitmap.png

7_42 AM 1_15_2018 - Bitmap.png

davepl · Poncho Master!

Well good news, bad news. Good news on the progress, bad news on some of what I found. But it's actually not as bad as I -expected-.

Got the body stripped; removed the body from the chassis. Got the chassis stripped down. Pulled the powertrain.

Then started on the motor. If you recall, I mentioned it was freshly rebuilt 20 years ago before being abandoned. It turns out that if they would have only put a SHOWER CAP OR BREAD BAG over the carb, then the motor would have been mint. But when we took out one of the plugs... Bloosh. Out came a bunch of water from one hole.

And sure enough, on tear down, that cylinder was about half full of water, which I assume was condensation collected drop by drop over 20 years. As you can see, that one hole is pretty rough now. And since they just went 0.030 over on this pointless rebuild, I get to go 0.060 and hope for the best. My engine builder said he used this very same '512 casting to make a short stroke 454 at 0.100 over, so he's not too worried. But it's just sad that for want of a baggie I'd have a freshly rebuilt motor!

davepl · Poncho Master!

Oh, I forgot some of the "good" news. It all checks out, and is numbers matching. I guess I assumed that, but it's good now that I've confirmed it.

There's no partial VIN I could locate on the trans or rear end, though, I'm only going from date code and so on (and the axle code matches the protecto card).

Looks like the engine was cast in November, mostly. Then assembled in December. The rear end was built in January, as was the frame itself. The transmission is from February (the car is April). So it all works out nicely! Even the distributor is original. Water pump is 1971, replaced under warranty, but that's kind of a service item, you can't win 'em all.

From some chats with John on decoding I found this car doesn't even have a clutch fan, because the clutch fan was still optional on the L36, which is crazy to me. But a different L36 said it was present on the doc sheet, and mine doesn't, so I assume it doesn't get one. On the plus side, the fan shroud is like new, and they're hard to find. So is the four speed console, for that matter!

The car is odd like that - the heater controls are TRASHED but the convertible top switch is MINT, just inches away.

4SPEED427 · A Poncho Legend!

I know you have a builder who is likely a lot more experienced than myself (a backyarder) but experience over the years, mine and others, has shown that the more you bore a big block the greater the risk of it being an engine that runs too hot. Be careful, don't bore any more than you absolutely have to.

davepl · Poncho Master!

I do like to brag on my engine builder because I normally build all my own motors. But he was a professional Winston Cup engine builder for a successful NASCAR team for a long time, then he got old and retired back up to my area, and putters around one motor at a time, so how can you NOT have a guy like that go through your engine while you ask 1000 questions?

I'm honestly not sure that overbore overheating isn't a bit of a wive's tale. At least I can't think of why... if anything you're moving the cylinder a touch closer to the water jacket, so, in theory, it should cool faster! But I don't actually know for sure. I think some of it may be that people bore a big block, make a bunch of other perf increases at the same time, it makes more heat, and they blame the overbore.

I might add a clutch fan if the fixed fan is super noisy, but will start out in the stock config, as I'm hoping to be 100% stock except for points, belts, and radial redlines.

bjburnout · Uber Guru

Carl Stevenson wrote:
I know you have a builder who is likely a lot more experienced than myself (a backyarder) but experience over the years, mine and others, has shown that the more you bore a big block the greater the risk of it being an engine that runs too hot. Be careful, don't bore any more than you absolutely have to.

......if the other 7 cylinders are OK then consider a sleeve for the bad one and a hone for the others.

Your machinist would then match they cylinder to the others and you even get away with cleaning up

(read glass bead) the piston. I have sleeved several engines in the past few years and no problem.

My machinist says if done right it is better than the original.

cdnpont · Canadian Poncho Superstar!

Sad that it's trashed. And strange how only one cylinder was full of water?? But one good thing is you'll now have 438ci at .060 over.

I'm 60 over and I run super cool in my 496. No issues there. I think a top notch cooling system is key though. I've read that the 66-69 427 blocks can go way over with no concern. The cores were apparently very thick. Thicker than the 454's. You have a pro builder, so he'll take a ultrasound of the bores before cutting I'm sure.

Hey, might as well hide a 4.0", or a 4.35" crank and a 6.385" rod in her while you're at it... Just kidding, the 3.76" stroke 427 is a sweet revving motor, and with that little boost of displacement shell be really nice.

seventy2plus2 · Canadian Poncho Superstar!

I see the block had the high distributor casting, so it's a very early 3963512 block. Mine are the low distributor castings.

davepl · Poncho Master!

My builder noted it as a "high tower" casting as well. I would imagine (but am not certain) that the date code moved to the bellhousing with the low distributor.

427carl · A Poncho Legend!

davepl wrote:

I might add a clutch fan if the fixed fan is super noisy, but will start out in the stock config, as I'm hoping to be 100% stock except for points, belts, and radial redlines.

My big block was 60 over and would not heat up or over heat . Will you have to declare the 60 over as "none stock" in judging ?

bjburnout · Uber Guru

427carl wrote:

Will you have to declare the 60 over as "none stock" in judging ?

.......shouldn't be a problem Carl........even NHRA allowed .060 over in their 'Stock' classes back in the day... smile

427carl · A Poncho Legend!

bjburnout wrote:
427carl wrote:

Will you have to declare the 60 over as "none stock" in judging ?

.......shouldn't be a problem Carl........even NHRA allowed .060 over in their 'Stock' classes back in the day...

Oh cool . I was teasing about judging anyway as long as it looks GM I'm happy most don't know what original is anyway

North · Guru

Ill check the frame on my hardtop and my friends convertible for that triangular thing.

seventy2plus2 · Canadian Poncho Superstar!

Dave, can you post a photo of the triangular thing on your frame? I'm not sure what you're talking about.

davepl · Poncho Master!

Here you go. It's profiled, drilled, and bent to fit, so it's either advanced craftsmanship made to look sloppy or it's factory!

I'll pony up a $250 donation to upgrade the board to the latest vBulletin! It knows which way is up on pictures and you can paste right from the clipboard, which is great for people trying to do pictures in threads...

4SPEED427 · A Poncho Legend!

davepl · Poncho Master!

Thanks Carl. If there was a shorter path to that than loading the picture into a paint program, rotating it twice, and reuploading it, let me know!

cdnpont · Canadian Poncho Superstar!

I think all the 69 frames, HT or rag had that gusset on the drivers side. At least 2 of the 69 frames I've had have had it.

Wonder why they only did one side?

Ragtop frame,

,

HT frame,

seventy2plus2 · Canadian Poncho Superstar!

The 69 2+2 hdtp frame that I put under my 70 Parisienne had it. I wonder if it's for the self leveling suspension to bolt to.

davepl · Poncho Master!

I found the VIN on the frame today - boy, is it ever faint. You can barely see it, and I can't capture a photo of it. But it's there.

Convertibles are in fact a different frame than everything else. Wagons, coupes, everything seems to share 3939115. My convertible is stamped 919113 and the convertible part number is 3919113.

So, in summary, only two different frames: convertible and "all other".

BUT, my Dec 1970 parts book says frame 3972707 supercedes 3939113, and is used for "ALL".

Does anyone know what "BUDD" means on a frame? It's referenced in the parts book too.

-- Edited by davepl on Friday 19th of January 2018 06:32:43 PM

CDN2PLS2 · Uber Guru

Budd is the frame supplier.There was a plant in Kitchener.

427carl · A Poncho Legend!

Here is a 66 does this help to "show"

66 frame #'s.jpg

StriperSS · Poncho Master!

davepl wrote:
I found the VIN on the frame today - boy, is it ever faint. You can barely see it, and I can't capture a photo of it. But it's there.
Convertibles are in fact a different frame than everything else. Wagons, coupes, everything seems to share 3939115. My convertible is stamped 919113 and the convertible part number is 3919113.
So, in summary, only two different frames: convertible and "all other".

BUT, my Dec 1970 parts book says frame 3972707 supercedes 3939113, and is used for "ALL".
Does anyone know what "BUDD" means on a frame? It's referenced in the parts book too.

-- Edited by davepl on Friday 19th of January 2018 06:32:43 PM

That would mean that convertible frames were .eady gone from the parts system by the time the 1970 book was released, and the next part number would bolt up, although not necessarily a convertible frame