1970 Oldsmobile Cutlass

[Der Bugmeister]

Back in late 2016, a friend put me onto a 1970 Cutlass for sale.  The story was that it had been put into a storage locker in 1996 and had sat there untouched ever since. 

My first viewing of the car was on a rainy November night with flashlights as there was no light in the storage locker.  The only other thing in the locker was a motorcycle which had also been tucked away for years.  The car still shone through the many years of accumulated dust, with drywall seam tap hanging from the ceiling.

The car had been repainted a couple years before being stored, and appeared to be very clean and complete.  The interior was white bench seat and original (worn) upholstery.  At some point the original 350 had been replaced with a later, anemic 260 (an uninspired V8 smog motor).

Although I already had 3 Cutlasses at home, this one was in much better condition than the others.  I tried not to look too excited when the seller told me his asking price...we shook hands and I basically stole the car.

[skfarmer]

looking forward to seeing cutlass updates.

i am an old olds fan.

[goodfellow]

looking forward to seeing cutlass updates.

i am an old olds fan.

Absolutely SK, it's been way too long.

[Der Bugmeister]

I'll just say "Progress has been made" for now...and leave y'all hanging while I post my way through the project.   

We pulled the car out of the locker where it had sat for 20 years, fed it some gas, primed the oil and cleaned the points, and...she fired up, and sucked gas from the gas tank (fresh gas)!

So I drove her home...about a 15 minute drive on back roads with some pretty spongy brakes. 

[Der Bugmeister]

Once home, a wash cleansed the accumulated dust and grime revealing a pretty damned good looking car!

First time running in 20 years:  https://www.youtube.com/watch?v=5eY4AoeqWUc

I'm behind the camera...the first fella leaning into the engine bay is my Oldsmobro who is currently helping me with the rebuild.  The other guy leaning in to flick the throttle was the seller.  The one who got into the car and tried a "one wheel peel" with that glorious 260 was my friend who connected me with the seller.  Unfortunately he passed away a few years ago.

Here's the car cleaned up.  The engine tick cleared up pretty good by this point although I really wasn't too worried about the engine's health.  https://www.youtube.com/watch?v=PwknXpaSW8Y

[Der Bugmeister]

I tucked this one into the shop while I thought about what I would do with it.  I had been debating a big block swap into my other Cutlass but was reluctant as that car has some family history and is a real survivor.  Great driving car as is. 

This new one was far from original - incorrect engine, colour change, Chev Nova wheels, etc...but obviously really clean.  I had a good Olds 350 on a stand but also had an Olds 455 potentially a good runner.  While the car sat, I acquired another 1970 Cutlass (not in this photo) which had a black bucket seat interior, console, posi rear diff and a few other shiny items.

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So, I pulled the engine although I hadn't decided whether to just drop in the 350 (quick upgrade) or the 455 (bit more to it).  Then other priorities got in the way and the car basically sat in this state until 2021 or 2022.

[Der Bugmeister]

In 2021 I decided to embark on a fairly low budget refurbishment of the car.  I had the 455, a TH400, a couple posi rear ends to pick from and that black bucket seat interior. I'd also picked up a wing for the trunklid and an OAI hood with the intent of building a car with the look I wanted.

The 455 had apparently been rebuilt and ran well when the donor car was parked over a decade earlier.  It turned over easily by hand, plugs looked decent and generally seemed to just need a cleanup.  After talking to a mechanic friend and hearing the list of things he would do to it before running it on the street it seemed like a rebuild was the best route.

A long story short, the budget had to grow.  The engine builder I used (a local one with a good reputation) suggested I source the parts myself, and made a lot of noises about the old iron heads I had wanted to use.  I translated those noises to "it will cost you just as much to use these as it would to buy new aluminum heads".

So the budget grew.

In the end I sourced the vast majority of the engine components from Bernard Mondello Racing Engines.  Bernard has been building Olds engines for decades following in the footsteps of his dad, Joe Mondello.  I'll get into the engine specs in another post.

With the engine shaping up to be more power than planned, I decided that the car really needed a third pedal to complement it.  Rather than chasing down 50 year old used parts and hoping what I bought was correct and functional I decided a Tremec TKX 5 speed was in order.

The budget grew.

This led to the determination that the gear ratios in the two rear ends wouldn't be good with the rest of the drive train.

Yes, the budget grew.

[Der Bugmeister]

So in late 2021 I took the engine block and crank to the machine shop.  Apart from some odds and ends, they were to be the only original parts used.  The shop does good work but is also known to take a while getting it done. 

One delay was the heads.  Edelbrock had discontinued their big block Olds heads while they redesigned a new generation head, and I had to wait a long time (a year?) before they shipped.  It quickly became apparent that the new heads suffered some quality control issues so I had Bernard run his blueprinting program on mine.  That way I knew the ones I got would be good - he'd already refused a few heads that were out of spec.

Knowing the timeline on the engine would be lengthy, I figured I'd have time to clean up the front end, frame, swap the interior and be ready when I got it back.  Well, that all changed big time...but more on that later.

I told Bernard that I wanted the power band to be usable on the street at lower RPMs.  Apart from some stop light racing it's unlikely to see serious competitive use.  Based on that, I wound up with:

1969 Oldsmobile 455 bored .030 over for a displacement of 461 c.i.
Stock "N" crankshaft
Scat H Beam Rods
CP/Bullet pistons
Hydraulic roller cam with 4/7 swap (Howard's Cams, intake 0.56 lift, 278.6 duration exhaust 0.566 lift, 284.6 duration)
Harland Sharp 1.6 ratio roller rocker arms and rockers with poly locks
Cloyes roller timing chain
Cam bearings with grooved back (better oiling)
BHJ billet harmonic balancer
ARP head bolts, rocker studs and main studs
Full length windage tray
Low profile 7 quart oil pan
High volume oiling system
MSD ready to run Ignition System
Edelbrock Performer Intake with divider modification
Quick Fuel SS 850 with mechanical secondaries
Edelbrock Cylinder Heads blueprinted by BMRE
RobbMC high output mechanical fuel pump
Compression ratio is right about 10.1:1

The engine went on the dyno in December 2023 and made 504 hp at 5300 RPM and 570 ft/lbs torque at 3800 rpm.

Here's one of the dyno runs (volume up!!!)  https://www.youtube.com/watch?v=gYaCWEQZnWc
Bonus video:  https://www.youtube.com/watch?v=5cqOm5pIlO4

[Der Bugmeister]

With the scope of the engine build expanding way beyond the original vision, I figured I wouldn't be satisfied with the automatic transmission backing it up...notwithstanding whatever transmission I used would need to be robust enough to stand up to the higher than stock power the engine would be pushing through it.

Yes, I needed a third pedal!

While I could have tried to find the parts for a conversion to an original Muncie transmission, those parts are hard enough to find never mind trying to find them in my local area.  The uncertainty of whether each part I found would be the correct part and in good working order led me to purchase a new Tremec TKX 5 speed with everything needed to convert the bench seat, column shift, automatic car.

The TKX is a fairly recent offering, redesigned with a slimmer body to allow installation in most cars with little to no tunnel modification needed.  In my case, I had to cut a small relief hole in my tunnel but no major modifications like would have been required with the TKO 6 speed.

If you can't make it out, the box reads "Warning - use of this product is addictive and may lead to burnouts and traffic violations."  Fair!

[Der Bugmeister]

When I embarked on this journey, I had two Oldsmobile rear ends with limited slip differentials (posi, of course) from which I figured one would work out well.  One of them was in my parts pile and the other was still installed in the 1970 parts/donor car.

Let me tell ya, identifying the rear ends from the cars of this era is anything but simple.  In the end, I was able to confirm that the one in the pile was an Oldsmobile "corporate" rear end with 3.08 gearing.

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These rear ends can throw people off the track.  The cover has 12 bolts, but the ring gear is an 8.5" 10 bolt.  These aren't the same as the GM 10 bolts and the gearing options available are quite limited.

The other rear end was a GM 8.5" 10 bolt with bolt in axles.  No circlips to flip off at the wrong time, these use retainer plates at the outboard end of the axles and are preferable for this application. The gear in this one was a 2.73.

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After a lot of discussion with some people far more knowledgeable than me, I decided to use the GM 8.5" for the build.  Unfortunately it turned out that the posi carrier was a less desirable two piece unit from Borg Warner, and was very dirty and worn.

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[Der Bugmeister]

After looking at the transmission gearing I figured I wouldn't be too happy with either of the rear end ratios.  The options and availability of parts for the GM 8.5" led me to go with that one as the basis for my project.

Pretty much everything except the housing, bearing caps and backing plates went in the bin to be replaced with a Yukon Duragrip Posi Carrier, 3.73 gears and Moser 30 spline axles.  (The original carrier was 28 spline)

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I sent the housing off for sandblasting and painting, then up for assembly.

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[Der Bugmeister]

Meanwhile, my plan had been to remove everything from the firewall forward to give me access to clean and paint that part of the frame and detail the engine bay.  I had no intention of doing anything to the suspension, only to install a Wilwood Disc Brake upgrade kit which was designed to bolt right onto the brake drum spindles.

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I mocked up the Wilwood brakes to see if the stock 14" rims I was planning to use would fit.  They did.

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Then I discovered that the lower balljoint boots were torn.  Ok, so the spindles had to come out, may as well replace the rest of the 50 year old bushings while I was at it.  I tackled the balljoints and springs, removing them surprisingly quickly.  I found a technique to apply pressure to the ball joints so they'd separate without relying on the weight of the car, etc. 

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[Der Bugmeister]

And this was when it all changed.  After removing the front control arms I stood back (with an adult beverage) to survey the situation.  I realized that I would eventually be removing the rear end for the swap...and the reality was that there were only 8 bolts (turned out it was just 6) standing between me and a frame off situation.

Although the underbody looked fairly clean there were still a couple areas that bothered me.  The main one was under the trunk pan towards the back of the car.  Despite all the previous restoration and rust repair work that had been done on the car, this area was untouched and covered in surface rust.

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This photo shows the underside back edge of the trunk, normally obscured by the rear bumper.  The black cross member is the back of the frame and the newer black undercoat or tar was the edge of some metal replacement on the trunk.

The undercoat on the frame was flaking off in various places although the frame itself seemed to be solid enough.  I had planned to address that at some point in the future when I had time - remove the loose undercoat, treat the surface rust and repaint.  One thing that bugged me about this approach was the inability to get at anything on the top of the frame.

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The body is held on by 8 bolts.  Two at the torque boxes on the firewall, two in the forward part of the passenger compartment, two at the forward end of the trunk and two at the rear corners of the frame.  All but the two at the front are secured with caged nuts and cannot be accessed from inside the car, so I went slow and careful with them.

One suggested approach is using an impact gun - first tightening then loosening, so I used my Milwaukee cordless tools for these.  Between that and the standard handraulic method I was able to remove 5 out of 6 bolts.  The final bolt, at the left rear corner of the frame was spinning.  I assumed that the nut had broken loose from the capturing cage.  The reciprocating saw made short work of that one.

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When we lifted the body off the frame, I was surprised to see the remnants of that mount still sitting on the frame.  It turned out that the mounting point on the body had completely rotted - the large hole through which we can see the remnants of the nut cage should be much, much smaller!

This discovery alone justified my decision to separate the body and frame despite the increased complexity and scope of the project.

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[Der Bugmeister]

With the decision to separate the body and frame made, I had to decide how to actually lift and support the body.  The most popular method seems to be the two post lift, which I didn't have.  My four post wouldn't provide enough height to be successful.  I'd seen people using an engine lift to do it, but with the weight of the doors, decklid and glass still in the car I wasn't feeling particularly confident about carrying that out without drama.

We (my Oldsmobro Steve) and I decided that the best approach would be to lift the body enough to slide a couple 4x4's under the body then use those to jack and eventually support the body once the frame was out.

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I was rather optimistic on my timelines at this point.  Send the frame down for sandblasting while I stripped the undercoat from the body and dealt with any rust.  A couple weeks, maybe a month...or so I thought.

This would be my work view for a while...

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[Der Bugmeister]

I sent the frame to a friend of mine who had an industrial sand blasting setup.  Once he had the frame cleaned, he identified a broken weld...another thing found that made me glad I had decided to go this route.

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He had a professional welder repair it with a plate, and the rest of the frame checked out ok, so it was coated with a self etching primer.

I still had to deal with the rotted body mount area.  The cross member didn't seem to be available aftermarket but I did have the majority of one in useable condition saved from a car I parted a few years ago.  When I cut the section out, I hadn't known I would need what I was after now so the cut wasn't where I would have now loved it to be.  But I could work with it.

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I make no claims, representations or apologies about my welding skills.  They're pretty much non-existent, but the metal is joined and it's gonna have to do.