Technical 1959 Pontiac 389

Recently I picked up an interesting and unique old Pontiac V8, a 10:1 compression 1959 280 HP 2-barrel 389. It was originally equipped with the 529472 letter stamp 'D' cam, the same profile as the 9779066 'N' cam (273/282 advertised duration, .406"/.406" lift). This same '472' cam was used in the 10:1 300 HP 4-barrel engines as well as the 10.5:1 315 HP Tri-Power engines in 1959.

Not sure what I will do with it at this point, but it certainly was worth picking up just to explore the differences between it and the later Pontiac V8s. The 1959 389 block is among the thicker Pontiac block castings if not the thickest. It has extra reinforcements cast into the oil pan rail area on the passenger side and is of higher nickel content than later blocks if I'm not mistaken. The 2-bolt main caps are also about 1/4" thicker than the caps on later engines. This 389 could very well end up as the basis for a late '50s/early '60s hot rod engine project in the future.

This was the first year of the 389 and the last year for reverse-flow cooling. These engines pipe water through the front of the cylinder heads first, then through the block. It was also the first year Pontiac used side engine mounts.

The engine code 'A' stamped in the front of the block just below the passenger side cylinder head indicates this engine is a 10:1 compression 2-barrel 280 HP version. The '295746' following the 'A' is the Motor Unit Number or MUN.



Block casting # on the passenger side 532000 confirms it's a 1959 389 block.



Here you can see the water inlets on the front the the heads and the cast iron timing cover with the corresponding water outlets on either side.







I was pleasantly surprised to see that it looked to be mostly intact after 56 years. Other than a few spliced hoses and various small repairs that kept it running over the years it looks to have retained all of the original equipment.







Cylinder head casting # 531395 was used on all 1959 389 engines. Like all Pontiac heads they featured fully machined combustion chambers. The stamped steel rocker arms were oiled through hollow rocker arm studs that were fed by a long oil passage cast into the heads. Valves sizes are 1.88"/1.60" for the intake and exhaust.





Water pump casting # 518040. This is a 4-bolt pump that was used until the 8-bolt pump and timing cover was introduced in 1963 and used until 1967.



A road draft tube was used on these engines before a PCV valve was standard equipment, this one is still in perfect shape.



Intake manifold casting # 532119.



Note the unusual engine lifting loop that was cast into the front of the intake itself.



What looks to be the original 2-barrel carb.





Both exhaust manifolds are still intact, the passenger side manifold has an interesting cast iron 'Y' connection bolted to it for both sides to feed into a single exhaust. The original canister oil filter has been replaced with a later spin-on filter.



The Dual-Coupling Hydra-Matic trans is very heavy at over 200 pounds, most of the trans case is cast iron. In order to use a 1964 or later BOP pattern trans you must either buy or make an adapter. The trans is held to the block with big 7/16-14 threaded bolts, it wasn't until 1964 that 3/8-16 bolts were used here.

First gear is a low 3.97. Even the 2.55 second gear is steeper than 1st in most 3 speed autos. The transmission is "locked up" once in second gear and uses a unique split torque design that's incredibly efficient. Dual band/dual couplings were the most efficient automatic transmissions around until lockup torque converter trannys became common in the 1980's.



This 389 looks to be a runner as-is with a little clean-up and inspection, it turns over freely by hand and feels like it still has some compression. It's only 56 years old and looks to have been kept out of the elements, by all indications it looks like it should be able to come back to life.

Rebuild the carb, put some new oil in the pan and a new oil filter, squirt a little Marvel Mystery Oil down the cylinders, prime the oil passages and bearings by driving the oil pump counter-clockwise using a tool made from an old distributor, pull the valve covers and oil up the rockers.

First of the 389s and still 99% complete, a great score for a Pontiac guy.

 

Not bad.....I had a '59, 389 but may have damaged a cylinder wall knocking stuck pistons out...needed a BIG bore job. Tried to sell it at swap meets but nobody wanted it....sold it for scrap last summer.
I was able to salvage the complete stick setup from it for my 34 ford project...now has a muncie 4 speed bolted to it behind a 370 Pontiac.

 

Shed a tear when I read you'd scrapped it, but when you're running out of room to store stuff and can't sell it......so it goes.

Found this one (actually it found me through the power of the HAMB) only 20 miles away, so I had no choice but to grab it.

Now to find a cheap '59 Tri-Power intake, and perhaps a '58 -'60 stick bell housing so I can run my old Doug Nash 5-speed behind it.

 

@applekrate builds big cu in pontiacs from these blocks. 577 inches according to his awb tempest thread.

 

Did some cleanup today to get the 389 ready for storage. I did as much cleaning as I could muster before calling it good enough for now.

After a half-hearted effort at trying to separate the engine from the trans I stopped for the day. I only got as far as removing the six nuts from the flex plate to the fluid coupling through the starter hole (bottom picture), but I really don't know how to go about finishing the deed.

Any tips or words of wisdom on how to separate the two would be appreciated, I'm in uncharted waters here.

























Block casting number 532000 is now visible.



Cylinder head date codes are both the same, 'E 28 9'.



Cylinder head casting number 531395.



Timing cover casting number 532444.

 

If the six nuts holding the flex plate to the coupling have been removed, then simply remove the bolts holding the front bell to the rear bell. Then pull back on the hydramatic and carefully lower.

 

Hey, it's looking better with some cleaning. I always liked that "powder blue" color on those engines and the water necks on the heads. Very cool.

 

Nice find. I've got to keep my eyes open for one of these. I've had this secret fantasy of replacing the SBC in my '58 GMC with a 389, especially since a Pontiac V8 belongs under the hood anyway.

 

So I got a question for the masses and hopefully it is not in the text and I haven't missed it.

Does the 280 horse motor use the same heads as the 300/315 horse motors?

 

The 389 makes a good hotrod engine, a wide engine but they will fit in a "A" chassis. This 1959 has been trouble free so far. Nice to see you saving one, good job.

 

Yes, all 1959 V8s used the same cylinder heads, casting # 531395.

I've read that the higher-compression 10.5:1 engines had heads that were milled .030" at the factory.

 

Thanks very much, that's the info I was looking for.

 

A friend of mine had one that he raced (back in the day) it ran some sort of "J" stock or similar. It was virtually unbeatable in NHRA competition. I drove it once @ the old Golden Triangle dragstrip probably 1961 or 62. We towed it over there with his almost new 61 poncho. I drove it in the final against the guy that owned it in his 61...I had to jump on the brakes to keep from beating him and preserve my ride home. Hadn't thought of that in many many years...

 

I have a 60 389 that I was going to rebuild and put in my 40 ponti coupe, that had a 55 v8 in it. I found a 63 super duty that won out. The 60 needs a bore and new pistons and I have a stick bellhousng for it. The whole shooting match can be bought and you too can have one! Gary

 

Cool, so you are already using the same cam, you are just compression and induction away from the high output mill.

 

Today I was getting the 389 ready for storage. I separated the engine from the trans by unbolting the aluminum trans bell from the iron bell housing attached to the block.

Raising the engine with my hoist was the easiest way to accomplish this, after pulling the trans back just enough to disengage the six torus studs from the flexplate.



I set the 389 on an engine dolly that I made from the bottom tray of a discarded shop cart and some tubing scraps.



Now safely parked behind my freshly built '64 421 HO.





I hoisted the trans back into the bed of my truck for now, I'm not sure what I'll be doing with it just yet.

 

I built a '60 389 for my 59 biscayne, they do have some weak points (non heat treated rods, piston cost and availability, valve availability), but make a good hearty motor when done

 

You may be interested in this

 

Did some investigating today to start assessing the condition of this old 389.

Pulled the valve covers and saw a fair amount of sludge buildup, pretty much what I expected to see on a 56 year old engine that had no PCV system for it's entire life.

All in all not too bad nor too excessive, drivers side shown here.



The passenger side clearly has some thicker sludge buildup compared to the other side.



Someone must have removed the driver's side valve cover fairly recently during the engine's lifetime and cleaned out most of the sludge from the underside of the cover.



I had soaked both breather caps in Simple Green for about a week, they're now quite clean inside after a good rinsing. They were completely clogged with crud, obviously contributing to the sludge problem.

The larger drivers side breather has horsehair inside, the passenger side looks to be filled with stainless steel wool.



I removed the carb and saw that a small amount of water had made it into the intake manifold. Not enough that it ran down the intake runners and into any of the cylinders, just enough to leave a small rust puddle right under the throttle plates.



The topside of the throttle plates show some surface rust buildup from the water ingress, but nothing too excessive that won't clean up fairly easily.



Bottom side of the throttle plates look pretty clean, looks like the carb had been recently gone through not long before the car went to salvage.



The carb is actually a 1964 unit from a 283 HP 389 with A/C and auto trans. Pretty much a perfect application matching replacement for the 280 HP 1958 A/C auto carb, only 5 years newer.



Spark plugs (Bosch WR9FC) must have recently been replaced, they look almost new. Cylinders look to be pretty healthy, but the fact that they were not run for very long doesn't really give me a true indication.

Cylinders 1, 3, 5, 7.



Cylinders 2, 4, 6, 8.



I'm going to lube up the cylinders and begin freeing up any sticking piston rings with a little dose of Marvel Mystery Oil.



I used this 3oz oil bottle to squirt a little into each cylinder, trying my best to evenly distribute the contents of the bottle between all 8 cylinders. I'll do the same thing again in about a week to give it time to soak in.



I lubed up all of the rocker balls and pushrod tips with some 10W-30 motor oil.

Surprisingly enough, the distributor not only turned back and forth freely after loosening up the clamp, it popped right out after removing the clamp. No stuck distributor nightmare for me, needless to say I'm pretty happy about that!



Overall the carb didn't look too bad, it just needed a good external cleaning.







After about a half hour of going over it with a toothbrush and some Simple Green it came out looking pretty good.











It took a little wire brushing to get most of the rust off of the top of the throttle plates.

The way I see it, this carb's a runner now.



I did manage to pick up a cast iron 1960 stick shift bellhousing in good condition from a fellow H.A.M.B. member. In order to use a stronger modern stick trans you need to use a 1958 -1960 bellhousing, any of the 1955 - 1957 bellhousings just won't do if you want to use a 'good' trans.

Using a stick trans behind the early 389 eliminates the need for any kind of adapter. If you want to run a modern auto trans like a TH400 you would need to spend about $700 for an adapter from Wilcap.









Here you can see where the starter mounts to the bellhousing, there's no way to bolt a starter to the 1959 block.

Let me tell you, this sucker is heavy!

 

Good stuff I liked your "421" build and this one looks to be another good one.

 

Pulled the intake today so I can clean and reseal it. I also really need to clean out the valley pan that is surely packed with sludge before firing up this 389.

The factory 2-barrel intake takes the large base Rochester carb. To remove it you must pull it towards the passenger side to get it off of the 4 studs that retain it on the drivers side, rather than pull it straight up.





As expected there's plenty of rat droppings and debris sitting on top of the valley pan.



The intake ports look fairly clean with just a thin coating of black deposits. There may have been a vacuum leak from the look of some of the intake gaskets.

Cylinders #2 and #4.



Cylinders #6 and #8.



Cylinders #3 and #1.



Cylinders #7 and #5.



A small amount of water did make it into the #2 intake port, but luckily enough the valve was closed so water didn't get into the cylinder. I'll close the valve and pour a little Marvel Mystery Oil into the port to clean it up a bit, a few flakes of rust should be easily digested without hurting anything.



I stuffed the ports with paper towels to get ready for all the gasket scraping.



The exhaust crossover uses separate steel shim gaskets to seal it on each side, there's actually a formed lip stamped into the gasket that fits inside the port.





Scraped and wire brushed clean, pretty much ready to accept some new gaskets. I had to get these areas as clean as possible in order to minimize the amount of crud that will drop into the engine while removing the valley pan.





The sludge accumulation isn't too excessive for a 56 year old engine, however there were a few large flakes that had come loose from the underside of the valley pan resting in there. After many years of sitting the thin layer of sludge just dries out and flakes off.

Now I can assess the condition of the cam and lifters, there's sure to be a couple of cam lobes that are going flat.



The valley pan will eventually come clean after a good long soaking in some cleaning solution.



The top side will need to be bead blasted, after masking off the underside and any openings in the top side to keep the blasting media from getting inside.



This opening is where the road draft tube connects, as you can see it's packed with crud.



Putting the 389 to bed for the night.

 

Little by little.

After a few good long soakings and several rinsing sessions the valley pan came out pretty clean, probably 95% of the accumulated crud was cleaned out of it.





Going to put the intake back on so I can use my lifting plate to put it on the engine stand. I want to remove the oil pan to clean it out and check on the condition of the bottom end.

First the valley pan.



Now the intake.



Lifting plate installed, ready for the engine hoist.



Warming up the sump a bit with a heat gun to help the cold oil drain a little better.



Dirty old oil - it looked like 4 or 5 quarts drained out, a good sign.



Pulled off the auto trans flex plate and bellhousing. A bit of a strange arrangement compared to the later Pontiac design, first you must remove the flex plate and drop it straight down out of the bellhousing. Next there is a rear sheet metal shield that attaches to the bellhousing with two bolts as well as the two rearmost oil pan bolts, the shield also serves to support the rear oil pan sealing area. After all that you can finally remove the cast iron bellhousing.



Up on the engine stand, ready for oil pan removal as soon as I get some time.

 

Here's a closer look at some of the unusual features of the casting # 531395 1959 heads, all 1959 engines used this head casting.

Valve sizes are 1.88" intake and 1.60" exhaust.



The intake and exhaust crossover port placement is exactly the same as the 1961 - 1964 heads. The bolt pattern is identical as well.



For the sake of intake and crossover port comparison, a 1964 9770716 389 head is pictured at the top, a 1970 #13 400 head below. Port entrance size is nearly identical between the two heads, 2.050" X 1.110" for 1964 and 2.070 X 1.100" in 1970.



Here is a 1964 intake gasket laid over the 1959 head. As you can see the water ports are in a completely different location.



Here's the 1959 intake manifold.



There isn't much material cast into it in the exhaust crossover region, it uses studs, castle nuts and large thick flat washers to clamp down on and seal the ports in this area.

It doesn't use a thermostat bypass port to the timing cover.



1964 intake, showing a lot of added material around the exhaust crossover flanges and different water port placement.





Here is where we will see one huge difference between the 1959 (1955 - 1960) and the '61 - '64 heads. The intake ports are almost the same exact size as the '64 head at 2.050" X 1.100", but the cylinder head itself is .320" taller than the later heads.

The valve cover rail is higher, both cylinder heads have the same .850" measurement from the cylinder head deck to the bottom of the port. However the '59 head measures .720" above the port compared to only .400" for the '64 head.



Note that since the valve cover rail is so much higher on the '59 head it doesn't have the small bump cast into the roof of 2 of the ports to keep the valve cover bolt hole from breaking into the port roof like on the '64 head.

Also take note that there are no openings on the intake side of the head that lead to the crankcase like on the later heads.



Again for comparison here's the round casting protrusion in the roof of the two end intake ports on the '64 head, put there to seal off the bottom of the tapped holes for the valve cover bolts.



Another unusual feature that likely was the main reason the heads were so much taller, are the 4 intake valve guide vent holes in the side of the head just below the valve cover rail. These were put there to provide a vacuum break for the valve guides, to prevent them from sucking oil down into the combustion chambers.

These tall heads must have made these early engines look just a little bigger and wider than their later cousins.



Vent hole diagram from the factory manual.



A closer look at the vent holes.



1959 was the last year that Pontiac used reverse cooling, pumping water first through the front of the cylinder heads and then down through the block. Here is one of the water fittings on the front of the head.



A view of the rear of the head, better showing the placement of the water channel. The small soft plug above the water channel blocks off the ends of the oil passage cast into the head that feeds oil to the rocker studs. All Pontiac heads oiled the rockers through the rocker studs until the introduction of the '63 -'64 9770716 heads, the only exception being the early Super Duty heads.

 

this is a great resource for old Pontiac fans. Nice job reporting all the differences.

 

I picked up a very nice 1959 Tri-Power intake today.

1959 was the 3rd year that Pontiac offered the Tri-Power option, however the large-base Rochester carbs were used as the secondary carbs for the first time in 1959.

Now to find a center carb and a front carb, I already have a rear carb.









Casting # 532422



Date code 'L 15 8' (December 15th 1958)

 

I really enjoyed this thread. Ive got a 55 GMC with the 287 engine. and a 69 400 engine. both have the stick shift. I would like to find a 59 389. Ive got a 57 tri power intake.

 

Thanks for taking the time to do this thread, great step by step information and pictures.

 

Decided it was time to drag out the ol' 389 and drop the pan today. Topped it off with a nice '67 326 2-barrel air cleaner I had laying around just for grins.



The pan practically fell off after removing all of the bolts, the gaskets were old and tired. There was a pretty big leak going on at the rear of the pan from what I could see.



The sludge buildup in the sump was pretty thick, anywhere from 3/8" to 3/4" depending on the shape of the sump area. The drain plug was almost buried in sludge.



Here's what I harvested from the sump, a pretty good amount.





One of the features of the older Pontiac engines was this 'floating' oil pump pickup. Perhaps it was designed to keep the pickup above the layer of sludge that older engines were known to accumulate over time, surely the engineers knew that non-detergent oils and leaded gas would be laying down a decent amount of sludge during the engines' service life.





Here's a look at the windage tray/sump baffle, a design that was used up through 1964.





Very thick #1 main cap, looks to be at least 1/4" thicker than on '61 and later engines.



The connecting rod nuts are backed up by a sheetmetal locking nut, an interesting feature that I didn't expect to see.



Here you can see the heavy webbing cast into the block on the passenger side oil pan rail area, a feature that would disappear from common production blocks after 1960.

 

The exhaust manifolds cleaned up nicely.

Pontiac exhaust manifolds have a nice free-flowing design, much less restricted than the standard exhaust manifolds of most other makes.





I'm particularly fond of the driver's side manifold with the center outlet, purely from an aesthetic standpoint. A pair of these would look great on a fenderless late '20s or early '30s roadster with an open engine compartment.

 

Oh man, how i like such pics of engines...