I cleaned up my Tri-Power front secondary carb today and took a few pics. Tri-Power secondary carbs have no choke or idle mixture screws. The throttle plates are thicker and designed to close off tightly so as not to affect the idle mixture. Top view of the carb where you can see the large vacuum diaphragm that was used to actuate both the front and rear secondary carbs depending upon engine demand (wide-open throttle). That vacuum actuator is huge (camera perspective makes it look even bigger), it has to be in order to pull those two carbs wide-open. A look at the linkage from the actuator to the throttle shaft. I removed the actuator since I'll probably be using 1965 - 1966 manual-trans mechanical linkage instead. All Pontiac Tri-Powers had vacuum actuated secondary carbs up until the introduction of the 1965 GTO stick-shift engines. All GTO auto trans Tri-Powers were vacuum actuated. A lot of Tri-Power owners didn't like the scary one or two seconds that the vacuum-controlled secondary carbs took to close after lifting off the throttle, and who could blame them. Many were converted to aftermarket mechanical linkage and some owners had the Tri-Power setups removed altogether and replaced with a standard single 2-barrel or 4-barrel. I checked the angle of the throttle plates at wide-open position and found that they don't open all the way. Very likely this was engineered into the setup to keep from adding too much airflow for the engine to handle. Here's the stop on the side of the throttle body.
years ago had 400 street Pontiac, with little bracket racing. Lots of miles - forget now. Torn down for rebuild & shocked to find bearings like new. needed hone & rings - sold to convertible firebird rebuild. great motor - great post thanks for post.
Today I decided to check the condition of the reverse-flow cooling system pieces. So off came the valve covers, intake manifold and valley pan. The water pump still turns freely and the pump cavity looks to be in pretty decent shape. After removing the balancer I can see the primitive cork front seal assembly has long ago stopped doing any sealing. Getting the front cover cut for a modern neoprene lip seal is definitely on my list of things to do. Timing cover assembly removed, there's really no other way to get access to the cooling tubes in the heads since the rubber connecting hoses are rock-hard. First peek at one of the thin stainless steel cooling tubes, driver's side shown here. I was sort of wondering if they'd even be in there at first. Passenger side tube, clearly somebody in the past just crammed in the last bit and made a mess of the end of the tube, worse than on the driver's side tube. I managed to straighten the end of the tube enough using long needle nose pliers and a thin screwdriver to be able to coax it out. Here you can see one of the gusher holes in the tube that directs the coolant toward the valve seats. Here's the cooling tube in all it's glory, there's really not a lot of information or pictures of these things available. The cavity in the head is cast so that you can't insert the tube in the wrong orientation. The driver's side tube was a lot more stubborn, I ended up using a C-clamp to hold the pliers tightly and then I tapped on the clamp with a lead hammer to finally free it. Here again you can see the gusher holes in the tube pointing inward toward the valve seats. Driver's side tube laid out for inspection. I'll have to do some careful straightening of both ends of these tubes before putting them back in the heads. Another attempt at showing the shape of the cooling tube cavity in the head. Cooling elbows after extracting them from the old hoses. Timing cover ready for a long soaking in some cleaning solution. I stuffed some rags into the cooling passages at both ends of the heads to keep any errant coolant or rust flakes out of the engine while I flip it upside down. Some nice green coolant trickled out, a good sign. The bottom end looks fairly clean. A closer look at the heavy webbing cast into the lower end of the passenger side of the block. A better look at the thick front main cap. Measuring the the cap thickness with my cheap Harbor Freight garage calipers. We have a 1.375" measurement. All of the connecting rods have their corresponding cylinder numbers stamped in, telling me that someone's been inside here before. Not only that, I see clear evidence of some knurling on the piston skirts as well. I pulled the windage tray and dipstick tube, exposing some pretty clean-looking rear crank counterweights. The oil pump pickup is pretty clogged-up with crud, I'll probably treat this old soldier to a lightly used modern Melling M54D 60 psi pump and pickup before buttoning it up.
I've never seen an oil pan in better shape than this one. Imagine that, the oldest Pontiac engine I've ever had the pleasure to play around with has the most perfect oil pan, not a dent or ding to be seen. It was also the filthiest one I've ever had to clean. Oil pan porn. Here you can clearly see where the new for 1959 Pontiac light blue paint dripped down the sides of the pan while the engine was being painted on the assembly line over 56 years ago. Back on again keeping dirt out of the 389. The timing cover cleaned up pretty nice too. I can't believe how heavy it is.
A member of another website where I'm running this same thread subject pointed out how deep the '59 pan looked compared to later pans. I really hadn't noticed it myself, but I was curious and got out the tape measure. I measured my '64 421 HO oil pan and it is 6-7/8" deep at the center of the flat portion of the sump to the top of the pan rail. The 1959 pan measures 7-7/8" in the same spot, one full inch deeper. So here's a factory deep-sump Pontiac pan for those who know what to look for in the boneyards.
I took apart a few more things before the holidays are over with. Tomorrow it's back to work so there will be less time to fiddle around and clean filthy old engine parts. I removed the fuel pump eccentric, the timing set and the cam thrust plate. Everything came apart easily without a fight, I gently pried with two long screwdrivers on each side of the cam sprockets and slid them off without any fuss. The timing chain is a bit stretched, but really not all that bad. Being in decent shape tells me that it was serviced not all that long before the car was sent to the boneyard. It will be replaced with a good used double-roller set I have kicking around. Trying to ID the cam here, not quite sure what that stamping indicates. The factory stock '472' cam would have letter stamp 'D' on the nose. Not that it really matters all that much, I just want to know for the sake of learning the history on this old 389. This old worn cam will be replaced with a good used 068 cam and lifter set, that is if it all checks out good. If not, I'll buy some new parts. Here's the fuel pump eccentric assembly that also serves to fasten the upper timing sprocket to the nose of the cam. Note that the outer sliding ring on the pump eccentric is not trapped or held onto the inner eccentric other than by the fuel pump drive arm, unlike later designs. This means you can't run the engine with an electric pump by just simply blocking off the pump opening in the timing cover with a plate, you must remove the timing cover and take off the outer ring so it won't foul up the works in there. The distributor slipped right out, often on Pontiac engines they're stuck tight from varnish buildup. I've struggled with these in the boneyards and given up and left them there, even after standing on top of the engine twisting and tugging with all my might while using penetrating oil or solvent to loosen it. Turns out it's a distributor that's used on a lot of '64 -'66 GTO engine applications, part number 1111054. I have the same 1111054 distributor that's been rebuilt and re-curved in my '64 421 HO. Looks to be in good shape, so I'll give a good wiping down and use it as-is after putting a new set of points in it. These old iron-body distributors are very nice and accurate. The shaft bushings don't seem to wear out on them easily, they're a very good basis for a performance distributor build. Here's the sexy, professionally restored/rebuilt 1111054 that now resides in my '64 421 HO. Back to sleep until next time, I left the oil pan off to give the last bit of dirty oil a chance to drip out.
It'd make a great engine for a 62 Tempest 2 door sedan with '64 rear suspension, Muncie 4 speed etc etc. Or any other car for that matter.
Been considering shoehorning it into a '61 Tempest, it has the split grille that resembles a '59 big Pontiac. Either that or into a fenderless channeled Model A roadster. Doug Nash 5-speed already sitting here.
I was told by the guy who sold it to me that it was a 57 tri power intake. however it takes three small base carbs. and the casting date ends on zero? ive been wanting to install it on a 55 GMC 287 engine.
What you have there is a 1958 Tri-Power intake from a 370 engine, 1957 & 1958 Tri-Powers all used 3 small-base Rochester carbs. It is easily identified by the casting # 529571. 1959 was the first year that the end carbs were large-base Rochesters, all the way through 1965 all Pontiac Tri-Powers were that way. In 1966 they finally went to the large-base center carb, after that Pontiac pulled the plug on Tri-Power engines. I wouldn't put too much stock in the casting date, it easily could have been cast later than '57 or '58 as a service replacement part.
Thanks. Im planning on installing it on my GMC 287. and just running on the center carb. The end carbs will be dummys. I know the little 287 don't need a tri power. Its just the look im after. I plan to install it in a 66 GMC truck. The 55 GMC is just too rusty it wouldn't be cost effective to try and save it. Now If I could find a 59 389 all three carbs would be working.
Tossed a few items on our shipping scale at work. The bare iron timing cover weighed in at a whopping 18 pounds. The water pump added another 4.5 pounds. Tri-Power intake weighs 39.5 pounds. Comparable to the weight of the popular 4-barrel '67 -'72 iron Q-jet intakes that are known to be excellent performers on both street and mild race Pontiacs. The 2-barrel intake weighs 38.5 pounds, surprisingly just one pound less than the Tri-Power.
I removed the oil pump, took it apart and cleaned it up. Here are a few of the differences between it and the later Mellings M54DS 60 psi replacement pump. To begin with it has helical pump gears in it, something I really didn't expect to see. Melling straight-cut gears on the left, 1959 OEM gears on the right. The pickup tube on the Mellings pump is .750" O.D. with the 1959 pickup tube measuring only .575". Here's a look at the pump castings themselves, note the different angles of the relief valves. The pump cavities look very much the same on both, no real differences that I could detect.
Thank you sir for an excellent tech thread.One of the best that I have seen. Good luck.Have fun.Be safe. Leo
I put most of the cleaned-up parts back on the 389 so I can begin figuring out mounting it on a test stand that I'm trying to put together. Starting to look more like a hot rod engine now with the Tri-Power intake perched on top. The thermostat housing shown here is from a 1965 Tri-Power, I also have 1964 and 1966 housings I can use depending on which way the radiator hose needs to go. I may even decide to search out a 1959 housing that has an engine lifting loop built into the casting. I put the front cover and water pump back on temporarily so I could check out the fit of the water pump pulley I was able to find a few days ago. Everything lines up just like it should. Also found a nice 1959 distributor, just for the sake of having as many 1959 parts as possible on this engine. This old iron body distributor features an oiling cup, you add a few drops of motor oil to keep the upper distributor bushing lubed every 1,000 miles. Distributor ID tag shows part # 1110943.
A tale of two filter adapters will be told here to show that you can use either the 90-degree or the angled spin-on filter adapter on the early '55 -'60 blocks. The blue filter adapter is the 90-degree one used on B-body big Pontiacs and first-gen '67 -'69 F-body Firebirds. The angled filter adapter is used on all A-body GTO/Le Mans/Tempest and second-gen '70 -'81 F-body Firebirds. Note that the 90-degree adapter has the oil sender coming straight out the side, while the angled adapter has it coming out towards the rear. The angled adapter is shown here installed on the '59 block. As you can see here it's a very close fit. Same shot, but this time with the stick shift bellhousing in place. As you can see there's plenty of clearance between the filter and the bellhousing. The only point of interference was the head of this bolt, if there is a lock washer underneath it it hits the filter. The answer is to either go without the washer or shave down the head of the bolt a little. Here's the 90-degree adapter installed, there's tons of room between it and the engine block. Side view of 90-degree adapter. Side view of the angled adapter.
Started building the test stand today. First order of business was to liberate the engine from the engine stand. For those of you who aren't comfortable using a lifting plate, here's close to 700 pounds being supported by the four 5/16" carb studs on the 2-barrel intake. Here's the main reason that these older blocks don't get used for many engine builds, the odd-ball '55-'60 bellhousing bolt pattern. This, along with the fact that the block doesn't mount the starter. I attached my 1960 stick bellhousing so I can build the rear test stand mounts off of it. The '58-'60 stick bellhousings will accommodate the stronger and more modern stick transmissions. To start with I used some 1.25" wide by .250" thick metal strap iron to locate the bellhousing approximately where I want it on the test stand. There's plenty of clearance between the floor of the stand and the oil pan as well as the lowest hanging item, the road draft tube. With the rear of the engine somewhat secure I can move on to the side engine mounting. Here's why you never throw anything away made of steel that might be useful later on, a pair of camper hold downs that I almost sat at the curb for the scrappers. After about 2 minutes with the Sawzall and I now have these, 2.50" wide by .375" thick material already bent very close to the shape I need. They'll work out just perfect here. The supports tuck in nicely to clear any type of exhaust that I might need to use. After drilling a hole for a 1/2" bolt, they're now attached to the mounts and supporting the front of the engine. I'll weld the bottoms of the support legs to the pieces of channel that were cut off from the camper hold downs, then bolt the channel to the floor of the test stand. Now to do something about mounting the bellhousing properly, this certainly won't do as it now sits. After some cutting and drilling using the same two pieces of material we're good now All self-supporting and stable, even without doing any welding on the front supports. That's it for today.
I did some work on a customers "59" convertible awhile back. I had to pull the pan and was I surprised to see 4 bolt mains. I never new 4 bolt mains where used that far back. The owner of the car couldn't care less. He just thought the tri-power was neat. AAARRRRRGGGHHHHHH.
Today I wanted to try to get some compression numbers, just to get an idea on the general health of the engine before I tear it down any further. I put the auto trans bell and flexplate back on it along with the starter motor so I could run the compression test. I also installed a nice tight lightly used double-roller timing set. This way the valve action wouldn't be retarded because of a loose chain, perhaps giving me a better chance of getting some decent compression readings. I pirated a couple of good used battery cables from my stash and hooked up the battery. I also put the 2-barrel carb back on and blocked the choke plate and throttle linkage wide-open, to better simulate a test you'd do on a complete engine. Now I'm ready to do some testing. Since the engine is obviously cold and the lifters aren't pumped up the readings won't tell the whole story, but here they are: 1 - 110 3 - 80 5 - 65 7 - 105 2 - 95 4 - 70 6 - 65 8 - 110 Tested again after adding a squirt of Marvel Mystery Oil to each cylinder: 1 - 120 3 - 100 5 - 100 7 - 115 2 - 80 4 - 80 6 - 70 8 - 130 So at this point I'll let it sit for a week to give the MMO a chance to soak into the rings a bit more to perhaps free them some and test again, then I'll pull the heads.
My mostly untouched 389 gives 130-135 readings.It has edel performer plus camshaft (original was worn out)with new lifters and timing gear. My sun distributor tester data card claims that correct reading should be 170psi, if i remember correctly. Of course i talk my 59 2bbl 280hp similar engine. interesting to see what you find when you take yours apart.
What a great thread for us Pontiac lovers. My Dad and I rebuilt a 1960 389 that we found in a wrecking yard way back in '65 or '66. It had the 3x2 set up intact and 4 bolt mains, windage tray. I remember pulling out the stainless water tubes - what a pain. We had new ones to install back then! The 389 replaced the little 287 inch motor that powered our family V-drive ski boat. We rebuilt it with factory parts, since my Dad's friend was the parts manager at Dolman Pontiac in Inglewood, Ca. Even a factory performance cam (can't remember which one) We kept the 3x2s on it and added a complete Edelbrock marine conversion kit and Cal Custom valve covers - it looked bitchin'. That engine ran great for the next 15+ years and was still running great when he finally had to give up the old boat to make room for a newer one in the late '80s. I think your old 389, all freshened up, would be a perfect match for that Tempest!! Here's Dad's pride n joy (the 3x2s eventually swapped for a single Holley)
The Jalopy Journal
