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1967 Firebird Engine Refurbish

7/17/2020
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Tags: Tech, Tech, Street, Street

My recent purchase of a 1967 Pontiac Firebird convertible has begun a tailspin of long garage nights. I've given myself a short window to get much of the car rebuilt and in running order before the snow hits the ground for a long Nebraska winter. I bought the car in mid-October, and I wanted to get as much work done as I could before the temperature was in the 30s in my garage.

The most significant issue was that the car was mostly disassembled when I got it. The engine was looking like it was swapped a few decades ago, and not much attention had been paid to it since. I believe that the Pontiac motors look great in any engine bay, but maybe that's a little biased like a mother loving their ugly son (thanks, mom.) The physical size and teal color of the engines, as well as having the separate valley cover and intake, allowing air under the intake, make for a cool, high-performance appearance. The details were all there, but the execution was all wrong. Stacks of washers and nuts as spacers behind the power steering pump bracket, and outdated t-style valve cover bolts made the car less of an attractive muscle car classic and partially a demolition derby-style engine install. It was also very apparent that at some point, this engine was painted yellow, and the Pontiac blue paint over top of it was flaking off in 30% of the surface area, leaving a terrible blue and yellow eggshell color.

I checked some casting numbers anxiously, as I was impressed by the 400c.i. air cleaner decal and Edelbrock intake, carb, and headers. I was praying to the ghosts of the Pontiac Motor Division that I had enough cubic inches and compression to power the bird. The car was bought mainly for the overall condition of the body, interior, and suspension. I figured I would likely build a fresh Pontiac motor for it down the line if the existing mill was too tired. The numbers came back as a 1972 350c.i. 8.2 compression ratio motor. So it was pretty dismal power-wise from the factory, but at least it weighs as much as a 455 or 400. I sulked for 20 minutes but I figured it will do as long as it would run and power the firebird reliably for the first few years. In the meantime, I can sort out the brakes, interior, and all of the other details of making a reliable car, it will be a good placeholder. Since all the Pontiac blocks all share the same architecture as the later and smaller 350, I figured I had lots of nice performance parts to outfit whatever Pontiac long block I eventually get put together.

Getting to work, I prepped to fire this motor to confirm that it was in good running order before refurbishing it. The previous owner had it running several years ago but took the subframe and driveline out to move towards an LS swap. I am fine with most LS swaps, but also see my Pontiac love letter above. The firebird had some factory warning lights and a set of auxiliary mechanical gauges that were added below the dash sometime in the mid-80s. I took the auxiliary gauge panel out from under the dash and moved it over to the engine bay. I connected the capillary tube for the oil pressure gauge to the filter housing on the back passenger side of the motor. Pulling the rubber hose connection off of the inlet line of the mechanical fuel pump, I connected a new rubber line fed out to a plastic gas can sitting in front of the car. I am currently unaware of the condition of the factory gas tank, but I assume that there could be lots of bad news hiding inside it. I know this car was on the road about five years ago but wanted to avoid any complications it could bring. I have a little primer bottle for the carburetor that I keep in my shop. It's a 20-ounce pop bottle with a little gas in it. I took a small clear 3/16" carburetor vent line, like the ones found on motorcycles, and drilled a hole in the cap of the bottle slightly smaller than the O.D. of the line. I forced the line through the hole in the cap, and it made a relatively good seal. Inserting the loose end of the into the float bowl overflows on the carburetor and holding the bottle upside down above, I was able to fill up the float of the carburetors without having to crank the engine over to pump fuel.

Next, I checked the engine oil. I pulled the dipstick to find it dry, as well as slightly mangled. Maybe we're buying a new Pontiac engine off of Craigslist this week; I laughed and cried. I kept a cool head because I know of a common issue on these engines that seems to develop all too often over their years of use. People replace the dipsticks with a common chrome aftermarket dipstick and tube. The boss on the Pontiac engines for the tube needs to be pressed into angles towards the crankshaft. Once it's in the crankcase, there is a second lower tube that turns the angle of the dipstick downward towards the sump and away from the crankshaft. If the wrong tube is installed or the lower tube left off during reassembly, it gives and improper reading and can get hit by the crankshaft. The oil pan has to be removed, and the engine needs to be pulled out to correct this. I have seen several Pontiac engines over the years that are living their best life, with an unknown amount of oil in them and a shortened dipstick to be sure not to hit the crank. I assumed this was the issue by the looks of the cheaper aftermarket chrome tube and dipstick handle.

Seeing that I had no way to confirm how much oil was in the sump, I pulled the valve covers off to inspect what was going on. I traced the starter solenoid wire (a thick gauge purple wire on GM's) back to the firewall bulkhead wiring connector that clips to the back of the fuse block. I made up a similar gauge of wire with a female spade connector on the end to shove on to this starter wire. Then, I strung my new jumper wire across the engine compartment to the battery. When I held this jumper to the positive post of the battery, the old Pontiac mill began to roll over, and with the fresh battery and low compression, it was spinning quite rapidly. I let it turn over a few revolutions and then stopped. Keeping an eye on the pushrod tips in the rockers and the newly rigged up oil pressure gauge on the firewall, I continued to roll the motor over in small increments, avoiding higher RPMs on the likely dry bearings. After a few rounds, there was oil pumping out of the top of all of the rocker arms, and 40 PSI of oil pressure with just the starter turning the motor over. With oil volume confirmed, oil pressure confirmed, dismally low compression ratio more than likely.

Making a second jumper wire, I clipped it on to the ignition post of the HEI distributor and routed it near the battery. I jumped in the car and confirmed that the 4-speed shifter was in neutral and rolled the car a little forward and backward to confirm I wasn't going to be getting any surprise when the car came to life. With our new jumper wire secured to the positive post, I gave the starter wire 12-volt power as well to hear the starter quickly turn the engine over and fire to life. I let it run for 90 seconds or so and then ran the throttle a bit to let it stabilize its idle. The engine seems to run very smoothly; no misses or stumbles with a quick stab of the throttle. It read 60 PSI of cold oil pressure. I considered that the mechanical gauge was reading a bit high, or possibly this engine had been rebuilt once with a higher pressure oil pump.

Now that I knew I had a good V8, I removed it from the car and began to gave it an exterior makeover. Mounting the engine on a stand, I left the intake and carburetor lift plate on the engine. The flaking paint was easy to chip off by hand, but I would need a good base for the new paint job and a way to remove as much of the engine oil as I could. My pressure washer with the 0-degree tip at close range was an effective paint remover. It's important to note that you should pay attention to every spot you are pressure washing, being sure to avoid gasket areas and spots that aren't sealed well like the PCV valve and grommet in the valley pan. I was able to remove most of the loose paint and the bulk of the oil and grease.

Next, I removed the intake and gaskets and drained the oil into a pan. It's essential to drain the oil immediately after pressure washing the engine to make sure if any excess water got into the crankcase, it wouldn't cause any problems. After 30 minutes of pressure washing, only a few tablespoons of water were present in the drained oil. I flipped the engine over both directions and allowed all of the antifreeze to drain out as well.

Continuing to prep the block, I took a 3/8-inch coarse tap and chucked it up in my cordless drill. I dialed the clutch function of the drill down to its lowest setting and threaded the tap into all of the header bolts bosses, intake bosses, and many of the bell housing and accessory mount holes on the front of the head. Years of rust and corrosion were removed out of the bolt holes, and shiny threads left for years of smooth wrenching.

I taped off the intake and exhaust ports of the engine to prep to paint and wrapped up my vintage Micky Thompson valve covers with paper and tape to keep them from being over-sprayed. I had heard good reviews online from other restorers about Bill Hirsch engine enamel paints. They seemed to have a great finish and withstood the heat of the engine quite well. I had ordered some up in anticipation of repainting the long block. A few coats in, and it was easy to see that I would never be using spray paint cans of hi-temp engine paints again. This was as close to a SEMA build/riddler award-winning restoration work as my low buck hot rodding had ever come. I also painted most of the hardware for the oil pan by pushing the bolts through the top of a Speedway Motors parts box.

With the engine now dressed in a new fresh four coats of enamel, I turned my attention to the smaller details. The intake was power washed and then put in a parts washer to clean up the old Edelbrock intake. The pullies, alternator, and power steering brackets were sandblasted and painted with 60-degree gloss black. It was also handy to keep a running list on a marker board in the shop of all of the hardware I was looking to replace. Over the years, there were many grade 5 ag and industrial bolts tying the accessories and engine together. The haphazard hardware was not consistent all over the engine and was a distraction. I sourced black oxide grade 8 bolts to remount everything. The bell housing, transmission, and intake bolts were bought with the correct flanged heads.

I spent several weeks worth of evenings and weekends preparing this engine to go back into the car. With the added work of repainting the subframe and firewall at the same time, I had a completely new engine bay. Several pieces are flying together in this mini restoration of my new Firebird. Hopefully, some of my tips on detailing an engine can help get your project up and running this year as well.

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