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The engine needed to come out of the car. Since it was rebuilt only a few thousand miles before, I planned on replacing the leaking oil pan gasket, and then cleaning up the engine and giving it a fresh coat of paint.
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After I pulled the engine out, I bolted it to the stand. It was dirty, but that all came off with some engine degreaser and a good rinse. After cleaning it, I took off the oil pan to replace the leaking gasket.
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After removing the oil pan, I noticed a lot of metal particulates down in the pan. Not a good sign. All the main bearings looked OK. Unfortunately, the same could not be said for the #4 rod bearing. Looks like rebuilding another engine was in my future. After disassembling the engine, I took the rods to the machine shop, and sure enough, the #4 rod was not true and had to be resized. I also had to cut the crank .030/.030 due to scarring.
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I wanted to pour aluminum into my heads to block the exhaust gas crossover from heating up the intake manifold and to provide a single path for the exhaust gases to flow out of the heads. So I found a cast iron ashtray for sale on Amazon.com. It was the PERFECT size for pouring molten aluminum into a Pontiac head.
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First, I stuffed steel wool into the exhaust bowls and pre-heated the heads in my gas BBQ grill. I used cut up 1"x1" pieces of aluminum diamond plate as my raw material. After placing the cast iron ashtray into the vice, I used two MAPP gas torches (one on top, one on bottom) to melt the aluminum squares inside the ashtray until I completely filled the cast iron ashtray with molten aluminum. Then I just poured the aluminum into the heads from the intake side. It was the exact right amount of aluminum needed. After cooling, I used the die grinder to blend the new aluminum into the bowls and intake face.
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I took some time to do a mild porting of the heads. I slightly enlarged the bowls and did a complete blend of the bowls around the valve guides. Finally, I smoothed and blended the intake and exhaust runners.
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Just a pic of the intake runners after the mild porting.
FYI: I media blasted the heads to clean them up before snapping the above two pictures, so all my die grinder marks on the heads have disappeared.
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On the combustion chambers, I took the advice of my local engine guru and modified the chamber wall across from the spark plug (bottom of the picture). I used a die grinder and moved the wall outward about 3/8" and then blended that back to the original chamber. This modification was recommened to allow the intake and exhaust valves to breath better near the chamber edges.
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After many hours of modification work, the heads are finally assembled and ready to go back on the engine. Each chamber on both heads was measured and came in at 75/76cc.
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Short block rebuild #1: The original block that came out of the '77 was bored a little too loose to for the .030 over forged pistons that were in there. There was wall scarring where the pistons were slapping. I had another 400 block, so I had that one bored and honed to match the .030 forged pistons from the old engine. I cleaned up the pistons, installed new rings and bearings, cut the crank to .030/.030 (due to scarring) and re-assembled the bottom end.
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Short block rebuild #2: After measuring the deck height with the stock rods installed, I found that the stock rods varied .013 due to a few of the rods being shortened when resized sometime in the past. This was giving me numbers of .015 to .028 in the hole. So I decided to get a set of forged H-beam rods, and then deck the block .015.
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Short block rebuild #3: After putting in the new forged h-beam rods, I measured the side clearance on the rod journal, and was shocked to find it varied from .032 to .040. I examined the crank I guess some machine shop cut the radius at one point when they were cutting the crank. The combination of the radius cut and that the width of the forged rods were .004 smaller than stock lead to the problem. So, I had to get another crank that I had (.020/.020 already) and get it cut to .030/.030 to match the bearings I already bought.
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While I had the engine apart for the third time, I went ahead and made some custom modifications to my TRW forged pistons to help reduce the compression ratio. The original pistons were the standard 6.6cc double valve-lash recessed pistons. After reading Jim Hand's book, I put these pistons on the drill press and took out .100 of aluminum material between the valve lashes. I increased the dish size from 6.6cc to 12.5cc. This will make the approximate compression of my engine right at 9.5:1.
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Timing chain installed.
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!!! UPS FAIL !!!
The darn box was even clearly marked "Please Do Not Bend". Destroyed that set of head gaskets, and it put me back a week waiting for another set to arrive again in the mail. Sad.
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I marked the top of the valves with dry erase marker, then installed the pushrods and the rocker arms and spun the engine over a few times. The rocker arms rubbed off where they contacted the top of the valves. The mark is a hair above the centerline, but it's close enough. Also, when the lifters completely pump-up under normal conditions, the rocker should travel down farther on the valve stem.
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Here is the assembled valve train. I'm going to run shorter custom Pontiac black powder coated aluminum valve covers, so I had to do some clearance work on these large aluminum rocker arms. I had to shave the top corner of the outermost rocker arms. Then, I also had to shave the top corner of the next rocker in to clear the aluminum rib cast into the valve covers near the bolt holes.
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Here is a closer view of the rocker arms I modified. I didn't take any structural aluminum off the rocker arms, just a small bit from the very top corner.
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I'm using wider RA-IV 11/32" pushrods, so I had to reset all of the pushrod guides to re-center the rocker arms to the valves with the wider pushrods. After doing this, I noticed that some of the guideplates developed stress cracks where I bent the tabs to center the rockers. So, I mixed up some trusty marine epoxy to make sure that none of the cracks caused the tabs to break off during operation.
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Instead of spending $170+ on a new timing cover, I decided to have some "fun" and restore/recover the existing timing cover I had. So I sand blasted the timing cover to remove any oxidized aluminum and crud. Then I used the same marine epoxy to fill in the pitted holes on the radiator hose fittings and sanded them smooth. Next, I used JB Weld to fill in the pitted holes in the front and back gasked surfaces and sanded the JB Weld down with a table belt sander to ensure a flat mating surface.
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I noticed that the water crossover hole in the manifold that came cast from Edelbrock was significantly smaller than the matching hole in the intake gasket. So I took my die grinder and enlarged the water hole in the intake to match the intake gasket. I'm not sure why it was machined/cast so much smaller from Edelbrock, but it makes me wonder how the many people that complain about Pontiac motors overheating. Maybe their brand spanking new intake manifolds are restricting the water flow. I also did a mild port matching of the runners to the gasket.
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After completing assembly with the temporary valve covers and giving the motor a fresh coat of Pontiac Metallic Blue engine paint, I started with the installation of the Tremec TKO-600 transmission. After checking the runout of the bellhousing to ensure it was centered, I installed the pilot bearing, flywheel, clutch, pressure plate, and bellhousing. Then I bolted up the brand new Tremec. Sexy.
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It's always a good day when your engine finds it's new home.
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After dropping the engine into the frame and then building the exhaust front to back, I decided it was time to start getting things ready to fire up the new engine. So I put my trusty 15/16" socket on the harmonic balancer bolt and started to turn the engine to TDC to stab the distributor. I got maybe 1/16 of a turn on the wrench and, Clunk! I attempted to reverse the wrench, and got the same metal-to-metal hard stop. I knew it turned freely on the engine stand. So I peeked into the bellhousing. Sure enough, the pressure plate was hitting the bellhousing. Doh!
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I had to unbolt the exhaust, drop the driveshaft, take off the crossmember, unbolt and remove the transmission, and then finally take off the bellhousing. Now I could clearly see where it was rubbing. So I took my die grinder and clearanced the aluminum right in front of the clutch fork hole to give me .100" clearance in the area as the pressure plate passed by. After verifying clearance by measuring while spinning the engine through several revolutions, I put it all back together. That was a day lost and a lesson learned.
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What's the moral of this story? Run part numbers when you buy things used from the swap meet. I put a standard 11" clutch and pressure plate on the engine and I assumed that ( since this had worked in the past) all Pontiac bellhousing were the same size. Not true. A quick run of this part number will tell you that this is a bellhousing specifically from a OHC-6 (Sprint-6) motor. These smaller 6 cylinder engines came from the factory with 10.5" clutches. Thankfully I was able to safely clearance this bellhousing to handle the larger 11" clutch.
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