Engine Swap

[520SC]

I've been posting a whole bunch of questions about an engine swap I've been working on. Thanks to everyone who replied. Your help is greatly appreciated.

Someone suggested that I post a "rebuild" thread to explain the nature of the engine swap, so here it is.

During the first week of April, I took my car out for a cruise through Waikiki. While traveling on the highway, my thermostatic engine fan relay turned off the radiator fan. My guess is that the intake manifold water temperature sensor open-circuited, sending an "all clear" signal that turned off the fan. I was traveling at 50 mph at the time, so there was more than enough air flow to keep the engine cool. After turning onto a crowded side street, the problems started. The engine started overheating, and I wasn't watching the temperature gauge at the time. It wasn't until the idle started getting rough that I saw the temperature gauge reading 260 degrees and noticed that water vapor was pouring out of the passenger side pipe. I immediately shut off the car and called AAA for a tow home. After removing the passenger side cylinder head, my suspicion was confirmed. I had warped the head, and the gasket blew. I brought the cylinder head to a local machine shop, which welded up a small corrosion/erosion cut between a coolant passage and #3 cylinder, then milled the head 0.010". A couple of days later I was back on the road (or so I thought). The engine seemed to run fine except for an intermittent backfire out of the carburetor. I rechecked the ignition timing several times and it was correct. I ran the car a few more times over the next two days without incident, but then the backfire eventually returned. While idling the car in the garage, the backfire suddenly became much more frequent, the idle became very rough, and then finally, the engine died. Removing the passenger side valve cover revealed that the #1 intake rocker arm was broken, and the #1 exhaust push rod was loose. I saw a few needle bearings lying on the cylinder head near the broken rocker arm. I removed the intake manifold to discover more needle bearings lying in the lifter valley, and the really bad news: #1 exhaust lifter could not be removed. The lifter was mushroomed and the cam lobe was becoming flat. (Obviously, #1 cylinder's intake/exhaust lifter preloads had been improperly set. I still don't know what went wrong.) In any case, this engine was now in need of a complete tear down and rebuild due to the camshaft shavings that had been splashing around the crank case with the oil.

So, at the moment, I have a brand new ATK Performance Engines 502 long block sitting in the engine compartment. We just hoisted/bolted it in there yesterday. I hope to have it fired up and running by end of week.

Here are the specs on the old engine and the new engine:

OLD ENGINE:
Bore - 4.39", Stroke - 4.30", 520 cid
Compression ratio - 10.4:1
Camshaft - Hydraulic flat tappet 268/268 degrees duration (advertised), 218/218 degrees @ .050", .494"/.494" lift, 110 degree lobe separation angle
Cylinder heads - Edelbrock Performer RPM with 95 cc chamber volume
Intake manifold - Edelbrock Performer RPM Air-Gap dual plane
Carburetor - Holley 750 cfm vacuum secondaries

NEW ENGINE:
Bore - 4.39", Stroke - 4.15", 502 cid
Compression ratio - 9.5:1
Camshaft - Hydraulic flat tappet 279/289 degrees duration (advertised), 225/235 degrees @ .050", .536"/.541" lift, 112 degree lobe separation angle
Cylinder heads - Edelbrock Performer RPM with 75 cc chamber volume
Intake manifold - Edelbrock Performer RPM Air-Gap dual plane (from the old engine)
Carburetor - Holley 750 cfm vacuum secondaries (from the old engine)