Engine Swap

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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)

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1BEAST is finally back on the street. These past three days were outrageously stressful. It almost felt as though the car had no intention of giving up its home in the garage!

I'm trying to decide where my "502" emblems are going to go. Hood scoop or fenders? (Or none of the above?) What say you?

[olddog]

502 emblems - personal taste. Me, I wouldn't put them on. I like seeing them on the hood scoop. All I have ever noticed on a Cobra is on the fender, so I expect that is where the original cars had them. Since 502 is not original, it doesn't matter.

[olddog]

Your old engine must have purred as smooth as a kitty cat, with that mild cam. I expect most would have put more cam in the new engine. The new engines cam, in my mind, is the mildest I would put in a performance engine of that size. I certainly would have went a bit more on the lift. If the heads flow well, then it should be enough. If those heads are out of the box - not ported, the engine may be short a few pony's that it could of had, but at 502 cid in a ~2500 lb car, I doubt you will be lacking.

All of those random thoughts on the table, I would love to hear how it runs and performs. I find your engine choice most interesting.

My working theory is that the better the heads flow the less cam you need. Back in the day when all we had was factory cast iron heads, and few could afford to spend the time on a mill to attempt to port them, we ran ridiculous cams. Now good heads are everywhere.

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The cylinder heads are "off the shelf" Edelbrock heads, not ported, just gasket-matched.

I told ATK that I really wanted to maintain 12-14 inches-Hg to run the power brakes. Given that limitation, the most aggressive cam they could recommend was the 225/235 @ .050" with a 112 degree LSA. Installing an electric vacuum pump would have worked, but I didn't want to bother with that. We also discussed the use of a hydraulic roller cam, but concluded that the additional cost associated with a roller cam couldn't be justified because of my self-imposed engine vacuum limit, which was going to severely limit the cam duration. So, I agreed to use the 225/235 hydraulic flat tappet cam, which is just a bit more aggressive than the Comp Cams 218/218 in the old engine.

I did a couple of full throttle pulls up to 4500 rpm in 2nd gear yesterday. So far, so good. The engine seems to pull hard.

[olddog]

Well the cost verses benefit on the roller cam is a personal choice.

At least in theory, the roller lifters allow a steeper ramp at both ends, thus the valve can be opened quicker and held open longer (because it can be close quicker). So a roller cam is the solution to your problem. It would act like a bigger cam, without sacrificing manifold vacuum. Again you have so many cid to make power with, you may not need or want it.

I haven't a clue what gearing and tires you are running, but I'm surprised you can hook that monster to the ground.

[cycleguy55]

Originally Posted by olddog

Well the cost verses benefit on the roller cam is a personal choice.

At least in theory, the roller lifters allow a steeper ramp at both ends, thus the valve can be opened quicker and held open longer (because it can be close quicker). So a roller cam is the solution to your problem. It would act like a bigger cam, without sacrificing manifold vacuum. Again you have so many cid to make power with, you may not need or want it.

Fully agree. Plus, of course, the roller cam allows you freedom to select the motor oil of your choice without worrying about low ZDDP and/or wiping out a lobe.

Originally Posted by olddog

I haven't a clue what gearing and tires you are running, but I'm surprised you can hook that monster to the ground.

That was the thought I had, when I saw "I did a couple of full throttle pulls up to 4500 rpm in 2nd gear yesterday." I would think 'full throttle pulls' in 2nd gear would break the tires loose unless running wide, super-sticky rubber, perhaps even then.

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Originally Posted by olddog

Well the cost verses benefit on the roller cam is a personal choice.

At least in theory, the roller lifters allow a steeper ramp at both ends, thus the valve can be opened quicker and held open longer (because it can be close quicker). So a roller cam is the solution to your problem. It would act like a bigger cam, without sacrificing manifold vacuum. Again you have so many cid to make power with, you may not need or want it.

I haven't a clue what gearing and tires you are running, but I'm surprised you can hook that monster to the ground.

Originally Posted by cycleguy55

Fully agree. Plus, of course, the roller cam allows you freedom to select the motor oil of your choice without worrying about low ZDDP and/or wiping out a lobe.

That was the thought I had, when I saw "I did a couple of full throttle pulls up to 4500 rpm in 2nd gear yesterday." I would think 'full throttle pulls' in 2nd gear would break the tires loose unless running wide, super-sticky rubber, perhaps even then.

The added cost for a roller cam would have been a bit over $1000, about 13% more than I paid in total for the long block (plus shipping) from Texas to Hawaii. ATK recommended against a roller cam because they felt that the power increase wouldn’t justify the added expense. I once watched a YouTube video (https://www.youtube.com/watch?v=8VjFZMKvEwY) produced by Engine Masters, which compared dyno results for two Isky cams, identical in duration with 244 degrees and identical LSAs of 108 degrees, but one was hydraulic flat tappet with .505” lift, and one was a hydraulic roller with .558” lift. The roller cam provided +21.4 hp and +6.4 ft-lbs over the flat tappet cam. So, in their case, with an added expense of $900, they gained 0.024 hp per dollar using the roller cam. Here’s the graph. I was surprised at the result. http://imgbox.com/EyzjA0Yf

Agree about the need for cam lobe protection. I'll have to use a ZDDP additive with every oil change until I convert over to Royal Purple synthetic in about 4000 miles.

As for the full throttle pulls, I started them at 2800 rpm and brought the throttle in gently, so as not to break the tires loose. My rear tires are Firestone Firehawk Indy 265/60R15s, so they'd go up in smoke if I were to suddenly floor it.