Potential spun X302 rod bearing

[C5GTO]

Originally Posted by C5GTO

On the first road trip after fixing the gas tank venting on my Cobra, I think the engine spun a rod bearing

I hadn't published this adverse outcome yet as I haven't pulled the engine to verify, but the rpm variable clack and metal sheen in the oil are fairly telling symptoms. A friend and I checked the whole top end and no major issues found there, the compression is good on all 8, and so there's only one thing left that it really can be. So I'm now collecting up information about all the issues in my Cobra so I can create a "budget" for fixes to make it safely drivable again. I guess it's true that owning and enjoying a Cobra is a fairly constant drain on the wallet

Originally Posted by eschaider

I am not attempting to tell you how to build your engines but rather offering a thought that might be helpful.

Whenever an engine has run for some period of time without having spun a bearing and then suffers a spun bearing, it is always an oil starvation issue. Sometimes it arises from a high volume oil pump used with a stock or near-stock capacity oil pan. The oil level above the pickup can become marginal if the engine has a slow oil return path to the pan or just poor oil control in the pan.

In the scenario where the pickup is marginally covered with oil, any braking, turning, or acceleration can momentarily uncover the pickup allowing it to draw air instead of oil. The sporadic but repetitive presence of air bubbles in the oil feed to the engine will be a cumulative sort of failure scenario.

The first few times, probably no serious damage. Eventually, the bearing surface is sufficiently damaged that the oil film that usually supports the load on the crank pin is thinner than the physical scarring on the bearing. The first time this occurs, the crankpin grabs the rod bearing insert and rotates it between the other insert and the crank. At this point, the show is over, and the damage is done.

The mechanical failure process is always the same. The cause of the starvation is always an uncovered pickup. Drawing air into the oil system is always less oil in the pan than is necessary to cover the pickup. The fix is always one of the following;

• A larger capacity oil pan, if possible,
• Better baffling of the pickup to maintain oil coverage,
• Use of a dry sump system,
• Use of an oil accumulator.

Even when we attempt to run the largest capacity pan with the best baffling that is prudent, the oil starvation problem can still rear its head. Dry sump systems remove the opportunity to uncover the pickup because of their physical design — but they also cost an arm and a leg.

The last item, using an oil accumulator, is the poor man’s dry sump system for this type of failure. The accumulator retains oil under pressure and is “T’d” into the oil delivery line between the oil pump and the engine. When the pickup is uncovered and draws air, the accumulator sees the drop in oil pressure and begins to discharge oil into the oil engine oil galley to protect the engine bearings.

The accumulators are relatively inexpensive and great insurance for the engine. They also can be used to prelube a collectible car that we don’t start every day. Here is a pretty good YouTube video by Moroso to better explain the protection process; click here => Moroso Oil Accumulator.

In addition to Moroso, Canton offers the original oil accumulator called the Accusump. Both work equally well. You can not go too big, you can go too small. Get the 3 quart gizmo.

Moving this topic to it's own thread as it has nothing to do with brake sizing...

Here are some specifics about the engine. It's a Ford Motorsports X302 crate engine ( https://performanceparts.ford.com/do...-6007-X302.pdf - details on page 20) purchased from Summit about 10 years ago. It is outfitted with a Canton 8qt. 15-630SM Ford 289-302 Front Sump Road Race Pan and pan specific oil pickup. All the rest of the engine internals (e.g. oil pump, crank, rods, cam, etc.) are whatever Ford Motorsports put into the engine. For example, I don't know if oil pump is standard or high volume. The engine has about 25,000 miles on it from new and until now, no problems with it at all. After purchase and installation, it was dyno tuned and EFI ECM augmented with add-on chip to hold the tuning data. The oil level read full at the start and through out the road trip. The oil pressure read as normal through out the trip even after the motor started clacking. I seem to recall the motor oil being a Castrol 10w40 in either a synthetic or synthetic blend. The oil was about 3 years old or so as I had changed to oil prior to garaging/parking the car for about 3 years. During this 3 years, the engine was started and warmed every 2 - 3 months. Prior to the engine starting to clack, the oil showed pretty much clear/clean on the dipstick.

The road trip was an early morning drive (so ambient temps in low 70s) around Northern AZ. The first leg from Chino Valley to Ash Fork, no issues. The second leg from Ash Fork to Flagstaff on I40 is where the problem started. Posted speed limit is 75 mph. We traveled at least that fast and sometimes up to 85 mph when passing. My Cobra does not have overdrive so for this 50 minute segment, the engine RPMs were held between 3,800 to 4,000 RPMs. So somewhat high RPMs for extended period but not excessive for an engine carrying 8 qts. of oil. The Interstate is fairly straight for that whole stretch so no hard cornering to slosh the oil from pickup. Coolant temps were 180 degrees and oil pressure showed 50 lbs. (electric gauge so maybe not precise but pressure didn't waver at all) for this segment.

I first heard the clacking sound when we exited the Interstate for the segment down to Sedona. You can't hear anything in a Cobra at 75 mph so it likely started prior to the exit. When I first heard the sound, it sounded like an exhaust leak and I thought it was at the flange joint between header and side pipe so we kept driving. This segment was 2 lane road through the magnificent Oak Creek Canyon so speeds and RPM were very low but you could hear the clacking sound bouncing off the rock canyon walls.

We stopped for a visual inspection after about 10 - 15 miles driving after exiting the Interstate. The side pipe flange bolts were tight so the exhaust leak theory was ruled out. The consensus was that the sound was coming from the top end and likely a rocker arm had loosened. Given the EFI intake hangs over to valve covers, we couldn't take a look without upper intake manifold removal. The sound had become a bit more pronounced but not all that loud yet. Oil level and pressure were normal still and engine seemed to be running fine except the clacking sound.

I elected to drive the car for the 60 miles or so to return home. Since I first heard the clacking sound till getting the car home, the sound became a bit more pronounced but not the low knock that I've heard prior with spun bearings. The clacking sound would lessen and almost go away at about 2,500 to 2,800 RPMs during the remaining drive home.

At first, we were convinced it had to be an issue in the valve train. After going through the top end with a fine tooth comb, the only issue we found was a few roller rocker arms showed some wear in the aluminum where the roller tips contact the arms. There was no looseness anywhere, no loose rocker arms or bent push rods. The compression is between 115 and 120 on all eight cylinders. The top end is absolutely clean and all oil drain backs are open so no oil trapped anywhere. So conclusion, the sound is not being generated in the top end.

After draining the engine oil, a slight sheen is visible when moving oil around in direct sunlight. Through process of elimination and given the symptoms, I'm now thinking it's a spun rod bearing. I haven't pulled the engine yet as I don't have enough garage space until I get a new detached garage constructed.

Any ideas? Does anyone with experience on the Ford Motorsports X302 crate motors have a similar issue? I would hope an extended 4,000 RPM run would be fine with this engine, but if so, what's going on here?

[eschaider]

Certainly, the sounds, the silvery sheen, and probably fine particulate matter in the oil is a pretty good indicator of one or more bearing failures, Joel. Here is something that might help going forward.

The pickup to bottom of pan clearance in some Ford crate engines has been more than commonly thought appropriate. A safe distance that will not choke off the pickup and also not reduce apparent pan capacity is anywhere between 0.300" and 0.375" clearance off the bottom of the pan.

The easiest way to measure this is with the engine on an engine stand. You use a hamburger-sized patty of children's clay and place it on the bottom of the pickup. Install the oil pan with a gasket and cinch down the oil pan bolts the way you would finish up an engine build. Now remove the pan bolts, lift off the pan, and Viola! You have an exact representation of the pan to pick up clearance across the entire pickup face.

Use an Exacto knife or a razor blade to cut through locations of interest to see and measure the clearance. Try to shoot for the 0.300" to 0.375" pickup clearance space.

When the clearance space increases above 0.375", you are effectively reducing the volume of oil in the pan and potentially uncovering the pickup during mild to spirited braking, acceleration, and cornering. A high pickup and a potentially low oil level are an accident waiting for a place to happen.

The other increased risk operating condition is sustained moderate to high rpm. When the engine operates in the ~4000 rpm range, several dynamics are in play that the engine does not see at lower engine speeds. After the oil pump has done its job and gotten the oil to the correct bearing surfaces, the oil has to find its way back to the pan to begin the process all over again.

Each engine has an oil drain back behavior unique to its engine family. In simple terms, it is the time it takes the oil to return to the pan, de-aerate, and get pumped back into the oil galleys. At first, it doesn't sound like a big deal, but as we delve into the process, there are some interesting discoveries to be made.

The first thing we frequently forget is how much oil is required to wet the inside of the engine. Not lubricate but wet. The wetting process is how a lot of the oil gets back to the pan, but before it gets to the pan, it has to wet the inside of the block and run down into the pan. It doesn't seem like much oil at first, but a good number for most engines is 1 quart, sometimes a bit more.

The next consideration is crankshaft (and connecting rod) windage. As the oil comes down the crankcase walls, it is whipped up by the crankshaft into a foam-like substance. To prevent this, you need to use a good windage tray that protects the oil in the sump from the rotating assembly's windage and skims as much oil off the rotating assembly as possible while the engine is running.

Racers talk about the horsepower lost by whipping the oil into a foam. For guys like us, who are already overpowered, the issue is adequate lubrication for engine longevity. Ideally, you want a full-length windage tray that runs the entire length of the oil pan. A half-length tray and a smooth bottom oil pan will recover oil where the tray exists and whip oil into a foam where it does not.

Some parts suppliers offer what they call crank scrapers. These fit between the pan gasket and the oil pan. The fitment can be very close (0.030" sometimes less) to the crankshaft counterweights on both sides of the crankcase. They do exactly what their name implies. Here are two pics of a scraper and windage tray assembly from Improved Racing (the same guys that make those elegant oil T-Stats).

This is a pic of a windage tray and crank scraper installed on a darkside engine;

This is a pic of the windage tray and crank scraper before installation, viewed from the crank's perspective;

Sometimes you can find commercially available units for sale. You can also make your own with some cardboard, a pencil, and a box cutter when you can’t. It is not that difficult.

When you are done with the cardboard, go over to your PC, bring up the 2D/3D drawing program you downloaded from the internet, and make a drawing to take to your local water jet shop. He can easily cut out the crank scraper from flat stock for you. The same story with the windage tray, but use a sheet metal shop to do the fabrication for the windage tray. Consider how you will fasten the two together for your particular application.

The following comments would not apply to anyone who is scratch building a Lambo Miura, but — for everyone else, if this process is too much work, there is an alternative. You can put 2.92 gears in the rear end, run a 295x65x15 rear tire, and use a 5-Speed with a 0.64 OD, you will be able to cruise the expressways at 70 mph and 1500 rpm according to the Second Strike Gearing Calculator — assuming you have a cam that allows your engine to operate at that rpm.

[C5GTO]

An overdrive transmission is definitely required as part of the fix. I've been thinking about a transmission change in this Cobra for several years now but those funds always seemed like they'd be better spent on the homebuilt Ferrari and Lambo project cars. In hindsight, I'd have one less headache now and would have avoided a bunch of frustration in trying to get the Richmond Gear/Hurst shifter combination to have a reliable/smooth 2nd to 3rd gear shift. I've penciled in a new TKX in as a line item on the fix budget.

If it is a spun bearing, I'm thinking a good fix is likely a 347 rotating assembly kit. Does anyone have experience with the Eagle kit that comes already balanced with a harmonic balancer and flywheel included in the kit?


I'll also look into a windage tray and crank scraper, sounds like cheap insurance to me. I guess another good question is the oil pump. Standard volume or high volume? I'm fairly certain the current engine is outfitted with standard volume pump since the spec sheet didn't mention high volume. Is there a good way to visually tell if pump is standard or high volume?

[eschaider]

Originally Posted by C5GTO

An overdrive transmission is definitely required as part of the fix. I've been thinking about a transmission change in this Cobra for several years now but those funds always seemed like they'd be better spent on the homebuilt Ferrari and Lambo project cars. In hindsight, I'd have one less headache now and would have avoided a bunch of frustration in trying to get the Richmond Gear/Hurst shifter combination to have a reliable/smooth 2nd to 3rd gear shift. I've penciled in a new TKX in as a line item on the fix budget.

Painful cost-wise but a definite move in the right direction, Joel.

Originally Posted by C5GTO

If it is a spun bearing, I'm thinking a good fix is likely a 347 rotating assembly kit. Does anyone have experience with the Eagle kit that comes already balanced with a harmonic balancer and flywheel included in the kit?

If you are choosing the 347 rotating assembly because you believe it is more resistant to this type of failure, it is essentially similarly susceptible. It is certainly a step up if you are choosing it for additional power.

Although I have never built a 347, I have built other externally balanced engines. The experience is not a good one, and they are poor high performance candidates because of service parts interchange imbalance issues.

If you determine the 347 is going to be your engine, you should attempt to balance the rotating assembly internally. Assemblies that require matched external pieces like dampers and flywheels never can be balanced as well as the original components when these pieces are changed out for service reasons down the road.

Originally Posted by C5GTO

I'll also look into a windage tray and crank scraper, sounds like cheap insurance to me.

This is cheap insurance, and commercially available pieces are easily found online. If you elect to go the crank scraper/windage tray route, try not to use a scraper that is attached at the pan rails. With only 0.030" or so clearance, it is easy to have a pan rail scraper shift during assembly or later operation and strike the crank.

The most reliable way to attach the scraper to the engine is to bolt it to some fixed location on the block, like the main studs, to preclude movement. As you increase the air gap between the scraper and the crank to avoid counterweight contact, the effectiveness of the scraper diminishes very rapidly.

Originally Posted by C5GTO

I guess another good question is the oil pump. Standard volume or high volume? I'm fairly certain the current engine is outfitted with a standard volume pump since the spec sheet didn't mention high volume. Is there a good way to visually tell if the pump is standard or high volume?

The easiest way to check for a higher volume oil pump is to check the oil pump gear tooth face width against a known standard volume pump. Wider gear tooth faces equate to higher volume pumps. Here is a link to a pretty good explanation of high volume and high pressure pumps done by George Richmond at Melling, click here => Melling Pump Discussion.

When you go to a high volume or a high-pressure pump, you force more oil through the engine's oil system. For illustrative purposes, let's say your engine is capable of returning one quart of oil per minute (I pulled that number out of thin air for this example).

When you use a pump that increases oil flow to the engine by one quart per minute, so you now deliver 2 quarts per minute, you are in trouble. You are retaining 1 quart of oil in various forms of suspension each minute the engine is running.

Let's say you have a six-quart pan that is at 4.5 quarts capacity while the engine runs. That would be one quart to wet the engine internals and ½ quart in transit back to the pan. If you retain one quart of oil every minute in 4.5 minutes, your pan will be pumped dry, and the oil pump will draw oily air. This is a significant simplification of what happens, but you can get the gist of the problem/oiling dynamic.

It would not happen that way in the real world, but eventually, you will uncover the pickup. That fateful moment might be on a long sweeping curve while entering an expressway or just playing around with the car in one of our typical spirited driving moments.

Once you uncover the pickup, the damage is done. It will take some time before you become aware of the damage your engine has just suffered. You could be driving at a steady speed on the highway when the rod bearing finally fails, and you won't be able to necessarily hear the damage until you get off the highway.

High-volume and high-pressure pumps (and car owners) will be happiest with an oil pan with at least 8 quarts over the pickup while the engine is running.

All the words about the crank scrapers and windage trays are still valid. Be sure to use an adequately large pan if you elect to go the high volume or high-pressure oil pump route.

[C5GTO]

Going from 302 to 347 cid would purely be for the extra power. The main purpose for the OD TKX transmission would be to lower RPMs while driving on the Interstate.

A question related to the 347 stroker direction, will the current EFI tune be adversely impacted by the extra cid? If so, would the situation be that the dyno tune done for the 302 cid engine just might be non-optimized for the 347 or the extra displacement really requires a different tune to prevent engine failure?

As I'm putting together a budget for the fixes here, it's important to capture all the line items. I'm guessing a dyno tune is probably in the neighborhood of $750 these days thus a significant line item.

[MAStuart]

Joel Tune will be way different! Any idea what cam you are thinking about for the 347? Are you planning to use your same intake? Will it support more HP or is it restricting the power you have now. Injector sizing and mass flow?

Get what you have apart. I dough you drove it 60 plus miles with a spun rod or main bearing. Might be a very minor problem. If it has a bad bearing a set of bearings and a crank grind or polish might take of it.

As far as highway RPM's . Is your Richmond gear trans a non overdrive 5 speed? I so you must be running low rear gears with shorter rear tires. That combo needs a high rpm motor to use first and second gear . Change the rear gear to a 3.25 with some taller rear tires and your highway rpm's will be lower. That combo will still take off like a car with 4.11 and a close ratio 4 speed.

[eschaider]

Originally Posted by C5GTO

Going from 302 to 347 cid would purely be for the extra power. The main purpose for the OD TKX transmission would be to lower RPMs while driving on the Interstate.

A question related to the 347 stroker direction, will the current EFI tune be adversely impacted by the extra cid? If so, would the situation be that the dyno tune done for the 302 cid engine just might be non-optimized for the 347 or the extra displacement really requires a different tune to prevent engine failure?

As I'm putting together a budget for the fixes here, it's important to capture all the line items. I'm guessing a dyno tune is probably in the neighborhood of $750 these days thus a significant line item.

Joel,

Although you have not indicated the brand or fueling model (Alpha-N, Speed Density, MAF), my guess is Speed Density is what you are using. Fueling model notwithstanding changes in engine displacement, minimally need to be programmed into the EFI setup parameters because EFI systems, when everything is said and done, mix fuel with air in proportions you specify for an engine displacement you specify.

Some systems like the MAF-based variety make the process less time-intensive, but all will require some intervention. Speed Density systems will require the most intervention because although you inform the ECU logic of the new displacement, the engine's volumetric efficiency will change. A larger displacement engine fed by the same heads and intake will be more throttled (lower volumetric efficiency) than a smaller displacement engine with the same heads and intake.

The upshot is that the fueling Ve table(s) will necessarily be different and require a retune. The old tune for the 302, while adequate to start the engine, will be unsuitable to operate the vehicle safely (from an engine's perspective). It is time for another visit to your tuner's dyno.


p.s. I seem to remember your engine is carbureted and not injected. If that is the case then you need a retune for sure — carbs and speed density systems perform similarly to changes in displacement and Ve. If you are considering an EFI conversion for a carbureted engine that you are going to increase dispacement on, then only spend the tune dollars once. Pick your EFI system and take the rebuilt engine and car to your preferred tuner for the tune, don't spend the money twice.

[msinc]

I don't know what pistons are in your engine, but if they are the typical Ford cast style then you could have cracked or completely lost a skirt. This was a very common problem at one time and the reason everyone used forged pistons in rebuilds. You can pull one plug wire at a time while the engine is idling and see if the noise goes away or changes on one specific cylinder. Take away the fire and you take away the pressure that makes the knock. This stupid little trick wont tell you if it is a piston skirt, wrist pin or bearing, but it will locate it if it is in the bottom end. If the noise doesn't change then it's a top end issue. Sharp clacking is typically a piston. A heavier sounding deep "thunk" is usually more like a rod bearing noise. There are of course other things that can make noise in an engine. Piston skirts wont cause an oil pressure loss or drop, a rod bearing failure most certainly will. Best of luck and keep us posted.

Edit: I have had a couple small block Fords make the piston skirt noise that I would have bet money on and it turned out to be a rod bearing or once even a cracked flexplate. Also, if someone swapped over to timing gears, I have heard them develop one hell of a knock too.

[C5GTO]

Originally Posted by MAStuart

As far as highway RPM's . Is your Richmond gear trans a non overdrive 5 speed? I so you must be running low rear gears with shorter rear tires. That combo needs a high rpm motor to use first and second gear . Change the rear gear to a 3.25 with some taller rear tires and your highway rpm's will be lower. That combo will still take off like a car with 4.11 and a close ratio 4 speed.

Yes, I believe Richmond Gear called the trans model "4 +1" and 5th gear is 1:1. In addition to the lack of overdrive, the transmission (with a Hurst Competition Plus shifter) has never shifted very well from 2nd to 3rd. I've spent many, many hours adjusting it and changed out the shift linkage bushings to the best steel ones available. For up shifts over 3,500 RPM, the shifter has a tendency to "stick" between gears. The higher the RPM the more likely the shifter to stick. The trans is still in 2nd gear but the shifter is essentially "locked up" and thus no gear can be selected while car is moving. To free up the shifter, the car must be brought to a full stop, shifted into reverse, and once reverse gear is engaged it sets all the other gears to neutral. Bringing the car to a full stop to unstick the shifter can be a real safety hazard especially on curved mountain roads.

The current rear end gears are 3.5 ratio and tires are 255/50ZR - 16. The Tremec RPM calculator says that a TKX with .72 OD would give 2,440 RPM at 75 mph. That sounds about right for a 5.0L motor. This trans has a 3.27 first gear so it should also be good for a quick launch.

So the net of all this, I'd much rather change out the transmission and leave the rear end gears alone. Even though this will cost more, my frustration level with the Richmond Gear trans is such that it's got to go.

[C5GTO]

Originally Posted by eschaider

Joel,

Although you have not indicated the brand or fueling model (Alpha-N, Speed Density, MAF), my guess is Speed Density is what you are using. Fueling model notwithstanding changes in engine displacement, minimally need to be programmed into the EFI setup parameters because EFI systems, when everything is said and done, mix fuel with air in proportions you specify for an engine displacement you specify.

Some systems like the MAF-based variety make the process less time-intensive, but all will require some intervention. Speed Density systems will require the most intervention because although you inform the ECU logic of the new displacement, the engine's volumetric efficiency will change. A larger displacement engine fed by the same heads and intake will be more throttled (lower volumetric efficiency) than a smaller displacement engine with the same heads and intake.

The upshot is that the fueling Ve table(s) will necessarily be different and require a retune. The old tune for the 302, while adequate to start the engine, will be unsuitable to operate the vehicle safely (from an engine's perspective). It is time for another visit to your tuner's dyno.


p.s. I seem to remember your engine is carbureted and not injected. If that is the case then you need a retune for sure — carbs and speed density systems perform similarly to changes in displacement and Ve. If you are considering an EFI conversion for a carbureted engine that you are going to increase dispacement on, then only spend the tune dollars once. Pick your EFI system and take the rebuilt engine and car to your preferred tuner for the tune, don't spend the money twice.

The engine is fuel injected using a Ford EEC IV computer. It uses a MAF and has 24 lb injectors. I don't recall the throttle body or MAF size but they were considered large back in 1994 but are small by today's standards. All the EFI components (except for the ECM tune add-on) on the engine were supplied by Ford Motorsports in a "EFI package" purchased in 1994. The intake manifold is an Edelbrock Performer RPM of '90s vintage. So all components are old by EFI technology standards but I'd say they are time tested given the EFI has worked fine for 50,000 miles of driving the car.

[C5GTO]

Originally Posted by msinc

I don't know what pistons are in your engine, but if they are the typical Ford cast style then you could have cracked or completely lost a skirt. This was a very common problem at one time and the reason everyone used forged pistons in rebuilds. You can pull one plug wire at a time while the engine is idling and see if the noise goes away or changes on one specific cylinder. Take away the fire and you take away the pressure that makes the knock. This stupid little trick wont tell you if it is a piston skirt, wrist pin or bearing, but it will locate it if it is in the bottom end. If the noise doesn't change then it's a top end issue. Sharp clacking is typically a piston. A heavier sounding deep "thunk" is usually more like a rod bearing noise. There are of course other things that can make noise in an engine. Piston skirts wont cause an oil pressure loss or drop, a rod bearing failure most certainly will. Best of luck and keep us posted.

Edit: I have had a couple small block Fords make the piston skirt noise that I would have bet money on and it turned out to be a rod bearing or once even a cracked flexplate. Also, if someone swapped over to timing gears, I have heard them develop one hell of a knock too.

The Ford Motorsports spec sheet for this crate engine says:
• 9.0:1 compression ratio (nominal)
• Forged Mahle pistons 4.030”
• Hydraulic roller camshaft M-6250-E303, .498" lift intake and exhaust, duration at .050" is 220 degrees intake
and exhaust
• Double roller timing chain set

[eschaider]

Originally Posted by C5GTO

The engine is fuel injected using a Ford EEC IV computer. It uses a MAF and has 24 lb injectors. I don't recall the throttle body or MAF size but they were considered large back in 1994 but are small by today's standards. All the EFI components (except for the ECM tune add-on) on the engine were supplied by Ford Motorsports in a "EFI package" purchased in 1994. The intake manifold is an Edelbrock Performer RPM of '90s vintage. So all components are old by EFI technology standards but I'd say they are time tested given the EFI has worked fine for 50,000 miles of driving the car.

Thanks for the memory reflash, Joel. With no carb to EFFI conversion required the only thing you need to decide is the ECU you will be using. If your current ECU is the Ford EEC-iV generation then this ECU <= clickable, should plug right into your existing wiring harness.

The OEM wiring harness connector for all the EEC-iV ECUs used the same geometry and pinouts. There may have been the occasional pin that was reassigned year over year but that is easily repositioned in the connector.

Alternatively you can use what you are already using and just have the fuel maps and engine specifics updated for the 347. Although you loose the add on stand alone features of the aftermarket ECU, you gain the simplicity of just remapping the existing ECU fuel map — and you save $1,500.

[Mark O'Neal]

Originally Posted by C5GTO

Going from 302 to 347 cid would purely be for the extra power. The main purpose for the OD TKX transmission would be to lower RPMs while driving on the Interstate.

A question related to the 347 stroker direction, will the current EFI tune be adversely impacted by the extra cid? If so, would the situation be that the dyno tune done for the 302 cid engine just might be non-optimized for the 347 or the extra displacement really requires a different tune to prevent engine failure?

As I'm putting together a budget for the fixes here, it's important to capture all the line items. I'm guessing a dyno tune is probably in the neighborhood of $750 these days thus a significant line item.

Doing a 347 is ridiculously easy. I've (my old company...and this one) built thousands of them. Probably more than anyone in the industry...and I introduced the first (cast crank) version ever offered back around 1990. Back then we modified 351C cranks to fit the 302 blocks.

There are no balancing issues. Forged cranks come in either 28 oz or internal versions. Cast cranks are 28 oz. There are a ton of balancers available either way, and neither will give you any problems.

If you're going with the stock block, I'd probably stick with the cast crank versions (though I'd avoid Eagle). A Scat cast crank, Scat Pro Series I-Beam rods and an Autotec flat top (depending on cylinder head) will take far more power and rpm than the stock block will allow.

You will absolutely have to have the tune redone and may need larger injectors, depending on what you have now. I have no idea what it costs to tune anything.

[eschaider]

Something to keep in mind when using externally balanced rotating assemblies is that changes in the damper or clutch flywheel assembly should have the entire assembly rebalanced — which requires removing the crank from the engine.

The always asked 'why' question has to do with the precision associated with balancing the assembly. The advocates who say, " Don't worry, a few grams here or there will not matter, " are not pointing you in the right direction if it is a performance engine.

When you send your rotating assembly to a shop to have it balanced, they will balance to within a gram on a normal balancing job. On an engine that is expected to run over 6000 rpm, they will balance even more precisely.

Why do you balance? Well, several reasons; one is rotating assembly life, and another is that OEM parts can easily be off by 5 or 10 grams. When you are talking about a damper with an external weight measured in ounces that weighs a reported 28 oz, if it is off a little bit, it is off by a lot of grams.

One ounce is 28 grams. If your external damper counterweight is accurate to within ½ ounce, then you could be off by +/- 28 grams. That is a 56 gram window! We haven't even talked about the attaching bolt holes being off by a little and shifting the counterbalancing weight from where it is supposed to be to a different location — creating a new and different imbalance.

For a Sunday, go to meeting or proletariat daily driver (DD) that rarely gets over 3000 rpm not a big deal, but still not right. For a performance engine, we have moved into the big deal country.

When will the problem present itself? The first time you upgrade or replace the damper. The first time you upgrade or replace clutch and flywheel components. To avoid these unhappy experiences, use an internally balanced assembly where the clutch and damper are independently balanced.

When you need or want to change out a damper or a clutch, you simply balance the new pieces individually, and your rotating assembly balance will still be as it originally was — correct.

[Mark O'Neal]

Interesting post.

I suspect you can overcomplicate a bowl of Cheerios.

[MAStuart]

Mark what Co are you with now?

[eschaider]

When people ask questions they deserve answers that are factually complete. It is always possible to skip over the information you, as the reader, do not need, want, or understand.

It is a travesty to provide incomplete answers that could cost the requestor / implementor time, money and parts because the responder decided to dumb down the answer.

When the information is a bridge too far, it is better for all concerned if the reader does not begin the journey.

[eschaider]

Duplicate post

[Mark O'Neal]

Originally Posted by MAStuart

Mark what Co are you with now?

Vigilante Performance and Probe Industries.




......Probably until my ashes join my cat's.

[Mark O'Neal]

Originally Posted by eschaider

When people ask questions they deserve answers that are factually complete. It is always possible to skip over the information you, as the reader, do not need, want, or understand.

It is a travesty to provide incomplete answers that could cost the requestor / implementor time, money and parts because the responder decided to dumb down the answer.

When the information is a bridge too far, it is better for all concerned if the reader does not begin the journey.

Well it was certainly complete. Factual is altogether different.

I think describing it as an opinion would be more accurate.