Stroking an Explorer 5.0L engine?

[2000StreetRod]

I'm seeking information on what is required mechanically to stroke an Explorer 5.0L V8 engine. The purpose of stroking the engine will be to slightly increase low speed torque.

Rotating assembly balance: I've read that the stock engine is designed for an external balance of 50 ounce-inch that is provided by the crankshaft harmonic balancer. Apparently most stroker kits are targeted for Mustang engines with a designed external balance of 28 ounce-inch. For the Mustangs I've seen references to flywheel external balance and harmonic balancer external balance. It seems there are two methods of achieving rotating external balance for a stroker kit. One is to fabricate/assemble a new 28 ounce-inch harmonic balancer of the correct diameter fitted with an Explorer trigger wheel. The other is to retain the stock 50 ounce-inch harmonic balancer and remove an appropriate amount of metal from the crankshaft counterweights.

I'm looking for comments on cost, reliability, complexity, etc. comparing one method to the other.

Additionally, I'm aware that for the 3.4 inch stroke the bottom of the cylinder bores will have to be notched for rod bolt clearance and the ledge next to the oil pump support pad must be cut back slightly for crank counterweight clearance. Are both block modifications required for the 3.235 inch stroke?

Are any other mechanical modifications required? Please do not side track this thread with discussion about heads, cams, headers, blowers, ect. unless they pertain to actual required modifications. I suspect a custom tune is essential but that is not a mechanical modification.

 

[Axial32]

Have you looked anywhere for a stroker kit yet... sometimes they offer a fully balanced kit... My brother is boring and stroking his 351W to a 428W... the kit is completely balanced together for alittle extra...

 

[2000StreetRod]

351W balancer

Have you looked anywhere for a stroker kit yet... sometimes they offer a fully balanced kit... My brother is boring and stroking his 351W to a 428W... the kit is completely balanced together for alittle extra...

I believe the 351W comes stock with a 28 ounce-inch harmonic balancer which the stroker kit is designed for.

CHP used to offer stroker kits for either external balance. I've seen some negative comments about their balancing abilities on the Mustang forums for the standard balancer. I'm not comfortable with trusting them for a non-standard balancer.

 

[Axial32]

Ok, but my point wasn't that he has a balancer which is ok for his stroker kit (though he's getting the complete balanced assembly for more)...
I was trying to get at that some places should fully balance a complete kit for you... balancer and all so you don't have to go searching...

 

[99SportX]

Subscribing...

I wonder if someone could get a new trigger wheel laser cut and get it machined to fasten onto a 28 oz-in balancer?

 

[Axial32]

That would be sweet 99sport

 

[2000StreetRod]

local balance shop

I agree that it would be best to get the entire rotating assembly (internal and external) balanced and preferably by a local shop. I don't know if there is a shop with the experience and capability in Greenville, SC. And I don't know which balancing method is the best overall.

 

[2000StreetRod]

balancer diameter

Subscribing...

I wonder if someone could get a new trigger wheel laser cut and get it machined to fasten onto a 28 oz-in balancer?

The 28 oz-in balancer would also have to be the same diameter as the Explorer balancer. Those are no longer in production. According to ford99_1979 the pulleys that are approximately the same diameter were on the 94 and 95 Cobras.

 

[jds3403]

not to sound ignorant, however exactly what is the difference between running the 28oz and 50 oz besides obvious weight differences.

 

[2000StreetRod]

unbalanced crankshaft

I've read that an unbalanced crankshaft will eventually break due to vibration.

 

[2000StreetRod]

custom balancer

I read an article on the internet by an engine builder that internal balancing is preferable to external balancing. To me that means that a 28 oz-in external balancer would be preferable to a 50 oz-in external balancer.

Below is a photo by CDW6212R (Don) of the custom 28 oz-in balancer he had fabricated for the 347 he is building.

Here's part of his comments: "I'd consider the custom balancer hard. Weigh the high difficulty of balancing the stock balancer against about $330 for what I had done. Balancing the stock unit is bad enough that many shops will not touch it. What I found is that only one balancer can be fabricated to accept the OEM crank trigger wheel. That is the Ford stock balancers for the V8's. The backside of other balancers do not have enough metal there to machine space for the trigger wheel."

Machining a balancer would probably generate heat. I wonder if there's a possibility of heat damaging the flexible material that separates the inner and outer sections. If so, I guess it could be liquid cooled during the cutting process.

I checked eBay and didn't find any 94 or 95 Cobra balancers listed.

 

[Mbrooks420]

The balancer could be easily be machined without damaging the rubber inside. If the part gets that hot it would destroy the tooling in short order. I would think an internal balanced setup would be best.

 

[01explorer2wd]

Does anyone know if they make a storker kit for a 4.0?

 

[2000StreetRod]

Please start your own thread

Does anyone know if they make a storker kit for a 4.0?

This thread is only about stroking a 5.0L Explorer.

 

[CDW6212R]

Dale, the balancer issue is not so bad the way my machinist made one, and fixed the first. Those were both stock 28oz Ford balancers which came on most stock 28oz 302/351 engines. Those were the only choice to start with when I did mine. The aftermarket balancers have slightly different locations for the mass or material that they are made of, compared to the stock balancers. Mine worked because the trigger wheel mounting area is virtually the same on the 28oz OEM parts. A slight amount of material is removed to create the ledge for the trigger wheel to push onto. My machinist wisely had the answer to keeping it from spinning. He pinned the trigger wheel in three places, that wasn't done on my first one from Total Performance. They supposedly had done it before, and there was no mention of problems. When I got it back with my engine, I found the trigger wheel had moved. That was from the balancing process by the engine builder. So that's when I went to my machinist and he came up with the answer.

For the subject here, consider one massive point that is almost always ignored. The power potential and actual power curve is determined by the heads/intake/cam/exhaust used, not just the crank/rods/pistons.

It is this simple for a stroker, if you use stock heads/intake/cam/exhaust for it, the result should be stock power, at a different rpm curve. Meaning divide 302 by 347 and apply that to the stock rpm curve. If you have 200hp at 4500rpm, then expect to have 200hp at a 15% lower rpm. You will not gain 15% more power, the rpm range will just be lower.

I'm only trying to help people to understand that strokers are great, if built right. The stock heads/intake/cams are pitiful for anything but a stock engine. There are tons of aftermarket parts which are vastly superior to those. Try to budget any stroker to include upgraded induction parts, without those the results will be a disappointment.

You can make an Explorer 302 engine produce over 100hp more than stock with some expensive parts. The question should be how much does a stock rebuild cost, an how much more is a proper stroker going to cost.

The best deal for a Ford stroker that you can trust the builder is still from Fordstrokers.com, give Woody a call. The last I noticed he gets $2100 for a complete assembled stroker 332/347 shortblock. That's cheap given what the kits cost, and what most high quality labor is. The heads/intake/cam are another issue, they need to be a match for the shortblock. I'd suggest the heads be at least TFS Twisted Wedge, and never any stock type head(inline valve seats/angles). The stock type heads don't have the flow potential of the Twisted Wedge or High Port designs. Lots of aftermarket heads fall into that stock type category, such as AFR, Dart, GT40, Edelbrock, etc.

With the right heads/intake/cam, a 347 can easily make 400 rear wheel horsepower. I think on the cheap side a stroker with decent heads/intake/cam will cost about $4000, give or take. That's the longblock and inside, not the headers, injectors, tuning, fuel pump/lines, TB, etc.

I think most people want to do the stroker shortblock and possibly be done. That will not be very impressive, may Explorers have been built that way. I'd suggest finding one to get a test ride in it, before spending half the money needed and being disappointed. If the project will include the right heads etc, later on, then just understand all of this to start with. Best of luck,

 

[2000StreetRod]

Thanks for your input!

Don, thank you for taking the time to provide very helpful information based on your experience. I was hoping you would respond.

I visited FordStroker's website and was impressed with their very thorough block preparation. Their Liberator stroker (331 or 347) short block is $2399 but does not include a stock 28 oz balancer (+$70). I will contact them regarding the current cost of an Explorer compatible balancer. Their target purchaser is someone looking for 400 to 500 hp. At this time, I'm mainly interested in a small torque increase over the stock 5.0L that may result in a fuel economy improvement.

You have a good point regarding performance improvement potential. However, that introduces a huge number of variables. I want to limit this thread to what's required to stroke a 5.0L for an Explorer.

What is your advice regarding the use of a 50 oz vs a 28 oz balancer? Do you agree that the objective should be to reduce the amount of external balance?

If a person has a good local engine builder, what do you think about having the local builder order what's needed, prep the block and install the components vs an order and ship from FordStrokers? I suspect that even a short block from FordStrokers may require local balancing.

 

[CDW6212R]

That price has changed a lot since I bought mine. It was $1900 for the longest time, and the $2100 was last Winter.

For the balancer I think I found the best choice. A very small few people have suggested machining a stock balancer down to make it 28oz will work, but no one had first hand experience of how that was done. I don't like the idea of rebalancing a balancer(dampener), they aren't made to be able to do that. Most good machinists will decline to do that. Woody didn't want to do it.

What I had made will work great in anything but a high rpm engine, say 6500+. This is a stock balancer, thus not an SFI spec part, which means better rpm ability. I did run across a balancer made in Australia that looks a lot like the stock units in pictures. If I needed an SFI balancer or wanted that extra insurance, I'd buy one of those to attempt to alter and add the trigger wheel. I think they were about $120-$140 to buy. My cost for the trigger wheel labor was around $100 or so, my guy was very reasonable. Assuming he'd still do the work for that, I can help you to build a 28oz balancer which any machine shop can balance for a smallblock Ford.

The stock heads are really not worth much except for a stock rebuild. Start by asking some machine shops what the rebuild cost is for any stock Ford head, GT40 or otherwise. Counting the cost of springs and rockers and retainers, the cost is what nice Twisted Wedge heads would be. If a really cheap budget had to be used, I would at least spend the time it'd take to get a good deal for the heads. If you shopped around, you might get them for a cost within $200 or so of the stock GT40(P) heads.

I'd contact Jay Allen who specializes in custom cams and heads. He provides the best deal for complete heads and the cam. Each cam really really needs a specific spring package with matching retainers etc. It costs you more to buy heads with the wrong springs and then buy others, plus double labor to swap the parts. Valve springs are not one size fits all. Complete heads are advertised as having springs "good for .550 lift." That is crap.

Each cam needs a specific valve spring, to achieve a specific distance reached from valve float. That's a poor man's description, but true. If you buy a matched set of heads/cam/springs/retainers etc, from one place like Camshaft Innovations, the total price and performance is best. There is a lot of power to be gained in the right cam, the right springs, all set up to work together. That also means finding the proper pushrod which is needed for each set of parts, and adjusting the rockers for the proper tip wear pattern on the valves.

That's part of why the Fordstrokers deal is so good. Woody and Jay are in the same town, they do a lot of business together. You can pay Jay to ship the parts to Woody, and pay Woody to build the whole long block. That cost is much less than you can pay local shops to do it, and they are better at it. Shipping was about $250 for my whole engine, shipping for the heads/cam to them was about $60 I think.

I know that the shortblock price changed some, that hurts some. I'd still give them a call and see what a whole engine would be. They sourced every part for me except my balancer, and I sent them lifters I had. I hope to get my 347 in before it gets cold here. Regards,

 

[2000StreetRod]

Some responses

My question to The Mustang Depot:
"Are any of your 331 stroker kits compatible with the Explorer 5.0L engine that has a 50 oz balancer instead of the Mustang 28 oz balancer?"

Their response:
"Yes we can do kits for 50oz imbalance, it require more weight removal on the crank, but can be done.

If you are ordering a new engine rotating assembly you need to have it balanced! Precision Computer Engine Balancing, Matched Weight Rods, Pistons/Pins/Locks, Bobweight Matched and Spin Balanced Crankshaft. Includes Detailed Serialized Balance Card. Std OEM rotational imbalance is 10grams or less, we balance to less than 3grams! Got a severe duty application or want it balanced to less than 1 gram rotational imbalance, upgrade to the Race Prep option! We can also convert most 28oz kits for 50oz use as well as convert external cranks for internal balance!

Computer Balanced Rotating Assembly with Serialized Balance Card
Manufacturer: HawksRacing
SKU: Balance
Price: $180.00
Retail: $250.00
You Save: 28%

$230.00 B)Race Prep Balance
$590.00 D) Convert Std/Ext to Internal (Heavy Metal)
$180.00 A)Std Balance
$280.00 C) Convert 28oz to 50oz Balance"

My question to FordStrokers:
"Greetings, I am investigating the possibility of using one of your Liberator 331 or 347 short blocks in an Explorer. Acccording to what I've read on the Explorer Forum, there is a problem with the external balance. Apparently, most stroker cranks are designed for the Mustang 28 oz-in external harmonic balancer but the Explorer utilizes a 50 oz-in harmonic balancer. What solution do you suggest? What would be the additional cost?"

Their response:
"There is a guy who modifies 28oz balancers and installs the ring on the balancer. Balancing to 50oz on a scat crank is near impossible and I almost refuse to do it. You have to remove a ton of weight simply by balancing to 28oz. I dont have a balancer solution for you as I rarely do any explorer engines at 28oz, but I have done 2 with the modified balancer. Try searching over there, both of my customers are or were members there."

I suspect it is better to utilize a custom 28 oz balancer than to extract an excessive amount of metal from the crankshaft to utlize a stock 50 oz balancer. I've read that the stock 94-95 Cobra balancers are prone to have the outer section separate from the inner section. I will attempt to contact balancer manufacturers regarding a suitable custom balancer but there apparently is low demand for such an item even though it might be useable on a 5.8L conversion as well as a stroked 5.0L engine.

 

[2000StreetRod]

Dyno-Flow Racing response

My question:
"Is the 331 stroker kit compatible with an Explorer 5.0L engine that uses a 50 oz balancer?"

Dyno-Flow Racing response:
"Hi, yes it is. It will still need to be balanced to the 50 ounce, but it is compatible with the block and the engine layout etc."

 

[CDW6212R]

If you build a 50oz stroker for an Explorer, all of the builders will need you to send them the balancer. I know they talk about balancing to the number the weight, but besides a cheap OEM balance quality, real balancing must be done with all of the actual parts. So plan ahead for that and get a balancer in hand before pushing an engine builder for a schedule. Many of the best builders have a long build time. Regards,