Thoughts on bottom end rebuild and or stroker kits

Jack

on the subject of aftermarket stroker kits, the inexpensive crankshafts found in the stroker "kits" are Chinese made. They are notorious for very poor quality control, and the machine work is just as notorious. There are a few businesses here in the US which purchase Chinese cores and then do their own machine work, to a much higher standard. These businesses are also very picky about which cores they use, the poor castings and the ones with poor metallurgy are rejected, sent back to the distributor, they only use the cream of the crop. One such business is Scat, Scat has developed a fairly good reputation within that market.

If you must use a "kit", save yourself a lot of grief, and do business with one of these companies, like Scat, that do their best to maintain a decent level of quality control and precision machine work. Remember the castings which Scat rejects are sold to others, and then passed on to the public at a lower price. You do not want to put yourself on that end of the "food chain".

If you price the US manufactured crankshafts you'll likely skip a heart beat, they are pricey. They are worth it in my opinion, but not everyone's budget can take a hit like that.

The oil passages in the oem crankshaft are an integral part of the Cleveland lubrication system, if you are going to use an aftermarket crankshaft, it is in my opinion imperative to install bushings in the lifter bores, set the lifter bore to lifter clearance between 0.0007" and 0.0012", and drill a 0.040" orifice in the bushings for supplying oil to the lifters & valve gear. That hole may need to be a bit bigger if you plan to use a hydraulic cam & lifters, we can cover that later.

Another bit of advice, steel cranks are harder on the block, if you're gonna use a steel crank, invest in a "good" balancer. The common balancer I hear mentioned among experienced Cleveland racers is the ATI balancer, it seems to help the thinwall block survive a lot of abuse.

A 4" stroke and 6" rod will put the wrist pin in the oil ring groove, which normally results in oil burning. A contact at JE pistons tells me it is possible to spec a piston & ring combination that will not burn oil with the wrist pin in the oil groove. So if you decide to go that route I can put you in touch with him also.

I like the idea of the 400 cubic inch Cleveland, it wakes up the 4V heads and makes it possible to make big power over a reasonable, street-able powerband. But knowing how much the parts in the 351C are inter-dependent, I've never been 100% happy with the situation.

Which brings me to two alternatives.

Fist alternative: the 351C was designed by Ford to make 500 BHP at 7000 rpm, that's plenty of power in my opinion. The 351C is designed to be very durable at that RPM, the motor likes to rev. So instead of building a stroker, just build the 351C the way it was designed to run.

Second alternative: Off set grind the oem select grade 90% nodularity iron crank from stock 1.75 inch throws to 1.85 inch throws, reducing the diameter of the rod journals from 2.31 inches to 2.10 inches. The 2.10 inch rod journal allows you to use readily available 6 inch long I beam connecting rods designed for the SBC. SBC rods are lower priced than comparable Clevo rods (I beams weigh less than H beams). Choose a nice light, forged, full round skirt piston, compression height = 1.330 inches. After offset grinding the rod journals have the crank tufftrided, have it straightened, chamfer the oil holes, micro polish the journals, have the reciprocating assembly dynamically balanced.

3.70 inch stroke with 4.030" bores increases the displacement to 377 cubic inches. Everyone likes what that small increase in stroke does for a street motor with 4V heads. The oem iron crank is a very durable part. The iron is gentler on the block, the iron surface also retains oil better than steel. The oem crank also has the right oil passages and the standard 351C crank snout. A lot of the aftermarket cranks have Windsor snouts which requires a specialized hybrid timing set and a crank spacer. By using the Ford crank all 351C parts are used, no spacer is needed, etc.

quote:

I like the idea of the 400 cubic inch Cleveland, it wakes up the 4V heads and makes it possible to make big power over a reasonable, street-able powerband. But knowing how much the parts in the 351C are inter-dependent, I've never been 100% happy with the situation.

George, I'd be interested to hear your thoughts on just going to a 400M block for a build vs. stroking a 351C block?

Julian

Hey George:

Cheers for your thoughts on a bottom end rebuild. That said, I like the idea of the 377... So can you be a little more specific about parts you would recommend. Brands/Manufacturers and part#'s. Plus, would I need to get a new crank? If so, I assume OEM part. And what about the block... stick with a 2 bolt main M code. Or try to find a 4 bolt main?

Basically if I can actually get close 500BHP from most of the stock engine configure that would be great. I have the 4v heads, roller cam set up, and so on.

Please advise.

Best JC71

Jack

what do you plan to do with your car, strictly street, open road racing, track racing, track events (but not competitive racing), daily driver, strictly show car, etc.?

what parts currently on the motor do you intend to re-use?

why did you feel you needed to replace the lower end to begin with?

are you prepared to spend whatever it takes to do it right?
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Julian,

I can go either way. I have no problem with a 351C with a 4" stroker crank as long as the owner goes the full route, takes no short cuts. But the 400 (its not a 400M) is a viable route to achieve 400 cubic inches in a 335 series motor, and possibly the least expensive option. I prefer using the 400 instead of a stroker crank to a degree because it uses fewer aftermarket parts. There is one problem in using this motor in a Pantera, to my knowelege there are no off the shelf headers for that application.

The 400 is good for up to 6500 RPM (those 3" main bearings and the somewhat heavy crankshaft are the limitations), 4V heads bolt right on, adapters are available to allow the 4V intake manifolds to bolt onto the 4V heads. The difference in weight between the 351C & 400 isn't all that much either. Motor mount adapters are easy to fabricate. Big block to ZF bellhousings are available. Then there's always the FMX block if one is so lucky as to come across one. Just consider the 400 an inexpensive 351C stroker built by Ford, therefore using all Ford parts; the short blocks are dirt cheap at the wrecking yard. The 400 is a sleeper, a very over-looked motor in the Ford family of V8s. It can be a 500 BHP at 6200 RPM BEAST with just the usual stuff.


-G

Hey George:

Good questions. The car would mostly get used for fast canyon driving in socal. A number of multiple day road races, some hill climbs, etc.
Have NO plans currently to track the car, either strip or course. Looking for a good reliable engine, with plenty of torque, and some good top end. That is not gonna cost me a fortune. I do not want to over engineer the engine, it's not ever gonna be a show car. Unless you call driving as many miles as I can on the weekends showing off the car.
Best jc71

Hey George:

More answers to you questions.

I would like to keep most of the existing parts. Block, Heads, intake, exhaust, etc.

I need to have the bottom end rebuilt, as it is basic close to worn out. low oil pressure, etc.

Not looking for titanium space age tech... but will definitely spend on forged, good brand, good quality stuff.

Thoughts?

Cheers JC71

In the current "Engine Masters" magazine from Pop-Hot Rodding, there's a comparo of intakes and cams on a 'basic' 030-over 351-C buildup. I noticed that the worst as far as power delivered over 380 bhp with iron heads, stock intake and a Boss 351 cam. The best was some 50 bhp more. How much is enough? 400 bhp will push a Pantera up to 180 mph on top and turn the tires in 3rd gear.
A good tight bottom end on stock rods & a stock crank thats been cross-drilled, forged pistons and premium rings, will give you more power and capability than most drivers can use anywhere, any time. Save your stroker money for a good set of alloy heads & intake, a tuner carb and start trying to figure out which cam you'd like to try. On a mostly-street car, more displacement= less mileage, and less top end due to a lower redline (unless the innards are billet-everything or you regear the ZF). Stopping for fuel every 100 miles on tours is a real downer...
There's a really nice pro-built 385 Fontana for sale in N CA that dynoed at 615 bhp before final tuning and was driven less than 1000 miles, for $25,000 (less than it cost to build). The owner said it wasn't much fun on the street roasting 12" wide tires every time he touched the gas in his '73 and was undriveable in damp weather, so is building a nice street 351C of around 400 horses.

I understand.
So do you think it would be necessary to find a 4 bolt main block, I currently have a 2 bolt?
Is it worth getting a forge crank or just working with the stock oem crank?
When it comes to forge pistons and rods. What would be a good combo, based on type of use?
And like wise with rings and bearings?

Plus are there any other mods that would be worth making to the oem block, if the engine is apart?

Very much appreciate your guidance.
Best jc71

quote:

Originally posted by jackcarter1971:
... Looking for a good reliable engine, with plenty of torque, and some good top end. That is not gonna cost me a fortune. I do not want to over engineer the engine, it's not ever gonna be a show car. Unless you call driving as many miles as I can on the weekends showing off the car ...

Boss Wrench's advice is very appropriate. Your comments lead me to believe you want a strong performing street engine with some durability built-in so you can work it hard. This is probably the type of engine the majority of Pantera owners need.

So what do I recommend?

There are several choices still to make; several questions to ask. But consider this, we can juggle camshaft duration and engine displacement to build towards a certain horsepower goal over a certain powerband. For instance, the following 3 motors have roughly the same streetable power band:

Displacement .......... camshaft intake duration (degrees @ 0.050" lift)

351........................225 - 230 (~400 BHP)

377........................235 - 240 (~450 BHP)

408........................245 - 250 (~500 BHP)

The larger motors will make more power than the 351 even though they have the same powerband. It sounds like Jack may have you talked into staying with 351 cubic inches, if so, I agree whole heartedly.

Since you mentioned wanting a good top end my next question is do you want to run hydraulic lifters, or is that top end important enough to you that you are willing to adjust a set of mechanical lifters from time to time?

The iron 4V head will "hit" harder and harder as we put a bigger cam in it. That affects drivability. One way to smooth out that hit is with a custom ordered camshaft having wider lobe centers than what is the current trend. The drawback being less "peak" horsepower and a demand for less compression (less compression = less horsepower). I don't see that as a drawback personally. But the wide lobe centers also make the motor less finicky about the exhaust system. This could be an advantage on a street motor where you want to keep it quiet. Another way to smooth the hit is to employ a more restrictive exhaust system, the drawback is the exhaust system will rob top end horsepower. The advantage is the exhaust system is quieter, something very important if you plan to spend a lot of hours driving the car. Another way to smooth out that hit is with small port heads, like the CHI 3V or 4V heads. A second advantage to such heads is that they are made of aluminum and have modern high swirl combustion chambers. This makes the engine lighter and allows you to run about a point more compression, which makes more power.

I would like to read your thoughts on the cam, the exhaust and the aftermarket heads.

Jack,
Take a look at this, it might help. Would be in the car by now but I was side lined by another Hotrod purchase.

Mark

http://pantera.infopop.cc/eve/...=576105521#576105521