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pistons

Interesting. Ive torn apart around a dozen 302's in my life and never found one that came from the factory with cast pistons. Did I miss something?

Vertually every factory piston I have ever seen had a 1.6 compression height and with the exception of being, flat top, dished, or domed, all had the same length skirt.
 

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Discussion Starter · #4 ·
Well I know the Duratec V-6 has such squatty looking pistons, I didn't know if that was something they did on the latest 5.0's or not.

I'm planning on going with some KB hypereutectic pistons to lighten the weight. I thought if the late 5.0's had squatty pistons I would use those instead.


Thanks,
Steve
 

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pistons

Why would you want to run pistons with shorter skirts? This increases side thrust wear on the cylinders, as the pistons arent as stable in the side to side motion with shorter skirts. The KB's are good pistons, no problems with them that Ive ever known. At one time they were the rage in this area, but like all fads, that settled down to going back to run what ever you want brand.

It doesnt matter whether you are running 5 liter or 302 pistons as they are the same, as the engines are the same. The only exception was one year, they had pistons for one head combination in production engines that werent recommended to be used with other heads. Wish I could remember the year, it was in mid 90's, might want to check with a Ford shop on that one. The difference was that they had a higher compression height, which I dont think would really cause a problem, other than Ford protecting its legal derierre.

If you are planning to race this engine seriously, you should get it rebalanced if the pistons are appreciably lighter than the factory units.
 

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Discussion Starter · #8 ·
Thanks for all the info.

I don't plan on racing the engine other than just taking it to the track to see what it will do.

I want shorter pistons to reduce weight. That is how I've ended up at the KB silv-o-lite pistons. I don't want to stroke the engine. If I want a 347 I'll drop in an Aussie 351C that I am going to be pulling out of another car.

That's good thinking about the side thrust. I hadn't thought about that. So is that a nagging problem with the Duratec V-6 engines?

I plan on having the whole thing balanced together at the shop I am going to be dealing with. Hopefully with these pistons some extra weight can be removed from the counter weights on the crank.


Steve
 

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The only stock Ford 302's I know that had forged pistons were the 1987-90 HO in the Mustangs. In 1991 Ford Changed over to hypereutectic pistons in the HO Mustangs. The 5.0's in other makes and models only recieved cast pistons. The only difference I know in skirt length was in the 289 engine. The stock 289 pistons had shorter skirts than the 302 pistons. The pistons are interchangeable between the two motors as long as you grind clearance between the crank throws and the bottom of the piston skirts. This is only if you use stock 302 pistons in a 289. Aftermarket piston are designed with extra skirt clearance so 289 and 302 pistons would be interchangeable. BTW stroker pistons also have shorter skirts needed for that extra throw.
 

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I know in the 80's the Ford engineers started putting shorter skirts on the pistons whenever they were changing an engine design. Why I don't recall, I'll have to ask one of my old-timer design friends.

I work at the Duratec engine plant, and I never hear our guys talking about side thrust issues. Biggest weakness in the engine is the bottom end, it's a little marginal for the 220 horses they get out of that little thing.
 

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pistons

I admit total ignorance on the duratec engines. The only ones Ive seen were in new vehicles. I guess there must be some differences in how the 302's were assembled and I dont doubt they did use cast pistons in them, especially during the low performance years. Guess Ive just been sheltered in that all Ive ever seen in them from the factory are forged or hypereutectics.
As for piston differences in 302's and 289's, Ive never seen a difference in them, and both engines use the same pistons in replacements, according to the part numbers I have.
 

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pmeisel said:
I know in the 80's the Ford engineers started putting shorter skirts on the pistons whenever they were changing an engine design. Why I don't recall, I'll have to ask one of my old-timer design friends.

I work at the Duratec engine plant, and I never hear our guys talking about side thrust issues. Biggest weakness in the engine is the bottom end, it's a little marginal for the 220 horses they get out of that little thing.
Windsors had the long skirts that rev well,, clevos dont,,
 

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Discussion Starter · #14 ·
pmeisel said:
I know in the 80's the Ford engineers started putting shorter skirts on the pistons whenever they were changing an engine design. Why I don't recall, I'll have to ask one of my old-timer design friends.

I work at the Duratec engine plant, and I never hear our guys talking about side thrust issues. Biggest weakness in the engine is the bottom end, it's a little marginal for the 220 horses they get out of that little thing.

My wife started in Engine Plant 2 about 5 years ago. I've been in there a few times and marvelled at how short the pistons were. I haven't heard any problems with them either.

I know stroker pistons have shorter skirts for the extra throw as onebadmerc mentioned, but I don't know if the hole for the wrist pin is relocated any higher requiring a different rod length?


Steve
 

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Stroke is one thing, getting the lot to work in unisen is another,,

The skirt dooes have many functions, ( upp off over ya head )
but as you have said Pin to top of piston is comp,, the rest is maintaining oil throw,,
 

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I have owned a few mustangs and am currently working on another 88 cobra right now. I'd recomend 12.5:1 speedpro pistons. They work like a hot dam. I put them in my last stang which was shy of 400 horsepower and they were awsome, I am for sure putting another set in my new one. But if you want to use the Short skirt pistons I would. I mean Ford is using the
lightweight hypereutectic aluminum pistons in there new 2005 mustangs, and look at them go..
 
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