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Old 12-06-2004, 04:48 PM
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383 Stroker clearance question

Okay guys, building my first supercharged stroker motor and need a little advice. This is the combo I went with:
5.7" Eagle forged H-Beam rods,
3.750" Eagle Forged Crank,
JE Premium Forged inverted dome pistons (8.7:1 c/r with 64cc heads)

I was planning on doing the clearance work on the block myself, but I ran into more problems then I expected. The pistons are scraping the counterweights on the crank, the machine shop says to grind the pistons down it could be over $100 in work and it's "kind of dangerous" lol, if I were to just swap the rods for a set of 6" It would probably clear the pistons but I don't really want to go with a 6" rod because of the faster rev's of a 5.7" rod. I also debated on just trading the crank for a normal 350 crank and screw going with the whole stroker setup, but then I was told that a normal crank wouldn't work with the JE piston's.. sooo, what do you guys think would be the best bet, have them machine the pistons to clear or just go with 6" rods? Keep in mind it's going to be a vortech supercharged setup.
Thanks

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Old 12-06-2004, 04:56 PM
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I have a sneaky suspicion that your pistons won't work on 6" rods either.
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Old 12-06-2004, 04:59 PM
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Damn, well I'll probably just have them machined then.. How safe is this though? it's hitting right on the arc near the skirt on the bottom of the piston. I'd hate to see these $700 pistons fly to pieces
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Old 12-06-2004, 05:10 PM
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i would call JE tech support and see what they say. Most pistons are designed to work with a specific stroke and rod length. Call JE and have the JE part # for the pistons you have handy.
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Old 12-06-2004, 05:24 PM
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I called JE and they said to go with the 6" Rod and it should clear fine, so that's what I'll do.
Thanks alot for your advice
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Old 12-06-2004, 05:33 PM
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I had the exact same problem with my 383 blower setup, early 2 piece block, using the Eagle 4340 crank and 5.7 rods with a set of JE pistons I bought off eBay. My machinist said he could grind the crank throws a little, the small amount needed for clearance, the only issue would be balancing costs. These pistons were originally custom forged for an LT-1 motor, why they didn't fit I don't really know. I spoke to Eagle's tech and they said they have seen interference problems but never with JE pistons until now, and also recommended grinding the throws. I spoke to JE and without the original order number they couldn't help at all.

I didn't want to cut a new relatively expensive crank, so I sold the pistons and bought a set of JE "shelf" blower pistons with the -31 cc dish and they cleared fine. I didn't want to go with the 6" rods because of the pin interference with the oil ring location.

I didn't lose any $$ so I was lucky in that respect. What part number are your pistons? If you decide to go my route I'll get the part # for the pistons I'm using.

Also, those pistons won't work on a 6" rod anyway, they have a different compression height.

Larry
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Old 12-06-2004, 05:34 PM
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some handy calculators

Here is the location for some handy engine building calculators.

http://www.kb-silvolite.com/temp/calc.php

If the pistons are the correct compression height for the stroker crank with 5.7 rods, I don't think you can change to longer rods, unless you change to a shorter crank, too.
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Old 12-06-2004, 05:42 PM
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170817 Is the part# for them, I'm running into a hell of alot more problems then I expected, lol. So you guys think a 6" Rod won't work?? JE told me it would
Where did you get those pistons and how much were they?
I don't mind going to a 6" Rod but I don't know if I'll have any more problems with that.
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Old 12-06-2004, 05:50 PM
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Well those are 6" rod pistons. I wonder why the Machine shop didn't notice the low deck height?
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Old 12-06-2004, 06:07 PM
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So they'll work with a 6" rod then? JE told me they were made for a 6" rod with a 3.750" stroke so they should

Also on another note, what do you guys think of the rest of my combo:
Jegs 220cc 2.10/1.60 Heads 64cc heads,
Crane supercharger cam Adv. Duration: 286/294
Gross Lift: .525'/.543''
Mighty Demon 750 w/ mech. secondaries,
Crane Roller lifters,
Jegs 1.5 roller rockers,
Edelbrock super victor manifold,

4.10 Gears, Turbo 350 tranny with 3500 Stall in an '85 GMC 1/2 ton pick up.
What kind of HP/Tq should I see out of this setup with between 8-10 lbs of boost? Could I get away with more with an 8.5:1 C/R? Also thinking of adding a 150 shot of NOS, any problems there?
(Supercharger is the new carbureted vortech btw)
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Old 12-06-2004, 06:36 PM
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http://www.flatlanderracing.com/jepistonchevys400i.html

I went back a re read your 1st post. I see the machine shop did say to run 6" rods!

Where did your pistons come from?
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Old 12-06-2004, 06:41 PM
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I bought them from jegs a few months back. I called and they said it would clear fine with 6" rods. Looks awfully damn close to me though
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Old 12-06-2004, 06:45 PM
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I'm pretty sure if you got them from Jegs they told you they were for 6" rods. Why did you want to try to run them on 5.7 rods, rpm?

You surely paid more for a 6" rod piston than a comparable 5.7" right?
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Old 12-06-2004, 06:48 PM
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I bought them all at different times and didn't pay attention to the small note on the jegs website. Stupid me And yes, for faster rev's.. although I guess I shouldn't worry about that too much with the supercharger.
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Old 12-06-2004, 06:54 PM
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Be happy you've got the 6" rod pistons! You are well ahead using them in combination with a blower!(it will be less prone to detonation from timing or fuel problems...and that is what makes your engine self combust with a blower!) Be sure to run some cold plugs also, around an AC 42 or 43 temp range, depending on boost levels.
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