opinions on 340 stroker kits

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kdsmith07

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hey guys,
looking for some info on stroker kits for a 340.like which one to use and where to buy.or who to buy from.one's to stay away from?any advice is greatly appreciated.TIA,kent
thinking 408 btw
 
Hi,

if you use the 340 (with original 4.040" bore size) you will get more than 408 cui, usually around 414 or 416 cui with a 4" crank - just for information.

I´d stay away from cast eagle 4" cranks, noticed some broken ones here around this forum.

Material of crank / pistons is up to the task you have for the engine - my opinion is if it´s natural aspirated and below 6500 rpm then a cast crank, cast or hyper piston combo is fine. If you want to use nitrous and / or boost / high rpm (for example a strip only engine) i´d use a forged crank and forged pistons. It seems that the scat i-beams are a good value for the cost, i personally went with a scat kit (cast crank) with KB hypers - everything was ok, engine runs very strong.

But as i told before, keep future upgrades in mind.

Here on the board are some vendors (mrl engines, imm engines), i´m sure they can offer a good package that fit your needs.

Michael
 
I'm with 360 on most things - except I'll never use a hyper piston in a 4" stroke small block. IMO - the max piston speeds are too high for them - althought he mean (average) piston speed is right on the edge of "ok". So for the extra coin (less than $200 more) you can get a decent forged.
I agree 100% on building for future growth. I'll also add trying to do this on a meager budget means you really need to shop around and know what you're looking to get from the package. So be realistic with yourself.
 
When it came to my kit I went with a cast Scat kit. I popped extra for forged dished pistons. After shopping around I got it from Summit because they beat all other prices. Some by $100's some only by a few bucks. Cost me $1450 for the kit and another $1300 to have my block completely prepped and assembled with cam.
 
My opinion's based on my reading and the few guys I've talked to about it (that take speed into account) don't feel comfy about using a hyper with a predicted mean piston speed of over 4000fps or so. A 340 at 7200 is still about 9% slower than the 4" stroke at 6500. At 6500 the mean piston speed is 4333fps in a 4" stroke. That's over 7100fps at peak piston speed. I love KB hypers - but there is a point that I get nervous about them and just feel safer with a forged piston.
 
moper said:
my opinion's based on my reading and the few guys i've talked to about it (that take speed into account) don't feel comfy about using a hyper with a predicted mean piston speed of over 4000fps or so. A 340 at 7200 is still about 9% slower than the 4" stroke at 6500. At 6500 the mean piston speed is 4333fps in a 4" stroke. That's over 7100fps at peak piston speed. I love kb hypers - but there is a point that i get nervous about them and just feel safer with a forged piston.
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thanks to all the replys.they are very helpful.first time doing a stroker.no nitros.no drags.just want a peppy street car to sneak up on the "other" guys.any up or downside to using my 72 360 as opposed to the 340?again,thanks for the help
 
Make sure you have a good local shop balance it. If you pay extra up front for a balanced kit you will likely pay again like I did and have it balanced correctly by your local shop.
 
that's good to know.i'd would have assumed balanced meant balanced.i'm guessing you found out the hard way?
 
I bought a Scat rotating kit that was balanced. It's been fine.

IMM Engines (OU812) has had Scat kits checked and they were fine for street-strip cars.
 
Agree with Moper,on the piston speed.With 1000,1500 bucks involved in machine work,spent the extra 1 to 2 bills on forged pistons.Built a 360 based 408 ,cast piston wise.Buy the good stuff once.
 
kdsmith07 said:
that's good to know.i'd would have assumed balanced meant balanced.i'm guessing you found out the hard way?
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The balance on my Scat kit was way off. Others have had the same problem. Scat will not refund money if you find out the balance is off yet when I called before I bought they said they guaranteed the balance to be within 1/2 gram. They have good kits just get the balance done locally.
 
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