How would you build a 416 Stroker 340?

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Krazed

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(This is something I posted over at www.cuda-challenger.com incase you were wondering! I just want more feedback, I know you guys love bench racing :thumblef: )

Ok so, I've had some downtime with my car recently and it's had me thinking about the engine. It leaks, it runs poorly, it needs cleaning... it's just time to do things right.

Now, I've been looking and thinking hard and have decided that the direction I want to go is with a stroker. The motor is a 340, it has been bored 0.030 already, and I'm hoping there's some left for another machining to smooth things out. I also have an 833-od 4 speed with 3.55 gears and intend on keeping it that way.

I have a budget of about $3000 plus extra for little things if I need to.

I loooooove torque and wheel spin. It's why I own a muscle car!

The engine currently is in partial-stock trim, stock unported heads, stock exhaust manifolds, LD4B intake, Holley 650 Double Pumper. It's also running some after market flat-top pistons (Speedpro I believe) and eagle rods with stock crank ground 0.20. Camshaft is a MP 292/508 and its nice and lumpy, but absolutely no low end power below 3000rpm's. It absolutely kills my brakes, but after its warmed up they are workable.

Other parts I already have and don't wish to give up are: Edelbrock RPM Air-gap intake, MSD 6AL Ignition, Blaster SS Coil, Pro-Billet distributor. Down the road I may purchase some TTI headers as well.

So, my question to you is this....

If you were to build a stroker 340, that's drivable on pump gas (Keep in mind we only have 90 octane here in alaska), and usable with power-disc brakes... how would you do it on a $3000 budget? Is it even possible?

All options are open!

Enjoy!

(P.S. - This is not a numbers matching 340, so don't worry!)
 
For $3000 you may be able to buy a stroker kit from Mancini Racing and get the machine work done but you'll have to reuse everything else that you already have.
 
I think you can actually piece together a budget 416 rotating assembly for a little under what they want from mancini. I've seen cast eagle cranks for about 300$ a set of SIR rods for under $300...then those darn pistons...Diamond has 4.070 forged units for 567$ at hughes or KB stepped dishes for 52$ a piece..hmmm 8 x 52 = 416....weird. through in a set of rings rod bearing and main bearings and you might come in at or around 1200$ bucks. around here you can get a rotating assembly balanced for 125$, block clearancing you can do yourself. leaves little left over for head work if you've got 2000$ laying around
 
Check out Hughes Engines. They have a 416 balanced rotating assembly for $1585 or a 360 based 426 rotating assembly for $2495. The 416 kit would leave a little for heads and headers. :thumblef:
 
I can tell you that $3K is cutting real close to the low limit. You can run your heads, as long as they are done well now. The intake will be uslesss over 4K rpm..there's just not enough port or plenum there. There are "take offs" on the RPM Air Gaps, but I'd look for a swap meet M1 single plane if the real deal Air Gap is too much $$. The carb is way too small. A 750 on a 4" stroke engine is all used up by a little over 5K, so you'd be looking for at least a 780ish Holley Avenger or something like a 800DP 4150 series (as a budget saver...). Manifolds will not move enough air, but cheap headers can do what you want without loosing much. About the only other thing you can re-use is the block, and I'd run factory rods done with ARP bolts long before the cheaper new rods, but that's me. You might be able to get it done for that beign careful. But the pistons will be the biggest cost. More than the crank, because nobody makes a .040 over piston as an "off the shelf" deal. You can get them easy, but they cost more. I dont think KB makes a 4" stroker piston for 340s..They do for 360s IIRC. I wouldnt use a cast or hyper piston with a 4" arm tho. At 6K you are at about the rpm limit of hypereutectic piston (in terms of piston speed). A cheaper alternative might be to get your hands on a 360, and re-build that. You'll need the 360 only flywheel, but the rest can be used, even the manifolds, and it will make great usable torque..(tire smoke comes from torque, not HP...lol) You'll get more from a well done performance 360, then a ultra low budget 408 IMO.
 
KB makes a forged stroker piston for 408/416 engines in .070 over. the part number at hughes is 2308+070 its a step dish piston they're only 52$ a piece. they also have a listing for a part number 2020+070 for a hyper stroker piston for 408/417 engines they are 40$ a piece. as far as i know the compression height of these pistons are the same whether they are in a 360 or a 340 with a 4" stroke, and should not go any shorter than 1.250" or the wrist pin will interfere with the bottom ring. according to the website the compression height on the 2308 is 1.465" and on the 2020. the step dish design is going to poke out of the deck, which shouldnt be a problem with open chamber heads, but if the blocks been decked and the heads are milled you could be in trouble if you use them. on the 2020s based on a .030 overbore and .039" compressed gasket they list the CR as follows:
58cc = 10.0:1
62cc = 9.65:1
70cc = 8.99:1
74cc = 8.70:1
stock 340 heads are usually about 71 - 72 cc. i've got a few j heads that are milled .010 and average around 69cc's. if you were to use a thinner gasket you may be able to squeeze a little more compression if you needed it.
moper is right though you need a big set of lungs for a stroker. if your 340 heads are the 2.02" type with some porting they may do the trick, but if you are looking for a racier setup or plan on doing more track time that road time i'd step up to something else from the aftermarket to really unlock the strokers potential. i agree with moper on the 750 being used up after 5k, but how often is this care going to see that RPM. you said a streetable engine and with a 750 you should make it ok on the street.
just my 2 cents
 
Hey, thanks a ton for the replies guys. I'm just sitting here soaking in all the information!

The manifold I want to put on is a rpm air-gap as I already own it, just fyi. I hope that would work with the stroker?

Headers are an option down the road, but for now I can suffer with my stock manifolds and save up for some TTI headers and new exhaust w/ x pipe for later.

I also forgot to mention, I have X heads on my 340 right now, and wish to keep those and do some porting on them. (Home porting) The car is a 95% street machine, It sees alot of highway time being that I live 30 miles from work.

Also, I rarely shift it above 5krpm, only when I'm showing off or having a ton of fun. The car will be a daily driver when possible and only see track time maybe once a year.

The main thing I want is engine rebuild back to running stage so I can continue driving it and make more 'external' improvements later on.

Thanks a ton! The information I'm getting sounds great, keep it up! You're definately helping things along.
 
"The manifold I want to put on is a rpm air-gap as I already own it, just fyi. I hope that would work with the stroker?"

Yes, your manifold will work on this combo. Keep in mind that your powerband will be in the 1500-6500 RPM range.
 
Yes, your manifold will work on this combo. Keep in mind that your powerband will be in the 1500-6500 RPM range.
Click to expand...

Yes, that's right about where I want my power band to be as a street car. Mainly, the only reason I don't go above 5500rpm is that I'm afraid of breaking something with this currently weird and partially unknown combination of parts.
 
just another word of advice on selecting a cam for this engine. as a rule of thumb you should add 6 - 8 degrees of duration to a cam that would work well with a hi-po non-stroked set-up. if you are porting your heads you might want to take them somewhere and have them run on a flow bench so you can get the numbers to match up cam with the correct lift to work in harmony with where they flow the most air.
 
I'm selling my 408 stroker short block. .030 over 360 with 4" forged steel Eagle crank and I beam rods. Hughes solid cam. 246 & 252 @ .050 matching springs and Hughes roller rockers (1.5) Only 566 miles on it plus dyno time. Numbers are 517 horse with the edelbrock heads I used. I'm going back to another 360 for more of a cruiser engine. The stroker is in perfect shape. $3200.
 
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