How does a 360 408 stroker work?

[360-68cudu]

What are the parts that are interchanged. does it require machine shop work and whats the cost? what is the power benefits?

 

[70aarcuda]

in the short block..you can reuse the stock rods...you will need new 4 inch crank and you will need new pistons with lower compression height due to longer stroke.

other extra machine is depending on what rods you use....stock rods and h beam rods require small notches on the bottom of each bore for the rod bolts to clear.... I beam rods do not require this machining...

power benefits...depends on your compression...cam..heads.....with the longer stroke it will generate alot more torque at lower rpm...

 

[360-68cudu]

other extra machine is depending on what rods you use....stock rods and h beam rods require small notches on the bottom of each bore for the rod bolts to clear.... I beam rods do not require this

In your experience or knowledge how much is the machine cost with stock rods vs the cost of I beams ?

 

[70aarcuda]

i would buy Scat 4340 I beam rods and use those....no clearance problem..

 

[pishta]

Stock rods with a 4" stroke requires about 10 seconds with a carbide bur for each cylinder. EZ stuff. The clearance requires is about a 1/8" semi circle, but your rod bolt heads will dictate, give yourself about +.05 running clearance.

 

[Furious65]

i would buy Scat 4340 I beam rods and use those....no clearance problem..

Yep. When you consider that your old rods are, well, old and then you are also going to need new rod bolts, you might as well just pay a bit more and get some stronger new rods to begin with and save yourself from dealing with the clearance issue.

 

[autoxcuda]

How does a 360 408 stroker work?

Excellent! :cheers:

What are the parts that are interchanged. does it require machine shop work and whats the cost? what is the power benefits?

If it's under 500 hp you can just get a cast crank Scat rotating assembly. I bought mine from Brian at www.IMMengines.com

No special machining of block. The cost of the rods is about the same as the machine shop labor resizing used ones and installing ARP rod bolts. Piston cost is roughly the same stroker or non stroker. Seems like the net extra cost is about $400-$500 over just building a 360/340. Mostly for the 4" cast crank.

Bottom line, it is the most inexpensive $$/HP-TQ gain you can make while maintaining streetabilty.

 

[71swing]

I picked up my 408 Scat stroker kit for around $1450 from summit. Came with Cast crack, Forged dish pistons.

Just picked up my short block Saturday from the machine shop. $1370 for all the work. I had everything done. hot tanked, magnafluxed, sonic tested, bored, mains honed, cylinders plate honed, surface decked, shortblock assembled, cam and chain installed.

Im coming from a 340 that spun a rod bearing to this 360 stroked to 408. Im reusing everything from the 340 besides the oil pan which is different. Everything else for me swaps over since my 340 was internally balanced and this new setup is also.

Im hoping for 500hp to the rear wheels.

 

[moper]

What are the parts that are interchanged. does it require machine shop work and whats the cost? what is the power benefits?

The rotating assembly is new, plus the camshaft and heads/intake/carb should be revisited and matched to the new stroke. Cost depends on where you live, where you take it, and what you buy. Generally, I budget 25% more for a 4" stroker over a factory displacement.
The benefits are incredible and exactly what you want from a street car package. Drivability, torque, etc. It is more money. But it's money well spent.

 

[autoxcuda]

I picked up my 408 Scat stroker kit for around $1900 from summit. Came with Cast crack, Forged dish pistons.

Did you get the one that was already balanced? Brian at IMM said he's checked the Scat balance jobs at they are fine for under 500 hp. I got the one already balanced. Runs smooth.

Just picked up my short block Saturday from the machine shop. $1370 for all the work. I had everything done. hot tanked, magnafluxed, sonic tested, bored, mains honed, cylinders plate honed, surface decked, shortblock assembled, cam and chain installed.

And all that would be the same exact cost on a 360 stock stroke unless you picked H-beam rods or stock rod for your 4" stroke that would require additional labor for clearancing.

 

[71swing]

Yeah I went with the pre balanced kit. The machine shop I went to only deals with Scat and that's what he recommended. Basically he told me they could balance it cheaper than it would cost for him to do it with the cost of Mallory. That's how they order all their kits. They check over them but he's never came across an imbalance. I hope it runs like I think it will.

I don't know about other rod combos, but my Scat kit didn't require any clearancing. I'm waiting on a new oil pump to come, and have not looked into trying to get my windage tray to fit over the 4" stroke. I won't try to hard getting it to fit.

 

[autoxcuda]

Yeah I went with the pre balanced kit. The machine shop I went to only deals with Scat and that's what he recommended. Basically he told me they could balance it cheaper than it would cost for him to do it with the cost of Mallory. That's how they order all their kits. They check over them but he's never came across an imbalance. I hope it runs like I think it will.

I don't know about other rod combos, but my Scat kit didn't require any clearancing. I'm waiting on a new oil pump to come, and have not looked into trying to get my windage tray to fit over the 4" stroke. I won't try to hard getting it to fit.

I think I have the same kit as you. The Scat I beam rod didn't need any clearancing at all.

I used a Milodon adjustable windage tray.

 

[BrianT]

I picked up my 408 Scat stroker kit for around $1900 from summit. Came with Cast crack, Forged dish pistons.

I am going to go with this FORGED Scat kit from Summit for $1713 and let my machinist balance it for me.

Scat forged stroker kit

Why was your CAST kit $200 more? My machinist charges $200 to balance the assembly. So for basically the same price, I have a forged rotating assembly vs. a cast one.

 

[d55dave]

My 408 was awesome. a blast to drive and didn't break the bank to build it. I did however break the cast crank, I would fully recommend spending the extra few hundred for a forged crank. It was 9.8:1, ported 360 cast iron heads, old school torker intake, the only thing I spent extra money on was the roller cam, I used old 273 adjustable rockers. It was a legitimate street car, and ran 11.9 @ 113.

 

[360duster]

ouch!

d55dave: does not look like a eagle crank from what i can see - can you tell us the vendor / manufacturer?

Michael

 

[d55dave]

It was an eagle cast crank. Worked fine for 2 years with the auto, then I converted to a 4 spd and a month later an my first hard 1-2 power shift it fractured at the front main. It started vibrating like crazy, but was still driving the cam. I shut it off in time and didn't damage anything else. eagle credited me the cost of the cast toward a forged crank. The eagle forged crank was a MUCH nicer piece. I drove it for a couple more years without any issues, then sold the car. As a side note, due to the short piston skirt with the stroker pistons the engine always had more piston slap noise than non stroker engines, not too much though and I think that is just the nature of stroker engines with short pistons.

 

[jos51700]

Are these cranks made in USA or offshore? Or is there a choice?

 

[moper]

All that I know of int he price ranges we're talking about are cast offshore. Some are rough machined and finished offshore. Some are rough machined offshore and then finish mahined here. A few more pricey ones are rough and finish machined here.

Edit - Cast cranks made by Scat are fine for most build ups. If you're looking at boost, or mad rpms and power, a forged is a better crank. But the cast will take 500+hp forever. I personally know of one that makes 550NA, 675 with NO2 with no issues. The Eagle cast ($270-300 ea) are not something I would recommend any more. (although I have not lost any I built with them - it's just not worth the risk any more).

 

[70aarcuda]

I think we have seen pictures of several Eagle 4 inch stroke cast cranks breaking but I dont think anyone has reported a Scat cast crank breaking...yet.

 

[71swing]

I am going to go with this FORGED Scat kit from Summit for $1713 and let my machinist balance it for me.

Scat forged stroker kit

Why was your CAST kit $200 more? My machinist charges $200 to balance the assembly. So for basically the same price, I have a forged rotating assembly vs. a cast one.

You’re correct. I just guessed what I thought it was. Looked up the receipt because you asked. $1450 is what it cost me from summit for my cast crank with forged pistons internally balanced kit. So I was way off, I'll change origonal post quote. The cost difference in balancing would have been the materal. the cast cranks take more balancing effort and cost than the forged counter parts. But it only cost and additional $200 from Scat to have them balance it before shipping.

 

[BrianT]

Not a problem. Thanks for the clarification. I thought I was missing something there?!? Lol

 

[Guitar Jones]

Mine works pretty well and some day when I get to spend some time tuning it it may work even better.

 

[360-68cudu]

These kits consist of a Chrysler 400 blocks crank right? Why can’t I pull one off of a junk yard and build my own kit around that? I thought these cranks could take a beating.

 

[66dartman]

No, 400 chrysler is a big block. Chrysler never made a 400 small block, so the crank is aftermarket only.

 

[360-68cudu]

What’s the diff between Flat top (with two valve reliefs) and Dish (with a D-shaped cup)

I'm looking at the kits and want to know when does the forged crank really come in handy? How many people have had the scat cast cranks break on them?