Major Development! I feel a 408 stroker in the air!!!!!

[Bruceynz]

Hi Guys,

Well well well don't expect things to happen fast here!! But last night a picked up a new cast mopar 408 Stroker Crank at a bargain price, they are a bit odd ball here in NZ and if you don't have all the bits they are kind of a problem to sell. But not for me!! I have also picked up some Keith Black 416 stroker pistons for this future engine (Just remember I just got the 360 going so not about to build anything tomorrow)

What I am after is some advice on what combos are going to see me around 400 - 450hp mark, I have put these limits as my trans is built to 450hp and my 8.25" with LSD with good for approx 450hp.

So what I am asking are my stock EQ heads going to get me there? Does anyone have or keep an eye out for a set of heads that will do the trick?

What I have so far is my 770 Street Avenger and a 2500rpm stall converter.

My current engine has the airgap on it and headers. I am compression limited here with our stupid low octane fuels, our top fuel is about as good as your 87 over there, no ethanol blends here. So 9.5:1 is about it otherwise I need to retard engine a bit.

So what kind of cam are we looking at, who has built something like this, I don't want it to be to crazy radical, maybe I am being unrealistic but you guys will point me in the right direction.

Anyone got a good used roller cam that may do the trick thats hidden in your shed

See You
Bruce

 

[4speedjim]

Bruceynz Congratulations on the stroker! When the day comes, you'll be ear to ear grins! Your EQ heads are fine as is with 1.92 intake valves to make 450hp. A 2.02 upgrade wouldn't hurt if ya had a friend that did heads. The gain isn't worth a lot of money/power IMO, but if its was a buddy doing the work, its worth it. The 2.02s alone ie; no throat cleaning or smoothing will give 10+CFM avg, 20+ per .100 lift if you do open the bowl and throat. And that would be good from idle through red line. You'll want to move up 2 cam sizes or @ 14* more duration to be comparable to you 360 build. Around .500/513 lift should work with stock valve gear but check rocker/stud clearances of course. Now would be a good time to evaluate your current cam and decide if you had to do it all over again,( because you are) would you change anything or did you get it spot on? You'll need 20cc dish pistons to keep compression in the 9's - 10.1 @1.55 CD. Detonation should be near impossible with the pistons dish and magnum head with "dual quench zones". If you hear detonation use a thicker gasket, but only after you hear it ping. You can use stock 6.123 or GM 6.125 rods and machine the deck if need be. Your intake is good, but you will want to move up to a 750. That will give you 450-475hp and about the same torque from down low where you want it in your build. That's all you need. Pistons, cam and gasket kit! Its winter here and we are all suffering cabin fever from the unusually cold temps. So Lets build it now!!
I've abandoned my 440/500 and am strongly leaning twards going with a stroker Magnum myself. Less weight, and room for a turbo upgrade.

 

[4speedjim]

http://www.aamidwest.com/wp-content/uploads/2015/10/12-17-Mopar.pdf
Just stumbled on this. Easily duplicated. All you need is a cam, and some more traction.

 

[AJ/FormS]

If you got low-octane fuel, I highly recommend aluminum heads and crank the pressure up.
I have run 180 to 205, with various cams and gaskets and deck heights............. and every one ran on 87E10 Manitoba oxygenated gas.Our fuels are averaged (RON+MON) divide by 2 .
I don't know anything about strokers, and maybe a 4" arm won't respond the same, IDK. But If I lived where you live, I'd sure try to get the low-down.
Let me tell you,lol, even 180 psi is fantastic 367torque. Breaks 295/50-15s loose at 50mph and 4000 rpm, no problem. Can you imagine what it would do in a stroker?!
I can't see me going back to iron and 155psi......EVER.

 

[AJ/FormS]

I know what you're gonna say, and I understand; the above was just a motivational speech,lol.
But if the right aluminum heads come along............JUMP!

 

[Bruceynz]

I am thinking to use my EQ heads, the pistons are keith black 416 on stock rods, have ARP rod bolts to fit, just remember eddy heads a pair $1800 + $100 shipping costs upwards of $3300 - $3500NZD

Does anyone have a good deal on some used alloy heads?

 

[BudW]

The only input I have is the bigger the engine in displacement, the bigger camshaft you will need.
Example: 360 vs. 414 is 54ci more displacement – or 15% more displacement.
Not taking anything else into consideration, you will need about a 15% larger camshaft for the extra displacement.

I would recommend getting another 360 block for this project (or using your old 360, if you still have it) and finding a some good aluminum heads for it
BudW

 

[Bruceynz]

Where can I get a deal on alloy magnum heads?

 

[MiradaMegacab]

Isn't a 408 crank for a 360?
Aren't 416 pistons for a 340?

Bore and rod journal issues

 

[Oldiron440]

If your using 340 pistons you can use a 73 or 74 360 block, the cylinder walls are thicker.
It's been my experience that stock rods take more space than aftermarket rods and you might have to clearance the block for them.

I did this on my shop truck back in the 80s, 340 pistons in a early 360 block, I think it was 374 cid..

 

[Bruceynz]

This is a mid compression stroker kit rotating assembly for the 360 block using the Keith Black Hypereutectic Piston and Cast Crankshaft. Magnum blocks tend to have a slightly shorter deck height than the older "LA" style blocks. This particular piston has a 1.465" compression height and may come out of a Magnum block just slightly. If this happens on your application we suggest using a thicker head gasket to make up the difference.

This kit includes:

• SCAT 9-360-4000-6123-2125 Cast Crankshaft
• SCAT 2-ICR6123-2124-7/16 (I-Beam rods)
• Keith Black Hypereutectic Pistons #KB416.030 (4.030")
• Ring Set Sealed Power 2114+030 (5/64-5/64-3/16")
• Rod Bearings CB481HN Clevite "H" series
• Main Bearings MS1266HG Clevite "H" Series (Wide Flange 74-03 blocks)
• Precision Race Balanced

 

[4speedjim]

Edelbrock Mag heads are @ $1800 US bare I believe. Finding used alloy SB Mopar heads LA or MAG are like hens teeth. I'm on the road and cant do the computation now, but believe you'll be fine at or below 0 deck. IIRC @ 1.57 CD is 0 deck with chevy 6.125 rods. With 6.123 and 1.4XX CD you should be good to go and may want to deck the block.

 

[AJ/FormS]

Man,I feel for you on the cost. Here in Manitoba,Canada,those Eddies would cost me about $2750, which represents about 200hours of work, which today would be 17.5% of my annual semi-retired hours.
I bought then in 1999, when they were a little cheaper, but I worked a lot of overtime to get them. And it was soooooo worth it!
Here is a sort-of clone to my engine, that Hughes built a few years later. Theirs is slightly different;ported iron heads vs OOTB Eddies on mine.And I have the same 230cam, but with 10.9Scr

But I am such a huge fan of cylinder pressure, that for a streeter and in an A-body;that I would sooner put aluminum heads on a 360, with the pressure jacked up to 185, than have an iron headed stroker, especially in NZ, where you say the gas is crap.

The above is ported 596 iron heads and a 230 cam, with no compression specified, as far as I can see.

 

[Bruceynz]

Aj that's about where I want to be at, just around the 400hp mark, you got the link to that engine?

 

[AJ/FormS]

Here is a 9.4Scr, iron headed stroker with a 237* cam. The numbers seem low to me, but who can say.

 

[AJ/FormS]

Hughes Engines

Take a look at the above two graphs, and compare the curves. Point for point. If you were to overlay them, there would be very little difference in these two engines.

From what I can tell, iron headed strokers make similar power numbers to hi-Compression aluminum headed 360s, Sometimes the 360 needs the next bigger cam to make similar power on top. And the stroker usually makes a lot more torque sooner, and slightly fatter throughout the midrange.
This allows the stroker,usually, to run one or two rear gears smaller to the 360 for similar low speed performance.
The problem is that the HO 360 ALREADY HAS way more torque and power than the A-body can handle, with unmodified tubs, especially those poor Darts that can only accept 255s. Barracudas at least will accept 295s on a narrowed rear-end.
So when you drop a stroker into an A,
it basically annihilates the tires. But on the street, IMO, it's a waste of a lotta money. On the street,the HO 367 can do anything a stroker can do, probably up to 85 or maybe 95 mph. And the softer off-the-line hit, is just what a traction-limited streeter needs. The 367HO will leave the line on maybe one-third power to not blow the tires off. And the stroker will need to use even less. So since neither can floor it without tire-spin,to maybe 40 mph, you can see my drift.
Even a 340 will do well in this arena. Even an HO-318 will, cuz it still has too much power for the tires,out of the gate.
But I like the 360, cuz with a 225* or so cam and 11/1 compression, I can suck huge mpg numbers out of them, because less stroke has to be given up in the cam-timing,so more time can be devoted to power extraction, and because less overlap needs to be used, so you can run them down the road at a lower rpm, than a smaller engine with a bigger cam.
Forget a 318 with a 268 cam, that's a total gas-hog. I'll take a 360 with the same absolute power any day, cuz it will need 2 or3 cam sizes less and/or 2or3 rear gear sizes smaller to do the same damage, but in the mean time, it will make way more mpgs.You couldn't give me a 318 anymore........ unless it would accept a 4"bore, lol. Naw, still not.
IMO, the 360 is an ideal size for a street A-body, even a heavy one like the 2nd gen Barracuda.
And when you give the 360 pressure, well, they just come alive. The caveats are cost and octane. But I have proved the HO-360 has no problem on 87E10 at over 185psi,so that just leaves cost.
So compare the cost of the stroker kit plus the install and the balance job,as may be required, and all other machining costs that may be required to make it all fit together..... to;
a pair of loaded aluminum heads, that you can install yourself: BUT the compression has to be brought up into the 185psi zone. So if your current pistons are down in the holes more than about .011, then you will have to include some decking, which usually leads to an intake that doesn't fit the best.
It's all one big giant jigsaw puzzle, with the most successful combos, being the best fitting ones.
Just remember one thing:
95% of the time, 400hp is waaaay too much for a street A-body.
You will never get 400 hp to stick on a streeter with factory suspension and tubs. The first time you try to use that 400, you will be in first gear trying to get 150 to stick, off the line, and then trying to get 250 not to spin, and finally you will hit the magic 400 at 5000rpm or 44mph,still spinning; with 3.55s. Hyup 44mph.
Then you will continue to spin that, all the way to 56 mph.
Then you will shift, and you won't see 400hp again until 75mph,
you see what I'm saying?
Unless spinning the tires is your cup-O-tea,
You'd be waaaaay ahead of the game with more gear than 3.55s and a little less absolute power,but with more average power, and maybe an extra gear if the car spends time on the hiway.
Don't get me wrong, I love my 400hp. But it can spin the 295s from zero to 80 plus mph.Obviously I have way more engine than the Barracuda suspension/tires can handle.And when I'm spinning at those speeds, just one tiny mistake, or one parts failure...........and there might be a funeral scheduled within 4 days.

 

[Bruceynz]

What roller cam did you use aj?

 

[Oldiron440]

I like the torque @ 2500 on the last one.

 

[AJ/FormS]

What roller cam did you use aj?

I have a1971 LA360 not set up for a roller.
And in 1999, I spent a huge amount of money on this 68 Barracuda, and a retro-roler, I just couldn't justify. So it has always had FTHs in it.
My 367 has had 3 cams in it; the Mopar 292/508/108, and a Hughes HE2437 which was a 270/276/110, and finally a Hughes HE 3037 which is a 276/286/110.
The cylinder pressure has ranged from 170 to 190 at various installs. The Eddies have always been on it.
The HE2437 was by far my favorite. This was a 223@.050 and lifts of IIRC; .549/.571 with 1.6 arms. I ran this with a Q of .034 plus/minus .001. This was with the pistons out of the holes up to .005, and so the pressure maths out to;

Static compression ratio of 11.21:1.
Effective stroke is 2.86 inches.
Your dynamic compression ratio is 9.16:1 .
Your dynamic cranking pressure is 190.40 PSI.
V/P (Volume to Pressure Index) is 168...........................................................168
V/P Index Calculation
If you don't know; a VP of 168 is higher than any vintage Mopar, using factory math, Except the Hemi, I have no numbers for.

 

[AJ/FormS]

I like the torque @ 2500 on the last one.

Hyup, that would be good for a 1956 GMC grain truck.