Need help building 416 Stroker!

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2doorswinger

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Im going to be taking my 1970 340 and building a 416 stroker out of it this winter. Going to be going with a 4 inch cast crank (only looking to make 500 or so horsepower), a set of forged h beam rods and a set of forged pistons .40 over. I have a couple of questions for you guys!

-What kind of block clearance do I have to do for the rod/rod bolts to clear? Is it much?
-What pistons should I use (flat, dome, dish) and what's an acceptable pump gas compression (93 octane used)? (I believe x heads are 72cc chamber)
-The heads I will be using are a set of ported X heads for the time being and then eventually switch to a set of eddy's later on, can these ported X's meet my power goal?
- If I were to go with a flat top piston with valve reliefs, would I have a problem with my valves hitting the pistons with a 282/290 - .520/.540 cam? (stock 1.5 ratio rocker arms)

I believe those are all the questions I have for now guys! Any help is appreciated!
 
I will be dressing the motor with an eddy port matched air gap intake and 750/800 cfm eddy carb.
 
Scat stroker kits dont require any clearing of the block.

My setup is a 408 because my 340 block did not pass sonic testing so I found a 360 block to stroke to 408.

I have Scat kit, -22 cc dome pistons, eddy heads gets me 10:1. I run 93 octane.

I run a comp cams cam with .580 lift and I had plenty of cleanance on my domed pistons.

I have Fast ez efi instead of a carb.
 
If he runs H beam rods...the bottom of the Cylinder usually needs to be ground for clearance....

If he runs a Scat I beam design..then they usually clear with no clearance..
 
Okay, so i believe i will be using scat forged 4340 i beams so thank god no clearance needed! Now, what about compression with cast iron x heads? I think i was wrong about the chamber cc with the x heads? Anyone have any idea of the the chamber cc on x heads and what compression can i run for 93 octane? And what kind of power can i make with x heads, 416 stroker, air gap, 800 cfm carb and the cam i advertised? Thanks guys!
 
Scat I beams are plenty strong enough to support 500+ HP. X heads tend to vary some in ccs. I have 2 fresh sets that minimal was planed off, just to true them up. One set measures 68cc and the other is 70. Without actually measuring them a safe guess would be 68-72cc. With iron heads I would run 9.5:1 +/- and then if you swap to aluminum later you will still be safe on pump gas. Aluminum you can run a little more compression because they dissipate the heat better. As for power, depends on your head flow #s. Mike (MRL) built a 9.8:1 iron headed 416 a while back that made 500HP and TQ was rite around the same. I was originally going to use my X heads on my 416, but eventually just decided to go aluminum and be done with it. I had the Comp. .520/.540 cam in a 340 w with alloy heads and it made 428 HP on the dyno. Pretty sure you are going to want dished pistons. I used Icon forged pistons w a 20cc dish and my 416 is 10:1 w 63cc heads.
 
VERY lumpy with the short 3.31 340 stroke. Will be pretty tame with a 4" stroke. The 428 HP 340 was a blast. Guy at local cruise wanted it worse than I did. Bought it rite out of my car. Im now on my 3rd 340 in 5yrs. Bad habit of selling them and building another one. 11 spares, why not?
 
autoxcuda said:
Lumpy means different things to different people. What are you looking at for parameters??

If this was his cam it will still be lumpy even with the 4" If this is the cam: http://www.summitracing.com/parts/cca-20-231-4/overview/

It will be less than "very lumpy", but still lumpy.

That cam has 66 degrees of overlap.
Click to expand...

That is the beast I had in my 340. I consider that it was very to very, very lumpy. LOL!!! Ill look for the video of it @ idle.
 
autoxcuda said:
Lumpy means different things to different people. What are you looking at for parameters??

If this was his cam it will still be lumpy even with the 4" If this is the cam: http://www.summitracing.com/parts/cca-20-231-4/overview/

It will be less than "very lumpy", but still lumpy.

That cam has 66 degrees of overlap.
Click to expand...

Im looking for a very lumpy idle but nothing so outrageous that its damn near impossible to drive lol.
 
I have several 9.5:1 compression 360s with stock open chambers and a non quench pad piston. They are not very resistant to detonation granted they all have similar cams designed to make trucks run well at 2500 to 3500 rpm. The 408 I just built scat cast with hyper pistons .040 quench 9.8 compression with indy rhs heads is amazingly tolerant to detonation. I believe the chamber on the Indy RHS X head is likely the biggest contributor to its resistance to detonation. Brian at IMM suplied these to me and I can not say enough good about them. This engine is in a one ton truck and makes amazing power with a 228 232 540ish roller cam.
LONG STORY SHORT. I dont like the stock chambers of the chrysler heads they can be made to work with pistons for quench but then a future head swap for more power requires milling the pistons or new ones. The 408 i just built seems way more powerful than my eddie headed 11.2:1 422 ci engine in my Duster and its in a truck.
 
I would use a dished piston, set a little above a blueprint height deck. Initially you will lose a little static compression but you'll never miss it. And when you swap heads it will still be a liveable compression ratio. Build with flat tops now, and it will be too high with aftermarket heads.
 
I build my 416 with a Scat Kit with forged dish Pistons and RHS Indy Heads and have compression about 10:1.
Add a Lunati 03 hydraulic Cam 268° .494 intake and .513 ex,
Ede Airgap, 650 Holley 4011 DP, TTi stepheadders.
Very streetable and loads of torque! Runs pretty smooth.
Have with a 4-speed and 2.91 gears in the back no traction up to 3. gear!

Awesome setup!
 
Hey guys, thanks for the replies! I've decided to spring for a set of eddy heads (and forged DISH pistons lol)! Im going to get the chambers cc'd, bowls cleaned up and have the spring height (for the rocker shaft) leveled out. After that, I kind of want to assemble the motor myself! I have a little (but not much) experience building motors myself. If you guys could run me through the process and give me some advice on building the 416 stroker, it would be greatly appreciated! I heard Moper is a good guy for this. I would also like a "item buy list" for the valvetrain as im not too sure what to go with yet. I was thinking of using a mechanical flat tappet cam right now as that's what is currently in my 340 x head motor and it has adjustable rockers. Should I go roller rocker or stick with OEM style rocker? Stick with mechanical flat tappet? Im planning on putting in main studs and the Edelbrock head bolt kit and whatnot. Thanks for the help guys!
 
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