413 stroker on the cheap?

[k-ams]

I have a 413 block and want to build 472 stroker. I have 383 pistons, the stock 413 rods. Can I use a 4.125 stroker crank instead of the 4.15 crank?

thanks its only .025 shorter in stroke.

 

[Meep-Meep]

I take it you have done the math so if it all fits I don't see why not. Be sure to have it balanced.

Ford did a similar trick on the 71 390 truck engine but it was in reverse. In order to drop the compression they took a 410 piston (3.98" stroke) and put it in a 390 (3.78" stroke). Same rods and the block deck is the same.

 

[HT413]

Not sure that's 'on the cheap'. 413 bore is 4.18, 383 bore is 4.25, so you'd have to go 0.080" over, which most would say is too far. I too have a 413 and I've run about every scenario imaginable (including his one) and it just isn't cheaper.

Cheapest build I've come up with is a refresh consisting of hone and bearings (if the bores are in good condition), Hughes 413 flat top pistons (listed under "obsolete engines" lol) for like $400 and closed chamber heads in the 75cc area will get you about 9.5:1 or so. The reason still so low compression is because oem 413 pistons sit like 0.067" in the hole.

 

[62 Dart Convertible]

413 bore is 4.18, 383 bore is 4.25, so you'd have to go 0.080" over, which most would say is too far.

Sorry to split hairs here, but 413 is 4.1875 and to 4.25 is to go 0.0625" over (like mine is, stock stroke, and using std size relic TRW forged 11:1 426 pistons.) Most say the old blocks had loads of meat in them, but sonic testing the block would always be prudent to judge how far it can safely be over bored...

I can't answer your stroker questions....

 

[HT413]

Sorry to split hairs here, but 413 is 4.1875 and to 4.25 is to go 0.0625" over (like mine is, stock stroke, and using std size relic TRW forged 11:1 426 pistons.) Most say the old blocks had loads of meat in them, but sonic testing the block would always be prudent to judge how far it can safely be over bored...

Oops, I meant 0.070, but you're right, it's a shade over 60 in reality.

 

[Garys1969RR]

Once you have your bore and stroke figured out, then you will need to see if you have the correct compression height on the pistons you are using. In a stock stroke 413, you take 1/2 the stroke, plus the rod length, plus the piston C/H. Subtract this from the total deck height of the motor, and you will have the distance down in the bore of the piston top.

- - - Updated - - -

440 block height is 10.725". So 1/2 the stroke is 1.875 plus rod length of 6.768=8.643. subtract this from 10.725 and you get 2.082" to zero deck. 440 6 pak pistons are 2.065 C/H giving you a distance below deck of .017".

- - - Updated - - -

This may or may not be C/H for 440 6 pak pistons, but hopefully you get the idea of how to determine C/H. Just use your own numbers and do the math. Shoot for .015 to .017 below deck for the piston top.

 

[Meep-Meep]

To OP: Block deck is 10.7". Rod length is 6.76". Stock stroke is 3.75" and with a 2.065" compression distance piston you get zero deck. That leaves the compression distance of the piston to trade off with stroke in order to come up with a workable combo. I don't know off hand what the 383 piston compression height or block deck is. So really quick, 1/2 of stroke = 2.0625" + 6.76" rod = 8.822". 10.7" - 8.822" = 1.1875" compression distance piston needed for zero deck. With the 4.25" bore and 3.75" stroke you will need zero deck and a closed chamber head to get 9.5:1 but adding stroke you will need a larger chamber or have the piston dished. If using the 383 rod then I believe that is 6.36", so 2.28". Now that's a bit tall.

 

[Garys1969RR]

Thanks, Meep. Ross Pistons lists the 400 deck height as 9.98" which I assume is the same as a 383 deck height. To get a 383 piston with 1.1875 to 1.1860 (.015" below deck) of C/H may be the difficulty here. A 451 has a bore of 4.375", C/H of 1.320" for .017 below deck. Why not just start with a 400 block? There are a lot of pistons out there for the 400 block that have various C/H for different strokes. And you start with a larger bore which gives less shrouding for the valves. Good luck, K-ams

 

[k-ams]

is the compression height from the center of the piston pin to the top of the piston?

 

[HT413]

is the compression height from the center of the piston pin to the top of the piston?

Yep. One exception is the KB quench dome pistons, which list an 'effective compression height' due to the piston having a quench pad on one side, so they sort of average it to make CR calculations easier.