My 383 build plans.

[othtim]

I just assumed a 6 inch rod. There's benefits to a shorter rod and benefits to a longer rod. Shorter generally leading to more horsepower. Longer leading to more torque.

However, it doesn't really matter as I would recommend the same piston. It was just for reference as a piston with a 6 inch rod is different than one with a 5.7 inch rod.

okay, gotcha. Personally, on all the books I've read and people I've talked to - no measurable difference in moderate street applications with regards to rod length. I'm just considering the rod length as a measure of keeping the engine longevity. Reallly, that's my #1 concern - engine longevity.

 

[drogg1]

If you're looking for sustained revs, I think you probably are going in the right direction with the 5.7 rod as shorter rods tend to like to rev (i.e. Ford 302). For longevity, although i believe the 6.0 rod pistons MAY be lighter, I think that benefit may be equally balanced by greater wear due to the longer rod (or so I've been led to believe).

That being said, I don't believe you would gain (if at all) enough in longevity by going to the 350 to justify not going with 383. Regardless of rod choice, more cubes is more power and torque.

I think with the right cam overlap and around 235 duration @0.050, flat top pistons with 7cc reliefs, 180-200cc heads with 72cc chambers, with a well flowing dual plane intake, you'll see that flat torque curve from 2000-5000 rpm easy. In fact I think you'll be making around 450 torque in most of that power band.

Oh and I think that cast crank will do just fine for the power you'll be makin.

 

[mebe007]

Ok you want to rev it out. Go for it, but go with a roller cam. Check out howards for some nice priced retro roller kits, that's what I'm doing. For heads check out 1320 tech talk forum. It's run.by chad speier of speier racing heads. He will help you make a very well informed decision on them. He will go over multiple brands. He will prolly give you suggestions on other stuff. But we need more info on your car to help with suggestions, ie transmissions, tire size, gear ratio, weight, etc

 

[13bravo]

I think you are heading in the right direction. For the street I'd suggest at least a 5.7 rod, but don't get hung up on the rod length. I would also suggest getting an internal balance crank instead of an external, especially with the continued rpm you want to twist it up to on a regular basis.
As far as heads go, there are probably more 64cc chambered aftermarket heads available so if a flat top is not set in stone a small dish with these small chambers will work.

I just built a 5.7" 383 with the Keith Black Hypereutectic dished pistons(KB-135) and 305 cylinder heads that keep the compression around 9.8-9.9to1. It should be a stump puller as I used a small stock hydraulic roller cam, it only had .353/.384 valve lift with 1.5 rockers, but luckily I had some 1.65/1.6 rockers which bumps the lift to .388/.409
It should only have around 320hp but the torque numbers down low should be pretty stout.

A 383 will live at 7500rpm as long as all the rest of the parts are up to the job. I've done a couple of dirt track cheaters, but these did have 6" rods and solid roller cams.

 

[chevy2480]

Just a suggestion stay away from kieth black hypertec piston for 5.7 rod strokers. Me and two other buddies have came to the conclusion they are junk. First i built my 383 balances and blue printed all clearences checked. I had a leak in seam of pan pulled motor to find pieces of piston skirts laying in pan. My two other buds when it came time to do a freshen up after lots of abuse found the same thing. The skirts are very thin walled. Do what you want but i will never run them again.

 

[dogsht]

If the crank is rated to safely handle 500 HP why would a 420 HP lower rpm build be pushing it?

David Vizard's periodicals state that a longer rod (than stock) generally provides less wear on the block & piston. He suggests that for a high performance street engine that a 1.7 rod to stroke ratio is ideal. Unless a lighter piston is too weak for the application it is better for the whole rotating assembly or engine. Its unlikely you would find a piston to weak for this build. The stock rod to stroke ratio of the 350 was 1.63. The 383 useing the longer 6.0" rod still only provides a rod to stroke of 1.60. It may cost a little more but there are reasons people are willing to pay more to get it. Longevity and efficiency is what your after with the longer rod. Both tuned optimally you might find 3 to 5 HP but if so its just a bonus. Most people have no way of seeing the longevity benefit or any power gain but they can see the cost to build difference.

Cubic inches do not make more horsepower but they do make more torque. Although a bigger bore generally makes it easier to breath. More stroke helps to keep the power band down in a more use-able (for a street car) rpm range and helps longevity in the process. The average street car hot rodder miss applies the value of rpm for his use. If you can choose between two engines for your street car and they both make the power that you want (same HP & TQ) and one makes it between 2,000 & 5,000 rpms and the other between 4,000 & 7,000 which do you choose?

Stress & component wear goes up exponentially as rpms climb. Some say rpm stands for ruins peoples motors. Who cares how much rpm either can take as long as both can make the power you want well below their components sustainable stress tolerance.

On top of that there are many other benefits of useing a larger motor in a street car application to meet your power goals. Not only does a larger motor need less rpm it should also be able to do it on less compression (ie need for higher octane or even race fuel) need less converter, and less gear to name a few. On the flip side a larger motor generally requires more fuel.

 

[drogg1]

Thanks dogshit. I tried to give the best advice I could but I'm glad someone who actually knows what they're talking about stepped in. Hopefully that will help the OP.

 

[chevy2480]

If the crank is rated to safely handle 500 HP why would a 420 HP lower rpm build be pushing it?

I said it would be pushing it because he said 420 min hp. While it unlikely he will break the 450hp mark. I do believe everything i read about them says uptil 500 hp not saying they cant handle more seeing how that is the max they pushed it to in testing who knows could handle 700hp but I personally dont like pushing things to their max rateing.

But what do i know I have only built 6 383 strokers and a few 406 sbc and numerous sbc engines over the past 16yrs. I have seen top quility sh*t break well before their rating and junk run well beyond. Shoot i even pushed a stock cast crank and rods with trw fordged piston into the mid 11's on motor.

 

[dogsht]

I didn't mean to suggest you don't know what you are doing. "Because he said 420 HP minimum." OK. Seen sh*t break before it should and stuff last longer than it should. Yep. It's only about helping fellow hot rodders and your t houghts are at least as valid as mine. Given your sbc experience more so.

 

[chevy2480]

I didn't mean to suggest you don't know what you are doing. "Because he said 420 HP minimum." OK. Seen sh*t break before it should and stuff last longer than it should. Yep. It's only about helping fellow hot rodders and your t houghts are at least as valid as mine. Given your sbc experience more so.

Its cool. Your opinion and everyone else's opinions all have some sort of justification.