Ok guys, I am thinking of building a 383. Nothing radical, just 400-425 hp.

What rods do you guys suggest. I-beam or H-beam? Also what brand do you like.

The motor want see anything above 6500 rpm, but will see some track time.

Would I-beams be fine up to 450 hp?

thanks

 

I beams should be fine for your app. A set of GM PM rods would work great, an Eagle makes an SIR rod thats a bit lighter, and around the same price. They can both handle between 450-500hp. Just make sure you balance the rotating assembly.

Eric

 

Go with I beams, H beams are heavy and sometimes hard to balance. I would do whatever I could to lighten up my rotating assembly. Thats why lightweight pistons, cranks, rods, valves, retainers...etc, cost more

 

Yep just like what was stated H beams will be a little heavier than I beams. H's do resist twisting a little more. Would that really matter on a 450 hp motor?, No probably not. I've seen I beams rated up to 600 hp with balancing before. The bigger question might be, What type of forging you want the rods? Check out Ebaymotors for some good prices. I got a set of 4340 forged Ultra LW I beams off there about a 1 1/2 years ago for around 400 bucks shipped.

HotRod Tech Art. I beams vs H beams

HotRod Tech Art. on Connecting Rods Different Forgings

With the 383 also take note of the difference between the 6.0 and 5.7 inch rods too. The 6.0 rod has a higher wrist pin on the piston, which normally comes really close to the oil ring. It's normally not looked at for a good piston setup for forced induction but being the case here you could use it probably if you decided on it. Believe me the reading on the connecting rods will keep you busy for months alone once you start researching. It's been almost 3 or 4 years since I've decided to build a 383.

Also you'll more than likely need a small base circle cam to clear the add'd stroke.

 

I went with a 6" eagle rod because I'm planning on running a 250 shot of nitrous and running it up to 6500 rpm, maybe 7000. This pic shows what was said above about the wrist pin location.

 

Well, Im looking for a 5.7 rod. I wont be spraying, so I dont really need forged.

I had looked at the eagle I-beams. Seem real nice for the money.

 

it's going to be hard to buy a rod that isn't forged, unless you consider the PM rods.

 

Im just saying they dont have to be. I will probably end up going with a forged rod. I like the oliver rods, but for $100 each, I will pass.

I just dont want to use a stock rod. Doesnt make much sense to have them resized and new hadware, when I can buy new ones for about the same price.

Maybe I will just go 355, use my stock crank and get better rods and pistons. Seems simpler.

 

Went with Eagle H beams since 3 sets of Eagle I beams That i received were bad. The only set of I beams that are perect are the Eagle SIR with the old bolt and nut. Eagle is having trouble with their new cap screw designs. Its distroting and making it all out of round. I called Eagle and they are aware of the problem, along with www.gofaststuff.com, a few engine builders that I have talked too and even the guys at Summit. They have had numerous returns of bad pairs. When Aligning the holes, the rods were not torqued properly leading into problems. They can work but take about a whole day of work with cutting and realigning until its within spec.

Heres the H beams I used.

 

About the simplest way is just to buy a kit that is already done for you. You could get a nice kit with pistons, rods, and crank all forged and balanced together for around 1200 bucks depending on where you get it from and what is included. That might be the easiest way to go if you aren't really looking for a high screaming high horsepower motor. What type of heads are you planning on using?

 

I got the Eagle H beams, Eagle 383 crank, 10:1:1 Speed pro pistons all clevite bearings and rings for $689.00 through an ebay store

 

And sometimes you can get a balancer and flexplate too which makes it even easier.

 

sounds like I need to do somemore shopping. lol. I will look around and see what I can find.

Thanks for the info on the eagle rods.

As far as heads, I will probably go with either ported stock L98 heads or some dart iron eagles. My engine builder is getting great flow out of the darts, with some port work.

I would like to keep it around 10.3 to 1 compression. It will be a full roller setup with floating pins also.

 

With the kit I got it was 10:3:1 but that was at a 0 deck. I have the stock height. which lowered it to 10:1:1 I think.

 

blue i think you missed the point, you can't buy anything but a forged rod, at least for a SBC unless you consider PM rods not forged.

 

I bought Eagle SIR I-Beam rods that are bushed for floating pins and i'm running about the same horsepower. they hold up fine and I paid a very low price for them. I highly reccomend checking out, www.dirttrackthunder.com Click on the specials button in the top right hand corner. They have great prices!

 

Ede- I thought that I had seen reference to the PM rod still being a "forging" process...or am I all wet???
Older makes like Pontiac used a "cast" rod in their engines (when they still made engines) This is why Pontiacs are "RPM Limited".

 

for your application, i would go with a set of OHIO Crankshaft I-Beams. they are fairly cheap and rather strong.

www.ohiocrank.com

 

I'd look at the Eagle SIR rods. They'll stand up to that HP just fine. As far as 5.7 vs 6.0 rods, there is very little diference between the two piston speed wise.

 

"In the ’60s and ’70s, American Motors, Cadillac, Buick, and Pontiac all used cast rods in a wide variety of engine designs. In an effort to improve molecular binding and strength, the molten metal was injected into the mold cavity under high pressure. The resulting castings may have been good enough for use in everything from GTOs to Jeeps, but they have no place in anything other than the most fanatical numbers-matching restoration effort."

"Original-equipment forged steel rods are the next step up the strength and reliability ladder. Detroit-sourced OE-forged rods begin life as bars of carbon steel that are passed through a rolling die. "


That came off the link I had posted above. Course comparing a Stock Forged Rod to Aftermarket Forging is like saying a sheet of glass is just as strong as a sheet of titanium if it gets hit with a hammer.

We all know the factory doesn't spend extra cash unless need'd.

 

I understand now. I guess it would not be a good idea to go with the PM rods if I plan on making any hp over 400. Or would I be wrong?

 

10.0 to 1 compression would be fine with me. I plan on using pumped gas and dont want any problems with too much compression.

The eagle SIR I-beams look like a nice piece. I will probably go with them and a good TRW or SRP piston.

I just dont want to skimp on the parts, but dont want to go overboard either.

thanks guys

Oh yeah, I have already added the links to my favorite list.

 

Guys like the TRW Forged pistons for nitrous apps. They have really thick tops on them. Course being really thick their heavier than others too. I think Probe is around 50 or more grams lighter per piston than the TRW's.

I'm using TRW's in my motor just incase I feel like spraying a little after it's built.

 

For my stroker, I'm buying pieces one at a time, because I can't afford a balanced kit.
The rods I've chosen are scat 4340 cap screw rods. The reason for that is because with a cap screw, it's unnessecary to grind the rod bolt head, for clearancing. And I've seen some posts that say grinding the bolt head isn't suggested.