I am planing to begin building a new shortblock to replace my 2 bolt, cast crank and stock rods. I already have a standard bore 4 bolt block that will be bored .03" over and will be needing new rods and crank. I am leaning towards just building another 355, but am tempted to go to 383. If 355, I would like to build something that will hold up to 6500-7000rpm max. If 383, I will shoot for 5500-6000 peak power. My question is can I get by with the cast steel cranks made by scat or eagle, or is steel forged the only way to go? Others have said that these cast steel cranks will take much more abuse than the cast iron, but I have my doubts. Also, what would you recommend for rods?

 

If you're gonna buy a new crank anyway, I definitely vote for stroking it. And while you're at it, why stop at a 3.75" stroke crank? Maybe a SBC 396?

Anyway, with the rpms you're talking about, and the fact that you haven't mentioned NO2 or forced induction, a nice cast crank or maybe a 5140 steel crank would fit the bill. Alot of people overlook 5140 steel cranks, they are in between a standard cast crank and a forged 4340 crank in terms if cost and strength, and are completely suitable for almost any street application. Jeg's and Summit offer their branded forged steel cranks for around $500, hard to beat. But the old standby's, Scat and Eagle cranks are very popular and have been used in countless examples of applications similar to what you are proposing.

If I were you, I'd go for a 5140 steel crank with 4340 steel rods. You'll be plenty stout for almost anything you decide to throw at the motor you're talking about, as well as future enhancements. There are plenty of guys who are running in NMCA/NSCA/NMRA with the same bottom end combo, along with a good set of forged pistons, who are running 9's all day. Not saying that's what you want to do now, but the combo is strong enough for it, and not that much more than a cast Scat with average rods and pistons. As before, Jeg's/Summit sells there brand of forged rods for very economical prices, as do Scat, Eagle, Milodon, and Lunati. Even Crower offers there forged Sportsman rods for just a couple hundred $$ more than the Chinese made Jeg's/Summit/Scat/Eagles stuff.

I guess it depends on you personality. Are you going to build this motor, and never want more? Are you going to second guess yourself, and wish you'd gotten that steel crank and those forged rods?

 

based on the recommendation of my machine shop the Scat crank with the eagle rods, if you are going to keep it under 6000 to maybe 6500. they are inexpensive, have a good fit and are pretty strong. However, If you are are planning to see 7000 on a regular basis, i'd go with forged everything. Buy the best and lightest you can afford.

Like Monty said, if you are going to buy a crank/rods/pistons, why not go for the 383 or 396??? And if that keeps you from spinning to 7K and requiring top of the line stuff, it will probably be cheaper than the 355.



[Modified by ralph, 6:17 PM 8/28/2001]

 

Yeah, that is what I was thinking, but there is something about a screaming 350 that is appealing. However, since I already have a screaming 350 in my street rod, I might as well build a real torquer for the vette and see what it is like. You make a very good point about future needs and second guessing myself. I am seldom content for very long with whatever I produce as far as power and am usually changing things after about 2 years. A good forged assembly would make things much easier if/when I start shooting for even faster timeslips.

Thanks, Tom