i have a 86-99 350 block and i am thinking of making it into a 383 but i need to know what the difference is between running a 5.7" rod and a 6.0" rod

also i have heard about clearancing problems with 383s is this just with 6.0" rods or does this happen with 5.7" rods too

this engine is going to be used for a daily driver and strip maybe once and a while

 

O.k. here are my thoughts.


First it has to be clearanced, no matter what rod length.

Second, if you are going to make 550hp or less and keep it below 8000rpm then a Scat 9000 crank will be fine for the street.

I run a 6.0" rod because it does two things.
1. your piston will be lighter and you will have a lower bobweight, but that will put less street on the rod and crank throw
2. There is more clearance for the counterweight on the crank, this means no Mallory to balance the crank and that saves you cash and crank weight.

Plus I also like longer rods.

Bret

 

are there anymore differences between a 5.7 and a 6.0?

also what will need to be clearenced and can i do this by myself

if i have to clearence the bottom of the cylinder i dont think i would tackle this

 

The length from the center of each hole in the rod is the length difference and the longer rod will weight more.

You can do a 383 clearancing, but you might as well pay the shop that is doing your work the $ to do it. Or you can get some books, like those from Dave Vizzard that should tell you how to do it.

You actually clearance the block, but it is at the bottom of the cylinder, not in the cylinder but close.

Bret

 

What Bret said, just wanted to add one thing: the real world differences between a 5.7" and a 6" rod on performance are quite small and would be difficult to measure. But I agree with the conclusion in general. OTOH, unless we are talking a max effort race motor, if I had a good set of 5.7" rods I wouldn't buy a new set just based on length.

Rich Krause

 

i havent bought rods yet but for a street motor which rod would be better?

also with a 6.0" rod you would have a better rod/stroke ratio correct?

where can i find those books you were talking about?


thanks

 

just do a google search for David Vizzard and you'll find them.

Rod stroke ratio means crap anyways. I go with the longest rod for the other benefits.

Bret

 

what "other" benefits?

 

What I said above

 

One small downside to the 6" rods is that the wrist pin will be up into the oil scraper ring area. There are multiple ways that piston manufacturers use to make sure the oil ring scrapers get support, and my limited experience shows that they work OK. A 5.7" rod, however, you will usually have actual piston material supporting the oil scraper ring all the way around, depending on the exact piston you choose. Just something to keep in mind if you expect it to work for many thousands of miles on the street.

I have built many 383s and I used to say that they ALL require grinding of the block. And then I put together my latest one- everything fit with ZERO grinding on ANYTHING. That is the rare exception, however. And I'm using stock rods which typically have the fewest clearance problems to begin with.

And it's not just the block. You will often have to grind for clearance at the rod bolt head to clear a couple of cam lobes unless you buy a cam ground on a smaller than stock base circle.

 

since you are talking about strokers do you have an idea if the eagle or scat 6" I-beam rods that is not stroker clearanced ( the rods themselfs are not stroker ground) will they clear a small base circle cam in 383 or 396?

 

You need the dowel pin cap ones for that, if you get the other ones then you need to rebalance them. It's worth the extra bucks to get the right ones.

Bret

 

[Deleted]

 

SStrokerAce, thanks for the reply. i was asking about these rods because my friend is on a budget for building an adequite stroker. so the ones with bolts are not my choice where the dowel pin capped rods ( rods with screws) are my choice. but still some of those dowel pin cap rods are not stroker ground and the rest are as i can say not fully stroker ground. maybe the best and safest choice is to go with H-beam stroker clearanced rods.

badassbowtie400, i'm for real from Kuwait. [Deleted]

 

I thought the longer the rod the better. More TQ. and the piston hangs longer at TDC and the motor spins up rpm faster.