[2wld4u]

Originally Posted by coldknock

3-5cc is the norm for 2 relief pistons. It doesn't really matter anyway, except where valve clearance is concerned. Like I said, it's not enough to begin with. 252 degrees at 0.050" and 314 total, 110 LSA on a hydraulic roller cam is BIG. 11.5-1 will do but it's not optimal. I'd use a smaller cam, maybe one space up from the bottom of the page.

You can recite everything you've ever read in magazine articles and Smokey's books about long connecting rods, light weight pistons, dwell time, and decreased loads on the thrust side of the cylinder wall. That's all good stuff if we're talking about 500+ cubic inches, a difference of at least an inch in length, and we're shooting for 800+ horsepower over 7000rpms. Even then the results of using a longer rod would be less than you think.

In a 450-500hp small block Chevy, 0.300" of extra rod length ain't gonna amount to hill o' beans.

Been there and done it already.


Larry

I really dont think its all about performance from a engine builders standpoint, then again, it all has to do with how you look at it, durability? in some cases a longer rod will FREE up some power not only due to less weight to sling around, but also due to less friction.. and less friction means your also going to gain durability...


Most certainly, I would use a Small base circle cam, and you may need to have the rod bolts clearanced as well, people do this all the time on the long rod 406's.. Im building a 434 cid using 6" rods, 4.155x4.00x6.00" rods and there is no way, I can get by without using a small base circle cam..

some rod manufactuares have stroker clearanced profiled rods, all rods are not created equal... even with he so called stroker rods you always have to check, you can break a cam, I have seen this.. its not pretty, and you can bet more than just the cam and lifters will be damaged...


2wld4u

[68c10owner]

Originally Posted by coldknock

3-5cc is the norm for 2 relief pistons. It doesn't really matter anyway, except where valve clearance is concerned. Like I said, it's not enough to begin with. 252 degrees at 0.050" and 314 total, 110 LSA on a hydraulic roller cam is BIG. 11.5-1 will do but it's not optimal. I'd use a smaller cam, maybe one space up from the bottom of the page.

You can recite everything you've ever read in magazine articles and Smokey's books about long connecting rods, light weight pistons, dwell time, and decreased loads on the thrust side of the cylinder wall. That's all good stuff if we're talking about 500+ cubic inches, a difference of at least an inch in length, and we're shooting for 800+ horsepower over 7000rpms. Even then the results of using a longer rod would be less than you think.

In a 450-500hp small block Chevy, 0.300" of extra rod length ain't gonna amount to hill o' beans.

Been there and done it already.


Larry

Larry, first of all, I never knew the specs of the cam so I had no idea it was a hyd roller with that much duration.

Second, I never said the longer rod was going to make or brake the motor, just that the longer rod would internally balance easier than the shorter rod.

I`m not some dumb kid new to the game. I`ve been mbuilding chevy motors for the last 13 yrs so you don`t have to give me that "I know it all" act because it`s pure BS. I just gave the guy my opinion, what he does with it from there is his business.

[68c10owner]

I just want to apoligize to the original poster. You are just trying to get info and you ended up getting a pissing match instead. I don`t usually get involved in them but there is always someone who wants to start them. I`m not going to post anymore so hopefully the pissing match will be done. you have been given plenty of great info. just remember, check your cleances and you`ll be fine. good luck.

[dboyett38666]

Thanks to everyone.There is so many different beliefs,and I am sure all are right not every engine is the same but you learn with each one,

[coldknock]

I reckon I need to apologize to both of ya. I didn't intend for this become an argument. I just state facts based on experience with both schools of thought along with tips from professional engine builders. Jon Kaase and Gene Fulton primarily. If they say it, I believe it because they're not selling me parts.

A few years ago I wasted my time and money switching to 6" rods in two different engines. Both engines were Dyno tested at Reeves RPM Performance in Warner Robins, Ga. when they were first built and again after the rebuild with longer rods. Neither engine gained a single horsepower. Both engines did develop an appetite for oil in less than a year of racing and I had to pay for the rebuilds out of my pocket. But, If that's what you want... go for it.

Once again, I apologize for offering advice based on experience. You can bet I won't do it again.

Peace,

Larry