i know there are some great engine builders here

[David Lee]

I am not one of them. So I would like to hear some of your thoughts about this article.

https://www.enginelabs.com/engine-te...the-confusion/

[SSDiv6]

There are many advantages as shown in the article. Nevertheless, a reminder that in Stock and Super Stock classes you have a minimum weight for connecting rods.

[carl hinkson]

I have always preached that side clearance has nothing to do with oil flow it bearing clearance the regulates the oil the bleeds out between the rods.

I have worked on piston guided rod engines before, Mercedes was the first to introduce the piston guided rod engine a long time ago.

It's like Lingenfelter published if you leave the plug out that is under the rear main cap you will loose oil pressure from there it was published in a bunch of books only to find out its a myth, LOL All that happens is the oil bypasses the oil filter.

[Mike Jones]

Would have been interesting to hear Jenkins` response to the contradiction. He was talking about Cylinder wall oiling/ rod side clearance, "oil trapping" and its effect on oil pump volume. Hard to believe the Grump didn`t grasp the concept of oil pressure being created by bearing clearance. just sayin...
Here is Jenkins` book: https://www.scribd.com/doc/110755831...e-Bill-Jenkins
The paragraph the article referenced is on Pg.47
Mike

[Chevy55]

A pump doesn't pump pressure, it pumps volume that's measured in GPH. That was taught in Army Engineer School in the 60's and had to be common knowledge long before that.

The pressure of any full displacement pump will be dictated by the restriction it encounters before being dumped back into atmospheric pressure.

[Adger Smith]

Well as an old time builder I have a totally different take on the bearing clearance/side clearance topic.
First I would like to point out that it appears like some didn't grasp what was going on with the side clearance. I think it was a product of misinformation. It was an intentional misdirection of information.
Back in the day we had to use to use wide clearances to keep bearings and engines alive. Oil flow was not the real issue. The real issue was flex and parts moving around rubbing, touching and binding.
1. The older crank and rod material was not as strong as we have today.
The alloys were different and today the stock parts are stronger by design, too.
2. The size made a difference in the strength. As SBC cranks went from 2" rods to 2.100 they flexed less and bearing clearances and side clearance could be closed up.
3. The weight of parts decreased so the loads on the crank and rods decreased.
Modern day pistons and pins are stronger and lighter.
As the parts got better the clearances could be decreased.
I did find that some engines with large diameter mains and rod journals needed more clearance just for the growth created by the heat. I used the unscientific method of heating parts to operating temps to find the running clearances. The first pin guided rod I ever saw was in the model airplane engines we used as kids. As I started racing go carts I saw them used in the chainsaw engines we modified. There is quite a difference in what we had back then vs what we have to work with now. Progress...
I think the engine Guru's of that time never discussed the real issue of parts flexing. That was a real speed secret.

[SSDiv6]

Originally Posted by Adger Smith

Well as an old time builder I have a totally different take on the bearing clearance/side clearance topic.
First I would like to point out that it appears like some didn't grasp what was going on with the side clearance. I think it was a product of misinformation. It was an intentional misdirection of information.
Back in the day we had to use to use wide clearances to keep bearings and engines alive. Oil flow was not the real issue. The real issue was flex and parts moving around rubbing, touching and binding.
1. The older crank and rod material was not as strong as we have today.
The alloys were different and today the stock parts are stronger by design, too.
2. The size made a difference in the strength. As SBC cranks went from 2" rods to 2.100 they flexed less and bearing clearances and side clearance could be closed up.
3. The weight of parts decreased so the loads on the crank and rods decreased.
Modern day pistons and pins are stronger and lighter.
As the parts got better the clearances could be decreased.
I did find that some engines with large diameter mains and rod journals needed more clearance just for the growth created by the heat. I used the unscientific method of heating parts to operating temps to find the running clearances. The first pin guided rod I ever saw was in the model airplane engines we used as kids. As I started racing go carts I saw them used in the chainsaw engines we modified. There is quite a difference in what we had back then vs what we have to work with now. Progress...
I think the engine Guru's of that time never discussed the real issue of parts flexing. That was a real speed secret.

Agree!
Lets also add that new racing blocks have improved oiling and the majority of racing engines running piston guided rods have external or dry sump systems.

[Eman]

What brand and weight of oil was Grumpy using in 1976 with a wet sump, cast pump and a stock block?

[Mike Jones]

Here is Jenkins` book: https://www.scribd.com/doc/110755831...e-Bill-Jenkins
Mike

[David Lee]

is there a way to bring this idea into a 305 sbc?