Don Terrill’s Speed-Talk

I've put together a 572 aluminum Hemi based on INDY stuff. I'm using Eagle rods with a Callies crank. The question I have is regarding the rod side clearance. I see it as excessive at .030. The pistons are Diamond with the circlip pin retainers. My buddy builds engines at a prominent race shop in town here and says not to worry about the excess clearance and claims the oil pressure won't be affected. In reality, the motor will probably never see the high side of 6,200 rpm and is a street piece.
I'd like to have about .015 of side myself. The rods are steel. Will this thing knock the locks out of the rod(pin)? Will it consume excess oil from buildup on the bore walls?

Sorry for the long post, just looking for the right answer.

Listen to your friend. The side clearances you are suggesting should be a minimum.

Ed

illfish wrote: I see it as excessive at .030. The pistons are Diamond with the circlip pin retainers. My buddy builds engines at a prominent race shop in town here and says not to worry about the excess clearance and claims the oil pressure won't be affected. In reality, the motor will probably never see the high side of 6,200 rpm and is a street piece.

Sorry for the long post, just looking for the right answer.

Are you running a flat tappet Hydraulic with 100 seat pressure?

The side clearence will not effect pressure which is the same theory that a narrow rod bearing vs a standard rod bearing will not show a loss or gain either in pressure.

Here is the problem. With .030 clearence it is considered excessive and it will throw a significant amount of oil up onto the walls. This is not what you want and it is wrong. .018-.020 is fine. Personallly I wouldn't use Eagle rods in this application or any performance application.

No on the hydraulic. Running a flat solid with EDM lifters. Could I use a lighter weight oil that won't stick to the bores as much?

illfish wrote:No on the hydraulic. Running a flat solid with EDM lifters. Could I use a lighter weight oil that won't stick to the bores as much?

Stick to the bores?
I don't get it?

6200 rpm? That is where it makes steam!!!?

It is what it is...... What would you do buy a new crank?

Strange Magic wrote:
Here is the problem. With .030 clearence it is considered excessive and it will throw a significant amount of oil up onto the walls. This is not what you want and it is wrong. .018-.020 is fine. Personallly I wouldn't use Eagle rods in this application or any performance application.

What rods have you run?
I run Hawk rods at 6.125?
That is a nobody rod that see's 9000 rpm every run?
Why is the Eagle not good?
Not trying to be mean. But would like a reason why they are crap!

So after all this I see you're point on American made stuff. I agree and disagree the same.

Strange Magic wrote:The side clearence will not effect pressure which is the same theory that a narrow rod bearing vs a standard rod bearing will not show a loss or gain either in pressure.

Here is the problem. With .030 clearence it is considered excessive and it will throw a significant amount of oil up onto the walls. This is not what you want and it is wrong. .018-.020 is fine. Personallly I wouldn't use Eagle rods in this application or any performance application.

What has your research showed for quantity of oil on the cylinder walls. How much extra??? between .020 and .030 side clearence.

Eagle "SIR" rods , agreed they are junk.

Eagle "H" beam, disagree, between all the builders that visit this site there has to be thousands and thousands of engines with Eagel "H" beams and zero problems.

Keith

I always believed that the amount of oil thrown off the rods was controlled by the verticle oil clearance between the shaft and bearings than side clearance.
My old 355SBC drag engine had eagle H beams and .028-.030 side clearance. 300+passes at 8000rpm .No problems

af2

I mean that with a higher viscosity oil, it will tend to be more clingy on surfaces due to the viscosity itself. I know that Hemi's like to run in the higher rpm ranges but it is a street motor in a little Barracuda and with 800 horsepower, I don't have to spin it hard to get me where I'm going.

MELWAY wrote:I always believed that the amount of oil thrown off the rods was controlled by the verticle oil clearance between the shaft and bearings than side clearance.
My old 355SBC drag engine had eagle H beams and .028-.030 side clearance. 300+passes at 8000rpm .No problems

We've been over this numerous times. OIL splash is controlled by rod bearing clearence not rod side clearence. Common sense tells me .003 rod clearence is going to leak a hell of lot less than .015 rod side clearence. Modern ring design in a std tension ring package is more than capable of dealing with any amount of oil the rods my leak off. Look at engine with oil squiter rods like 390 fords and they have .018 to .024 rods side clearence. I build tons of these motor and any time they burn oil its in the heads.

k-star wrote:

Strange Magic wrote:
Eagle "H" beam, disagree, between all the builders that visit this site there has to be thousands and thousands of engines with Eagel "H" beams and zero problems.

Keith

I wouldn't say "zero". Some brave souls have tried these in place of Carillo or equivalent in endurance applications with almost immediate and disasterous results.

On the other hand, some have had luck. My point? They're not as tightly controlled from the time the metal is degassed to the time they are put in a box, and the manufacturer never did any pull or cycle testing with force to determine what the average limits of their parts are, based on a 30-unit sample set. This is what you do to ensure confidence that your stuff is going to be OK most of the time.

illfish wrote:I've put together a 572 aluminum Hemi based on INDY stuff. I'm using Eagle rods with a Callies crank. The question I have is regarding the rod side clearance. I see it as excessive at .030. The pistons are Diamond with the circlip pin retainers. My buddy builds engines at a prominent race shop in town here and says not to worry about the excess clearance and claims the oil pressure won't be affected. In reality, the motor will probably never see the high side of 6,200 rpm and is a street piece.
I'd like to have about .015 of side myself. The rods are steel. Will this thing knock the locks out of the rod(pin)? Will it consume excess oil from buildup on the bore walls?

Sorry for the long post, just looking for the right answer.

Don't worry about the clearance or oil clinging to the bore walls. That's what properly configured rings and bore wall finishes are for.

People have been running engines with large rod side gaps since the day the earth cooled and to my knowledge nobody's had any disasterous results. If this was dangerous the piston-guided arrangement that is common today would not work.

Aluminum Hemi Indy engine block and Eagle rods. Please don't get me wrong and I don't mean this to be sarcastic but you have one of the finest Mopar blocks produced and i'm sure it was not cheap and then it is outfitted with Eagle rods which are considered to be the bottom of the rod products.

Here is a couple of options:

You can get a Crower rod that is dimensionally correct and the way you would like it and sure it costs more money, but it will be correct. I'm sure you can also get an Oliver rod or a carrillo as well, and yes it will cost more money in comparison to the Eagle, but once again it will be of quality rather than quantity.

What has your research showed for quantity of oil on the cylinder walls.

My research has shown that Eagle deals in quantity and not necesarily quality and they make every attempt to bring their product to the market much cheaper than a connecting rod company that has much better quality control.

As far as quantity, it doesn't take rocket science to figure out that rods with .030 side clearence will source more oil onto the cylinder walls than a rod with .020. Thats a 33.3 percent increase