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-   -   Rod Cap groove?? (http://www.hotrodders.com/forum/rod-cap-groove-212850.html)

birkey 01-19-2012 06:31 PM

Rod Cap groove??
 
2 Attachment(s)
what is this?

birkey 01-19-2012 06:32 PM

None others had this in on them.

engineczar 01-19-2012 07:07 PM

That groove is an oil squirter. If it's only on one rod then you have a mis-matched set.

birkey 01-19-2012 07:08 PM

i thought it was fishy because there were major burs on the outer part. should all of them have it

engineczar 01-19-2012 07:21 PM

IMO for performance applications your better off without them. If it squirted at the bottom of the piston it might be helpful but the way those squirt they end up just overloading the oil rings.

cobalt327 01-19-2012 07:26 PM

Quote:

Originally Posted by birkey
i thought it was fishy because there were major burs on the outer part. should all of them have it

All the rods should have them. They helped lube the cylinder walls and cam but were found to be unnecessary.

If this is a SBC, those rods w/the oiler or "spit holes" weren't used after about '64 or so. They were commonly seen on the small journal SBC rods with 11/32" rod bolts. There were other engines besides the SBC that used them, too.

Centerline 01-19-2012 09:18 PM

Absolutely. All early hemis had spit holes in the rod caps. Here's one from the 331 I put in my truck. The one in my Deuce has them as well.

http://www.hotrodsandhemis.com/Rebuild/Spit1.JPG

Centerline

HotRodsAndHemis.com

"That's about as useless as a snooze button on a smoke alarm." - Jeremy Clarkson

birkey 01-19-2012 09:20 PM

should there be a matching groove in the rod as well?

oldbogie 01-20-2012 12:13 PM

Quote:

Originally Posted by birkey
should there be a matching groove in the rod as well?

No, but to get them to work there needs to be a half round hole on the mating edge of the rod bearing insert that is open to this hole, otherwise their will be no oil flow. These were discontinued a long time ago, modern bearing shells haven't included this feature for many decades.

Unless this is an engine that is going to see very heavy duty use putting an oil stream on the cylinder wall and the bottom of the piston just isn't needed there's plenty of throw-off from the rod journals.

In heavy duty truck and racing applications you still see squirters but these days they tend to be tapped off the main bearing oil supply and directed with a nozzle to the underside of the piston. Some engines use a drilling through the rod shank to direct oil against the piston's underside, found in upscale racing engines and hard working diesels these days.

Using this puts a lot of extra work on the rings as they have to manage the normal throw-off plus this indexed stream, it gets to be a lot of oil. I wouldn't encourage the use unless there is a big need as has been described for heavy duty use or distance racing where the engine runs for long periods of time at high power settings.

Bogie

birkey 01-20-2012 08:13 PM

i wasnt planning on it. haha thanks for the info

Jordan_Sullivan 04-04-2013 09:49 AM

Hey guys, i just took my motor apart and my motor has one, what should I do? there is only one.. disreguard it and use a different rod cap?? thanks

oldbogie 04-04-2013 10:32 AM

Quote:

Originally Posted by Jordan_Sullivan (Post 1663116)
Hey guys, i just took my motor apart and my motor has one, what should I do? there is only one.. disreguard it and use a different rod cap?? thanks

Ignore it, most likely new bearing sets will not have the matching notch so they won't feed any oil into the groove. If it becomes functional because you happened to get a set of NOS bearings with the notch it's no big deal if one works and the others don't.

Bogie

painted jester 04-04-2013 11:30 AM

oldbogie Post #9 is right on the button :thumbup: Ill add this: The main purpose in racing applications of the oil groove was so the oil squirted on the pistons could absorber and dissipate forged high compression piston dome heat (keeping pistons cooler), the groove on the rod isn't needed in lower compression street engines. My pink rods in my 12:1 302 have the grooves, I had to add the groove to my new inserts.

Some of the top racing engine builders add remote oil squirters to lubricate and cool piston undersides. Especially on turbo or supercharged engines. If you depend on strictly splash lubrication to pistons, cylinders and rings? that's a decision for the engine builder:thumbup: or the engine owner to make!

Jester:thumbup:

TucsonJay 04-04-2013 02:37 PM

I remember those from many years ago. I've done Chevy sixes, smallblocks, and 348/409s. I know I have seen them, and was also told they were to oil the cam.


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