New IKF dipper rule

Rodney Ebersole · Posted: Tue Jul 24, 2001 5:26 am Post subject: New IKF dipper rule

I understand that the dipper in the stock classes is no longer a tech iteam. So the last few motors that I have made I have been triming them down a little shorter and knife edging the front side. One of these motors broke the rod in the first race. The rod bolts were still holding what was left of the cap togather, but there was aluminum welded all over the crank journal like oil starvation from dipper breaking. Are any of you playing with these dippers in this way? if so what luck have you had. I am temped to run the plastic dippers but haven't tried one yet. Have you? I wounder if my knife edge was at a little bit of an angle which made it pull to one side and break. I have two other fresh motors with my mod dipper in them and am half scared to run them.

Bob Vehring · Posted: Tue Jul 24, 2001 5:54 am Post subject: New IKF dipper rule

Rod, Did it break right away, or did you get several laps, or sessions on it? my thought is, if it broke right away it might not be throwing up the oil, but if you got several laps out of it, the oil should be beat into a mist by than and maybe it was a freak rod problem or a piece of metal that didn't get washed out got in there. On the early Inteks (before Animal rod) we ran for months with no dipper at all, but the ohv has a lower cam location and the gear helps get the oil moving Bob

John Neilson · Posted: Tue Jul 24, 2001 7:15 pm Post subject: New IKF dipper rule

Rodney,
Usually, the common cause of RII rod failure is clearance. Too little and you weld the crank/rod assy, too much and you will shake the assembly till it fatigues.
e-mail me your specs to compare.
clearance, type of oil, RPM range.
John

Rodney Ebersole · Posted: Wed Jul 25, 2001 4:40 am Post subject: New IKF dipper rule

Thanks for your time guys. My notes are still in the trailer but I did run that motor once on my brake dyno up to 5500 RPM's before I gave it to my customer. He then ran 1 practice run and it was quick. Ran at about 6200 R's and it's a 1 mile sprint track. I did have him use Camac mach 3 oil in it which may be some of the problem as I understand that mack 3 is a little heavy, more for mod motors. The crank if I remember right was .005 out of round but was about .998 I didn't plasti gage or measure the clearance to the rod. That's where I am going wrong hu? The rod was new and I push a ball hone threw once in order to loosen it up and put some cross hatch on it. O-well I got a couple of days before the next race. I guess I will tear down the other motor that didn't blow, it just went down on power, and see if it will tell me any thing.

Rick Dunwell · Posted: Wed Jul 25, 2001 2:57 pm Post subject: New IKF dipper rule

If the crank journal was .005 out-of-round, there's your problem. most likely you honed for .0025-.003 from the high spots, then when the force was on the rod at the low spots you had.008 clearance. it is almost as important to have a perfectly true crank as it is the have a perfect cylinder bore.

John Neilson · Posted: Wed Jul 25, 2001 3:14 pm Post subject: New IKF dipper rule

Rodney, you have been hit with the latest QA problem. I have seen some of the cranks from Briggs that were out .005"
To build a good motor, you need less than .0005 TIR. What happens is the rod shakes itself apart, first breaking the unsupported dipper, then without proper oiling, uncontrolled welding occurs.
I have played on the dyno with dippers, nylon, aluminum, and the RII rod.
No difference measurable.
IMHO, the RII is best. It has larger radius's built into the beam section and so it is stronger. We used to run 4 races on each rod and replace them. Usually the dipper would break off the tip, maybe 1/2" or so during the 4th race.
(we would twist the motors close to 7K with the RIII piston)
John

Rodney Ebersole · Posted: Sun Jul 29, 2001 8:41 am Post subject: New IKF dipper rule

I am sorry I meant to type .0005 out of round. I cleaned up the crank with acid and it was .001 out of round and small. So I'll blame it on the crank and put a different one in it. John, them RapIII pistons must be pretty good, I have a super stock that I have raced @ 8300 with the RapIII piston. I also twist my IKF stocker to 6900 or so but I am always a little nervous about the quality of the next rod I'm putting in there so I put off the replacement, I had gotten 8 sprint races out of my own IKFer before the poor little rapII rod gave up and ruined that motor. So yay I got to change them out more offen than that. It would be neet to log revolutions along with average RPM's with a datta aquisition system which I have on my kart, but it would too much for my computer skills at this time. Do you know of any places that will X-ray rods? Shoot I could blab on here forever, To many questions and to little a brain, later

Jack Burroughs · Joined: 18 Jul 2001 Posts: 144

Rod i've seen a small portable x-ray unit,don't know who makes it. we "borrowed" it from the u.s. gov. when we worked at the arsenal. worked with poloroid film.