Q. I am looking to buy a Dyno 95-3 cam and I was wondering how do I beef up the lifter area like Dyno suggests for this cam?  By the way, I want to do this myself, I just started building my own motors.

Contributed by:mslippard@mindspring.com

     

     The 95-3 is extremely proficient at producing horsepower, but it's method of achieving it is often less than desired.  When the cam is rotating, the shape of the lobe moves the lifter up and down.  The taller the cam, the higher the lift, the more compression; but because of various tech rules, the cam lobe can only be a certain height, so in order to achieve more height the valve must be floated.  To achieve valve float the cam lobe's profile must change drastically so as to throw the valve higher than it would normally travel, hence the term "valve float".  The problem arises in this throwing action, the force during this action tends to push more outward instead of up causing excessive pressure on the lifter bore and in some circumstances produces cracking of the block at this area.  That's why you must "beef up" this area, it will (greatly) reduce this type of breakage.

Here's the breakdown...

Welding aluminum is not easy.  If you do not have experience with commercial type welding of aluminum don't even attempt this.  Aluminum is a very light metal, it also melts fairly easy.  Needless to say, if you ruin your block we're not responsible!

Things you'll need:
1. Welding machine capable of welding aluminum (Don't forget your shield!)
2. 3/32" Aluminum Alloy Welding rods
3. 1/4" Steel shaft (or anything you can find that's 1/4" to fit up in the lifter bore while your welding)
4. Chamfer Tool (DynoCams Part # CT-BS)
5. The block to be welded
6. Small handheld grinder with abrasive grinding bit (Dremel tool works great)

Procedure:

1. After motor is disassembled, start by using the grinder to clean the area that will receive the welded material.  Make several light passes until entire area is clean. (Remember we're cleaning here, not excavating)

Below is a block we received from a customer wanting to beef up the lifter bore area.
(Notice that the lifter bore has already been chamfered to allow more clearance for the valve tappets)

 

2. Next weld the area up that is subject to breakage.  Before beginning, insert the 1/4" rod at least 1" into the lifter bore area.  This prevents the bore area from collapsing. You should apply the weld so as to produce an evenly distributed cap around the lifter bore. Proper technique here is important.


(Welding of this nature is second hand for Tommy Perry, he's probably got his eyes closed)

Notice the difference between a good and bad weld.  A bad weld is basically an unfinished good weld.  The metal from the rod must be fused to the receiving metal in order to form a strong bond. 

3. Let the block cool and examine your handywork. Lifter bore area should receive approximately 1/8" weld around area.
(This picture shows welded lifter bore after welding, 1/4" retaining shaft has been removed)

4. Clean up excessive welding with the same abrasive bit you used to clean area originally (if necessary). Chamfer the area with chamfer tool (DynoCams Part # CT-BS) to complete the process. Verify that all internal parts can rotate normally and that there are no clearance problems created from the new weld.

(Finished block ready for reassembly)

 

Well, that's that.  We hope you've enjoyed this months installment of "The DynoCams Tech Question of the Month".  Join us next month as we delve into other mysteries of Karting issues.