The Cam & Pistons

Lets grow the sport

So if your going to be competitive you should have your cam reground. Vogle has been doing this for a long time and Zack Kerber offers this service as well but as far as I can tell its exactly the same grind.

The idea is to get more lift and duration in order to move more air through your engine. A 1105T cam from Kubota is ground with more lift and duration but still would not hold up to a reground cam. 

I am running a little different grind than Vogel. It was done by a small shop up here in Canada called Canadian Chrome very good price for grinding. So far I have been happy with it

Valve Clearence

So a stock piston has between .050 to .055 recess cut into them. I have found you need about .080 to .100 for these reground cams. An alternative is cutting 40 to 60 off piston tops and doing recess cut of only 20 to 30. 

You need to remember by cutting your pistons you will lower compression and to some degree this is a good thing and will improve high end performance when using a turbo.

The down side it will be hard to start and run like a bugger when cold.

I might add here that the newer stock D1105T pistons are a better choice over the non turbo pistons. The reason being they have steel re-enforcing for ring groves. I have found this only to be true of the newer turbo pistons the older generations are pretty much non turbo pistons.

 

Easy thing to do is remove them and take them to a machine shop. I decided to try a method you can do yourself if your a little handy.

I took a old valve from 1105 and tack welded a carbide cutter to it. I then used the head as a guide and used cordless drill to spin the valve and cut pistons. I used two bolts only to keep head in place and checked my progress till I got the needed clearance.

PS. turn the piston down a little when doing this and each time you check your progress do not use an air hose to blow away chips.

Use a shop vac to suck up the chips you do not want any of that in your lower end.  

Importance of Ring Gap

So I will try to explain briefly why end gap is very important. The end gap is the space found at ring ends when in the cylinder. As the engine heats up metals expand causing this end gap to close.

When putting our engines under extreme load conditions as we do these temperatures exceed far beyond the normal levels. If you have the normal end gap of .018 it closes very quickly as things heat up.

Once the gap is closed it will then start to expand outward into the cylinder. Increasing friction and heat. End result is melt down and scoring on cylinder walls and in most cases a scrap piston.

On our three cyl engines the center cyl gets very hot so larger end gap than other two is recommended.

  How much? well this varies greatly according to  how much boost and even gearing and water injection. Kubota has a tolerance of up to .049. I would suggest between .040 and .060. 

Decompressing

I have a little written about cutting pistons for valve relief this also lowers compression at the same time. 

Why lower compression?

Pretty simple, high compression and high boost, larger amounts of fuel equals blown head gaskets, cracked heads, strain on Rods ect ect. Another way to drop compression is to shave the piston tops off some in a lathe.  How much? its a trial and error thing. Could be as little as .020 or a lot more. Decompressing you will need most likely to use ether for start ups.

So after all that, let’s move on. We might as well begin at the begining. Click on the button to go to my first topic of Building a Limited Pro Stock Diesel Pulling Tractor.

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