llkoolskillet

I was wondering how similar the F4.6 and K4.6 are? I have an F4.6 and need to replace the crank case, would the K4.6 crank case work with the F sleeve and piston as well as crank, or do i need the F4.6 crank case?

cummins driver

My Feedback: (31)

Im pretty sure that wouldnt work out very well. If no other reason, because the starter shafts and one way bearing setup's are different. Id definately buy the correct block for your engine.

PrjctStrtFrce

My Feedback: (10)

+1 ^ AND if they were interchangeable, then I still wouldn't do it because the K block is known to have a leaky front bearing.

aussiexl59

my k5.9 has a stuffed front bearing aswell.can i replace it or do i need a whole new crankcase?

PrjctStrtFrce

My Feedback: (10)

You can replace the bearing with a higher quality bearing, but they aren't exactly cheap. You can just get another block with BOTH front and rear bearings already installed pretty cheap off of ebay.

llkoolskillet

So the K4.6 is not a true 28, i believe its a .26. The F4.6 piston sleeve is to large! I got an awesome deal on the K crank case so i decided to try it. Also the carb hole is larger on the K. I think im going to reem out the Crank case to fit the .28 sleeve and make a custom motor just for the hell of it. The Crank case on the K seems to have a better flow design than the F however the intake and exhast ports are smaller. so im just going to have fun with it!

BudBud

The F will out run and out live the K. The F is much easier to tune. The F was made by Force and the K is made by Kingstar. The Kingstar family includes the Axial 28/32 and the 5.9. The entire K clan is prone to bearing failures and carburetor problems. The F was a really solid engine that held a nice tune and had very little carb trouble. If you have a F4.6, it will be a 28. If your K sleeve is too big for the F piston, then there must be a stroke difference. The F line included the 4.1 that a lot of guys ran for a long time. I have run with a Force 32, but have never owned one personally. I unfortunately have way too much experience with the K engines. That is okay though, I learned a lot through them. Glen

llkoolskillet

I think i understood what you said when the F is better than the K but does that mean the F is better than the axial? I did notice that the F was able to keep the front wheels up alot more often than the axial 28 1s. I thought that the K was the same size as the F but now i know other wise, i believe the K is actually a .26 or .25. What actually happend was, i was running my truck with the stock motor F4.6 in it while i was rebuilding my axial. I popped a wheelie and it landed upside down and i heard the motor rev extremely high and very loud and then it just died. So i took a look at it and couldnt see anything wrong with it. it wouldnt start when i tryed so i took the motor out, when i did the left side motor mount seperated from the motor. Exposing the crank shaft and piston. basically a crack formed all the way around the motor leaving a gaping hole. Naturally i thought the K and F were the same obviously not, haha! So im going to reem "bore" the K crank case out to fit the F piston sleeve. Now i do have to remove the rear bearing to do this, so i will be upgrading and ill replace the front as well. I took the F crank and put it in the K housing and it fits beautifully. i just need a bigger carb, im going to run it with one shim. Hopefully something cool comes out of this. I might try to port the crank and the sleeve, i do realize that i need to be careful shaving off the crank because it will unbalance it. Ill just have to see what happens!

BudBud

The Axial 28 and the K4.6 are the same engine. I think the F is the better engine, but there are a lot of guys here that like their Axial-K engines. They do have some things going for them, an extremely wide tuning window, a nice pull starter, and they generally are very easy to start. If you are looking for speed and or power though, I think the F engine is the king.

llkoolskillet

LRP 30 spec 2 is my engine, its so easy to tune and so much fun. i think i might try the picco 28 p3 soon, after all ive already upgraded the diffs so why not!

BudBud

You will probably find it harder to maintain a long wheelie with a strong Picco as it tends to blow away the tires. The ground speed difference is pretty significant.... a lot of fun. In my opinion, they are the buy of the 200 dollar class engines. A screaming Picco 28 up on the pipe, sweet music...