overbore question

Does anyone know whats the biggest over bore you can go on the stock sleeve. Does the 416 use the stock sleeve. I'm wanting to punch mine out some, but i don't know what i can get away with, without haveing to change the sleeve.

[oynot400]

The highest over bore I have heard of is a 426, with the stock sleeve. If you are not racing and wanted a little more power then I would suggest the 416 and may be a xr cam. A lot of people around here use that set up. If you go with a 416 you will have room next time you want to bore it out.
You might want to look at a Sparks timing key. I installed one in the neighbors 400ex last night. It gave it a little more pep. Not bad for only $20. :D

Hey thanx for the info, i thought that the 416 was, but i wasn't for sure so i asked. What does the sparks timing key do. How does it help the motor.

[oynot400]

It advances the timing 6 degrees. I am not completely sure why it helps. :confused:

[VegasEx'r]

Originally posted by oynot400
It advances the timing 6 degrees. I am not completely sure why it helps. :confused:

Advanced timing creates more power & heat. You'll feel the power more in the bottom to mid-range, and throttle response is improved. Sparks says that a 6deg advance won't generate much more heat. and I'd say that I didn't notice the engine being much hotter than before (& the oil still looks the same).

[oynot400]

I talked to Sparks about puting one in my 440. He did not recommend it in a big bore because it would generate too much heat between the big bore and the key. I don't know if it would of hurt it or not, but I didn't want to risk it over a $20 part.