Ten mil cub port timing

[mx1986]

Couple question on port timing. Where's zero degree bdc or tdc. And on a ten mil cub setup for 300 ft sand drags what is good port timing and duration.

[tundish2800]

A lot of guys won't give up there port specs.

[J-Madd]

I got 1 at 200* exhaust and one at about 194 -195* and they run about the same as long as you have the right pipe and gearing. Not sure either is optimal, just sharing what I have. 198* is probably a good number. Not sure about transfers.

[possum]

More importantly the angles and port shapes.

[J-Madd]

I can't port motors, but I wish I knew more about what to look for in that^^^^. I always measure exhaust port timing, squish clearance, and squish band on motors just to see what the builder has done, but that's about it.

[RadarRacing]

10 mil cubs normal as cast porting is about 194/128 or 130.

[J-Madd]

http://www.cpindinc.com/pub/view_product/43?lm=3&name=CPI-6864

 

CP says 196*/130* with 0.012" base gasket.

[possum]

JM are you playin around? With those 75 drag bikes you got. haha..I know you know a lil more then that. Ive been shown cylinders from different builders. But one builder in particular turned on a light bulb!

[locogato11283]

I wouldn't even attempt to port a motor. I would imagine for some people it's just not worth their time or money to mess with it.

[trickedcarbine]

Different strokes for different folks. Some just have time and money to burn and really don't care about results. I'm fine with that so long as some one doesnt go boasting that they are a proven engine builder just because they ported a few sets of cylinders and they beat their buddies every weekend. Unless their friends happen to have motors from actual builders with good tune and chassis.

[Coupelx]

Port timings are only part of the story. Kinda like the preface to a novel.

 

I did a set of stock cylinders over a couple years always trying new things and was very happy with them but i decided to step up to a pv cheetah which Wildcard built for me. Its fast its smooth and no anxiety or headache i figuring it out on my own.

[camatv]

hell try 198/ 130

 

if your light and on alky you can go to 200/132.   hell of a LOT more than just port timings in getting a motor to run worht a shit.

 

take a bad ass port job  and crappy frame set up  vs a good frame setup and box stock porting..  guess who would win..

[registered user]

you can make a decent runner just using crank rotation but youll probly be better off figuring out specific time areas and working with that method

[J-Madd]

Assuming the rings won't get hung in a port, and negating the effect on piston life; can a motor have too much exhaust port time area?

[registered user]

i dont know the answer but i suspect its possible to have to much blowdown which is directly related to the size of the exh port.