finger ports?????????

[whatsamerc??]

is there anything about these that looks way off? i ground them in this evening on a junk block and if they look decent i am going to try my hand on a good one. i have a nice block that was done by jacks marine that i used to get the locations and heights from. how deep and wide do they have to be to be effective? i dont want to get too deep and get into the water jacket........thanks, benji

[berg969]

i would go as far down as you did. measure a piston from bottom of the skirt to the bottom of the hole your drilling and you have the lower height from the bot of the sleeve

[Da Bull]

Those will work just fine. I like the way you dropped them down all the way down to the bottom like a champ motor.

DB

[T-REX]

ANY, size fingerport will help!!....U kan make them more effecient by sharpn'in up the sides and tha thang about a fingerport iz the top iz what makes it work tha way U want it...Tha way your top iz will put tha income'in charge almost strate up...Try to ramp it to direct the charge to tha plug...U kan even shape the roof to make the charge spin tha comb chamber charge(along with tha other ports)...I have found that All blocks are NOT created equal...U may git away wit cutt'in 1/2" deep on one block, but cut thru on anuther...So don't git greedy and try to go to deep...I run them az wide az 5/8", but didn't see much differnce between them and tha 1/2" ones...Tha main thang I found iz match'in tha fingerport roof, and hole in piston!!!...JMO:thumbsup:

[whatsamerc??]

thanks for the input guys. i am gonna start grinding on a good block real soon. once i get the measurements right it only takes about an hour per cyl to cut them............benji

[baja200merk]

how did you cut them? They look like the FPs evolution used to cut into the older omc's that didnt have finger port bosses so they had to be kept shallow.

[whatsamerc??]

how did you cut them? They look like the FPs evolution used to cut into the older omc's that didnt have finger port bosses so they had to be kept shallow.

i cut them with drill and a long burr bit. i am sure that i can go deeper but i wonder how much difference it will make.........benji

[Bies]

Excuse my ignorance! is the finger port the reliefs in the cylinder walls?
and How does it benefit?.

[racer]

What year is the block some have more room than others you will poke out the side not get into a water jacket on a non finger port block. Berg mentioned the best way to match pistons/ports yours appear to be too long from the photo.

[whatsamerc??]

its an early ninety's yamaha 2.6 liter. i copied the length from a block that was already done. what is the disadvantage of having them lower than the hole in the piston? how far up on the piston do i need to drill?............thanks, benji

[powerabout]

What shape should the top be....squared off like a transfer port or like the one shown?

[whatsamerc??]

i am gonna try to go deeper with them. is it better if they are rough inside or smooth?

[brussrude]

How are these finger ports timed compared to the transfers and the 3rd port (boost port ) ??

Regards,

Bruss


ANY, size fingerport will help!!....U kan make them more effecient by sharpn'in up the sides and tha thang about a fingerport iz the top iz what makes it work tha way U want it...Tha way your top iz will put tha income'in charge almost strate up...Try to ramp it to direct the charge to tha plug...U kan even shape the roof to make the charge spin tha comb chamber charge(along with tha other ports)...I have found that All blocks are NOT created equal...U may git away wit cutt'in 1/2" deep on one block, but cut thru on anuther...So don't git greedy and try to go to deep...I run them az wide az 5/8", but didn't see much differnce between them and tha 1/2" ones...Tha main thang I found iz match'in tha fingerport roof, and hole in piston!!!...JMO:thumbsup: