OK, so i did say that i didnt think that i would have to resize my valve reliefs.

setup= 96 JDM B20B with p3f pistons & 91 JDM B16A head milled 1mm

i locked VTEC on, put the head on and tightened it up and rotated the crank a few times, removed the head and check the clay & pistons...(sounds easy eh!)

there WAS contact on the edge of the intake valve relief.

i think i will have to remove 0.6-1.0mm from the reliefs to ensure that no piston to valve contact is possible.

i tried cutting my old Prelude pistons with a 30mm round hand-drill mounted grinding stone which seems pretty easy.

is there a better way to do it (myself) or should i just use this method. (i do not intend on removing hte pistons from the block at this stage...)

thanks all!

t..

PS some pics of re-sized reliefs would be great!!!

 

I was thinking of...

Ive used one before
it'll take off 1mm of aluminum easily

 

dremel tool!

 

yep, cool!

now i know the tools i can use - how do i do it?

just rip into it? what should the finished piston look like?

should it be polished once completed to remove all burrs?

does anyone have pictures of pistons with resized valves????

TIA,

t..

 

i might just bump this one up a bit...

thanks for you reply!!!

t..

 

why not spend the extra cash for some nice forged aluminium pistons.......most of the ones avalible will have big enough valve clearences......

 

i assume that this was a rhetorical question?

it would be nice to be fitting 12.5 JE's with Probe rods, but i seriously cant afford it right now - next time for sure!

anyone got pics of a resized valve relief???

t..

 

smoothly round off the edges after using the deburring tool. The deburring tool deburs, but it still leaves edges.
It makes sense.. sharp edge = hot = chance of something happening prematurely.

Although Ive never done this and dont have a B20, I would take off .5 extra (at least 1.5mm) material taken off for heat expansion.

 

how is the depth of the valve? sometimes you can get away with just folding back the radius of the valve relief at the top. even aftermarket piston(s) valve reliefs are not always big enough. i'll try to take some pics of my pistons tomorrow at work of how i did mine

 

the depth i think i can get away with, it only touches teh outside edge of the relief.

i was planning on just removing the 'lip' of the relief (about 1mm) and re-claying.

some pictures are what i think i need. that would be great vhd!!
t..

 

Sorry, dont have any pictures, I have seen some at one time and I don't see any thing about it that would not be straight forward. When using the dremel tool, select the lowest speed avaliable, use one of the pink or orange in color bits that dremel offers at Lowes or Home Depot, use those to start the initial cut, make every move planned, take your time and you wont make a bad move damamging the piston, then after your done with that bit, grind down the final close finish with a diamond cut bit (use the bit with the 1 mm wide diamond cut sphere on the end of it. These wear down fast but are precise for the finish and are kinda pricy, but well worth it, you will probably have to buy 3 or so of them I forgot the price, not expensive, just kinda pricy for dremel bits. Then from there use the metal polishing wheel or the copper wheel for the final smooth finish if you want to take it that far, but the diamond bits do a good job in and of them selves. But the copper wheels wear out fast and I reccommend using the thinnest metal ones.

Hold the dremel with two hands.

 

Find a soft material to grind with just incase you slip. If you use stones, use aluminum tapping/grinding oil. Use it frequently, if will prevent shavings from collecting and making the stone unbalanced and useless. You may want to stick to sandpaper rolls instead of stones. There are buffing pads available for polishing afterward.

There is a company called Cratex. They make cutting media similar to extrude hone's material but on mandrels for rotary tools. There are different levels of abrasivness too. With them you can port and polish to a mirror finish. I believe they have a web site.

 

I always found sasndpaper rolls were less easy to work with because of the samdpaper's tendancy to move around.

And I would like to see that Cratex site if you got a link.

 

http://www.cratex.com/

 

tinkerbell, heres some pics of my pistons. i know its hard to see it clearly(gotta be there in person). the exhaust side is where i folded the top of the radius over. i used a die grinder with a burr, then used some sand rolls to clean it up a bit. to polish it back up, i just used some wd-40 with the cross buffs. i was gonna put it in a a mill to recut the valve reliefs, but they are already close to the edge of the pistons.










[Modified by vhd, 5:16 AM 9/12/2002]




[Modified by vhd, 5:40 AM 9/12/2002]

 

thansk vhd, those pics are good!

thanks heaps!

sorry to say that i have chickened out!

i am going to get them done by a machinist!

too much risk for me to try it myself...

(i will take your pics to the machinist though )

t..

 

Make sure to double check the motor's oiling and cooling passages for shavings after the work is done, I've seen this overlooked alot of times and has canned a few motors.

 

yeah if your not sure of what your doing, then bringing it to a machine shop will probably be a better idea. just hope they do a good job. try to bring it to a machine shop that does a lot of race type/custom stuff.

 

in australia? yeah! right!

nah - the place im taking it knows what i am talking about, and suggested using hte B20 head as a guide for the tool...

i have removed hte valves and the guy said he would make up a bit that goes into the valve guide and they would cut to a certain depth.

does this sound OK?

t..