93_hatch

so wondering what is a acceptable valve radial clearance / valve to piston releif side clearance? or engine build chime in with what you run for clearance? having trouble finding this spec

f20b jones

What motor are you building? Race motor ot street motor ? A little more info would help . What compression are you wanting to run ? I run a little closer clearences then most motors i build for other people for several reasons . I can tell when something isnt right and will tear my motor down and inspect it instead of keeping on beating on it. I also use a different method to check my clearences then anybody else and it makes me feel a little better seeing whats going on rather then checking the thickness of clay . I think 35 thousandth is a good squinch point but mine are at 26 thousandth. Im sure everybody has different ideas to each there own.

f20b jones

I can turn my motors over with the vtec pin locked in and the valves will never touch the pistons . Its not hard to cut big valve reliefs the valve to valve contact is what you need to worry about and you cant control that just prey your timing dont snap . I have seen a timing belt that somebody pryed on instead of using the proper h tool snap at the track and destroy a head . Piston had small scratches but overall ok.

93_hatch

its a b16 with 11.5 pistons, more like 12 with block resurfacing and head resurfacing, and flat face valves. motor use some daily and some road race/autocross. current measurement with the vtec locked in, intake .070in and exhaust .060in that is radial clearance not depth, my depth is like over .120in don't remember that off the top of my head. and what are u talking about preyed on timing belt instead of using an h tool? sorry i am not smart enough to pry on a belt.... that just stupid.

cibao2ner

.030 v2v is the standard minimum at 0 lash....

GhostAccord

It is true that clay is not the only way to check valve clearances. I use a dial indicator with the head installed and test springs. There is also the feeler gauge method. As for clearances I usually shoot for 0.03" - 0.035".

Unfortunately the dial indicator and feeler gauge methods are useless for checking your clearances for your valve diameter or side clearance to the valve relief. This is important if you are using aftermarket pistons or over sized valves. You should use clay for that. Pistons can rock in their bores and they also expand in high temperatures.

PyroProblem

Borescope?

93_hatch

got answer from wisco since i am using there piston they said .060 is min and i am right at .060. would like to be a little more so i have peace of mind instead of right at the edge.
lol borescope that would be cool but not enough room in the cylinder for it. i guess i just have to hope my claying measurement was good.

GhostAccord

0.06"......Is that their specs for the radial clearance or for both radial & vertical?

Clay is good enough when done & measured properly. Good luck with your build

jasonwinback

i want to to notch my b20 piston using this technique http://www.fordmuscleforums.com/engi...-notching.html but the thing is to have a good clearance i would have to buy a 1.5mm oversized valve. my question is is there anywhere they sell them (as single valves would be prefered) and if you have any other sugestion let me know

4piston

Most piston manufacturers will tell you between .050"-.080" depending on who you talk to and that is just them being super safe.

IF your valvetrain is in control, you can run down to .020" radial clearance. .030" is pretty safe. Also make sure that your valve pocket is actually in the proper location on the piston.