I hope this question is not too obscure....

I was wondering how close for comfort is the valve/piston clearance when using Spec C's with CTR pistons in a stock R head and also with a portflowed GSR?

I am aware of the clay test (putting clay on top of the piston and then cranking the motor by hand and then cutting the clay in half and measuring the clearance), yet there is one problem, how would using the clay test for the vtec lobe be accomplished when to my knowledge there is no manual way to engage vtec.....?? or maybe I do not know of it......

if there are no clearance issues, I appreciate the clarification, yet I would still be interested in knowing if there is a way to do the test with the vtec lobes engaged manually.

LSR

 

ttt.....fast tonight

 

I too am worried about Valve To Piston Clearance Issues. I plan to install Toda Spec Cs in a 95 GSR Engine who's head has been Milled for 11.3 to 1 compression and running with Stock Compression (10 to 1) Endyn Rollerwave Pistions. I recently got this out of The Old One's BBS regarding the Clay Test. Hope this helps you out:

Step 1:
Make sure the head and piston top is clean. Place a used head gasket on the deck. Spray a thin coat of WD40 on the piston tops and the combustion chamber.

Step 2:
Cut some small strips of clay. Place a strip that's approximately .5" long, by .10" wide, by .10" high on each quench pad of the piston. Cut pieces that are about .30" long, by .10" wide, by .10" high and place one in each valve relief (just off center) on the piston.

Step 3:
If the head's a VTEC head, slide the two rocker shafts out just enough so you can remove the group of three rockers, intake and exhaust. Swap the pistons in the rockers, so the long pin is in the short rocker and the short pin is in the mid (high) rocker. This will effectively lock the high rpm rocker arm in place. Slide the shafts back in place.

Step 4:
Make sure the WD40 is on the chamber in the head and set the head on the block. You can torque the head to 15 foot pounds....the use of every head bolt isn't necessary. Place the cams back in the head, making sure the pulleys are correctly lined up.

Step 5:
Rotate the crank a couple revolutions slowly with a 1/2" drive ratchet with 17 or 19 mm socket.

Step 6:
Remove the head carefully and use a thin machinist’s scale, preferably graduated in thousandths to measure the depth of the "mashed" clay. Just stick the end of the scale into the clay until it hits bottom on the piston and read the depth on the side of the scale. That measurement is the piston to head, or the piston to valve clearance.

Step 7:
If you're satisfied that you have sufficient clearance, remove the rockers and place the pins like they belong, clean everything up, wipe the deck and the head's deck surface with acetone, put a (new) gasket on, bolt the head on (torque it properly) and button it up.

Note: For N/A applications, the Piston to Valve Clearance for the Intake Valves should be 0.045" Minimum. For The Exhaust Valves the Clearance should be 0.060" Minimum.

 

Thanks for your reply, that helps tremendously......when do you plan on doing your c's and i was wondering what springs you are going to use....just out of curiosity.....

LSR

 

I plan on installing the Cs in Sept. Right now I'm waiting on the Toda Valve Spring Set, Portflow Titanium Retainers, and Toda Cam Pullies. I believe there is about a 1 Month wait for these parts.

 

LSR, please let me know how your Clay Testing does, as I will be doing the same test on my setup shortly! Thanks.