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Hope to get some input about how my numbers look before I move on and find valve clearance. Dialing in as much as I can while the engine is on the engine stand. Maybe get a couple answers from those who've been here.
Short block is all new internals. Head and cams have been run before by the previous owner, head has been resurfaced since then.
GSR build, block and head
Supertech, 81.5, 11:1 pistons
Eagle rods
Supertech flat faced valves
Supertech valve springs and retainers
S2 cam gears
Skunk 2 Pro 1 cams
Installed the Skunk2 Pro 1 cams and degree'd using the lift method @ 0.040, disregarding centerline all together.
Skunk2 cam card specs
Intake:
Open 30° BTDC
Close 48° ABDC
258° duration
Lift .498"
Exhaust:
Open 55° BBDC
Close 25° ATDC
260° duration
Lift .470"
My final measurements
Intake +2.5
Open 33.5° BTDC
Close 51° ABDC
264.5° duration
Lift .493
Exhaust -1.5
Open 56.5° BBDC
Close 26° ATDC
262.5° duration
lift .462
After running the centerline and lobe separation angle algorithm
My measurements
Intake CL 98.75°
Exhaust CL 105.25°
LSA 102°
Just checking if there's anything I should be looking for/at. Block has been decked, maybe a couple times. The head has had a good amount taken off as well.
Last edited by jdblock; 05-13-2017 at 06:58 AM.
Reason: added peak lift
looks good to me. thats actually much closer than I was expecting. almost all aftermarket cams will have a +/-5* or so variance. proper measurement of actual valve lift can add some variance too. even a 0.001" difference could mean 1-4 degrees difference.
what did you get for peak lift compared to card spec?
I made sure I had repeatable measurements before moving anything. I had the dial gauge stick a couple times, had to adjust the angle a little and it was good.
If I may ask, to measure P2V clearance at each of the degrees you have, are you having to remove the head and reinstall each and every degree with fresh clay each time?
Hell no. lol I have a dial indicator riding on the valve spring retainer. That valve spring is also replaced with a 1 lb spring I can compress by hand.
The piston goes down, and the piston goes up. The intake cam opens 33.5° before top dead center (TDC), and closes 51° after bottom dead center (BDC). The exhaust opens 56.5° before BDC (BBDC), and closes 26° after TDC (ATDC)
The valves will be closest to the piston when the piston is near TDC. So we measure for intake valve clearance when it opens, and exhaust valve clearance when it closes.
I rotate the crank and the cam opens the valves. Starting at 15° before top dead center I zero the dial gauge (the cam has the valve open) and press the spring down to check when the valve hits the piston. I don't care how much the cam is opening the valve, I only care about how much free space there is between the valve and the piston at that degree of crankshaft rotation. I then checked every 5° through to 20° ATDC, zeroing the gauge every time. This gives an idea about where the P-V clearance is most narrow. I then checked again in 1 degree increments where the P-V clearance was narrow. You see the final measurements through that range in the above picture.
I will probably run clay once to see the clearance between the valve and side of the valve relieves on the piston.
Last edited by jdblock; 05-18-2017 at 10:27 AM.
Reason: Correction
I locked VTEC by swapping the long and short VTEC pins. This only locks in one valve, but that's all I needed to measure p-v clearance.
They sell special lightweight springs for checking valvetrain at Summit and other places. The springs I bought, I found at True Value Hardware, its just a spring to hold the valve up.
The springs I used are pictured below. They're about 5" long, and they bind when compressed to about 1", plenty of range to check p-v.
05-12-2017, 07:23 PM
Degree'd my S2 Pro 1's
