R-1600 Cam spec.

Post by **Datrock** » Fri Jul 28, 2006 1:13 pm

I have a question for the engine builders out there. I put a degree wheel on the front of one of my 1600 engines and here are the numbers I cam up with.

Int opens at 30 BTDC
Int closes at 100 ABDC

Exh opens at 40 BBDC
Exh closes at 56 ATDC

If I do my math right that is a 310 intake duration with 276 exhaust duration. The valves open and close .356 with a dial indicator on the top of the spring retainer.

Do I still need to find True TDC??? Or does the crank pulley indicator always line up at TDC?

These numbers do not match the stock specs for a 1600 cam so could it be a race cam or could there be other issues that give me these readings. I have not removed the timing cover, yet. The engine does run but has not been driven while in the car. The engine does show signs of being rebuilt at one time. Stamped #'s on the head and new freeze plugs and ported intake and head.

Thanks ahead of time... Bill

Marky510 · Post by **Marky510** » Fri Jul 28, 2006 6:34 pm

Hey Bill,
I'm not sure of the stock specs for the 1600 cam. But when dialing in the camshaft you need to do some preliminary stuff. First thing that I do is adjust the valves. Secondly, find true TDC. I use the positive stop method. Once those baselines are set then the valve opening and closing values should make a little more sense. Hope this helps out.

Mark

Post by **Datrock** » Fri Jul 28, 2006 7:33 pm

Thanks Mark, I was not sure if the True TDC was needed since the crank pully only goes on one way, I made a stop and the True TDC is less than 1 degree after the TDC mark on the pulley, It stopped and 22 before then reversed the crank and it stopped ant 23 degrees after, that right in the ball park. The valves were set hot at .017 a few months back. I'm using my 1 inch dial indicator with a half inch button tip on it.

The stock specs should be.

Int open at 20 BTDC
Int closes at 56 ABDC

Exh opens at 58 BBDC
Exh closes at 18 ATDC

Stock duration is .256
Stock lift is .335

These figures came from my Clymers manual. There is also a cam chart in the Engine Area on this site. I was hoping that my specs might look familiar to someone that has more cam knowledge than I do.... Bill

keith0alan · Post by **keith0alan** » Fri Jul 28, 2006 10:49 pm

Just a quick note, measure the lift at the adjuster nut, not the spring. The rocker is not 1:1 and you will get funny numbers. Also "open and closed" are usually measured at some small amount of valve opening. Somewhere around .020" to .050", not sure what Nissan used. In a running engine the valve is still effectivaly closed till it's a little ways off the seat.