How far does my Intake and Exhaust Valves Open Up? 3.2L Carrera
 

Just curious, but with valve height properly set on my heads how much should I expect to see my intake and exhaust valves open up? I'm sure there must be some ball park numbers, I've already check my deck height and piston to valve clearance but I was wondering if anyone have every looked at this? Your feedback is greatly appreciated.

Best Regards,

Alex

Help us understand the question better. Are you asking about how much rocker mvmt you'll see at the valve tip? Are you asking about how much the valve will leave its seat when you look down the port?

Depending on cams, you'll see somewhere between .4-.500 lift at peak.

Thanks for your reply Luke, I'm interested in knowing how much the valve will leave it's seat at its peak. I have stock 3.2L Carrera cams, I assume you are talking about mm (.40 mm to .50 mm?).

Thanks,

Alex

Alex,
Looks like you may be up and on the site. Luke S is referring to .4/.5 inches. This would be 11 to 13 mm.
Remember 25.4 mm's per inch.
.50 mms would only be 20 thousandths of an inch, just over 1/64th.
Hang in there, it'll start to all make sense.
Keep asking the questions, it's the best way to learn.

Thanks Doug,

I just confirmed on my performance valve springs that peak lift is about .50 inches. I want to make certain that my Euro high compression piston domes do not impact, so I'm a bit worried about clearances. Thanks for everyone's input.

Best Regards,

Alex

at .5 lift what would be the ideal spring pressure?

Keith Epperly

Keith, just to clarify, your asking what should the spring pressure be over the nose of a cam with about .500" lift? I know this seems obvious, but if your asking what the spring pressure should be at .5 on a cam that has valve lift of .7, it could vary.

Sorry, don't have the spec off the top of my head, so looking for clarification first. What rpm, size of valve, weight of valvetrain, ramp design, etc. will all impact this. Someone like Camgrinder surely can give you some ranges to look for in this.

Hi guys I just got back into town, my valves at .500 inches produce I believe 100 lbs. I'll need to double check but I believe that is correct, maybe camgrinder can chime in.

Regards,

Alex

Alex, are these a set of my performance springs? If so, they set up at 90 lbs on the seat. The spring rate per inch is 350 lbs.
You take the 350 number and multiply it by the valve lift. For example, if you had an SC cam and the intake lift is .450,
350 x .450 is 157.5. this is the amount of pressure added to the 90 lb closed pressure.
So the closed pressure is 90 lbs and the open pressure is 247.5 lbs.

Hello John,

It's good to hear from you, yes these are your Porsche street performance springs for my 84 Carrera project. My cams are stock on my 3.2L, I was not sure how far open my cam would send them and how much force to open and close.

Thanks for your time and input.

Best Regards,

Alex