Praetorian27

iTrader: (1)

If I'm not mistaken, you start to measure when the valve is opened .050", and then stop measuring when it reaches .050" closing again. My question is, do you start measuring when the pushrod moves .050"...or when the valve itself opens .050"? If it is the valve...wouldn't the dimensions of the rocker affect the statistic? I have 1.5 to 1 rockers...if it was a longer rocker, it would be a longer duration if measured by the valve movement right?

Thanks!

SpitotRs305

i believe it would be more acurate to measure from the pushrod side of the rocker to get cam duration but there is 2 types of measured duration duration at .50 and .005 obvously the duration at .005+ will be longer but i think that any duration over .30 lift should also be calculated in proportion to lift at .50

SpitotRs305

sorry about that i lost sight of what was asked
duration at .50 lift should be measure with a dial indicator on a lifter starting as soon as the dial indicator reads the lobe lift suppled on the cam card then count degrees of rotation while at the specified lift

Praetorian27

iTrader: (1)

Herein lies part of my problem! I have no idea what the cam stats are and have no card. I bought the car as you see it and the seller really had no paperwork to hand over about the engine. I am trying to do some research on part numbers etc. to find out the ingredients!

SpitotRs305

i kinda figured you bought that car. well then the best way to tell would be to pull the topend apart and yank the cam to findout what it is... it is probably a custom grind so i am not sure exactly how P/n 's work with those but i assume you could call the company and ask what the grind is... HOW the hell does someone build a car like that and not save every scrap of paper about the car

Praetorian27

iTrader: (1)

Exactly what I want to know!!

Sonix

iTrader: (1)

You can use a dial indicator with a magnetic base, and a degree wheel. Find the max lift, average it over a few different intake lobes for accuracy, and a few exhausts.
Yes, you measure on the pushrod side. And you're right, using a 1.6 rocker changes your duration slightly.

Comp cams measures ADVERTISED duration @.006", crane at .004". So measure it at .050" lift, and the max lift, and the .006 duration, and .004 duration. That should give you enough info to find out what it is - before pulling it out.

Sexy car BTW!