valve lift?

[jonnyshaw49]

does changing the cam timing slightly or advancing or retarding change the valve lift?? as i measured mine on the car and its reading just over 8.5 could this be a standard cam at 8.2 just timing out? or do you think it will be an uprated cam?? eg the cat cam at 8.425 or ktec 260 at 8.635,is there any other tests i could do or is it just taking the cam out?

[jonnyshaw49]

just checked the valve lift again and it reads 8.45 could this still be a standard cam half a tooth out on timing etc? or is the lift too much more than standard?

[Chris Hebden]

Why have u got another thread going asking the same questions?

[jonnyshaw49]

Because it was ages ago and didn't get much advice so started a fresh just want to try n find what cam is tO go with my new hybrid and in this thread I'm askin how else I can check and if timing affects valve lift y?

[rs250nut]

If you have a look in the tech apps there is a program called cam wizard, this will answer all your questions.

[Markey Mark (BD)]

The lift of the cam is set by what its ground to, the timing of it will determine when you have full lift but will not chance the amount if lift.

[markey b]

is that the cam i sold you fella? if so its a 285 @ 110 deg

[jonnyshaw49]

nah the cam was already in looking at the cam wizard it looks like the cat cam at 8.425 but mymate from minisport measured it with a dti and said if the timing is out half a tooth it can change the lift of the valve, but wasnt sure if it could on a gt turbo, so is it not possible for the standard gt turbo cam to lift 8.5 mm from 8.2???thanks for your help

[Andrew Cooke]

I wouldn't let minisport near my car then:sad2:

[jonnyshaw49]

it was the head builder who did the dti check not the guy on the dyno as hes away,minisport are well known for good work and do well in the rallys, he was just measuring the valve lift before i put rocker on, so is it possible for a gt cam to lift to 8.5mm

[Andrew Cooke]

it was the head builder who did the dti check not the guy on the dyno as hes away,minisport are well known for good work and do well in the rallys, he was just measuring the valve lift before i put rocker on, so is it possible for a gt cam to lift to 8.5mm

Cam timing cannot change gross valve lift, on a mini, or a GTT, I don't care how good he thinks he is, he's wrong.

Can you get 8.5mm lift out of a std cam? Possibly, Scoff just used a nominal 1.5 ratio for those plots, mixing and matching parts can make quite a difference to the actual ratio, as can skimming your head, or grinding the base circle on the cam. To be sure you'd really need to measure the lobe lift, not the valve lift, as that removes the vagaries of the rocker gear (which is why I stopped measuring valve lift). Even if you do get a different lobe lift it could still be a standard cam as there is no guarantee that there aren't many versions.

I would say that it's highly unlikely that you have a cat cam, very few have been used in this country, and those that have are almost certainly the 327 cam. It's possible that you have a KTec 260, that would give you a slightly lumpy idle. Again, you might have a Piper 270, but they're pretty rare too. Most modified cams have the spec stamped on the face at the gearbox end.

[jonnyshaw49]

thanks for that info, ill just leave it now untill i take the engine out then have a look to see what it is, there was a fair bit of stuff done at ktec but no sign of a cam on reciepts, wish i would have looked when rebuilding the engine but was new to the gt scene then, has anyone tried replacing the cam with the engine in?, jacking it up and pulling through the perc fan hole in wing?? is there anything that can drop or move in the engine when taking the cam out? or is it fairly simple?

[Andrew Cooke]

http://www.rtoc.org/boards/showthread.php?t=4744

[jonnyshaw49]

thanks mate