More cam help

[Leslie]

The cam I have now has 228 degrees on the intake. I got a new cam with 222 degrees, how much of an improvement in vacuum should I see with 6 degrees difference?

[MrWillys]

Originally Posted by Leslie

The cam I have now has 228 degrees on the intake. I got a new cam with 222 degrees, how much of an improvement in vacuum should I see with 6 degrees difference?

Is there a difference in LSA and exhuast? How much advance is ground into the cam and is it a roller or flat tappet. What's the number?

[Leslie]

Originally Posted by MrWillys

Is there a difference in LSA and exhuast? How much advance is ground into the cam and is it a roller or flat tappet. What's the number?

Both have a 112 LSA, Im moving from a hydraulic flat tappet 228/230 to a roller 222/230.


The number is 119831

http://www.cranecams.com/pdf/Page258-265.pdf


This page tells all about it.

[MrWillys]

OK, I looked it up. I think you'll see 14 lbs. of vacuum with that cam. I really think it's about the same as the one you took out.... Sorry if I'm bursting your bubble here. Did someone tell you that you would see a difference? I think your trying for 15 inches if I'm not mistaken. You might get it by playing with 26 to 28 degrees at idle and staying to lean side right at 14.7..... What type of fuel intake are you running?

[Leslie]

Originally Posted by MrWillys

OK, I looked it up. I think you'll see 14 lbs. of vacuum with that cam. I really think it's about the same as the one you took out.... Sorry if I'm bursting your bubble here. Did someone tell you that you would see a difference? I think your trying for 15 inches if I'm not mistaken. You might get it by playing with 26 to 28 degrees at idle and staying to lean side right at 14.7..... What type of fuel intake are you running?

I realize its not that much different, 6 degrees on the intake lobe and more lift. I talked to Crane tech line, they seem convinced it will work. But I have my doubts as well. But its in my living room now, I'll probably just put itin and see what happens. Im running an Edlebrock RPM for an intake now.

[MrWillys]

usually the roller have a steeper ramp. This is why a roller with ten degrees less usually runs in the same upper rpm range and is a tad bit broader than a flat tappet. I asked about your intake hoping you were injected. It's much easier to adjust timing and fuel with injection once you're setup.
Does anyone else in the sport run injection?

[TEX]

Originally Posted by MrWillys

Does anyone else in the sport run injection?

Nope, against the rules (except for OEM or OEM equivalent).


TEX

[Leslie]

Interesting tid-bit of info I found out MrWilly's, running 1.6 rockers as opposed to 1.5's adds about 4 degrees of duration as well. Took me awhile to realize that, but it makes sense now

[MrWillys]

I know your right, but I have no idea how to calculate it. I would think it would have a greater effect for a larger lobe than a smaller one. So, let's say it adds 4 degrees. That would be 2 on the intake and 2 on the exhuast? Meaning your 222@.050 is now 224? I'm sure this also would depend on ramp design also. I know this is the advantage of the hyd roller having a faster ramp. This is why if you have two cams of the same duration. One being hyd, and the other flat tappet based @.050. The flat tappet will actually have more off the seat time because of the slower ramp. This is why teh hyd roller has a broader range. More vacuum on bottom with enough duration for the top.
Does this make sense?