is there a lobe diference between the 2. i was just wondering. because im looking at a custom grind or eiter of those 2.

 

I think they are this...

230/244-544/576-112 (306)

232/242-577/597-(not sure on this one)

All the #'s are on 1.6 rockers.

 

The 847 is 575/595 lift and 234/242 @.50 duration with 1.6 RR duration was correct.. IMO go custom grind.....

 

no... i guess i didnt give enough info.

im looking for the lobe profile diference. if there is any. (the shape of the lobes)

 

I am sure there is a profile differance seeing how one is cut by Comp Cams and the other by Crane Cams.

OH yeah and the 847 is a billet core like a Stock cam. You can custom order the 306 that way for extra money.

You will have to see if some one in the advanced section has plotted them out.

 

what im wanting is something about 3 degrees bigger than the 847. if i go custom grind.

 

I think you're going to have a difficult time obtaining lobe maps and whatnot. FWIW, methinks the 847 consists of more aggressive lobes, more comperable to the high lift magnum lobes, or normal XE's.

 

no the 847 has very soft lobes, its very similar if not identical profile to the cc306, you can tell the lobe profile very easily, you take the duration at .050 like 234 & subtract it from the advertised duration, both will be pretty equal.

The 847 has a duration of 296/304 for advertised
the cc306 is 290/307 for advertised

The 847 has a duration of 234/242 at .050
the cc306 is 230/244 at .050

As you can see, the cc306 is very similar but even the cc306 has a faster ramp up rate (xe is very fast) then the 847 on the intake, but the 847 is a bit faster then the cc306 on the exhaust. Basicly they are identical for lobe profile but LIFT will change the ramp up rate just a bit, so considering the very miniscule difference between the two cams for ramp up rate, they are considered identical for lobe profile in my books.

When you do the subtracting of .050 duration from advertised (.006), the lower the result the faster the ramp up rate, like if you subtract & get 60 for one cam & 63 for the other, the 60 cam is got a higher ramp up rate just a bit.


Now compare this to say a XE236/242 cam, advertised duration for intake is 288 & .050 duration for intake is 236, you get 52 for an answer, this compared to the cc306 being 60 & 847 cam being 62.

for intake:
xe236/242 = 52
cc306 = 60
847 = 62

So from .006 lift to .050 lift an XE236/242 is only 52* away from getting to .050 lift. But an 847 is got 62* to travel to get to .050 lift, which one you think is harder on the valve train? the XE obviously, it will get there first so its got a faster ramp up rate.

 

The difference you are quoting would be divided in two. As the valve opens, it goes from 0.006 to 0.050 over half the number. Then as it closes, it reverses the movement over the other half of the duration. Still, it does show how much more abrupt the XE series are.

 

OOps yeah thats all I'm trying to say in simple terms. But yeah I know what you mean, from .006 to .050 is only one way, but its a two way trip, it would be devided by 2.

 

well i called crane tuesday and they told me that the 110 lsa which i want will not rev any higher than the 112. he said its becuase of the lobe design. but it would lope more. but my question is how can it affect one area of the cam and not the other.

i sure hope this cam on a 110 sounds good. i know the sound clip i have of it on a 112 sure does

 

I don't see how it won't effect it, no matter what the lobe design, as far as I know the closer the lobe sep the higher you'll rev essentialy & more lope at idle, maybe what they mean is when they talk cams they talk cam kits! They know that even with a 112lsa this cam keeps reving to 7k rpm because its lobe profile is so soft (slow) which is good for higher rpm aswell, the problem is that with their recommended springs you hit valve float at 6800rpm, maybe thats what they mean? plus on your engine I doubt you'll see an advantage since this cam starts making power really late as is. As far as lobe sep not making as difference I can't see how it can't, I'm sure it does.

 

im no cam expert by no means.

but i agree i dont so how it wont.