I have a mini-ram and I am trying to figure out what cam to use. I currently have the 219 cam, which I've read, and have been told is not a good match for the mini-ram. I have been looking at some of the cams I find people suggesting (did a search), and there doesn's seem to be much of a difference at all in the cams. Thing I don't under stand is if there is such little difference in all these cams then how can one be labeled bad for the mini-ram, or LT1 style intake and the others be great? Here is how it looks provided my numbers are right?


LPE/Accel 219 cam 218/218(according to my cam card) .525/.525 w/1.5 rockers
LT4 Hot cam 218/228 .525/.525 w/1.6 rockers.
Comp cams 305 cam 220/230 .510/.510 w/1.5 rockers

The 219 cam is only 10* less on the exhaust duration vs. the hot cam which is considered a OK cam for the LT1 style intake. :confused:
Again the 305 cam has only 12* of duration difference vs. the 219 on the exhaust, and 2* difference on the intake, and has .015 less lift

So what makes the 305, and hot cam so much better for a LT1 style intake then a 219 with what appears to be such little difference in the specs? :confused:

 

People are looking at the power peaks of the cams, the latter two make power at high rpm a little better than the 219 which was designed for the SR, and are slightly better suited to MR.

You can run the 219 if you want though, it makes plenty of power.

 

:iagree:

 

I have a custom grind 225/233 with .541/.525 lift at 280/289 advertised duration. It pulls really well and made 350 RWHP 376 RWTQ with the poor low lift flow of the Dart 215 CC heads that I have sold,, and now have AFR 210 heads. I believe that I can pick up 30-40 HP with the AFR heads since they flow @ 30 CFM on the low end and @ 10 CFM better on the top end.

 

The words "only" and "10*" should not be used in the same sentence when discussing cam timing. "Only" 10* less than the 219 cam, both intake and exhaust, makes an RV cam. "Only" 10* more makes it something totally different, still. As an illustration of the value of 10*, try retarding your base ignition timing by "only 10*". Then set it "only 10*" advanced from where it is now. Did you feel and difference? Good luck, and...

RACE ON!!!

 

:iagree: It amazes me how the cam is classified as a "truck or RV" cam based on 10 degrees or so difference.

 

As a rule of thumb, I use 6 degrees as the difference between cam sizes (duration wise).

212/218/224/230/236/ etc. For each 6 degrees, I consider the the camshaft to be one size up/down in duration.

Most of the cams I look at are rated at .050 with even numbers (see above) but then along comes LPE who uses odd numbers, like 211/219, etc.

So to my way of looking at it, a 10 degree difference is quite a bit, almost 1-1/2 times larger/smaller in duration.

Not particularly scientific, but it serves my purposes.

Jake


[Modified by JAKE, 1:54 AM 12/10/2003]

 

Thakns for the info guys. I was thinking along the lines of what ya'll said, but just didn't know for sure if I was heading in the right direction in my thoughts.

CFI-EFI
Tech. it is "only 10*" how much that 10* effects things, I see is a totally different thing.

So on the 305 cam does the lift being less hurt it? Does more duration and less lift cause a cam to equal out with a cam of less duration and more lift?

 

In Lingenfelter's book, I believe he says " choose duration first and lift second and if the two cams are clsoe in duration choose the higher lift cam".

 

I'm sorry, but I don't understand what you are saying here.

Id85 is on the right track. The opening and closing points of the valves, determines the operating characteristics of the engine. Changing any one point has it's infuence. Combined, the opening and closing points define the duration, LSA, and overlap. Within a set of defined opening and closing points, a greater amount of valve lift allows the opportunity for more flow. Lift is generally limited by physics. Increased lift "making up" for a difference in duration is a non sequitor. It is the opening and closing points (duration) that define the characteristics of the engine (mostly). Once you get those characteristics, what is there to "equal out"? Good luck, and...

RACE ON!!!

 

The tech it is only 10* statement was my way of saying I see whatyou are saying.

Thanks again for the info guys on the duration thing. This cam stuff is starting to make more since. Just wish I could have the ability to have hands on to learn even more. Like work for a race shop or something :yesnod:

 

:thumbs: