I'm having trouble selecting a cam for my 454. I've narrowed it down to two cams, both of which I already own.

I have 10.5 : 1 compression, air-gap intake, 750cfm holley, steel block & heads, 1.7 roller rockers.

Cam #1: Comp Cam 11-207-3
1500 to 5800 RPM
270 / 270 duration
0.510 / 0.510 valve lift
110 lobe-center angle
106 intake center line

http://www.compcams.com/Cam_Specs/Ca...?csid=387&sb=2

I have used this cam in the past and it performs well and has a noticeable idle, which i really like.


Cam #2: Crane Cam 132561
2800-5800
298 / 306 duration
0.530 / 0.551 valve lift

http://www.cranecams.com/index.php?s...61&lvl=2&prt=5


My heads are already set up for cam #1 and I'm not sure if I would need to replace anything if i switch to cam #2. Would there be any performance and/or reliability gain between these two cams?

....Thanks

what exhaust are you running ? have to be careful, the second requires water entering near the tail pipes....

Quote"FAIR IDLE, STANDARD CAMSHAFT FOR MERCRUISER 400, 405, 420, 425 HP AND 525SC-454 CU. IN. ENGINES"

I have called Crane and they said this is an improvement from the stock merc 425 cam The only way to do better than this one would be with a Roller or a custom grind. With that compression the first one will not have enough duration to work well with your compression ratio IMO.

Check the specs on the springs to see of they will work with the Crane.

I currently have aluminum exhaust manifold + risers. Same style as typical stock systems. I'm looking to upgrade to headers but wasn't sure it was necessary with the 132561 grind. Is there a good chance for water reversion with that cam? Crane wasn't sure if it would revert water with the stock exhaust or not.

Also, how much more performance would the 132561 grind provide over my current setup. Any thoughts??

Looks like headers it is.

Anyone know if I will see much of a performance gain using headers and the 561 cam? I have a 25ft boat and could get 58mph @ 5000 above sea level with my current cam/exhaust config.

This may sound like a stupid question, but is it possible to have headers that are too large. I have found a set of headers, i belive they are CMI big tube, that would work perfect for my exhaust port locations, however the CMI site says the big tubes are used for 750+hp. If im only in the 450hp range would these adversely affect the engine??

I don't know if it will hurt, but they will look bas azz in there.

One reason for headers (30-32 inch runners to the collector) is to take advantage of their scavanging affect. I believe that if the ID of the runners is too big, then the headers would loose that ability. For a 454, it seems you'd want runners in the 1 3/4 to 1 7/8 inch range. I may be wrong on the ID range/size, but I'm sure someone more knowledgeable will chime in and kick my azz if I'm wrong

rmbuilder (not Bob the builder LOL) would be the guy to talk to about your cam. He can also give you advice on header/runner size. He can be reached at 585-654-8583.

Yes, you will loose low and midrange torque and power. You would be better off with E Tops.

Also, I did about what you are wanting to do on a 454mag/365hp.

I used a Crane #134241(kit #134242) which is very close to the 132561 cam (and cheaper), Imco exhaust, Holley 800cfm, carb spacer, roller rockers and milled the heads to get comp around 9.0:1. I picked up a solid 4 mph in a 24 Outlaw. That would translate to at least a 60-70hp increase. I gave the specs to somebody else who dynoed the combo and made 425hp at 5000rpms. I spun mine to about 5400rpms.