iamfaster

Can some one explain in simple terms "cams for idiots", what is the difference between the crane 132561(stock 525s) and the 139731. Would there be much perf. gain with the 731?

468
weiand 177(5lbs)
8.5:1
Dart Eagle Iron 310cc
full hydrolic
1050 dom
max HP r's at aprox 5200
Want aprox 625hp

Want durability and minimal chance for water reversion.

iamfaster

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iamfaster

cam will be hyd Roller

KAAMA

iamfaster,

With your engine being only 468cid and using a 310cc sized head, then I would suggest using the smaller cam of the two. Simply because a 310cc head is too large for a 468cid marine application. Also, I highly doubt you will see 625hp from a naturally aspirated 468cid engine.

I once had a pair of 468cid engines in my 32' A/T that made about 600hp @5500rpm on the dyno. However, these engines had 9.5 comp ratio with Merlin oval port heads with 2.30" intake valves. The heads were professionaly ported as well in the bowl/pocket areas, and used Dart single plane intakes, and MECHANICAL/SOLID roller cams.

Griff

The stock 525sc cam #132561 is NOT a roller cam. Its a flat tappet hydraulic.

The 731 should make 20-30 more hp. As I said in one of your other posts, I did the switch on a stock 525sc. I saw 50-100rpm increase and more torque from 3800-5200rpms.

Griff

Without an intercooler, I doubt you will ever see more than about 575-600hp. The 177 blower just gets too hot to move enough air to make that HP.

I'm at 7lbs of boost w/o a cooler and I'm probably around 550-570hp.

iamfaster

Kamma, I am using my existing 177 weiand blower.

Griff, Yes, the stock cam is a hyd tappet, but i want to go with the Hyd roller. Is that #168731??? The flat tap 731 is part#139731. Which one did u use? We will also be bumping the Comp to aprox 8.5:1.

need some help understanding the specs when comparing the stock cam to the hyd roller. #168731. Have a longer duration? taller exaust and intake? Crane rep recommended 741. But thought that it may be more than i need.

I will finally be meeting with builder this week to spec. I appreciate yours and others advice last couple weeks.

Griff

I'm pretty sure #139731 is for a Gen IV and V engines and the #168731 is for Gen VI engines. They have the same specs and are both hyd rollers. I have a Gen V engine and used the 139731.
This has been discussed before about the 731 vs the 741. That info is largely what I based my decision on. The general concensus was that the 731 is a better cam for a SC'd 454 and the 741 was too big. The 741 would have to be run at too high of an rpm on a 454 to make it real power. The 731 will make more torque in lower and midrange cruise and make more power than the 741 unless you are at 5500+rpms. The 741 would the better choice for a 502-540ci.

iamfaster

Griff, Do you plan on new heads or porting? Would that help compliment your cam for more top end as well as mid?

cstraub69@comcast

Cams are a little more difficult then, which one will make more power? There are to many variables that have to be known before an educated selection of a camshaft can be made. Just because a cam may be bigger then another doesn't mean it will make more power under the curve. Sure it will more then likely make more peak power but if that power occurs at 6K and you are propped to make max power at 5500, then the cam is worthless.

The cam is derived from the combination to be run; ie bore, stroke, rod length, compression and cylinder head flow and cross section numbers. In your case the added blower will change everything. An OEM headed blown 454 will take a much different cam then a Merlin Headed 454 due to the fact the airflow is much greater on the merlins.

Chris