pb

Contemplating the opportunity to install a Weiand 177 blower on a 1997 454 mag in a 25'Sunsation.

The current cam grind is 215/[email protected], .566/.566, 110*LSA
I was informed that a cam change would be required for the blower install. What cam would be optimal for this application.

Current carb is Hollley 800cfm. Is this sufficient or would I have to go larger.

Exhaust is EMI with stainless risers. Ignition is MSD.

My biggest concern is reliability, so keeping the boost on the low side is warranted.

Any advice would be appreciated.

Thanks
Paul

PatriYacht

Generally you want a split pattern cam, one with more exhaust duration and lift than intake. Is that cam you have a hyd. roller? If so, a Crane 731 would work well. Check www.cranecams.com. Look in marine cams.

pb

Yes, it is hydraulic roller.

rmbuilder

PB
Lunati (Owned by Holley,same as Weiand) offers 2 profiles(02004LSK/02005LSK) matched to your blower. You can view them here,scroll down the page.

http://www.holley.com/HiOctn/ProdLin...CC/Chevy3.html

This is the Crane profile that is factory with the 454/525SC Merc engines.

http://www.cranecams.com/?show=brows...61&lvl=2&prt=5

They are all flat tappet designs as blower cams (under 800HP) generally do not require profiles needing roller lifters, eliminating roller lifter and spring reliability issues.
Bob

pb

Thanks guys,
Any input on carb size. The 800 already on there is practically new and would like to re-use if possible.

Griff

Here is the thread you want.


http://www.offshoreonly.com/forums/s...cam+wieand+177

Dave F

An 800 is small for that app. in my opinion.

Just to throw some numbers at you:
If you want to turn 5200 rpm with 3-5 lbs of boost
you need approx. 822-915cfm.

Apps like yours I usually see modified 850's to 1050 Doms.

DAVE

PatriYacht

The Merc. 525sc used a 1050 but some people say it was overcarbed. Your 800 could be made to work in a low boost setup.

If you compare the 525sc cam(.530,.551 lift, 228,236 duration) to the 731 cam(.587,.610 lift, 226,234 duration) you see that the 731 cam actually has less duration but opens the valve farther and faster. Since you already have a hyd. roller that makes it a no brainer to me. Just make sure your valvesprings have the correct pressure and don't coil bind. If they are old, replace them.

pb

Thanks for all the input. This would be my first blower motor with reliablity being the the main concern.

Paul