Big Block

[falcon]

looking for comments on increasing performance in an inboard application--it is not in a donzi.

i have twin BB-454--that have 370 hp at shaft and max rpm 4600----i am looking to increase torque at my cruising speed of 2800-3200 rpm---originally i was going to change my exhaust manifolds to stainless marine--but realize that this will only help me at higher rpm---the motors have a midrise alunimum intake and rochester 650's--square port exhaust and i think compression is 8.25 or 8.5

[HyperDonzi]

Just a guess, but I would think a different camshaft with more low end in it (could someone explain diff between low and high end cam's? diff in rise and duration?).

Tommy

[krakmeup]

Hey falcon, I just emailed you a loooong article about more power - post it if you think it is worth the length, good luck!

[BigGrizzly]

Falcon, that is not true those mamafolds help in the midrange too. What your looking for it would be best to put in a 502. Anything short of a supercharger won't help much at thoes rpms.

[MOP]

I have a buddie thinking about this cam for the same reasons, would like any input to pass on to him.

http://www.cranecams.com/master/apps/chevy47.htm

[BUIZILLA]

I have used the 278-2 Crane installed at 110* intake centerline, and the 268H COMP installed at 108*. I am a serious fan of the 268H grind. I would NOT go any bigger than either of those 2 grinds for a STOCK compression 8.0-8.5 eengine.

A BB Chebby will LOVE either cam in pleasure craft use. Especially with good manifolds or transom exhaust with stock manifolds.

The fast-ramp COMP CAM series is another prime choice for marine use where max rpm stays under 5400-5500. Basic Erson roller rocker's in 1.7 ratio would be a nice touch and *may* even fit under stock aluminum valve covers using the THICK cork gaskets with the metal center insert, or the THICK rubber gaskets from GM, designed the same way. Throttle response with the COMP fast ramp cams is VERY crisp, and idle quality is excellent. Count on 45-55 hp increase doing both cam and rocker combo. You *may* have to *jet up* 2 numbers square. Set TOTAL advance to 34* @ 2800 rpm. 12* @ 800 rpm idle.

If you can, remove the heads and basic port match the pathetic alignment/mismatch if at ALL possible of the intake to head air dam, especially on 454's. Ask me how I know this...

I would not go over 232*-236* in a BB and 218*-224* in a small block for pleasure use. But, that's just MY opinion. I tend to be conservative.

Standard rule of thumb, is to pick the cam you REALLY would like to have, then buy the one just below it (as in smaller) in the catalog. You won't be sorry this way.

If the budget is more flexible, a hyd-roller is hands down the E-ticket these days. Just my .02..

J

<small>[ March 09, 2003, 05:21 PM: Message edited by: BUIZILLA ]</small>

[MOP]

Hey thanks a bunch will pass it on!

[falcon]

thanks for your reponses--

i did not receive that article that was sent by Krakmeup--could you resend? i could have deleted by mistake if i did not recognize the sender.