Looking for cam ideas 5.7 Vortec Carb
 

Having a 1997 Roller cam 5.7 engine rebuilt. Speed Pro pistons(dish with 4 valve reliefs) bored .030, decked .017, with a .028 head gasket. Quench should be .046. Should be around 9.3 compression. 600 CFM Edelbrock 1409, and a Performer RPM Air Gap intake. Heads will have Alex's parts Valve springs to handle for lift, and more pressure.

I am running thru Prop exhaust, with stock manifolds. I do not want to go to thru hull Hull exhaust. Manifolds are stock.

I have used Howards Cams before in engine builds for cars, and have been pleased. When I spoke to him, he suggested this cam as a good choice for that engine.
http://www.competitionproducts.com/H.../#.WJ9bjCyV7L8
I have read you don't want to go beyond 112 degrees separation, and this is 114. He said he thinks this would work great

I am not looking for a monster, engine. Would love to see around 325-350 hp at the prop. I know I am getting to the top end of the spectrum with a Alpha One Gen 2, But I think as long as I don't get the prop out of the water, and don't lay on to hard on takeoff, it will live. I also will be installing a drive shower on the drive
Does this seem like a decent combo? Thanks for any input.

Also, specs on the boat. 1997 Larson 206 SEI, bowrider, 5.7, Alpha One Gen 2, 1.62 ratio, 21 pitch Turning Point prop

Ayuh,.... That sounds like a steel shim gasket,...
Ya don't want that in a boat motor,....

Ya want a composite gasket, or a multi-layer SSteel gasket,....
Both usually run 'bout .040" or so, which means the block oughta be decked lower to get .045" quench,....

That cam is abit bigger than I'd be lookin' for, it runs 1500 rpms, to 5500 rpms,...
I look for Idle, to 5200 rpms,...

I'm doing a engine like that right now with exception it does have thru hull exhaust, I had Comp custom grind one, to me thats the way to go, they charge no more for a custom one

Bondo, The head gasket that came in my engine from GM/Mercruiser was a .028 thickness. This is the specs of the GM multilayer Stainless Steel and graphite composite head gasket I will be using.

Brand:Chevrolet Performance
Manufacturer's Part Number:14096405
Part Type:Head Gaskets
Product Line:Chevrolet Performance Head Gaskets
Summit Racing Part Number:NAL-14096405
Bore (in): 4.100 in.
Bore (mm): 104.140mm
Gasket Material: Stainless steel and graphite multi-layer
Compressed Thickness (in): 0.028 in.
Lock Wire: No
Quantity: Sold individually.

What happened to the cam you had? Thats the gmpp shelf cam ,pretty well optimized unless you upgrade exhaust, displacement and valvetrain and or heads .supports a nice alpha slash reversion friendly low idle.
And they are reasonable priced. Oem right up the the 5.7 scorpion

That's about as high as you would want to go with stick exhaust. It shouldn't revert, but you are getting close. The 114 LSA helps. 212-215 you'll be even safer. Had a comp 260H flat in my original 5.7 and no problems. You would probably be able to get away with it the cam you picked, but it could have issues.

Stock vortec heads are good to .48 lift or so. Make sure to check the retainer to valve seal clearance at full lift and have .020 or so.

I ran a comp xtreme marine 262 cam in my last boat. 355 with vortec heads. Ran awesome.

That's the cam I like.

I run that same 264HR in both my 355 Vortec motors. I'm running stock Vortec heads with reliefs cut for Beehive valve springs.I also am running stock MerCruiser exhaust thru prop. the engines make great torque and have great dock manners.

Any roller with similar specs to the 264 HR will make you a great package.

^^^Good pick^^^^

Grind Number: XM264HR
Cam Style: Hydraulic roller tappet
Basic Operating RPM Range: 1,200-5,200
Intake Duration at 050 inch Lift: 212
Exhaust Duration at 050 inch Lift: 218
Duration at 050 inch Lift: 212 int./218 exh.
Advertised Intake Duration: 264
Advertised Exhaust Duration: 270
Advertised Duration: 264 int./270 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.488 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.495 in.
Valve Lift with Factory Rocker Arm Ratio: 0.488 int./0.495 exh.
Lobe Separation (degrees): 112

I'm running comp 270 marine cam with Alex's valve springs rpm intake with a 1409 carb and through hull its a nice working combo and sounds great i get comments from other boaters every time out about how good it sounds

Thanks Everyone. I am going to try the Howards Cam that I mentioned in the original post. Specs look really close to Mira Boaters Comp 270. Shortblock should be back this weekend hopefully. Then the fun begins.

Keep in mind, he has through hull. You have stock exhaust through the prop. I wouldn't go more than the XM264 comp grind, but that's a choice you have to make between averting reverting and maybe 10-15 hp.

Spoke with comp cams about the XM270HR cam, and asked about reversion with factory wet, thru prop exhaust. He said that it would be fine with stock exhaust. The XM270HR has almost identical specs to the Howard's Cam I am planning to run, with the exception of the Howard's cam being 114 lobe seperation. If the overlap is less, will that mean less chance of reversion?