Yet another winter 5.7 engine build, oil pump, camshaft choices

[NHGuy]

Wow, that's a lot of compression ratio. 10.15. .Can't you get a bigger dish piston? It would lower your cr to something more manageable. A 12cc dish with a vortec head would get you 9.485. Better for regular pump gas. My calculations are based on a 4" bore, a 4.03" by .016 head gasket, a .025 deck height, 3.48" stroke and the normal vortec sbc 64 cc combustion chamber. That gets your quench and CR right.
I also ran the Comp 268 flat tappet marine cam in a non vortec 350. It worked well, but the motor ran out of breath at 4400. Vortecs are much better.
The 268 is ok with wet exhaust. Just break it in at 1500 to 2500 for it's first 20 or 25 minutes with the correct oil. Then use oil with zinc or additive to keep the cam & flat lifters alive.

 

[funk6294]

Looking at a different set of Pistons. If I am doing my math right, here is my new plan. Pistons are a Keith Black silv-o-lite, with a flat top, +6.00cc dish taken into account for the valve reliefs. They have a 1.56 compression height http://www.summitracing.com/parts/ue...-std/overview/
If I use a .016 Fel-Pro head Gasket, http://www.summitracing.com/parts/fe...et?prefilter=1
That should put me right into a .41 quench. But if my math is right, will also get me really close to 10.01 to 10.03 compression. Will I be limiting myself to running 91 octane or better with this setup?
Or would I still be better just to have my block decked?

I just went through some of what you are doing about a year and a half ago when I did the engines in my boat. A couple of things to keep in mind. One, don't trust the summit catalog to be 100% accurate on the compression height. Check with piston manufacturer to verify this. While doing mine I decided to check the manufacturers catalogue and found one was stock height the other a rebuilder height. What I woulddo is have the block decked to match the pistins, it's pretty inexpensive and will ensure you motor stays sealed and reliable. Which brings me to point two. While you can run a 10:1 with premium, I would knock it back to 9-9.5 to provide some safety margin, i.e your out at the lake and fill up at the gas dock and they either don't have 91 or the gas is a little stale. The resulting power difference will be pretty small and probably won't even show up on the speedo.

As for the LT4 hotcam. Those are what I put into mine and they run well. Idle nice and low for the alpha and has some some chop. I have about 25-30 hours on them now and I have pulled the plugs and the manifolds to check for signs of reversion and so far so good. There are several guys on OSO running them, and if you do some googling there are others.

 

[christoner2002]

Would love to find out what the specs for the cam are that is used in the Mercruiser 357 Magnum bravo engine are. Looks like the 275hp alpha version takes the same camshaft that my original 350 has.
The cam I have in the original engine is the 431-811658.
The cam I would like to get the specs on are the 866022t, which is the cam used in the 350mpi. The 357 MAG Bravo reman uses the cam 866022t01. Anyone know what specs are on the 866022t cam?

 

[Scott Danforth]

crane 109811 is really close to the Mercruiser cam

 

[Tail_Gunner]

Would love to find out what the specs for the cam are that is used in the Mercruiser 357 Magnum bravo engine are. Looks like the 275hp alpha version takes the same camshaft that my original 350 has.
The cam I have in the original engine is the 431-811658.
The cam I would like to get the specs on are the 866022t, which is the cam used in the 350mpi. The 357 MAG Bravo reman uses the cam 866022t01. Anyone know what specs are on the 866022t cam?

The xm 270 @112 lsa will work just fine it is not a hot cam by any mean's and has only 6 degree's of overlap @ .050 you will need ls6 spring's and comp cam's 050 retainers... that is a move that eliminates the need for head work and improves the valve train at the same time. Below is well documented build

http://www.pacificp.com/forum/viewto...er=asc&start=0 there

 

[christoner2002]

Thanks for all the advice guys. I did call Crane Cams today as well, and their tech guys seem really good. He wanted to know weight of boat, gear ratio of the drive, prop pitch I currently have, and what rpm I run now. Along with a whole bunch of info on the engine I am building. Originally I asked about this cam, 109821
http://www.cranecams.com/product/car...detail&p=24207
He said it is too much cam for stock manifolds and wet exhaust.

He recommended a different cam, 109851
http://www.cranecams.com/product/car...detail&p=24210

He said the compression I will be running, which is right about 9.5 will be at the top of the spectrum for this cam, but he thinks it will a great choice. It also has a small base circle, which works very well for Stroker combinations. He also told me about a custom grind cam, that they have that has mostly all the same specs, and multiple times he made mention of a large company using this custom grind for many small blocks. Makes me wonder if he is not referring to a large marine company that is very quiet about their cam specs. I have the number written down at work, basically it is the same as the 109851, but with .497intake/.497exhaust. He said since it is made so often, there is no extra cost. They are very proud of their cams, being anywhere from $425-$500 (cam only)depending on where you look. Still have a little time to decide before I put it together. We will see.

 

[alldodge]

If you are going to go custom cam then I strongly suggest calling Bob Madera at Marine Kinetics. He is the best in the business and can walk you thru everything. Real nice guy and at the top of the field. After talking to Bob if you choose Crane go for it