5.7 vortec cam upgrade or stay stock?
07-01-2025 | 06:32 PM
#1
Thread Starter
Registered
Joined: Jul 2025
Posts: 1
Likes: 0
From: Napoleon, OH
5.7 vortec cam upgrade or stay stock?
Hello, I’m sure this has been covered already, but it’s hard to sift through 50,000 posts and find what I’m looking for.
I recently picked up a new vortec short block to drop in my boat. On my original non vortec engine I blew a head gasket, overheated, burnt the valves on number 7, and got water in my oil. This happened wide open 4800rpm and I shut her down then got a tow.
I decided to go with a set of reconditioned automotive vortec heads from a 98 vehicle and Edelbrock air gap dual plane intake for the alleged performance gains from them. Flushed the engine and gave it 3 oil changes by just running the oil pump with a drill then gave it its final oil change using quicksilver 25-50 and a 1 quart filter. Took her out on the water babied her for about 30 minutes then ran flat out and trimmed up holding a steady 4820 rpm for about 10 minutes. Brought her back to about 3k for cruising for another 15 minutes then ran her wide open for about 5 minutes and back to the dock. When I backed off and brought her to an idle all of a sudden I heard a rod knock….. so time for a short block, my heads are good as they only have about an hour on them and they didn’t get hotter than 150°.
Anyway, the short block I’m getting is a 4 bolt main 880 casting number from the automotive world. It’s has been gone through and has a new crank, new 604 roller cam, 604 GM forged rods, summit hyper tech pistons, grant rings, and high volume oil pump, 1.5 rockers, stock springs, stock valves. Stock manifolds, stock risers, through prop exhaust, alpha 1 gen 2, 19 pitch stainless prop. Unsure of valve to piston clearance at this time, I’ll cross that road later.
I do mostly just cruise 2800-3500 with this boat and pull a tube or skier, but I do go wide open for miles at a time down the river. Wide open she runs 52mph.
my question is about the cam as well as rocker choice. Should I just stick with stock mercruiser cam or go for something a little more aggressive to achieve a little more top end speed? Get a better cam and change to a 21 pitch prop to keep the wide open rpm around 4800 while maintaining a good low end for pulling skies and wakeboards? If the latter, what would be a good cam for that?
I recently picked up a new vortec short block to drop in my boat. On my original non vortec engine I blew a head gasket, overheated, burnt the valves on number 7, and got water in my oil. This happened wide open 4800rpm and I shut her down then got a tow.
I decided to go with a set of reconditioned automotive vortec heads from a 98 vehicle and Edelbrock air gap dual plane intake for the alleged performance gains from them. Flushed the engine and gave it 3 oil changes by just running the oil pump with a drill then gave it its final oil change using quicksilver 25-50 and a 1 quart filter. Took her out on the water babied her for about 30 minutes then ran flat out and trimmed up holding a steady 4820 rpm for about 10 minutes. Brought her back to about 3k for cruising for another 15 minutes then ran her wide open for about 5 minutes and back to the dock. When I backed off and brought her to an idle all of a sudden I heard a rod knock….. so time for a short block, my heads are good as they only have about an hour on them and they didn’t get hotter than 150°.
Anyway, the short block I’m getting is a 4 bolt main 880 casting number from the automotive world. It’s has been gone through and has a new crank, new 604 roller cam, 604 GM forged rods, summit hyper tech pistons, grant rings, and high volume oil pump, 1.5 rockers, stock springs, stock valves. Stock manifolds, stock risers, through prop exhaust, alpha 1 gen 2, 19 pitch stainless prop. Unsure of valve to piston clearance at this time, I’ll cross that road later.
I do mostly just cruise 2800-3500 with this boat and pull a tube or skier, but I do go wide open for miles at a time down the river. Wide open she runs 52mph.
my question is about the cam as well as rocker choice. Should I just stick with stock mercruiser cam or go for something a little more aggressive to achieve a little more top end speed? Get a better cam and change to a 21 pitch prop to keep the wide open rpm around 4800 while maintaining a good low end for pulling skies and wakeboards? If the latter, what would be a good cam for that?
