Zep654

  • Karma: +1/-0
Good or Bad cam choice opinions?
« on: January 03, 2020, 03:03:23 PM »
The machine shop picked out some of the parts for me on my build.  I am a newbie so I never considered they might not know the proper cam for a jet boat because of how they run, where they need power, etc...  I proceeded to put the engine together and now it is done.  I am worried about the results.  It may make good numbers, but in the wrong places if you know what I mean.  It should be going on the dyno here in a few weeks, and I hope it will run good obviously and not grenade haha, but when it comes to running on the water, am I going to hurt the motor or severally hurt my performance?  I am not looking to go 100 mph, but I am worried about motor longevity and cruising performance.  Any input would be appreciated.  I feel like I am going to hear a lot of "it will run, but not as good as it could comments."  I'm not looking for all out max horsepower numbers, but obviously its nice to know I have an ok setup, or that it needs instantly changed or bad things will happen.  If I can run it for a summer and then look into the perfect cam later, that would be best to know as well.

Here are the basic specs:

1975 18' Hallet bubbledeck (not light layup)
472 Gen IV BBC
6-71 Mooneyham blower at 6-8 psi
World Products Merlin 119cc iron heads
8:1 compression
Comp 1.7 roller rockers
Comp Cams solid roller cam
Crower roller lifters
2 holley 850's
Timing is locked at 31*
A Agressor impeller Berkeley 12JC pump

Here are the PREVIOUS cam specs before rebuild:



Cam that is in the engine now waiting to be dyno'd:



Am I going backwards from the previously installed flat tappet hydraulic cam?

Any input is really appreciated!! Thanks guys

Here are some pic for kicks:







« Last Edit: January 03, 2020, 03:13:31 PM by Zep654 »
  • Boat #1: 1975 Hallett Bubbledeck
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eliminator18

  • Karma: +2/-0
Re: Good or Bad cam choice opinions?
« Reply #1 on: January 03, 2020, 03:08:40 PM »
You need to know the clearance on your piston to wall, and bearings! Otherwise it looks good


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  • Boat #1: 1976 eliminator 18
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Zep654

  • Karma: +1/-0
Re: Good or Bad cam choice opinions?
« Reply #2 on: January 03, 2020, 03:17:20 PM »
I badly/sadly never checked the piston to wall clearance as I was using the same srp pistons again, however I installed total seal rings (conventional top ring, gapless 2nd ring) gapped at .034.  Crank endplay was .0045.  Cam endplay was .004 with roller button installed.  Rod bearing clearances were .0028.  Main bearing clearances were .0033.  About .200 piston to valve clearance I think (might be way off).  Cometic 5 layer stainless .070 headgaskets.

I know its not a huge cam, but I was wondering if it a good cam to run still even though it isn't a blower cam or on a 112-114 LSA

NOTE:  I installed cam timing straight up and at 106 intake centerline.  Not like the settings I've been reading about lately (makes me worried)
« Last Edit: January 03, 2020, 03:27:06 PM by Zep654 »
  • Boat #1: 1975 Hallett Bubbledeck
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