engine break-in question

**Romper Stomper** · 05-01-2012, 02:11 PM

Well, I finally got most of the glass work and wood work done on my cvx-20 and mildly built the engine. Stock bore, 9:1 comp, mild cam, basic port on heads, alum. intake, 750 carb. My question is about the cam break-in. Can I do it on the trailer or should I do it on a stand before I even install it? Are there any straight up no-nos when it comes to running a jet dry? I am a car guy and this is my first boat, so I would appreciate any info from you folks that have been doing this for a while. Thanks in advance.

**ATM** · 05-01-2012, 02:28 PM

Originally Posted by Romper Stomper

Well, I finally got most of the glass work and wood work done on my cvx-20 and mildly built the engine. Stock bore, 9:1 comp, mild cam, basic port on heads, alum. intake, 750 carb. My question is about the cam break-in. Can I do it on the trailer or should I do it on a stand before I even install it? Are there any straight up no-nos when it comes to running a jet dry? I am a car guy and this is my first boat, so I would appreciate any info from you folks that have been doing this for a while. Thanks in advance.

I would do it on the stand. You have to be very careful doing it on the trailer because the oil can flow to the back of the pan and possibly be whipped by the crank causing aerated oil. Aerated oil does not lube cam lobes very well and you could end up with a flattened cam lobe (ask me how I know).
Also my experience tells me not to use anything over 30wt for cam break-in, also get the engine really close so when it starts DO NOT LET IT IDLE. Better yet call the cam MFG and ask for their recommendations.
Ron

**Michael Thomas** · 05-01-2012, 02:29 PM

If you could start it on a stand it would be best....it is easier to fix any issues you might have on the stand.. if you run it in the boat, leave the pump disconected

**Futs** · 05-01-2012, 02:36 PM

What kind of cam? roller or flat tappet?

**jamesblown97** · 05-01-2012, 03:23 PM

if the motors in the boat on the trailer level the motor out with the trailer and leave the pump disconnected DO NOT RUN THE PUMP DRY. flat tappet cams and roller cams have different break in methods which kind do you have? and make sure timing is pretty close before you fire it up and try to make sure evreything is lined out motor wise before you fire it wiring water lines timing fuel ignition etc.. let us know what style cam you have and we can go from there. Pig

**mpkardell** · 05-01-2012, 03:34 PM

Originally Posted by Romper Stomper

Well, I finally got most of the glass work and wood work done on my cvx-20 and mildly built the engine. Stock bore, 9:1 comp, mild cam, basic port on heads, alum. intake, 750 carb. My question is about the cam break-in. Can I do it on the trailer or should I do it on a stand before I even install it? Are there any straight up no-nos when it comes to running a jet dry? I am a car guy and this is my first boat, so I would appreciate any info from you folks that have been doing this for a while. Thanks in advance.

Build yourself a hillbilly break-in stand.

Make sure you prime the pump thoroughly with a drill before dropping the distributor in. My BBC took forever to flow oil out of the left side pushrods when I primed it. Use a high-zinc break-in additive. Make sure the carb has fuel (use a cheap electric pump like I did) before you try and fire it. Ensure that the float isn't hung up and dumping fuel straight into the manifold. Triple-check the distributor phasing and initial timing so the mother (hopefully) fires right up. Don't give it any water until it fires. Bring up to 2000-2500 rpm for 20 minutes. Check timing after it's running to ensure that it's not retarded too far so you don't burn up your exhaust valves. Shut it down abruptly (and turn the water off) if you have any issues that you need to fix, then start it up and run at 2000-2500 rpm for the rest of the break-in period. Keep a fire extinguisher nearby. Good luck!

Oh, and post pics of your CVX-20. I always wanted one of those.....

**Romper Stomper** · 05-01-2012, 05:57 PM

Thanks for the feedback. It is a .503/.503 lift, 276/286 adv duration flat tappet cam. I have quite a bit of experience doing cam break-ins. Hell, I did one this morning on a '65 GTO with a. 060 over 400, thats what made me think about my boat. I've done probably 15 so far with no flat lobes yet (knock on wood!). I've found that Joe Gibbs BR break in oil does the job pretty well. Its a 15-50 wt. with a bunch of zinc in it. I've used it on the last five break-ins including one I had to stop in the middle because of a fuel leak and I've had no cam issues. Also, I've found that running the timing up to about 50° helps keep the exhaust cooler so it doesn't cook the ceramic off the headers. I think a am gonna make an african engine stand. If anything, just so I can see it real good when it explodes, lol. Btw, I'll post some pics when I get it cleaned up. Right now it looks like I had an epic battle with a fiberglass monster in it.