mrhorsepower1

I'll bet you a million dollars your completely wrong. For one you need to bench set the carbs before you just fire the engine . As soon as your of the idle circuit you are into the intermediate circuit and the primary main jet.

TylerBurich

so are you saying that the marina could have ruined my new cam by running it at 2500 to 3000 for twenty minutes on the hose? doesn't make much difference to me the boat is under warranty but we don't have that long of a boating season in illinois. i don't exactly have time to do another full rebuild, already on #2 for the season!

jeff1000man

Flat tappet cams historically need Zinc in them to ensure a proper cushion.

Both of you guys could be correct about the rpm range. It depends on the lift of the cam. It also depends on the spring pressure. If you have a heavy spring pressure, you need to run the outer springs only for the first 20-30 minutes to keep the load off the lifters and ensure they spin properly.

I have always heard and practiced the following guidelines for flat tappet break in.

Outer springs only for heads with greater than 150lbs seat pressure.

Use oil with Zinc, if possible. Valvoline racing ( red box- Silver bottle) 50w works good. Rotella is also reportedly relaiable. You can use GM liquid assembly lube also

Remember to pre lube the engine by pulling the distributor before initial fire.

Initial firing of the engine is the key. I always set the carb to idle around 2000 as soon as the engine runs. The first couple sputters and spits or if it keeps dying will flatten a flat tappet cam. I set the timing while it is idled up and then leave it alone for 20-30 minutes.

I am by no means an expert, but I have ruined several cams by not following these roceedures, and have been succesful when I have. THis may not be the law, but most engine builders I talk to agree since they are where this info came from.

On your experience. I had the EXACT same thing happen to a motor I built at the beginning of the season.

Engine started popping. I though I lost a plug or a wire fell off. I didn't stop. I kept tinkering with it and eventually broke a valve. The #1 intake lobe flattened on cam and pushrod wedged under bottom of rocker. THis held valve open until the picton broke the valve off. Had to rebuild entire engine.

My cam problem stemmed all the way back to initial firing of engine on dyno. We had a carb problem that would not keep engine runniing initially and it started and died several times. We thought that engine was broken in properly on dyno, but did not run it for a long time. All goes back to initial firing of engine and running at proper rpm's with proper oil, with proper spring pressure for an adequate amount of time break in the cam the right way.

I do agree with Mr horsepower on the idle cicuit and fuel issue, but I don't understand why allowing an engine to run a little fat during break in is a bad thing. I usually change toh plugs after the hour of running anyway. I can see why 2000 initial rpms would be dangerous if something was not put together correctly, but you have to have a little faith in what you are doing.

This has turned into an interesting thread. Can you elaborate more on the theory o f engine break in.

[email protected]

Gotta agree w/ Jeffman on this one 120% Outer springs only on break in 1/2 45 mins or keep sucking tail pipes to go boating.

jmherbert

I'd take that bet, all you have to do is crank your idle speed adjustment up until your spinning those RPM's, then look down the carb throat and see if any fuel is coming out the boosters. If not, you are still on the idle circuit. Then again, maybe I am overgeneralizing from one experience I had. This only applies to a no-load, in neutral situation here, not cruising down the water. It takes very little energy to spin a motor with no load.

I follow what jeff100man and the cam manufacturers recommend. I also use and recommend a bottle of GM EOS in the oil for the break-in.

I've never had a single problem, but I also haven't built dozens of motors.

jackhammer

Be careful with that bet... there is no context in this sentence.

"As soon as your of the idle circuit you are into the intermediate circuit and the primary main jet."

It is essentially correct under any circumstance. But without a load I believe you are correct... spinning 2000 doesn't take much.

MESABALANCING

There is two great ways to follow the break in and know you wont have a failure the first and the one I use on the dyno is before you start the engine make sure you are as close to timing as possible and that you have fuel in the carb because you don't want to turn the engine over any more than neccesary to get it started and get the oil splashed from the bottom right away mark all the pushrods at the top with a white marker and when the engine gets started open the valve cover slightly and make sure all the pushrods are truning all the way around if they are all is good if they are not you're going to have trouble this is the only way to be 99 % sure if the lifter doesn't turn it will eat the lobe up. Best of luck to you hope this helps you Sincerely Laz Mesa

jeff1000man

That is a good tip.

johnny b good

I hear using G.M. E.O.S. ( engine oil supplement) is a good idea too during break-in.

jeff1000man

GM liquid assembly lube. EOS one bottle per oil change. It's expensive, but it is good stuff.