Cam break in procedure
 

Yesterday i had the boat out with hopes of breaking in the new motor. Boat is a 88 formula 311 with merc 420hp 454's. Boat ran great for first hour of use, did a lot of cruising sweeping from 3k rpm all the way to 3800. On the way back to the ramp the motor started popping through the carb so i shut it down immediately to prevent any more damage. After reading some threads on here i am almost sure it is a valve train problem more specifically a cam issue. My question is.....what IS the proper procedure to break in a new cam. My new motor was not dynoed before installation, i believe the motor only had just over 1 hour of run time before popping occured. Did i do something wrong???? I hope the marina can fix this before labor day, boating season in illinois just ain't long enough!:angry-smiley-055:

You need to run a flat tappet cam at 2500-3000 rpms for the 20-30 mins on a new install. Run it in nuetral at the dock. Do not let it run at idle!!!!

break in
 

the marina ran it for about 15 min. at that rpm, i was there when they did it. who knows, maybe it's another component in the valve train that failed....we'll see. she goes in tomorrow for them to look at.

I chased a popping carb all the way from valve train through carb... finally replaced distributor and all ignition components for the fix.

Cut open the oil filter and look for magnetic flakes of death. In addition to what Griff said, it is important to run the right oil with flat tappet cams. Rottella T works well and add in STP oil treatment for extra protection. Heavy metals are not in the non diesel oils anymore, they are what helped make flat tappet cams live. Roller cams are fine with todays oil.

backfire through carb
 

Heard back from the marina today. Intake valve on cylinder #1 stuck open, that is causing the backfire through the carb. The head comes off tomorrow for further inspection....in the meantime...any guesses anybody?

Not exactly sure what may be the cause, but it sounds like perhaps the valve guide clearances may be too tight which is usually typical of an engine builder who is used to building car type engines vs marine engines. Marine engines usually need to have the valve guides of the heads honed for greater clearance vs a car type engine.

The proper camshaft break in procedure would be to NOT run the engine at 2000 RPM in neutral. This is the ABSOLUTE WORST thing you can ever do!!! When you are off the idle circuit of the carb, you are into the main jet. You are dumping tons of fuel into the engine which is not being effeciently burned because the engine is not under load. Let the engine warm up slow and get water temp, Take the boat out and run it normal. Ease on plane, tuck the drive in and build oil temp slow. After you have oil temp you can loosen up the trim on the drive a bit and vary the engine RPM. RPM range for the first half hour should be between 2500- 3000.

Thats OK for rollers but not for flat tappet, not per cam manufacturers!

http://www.cranecams.com/pdf/548e.pdf

I'd bet 99% of engines in neutral @ 2500-3000 RPM are still in the idle circuit. You barely need to crack the butterflies when there is no load on the engine. I've had brand new carbs idle that high out of the box, before the idle speed screw was adjusted.

BS....Camshaft manufacturers recommend the 2000 RPM to protect themselves. There is plenty of oil flying of the rotating assembly at idle to lubricate the camshaft. Believe me.....50 years of experience in the biz here bro. I am just trying to shine some light on a topic which is very misinterperted. I have never lost a camshaft yet doing things our way but, I have seen others kill engines do things the cam company way.

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.

cam break in
 

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!

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.

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.

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.

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.

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

That is a good tip.

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

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

lifter failure
 

it turns out the lifter on the #1 intake valve broke in half.....anyone ever hear of this before??? what causes it???

454 I had a lifter break on me last year the bottom of the lifter had a small groove like the old GM lifters did and I started the engine and heard a snap noise pulled the valve cover off and found a loose rocker pulled the intake and the piece under the groove had broke off. Comp told me to eat it . Any lifter you use you can check on a surface plate for crown and rockwell. If you need these numbers I've got them . Best of luck Laz Mesa

Check your spring pressure?? Also you might have to much lift on the cam to run a flat tappet type lifter set up. Glad you didn't hand greande it.

Good luck in future. Ruben's racing came in CA has really good lifter sets for really cheap. I don't know where they come from, but I tried a set a while back and they are working well. I think I paid $50 a set for them. It was worth the experiment.

lifter
 

Don't know the specific cam specs, cam by crane..lifters also. Motor is built back to stock 420hp specs. bottow 1/3 is where lifter actually broke, sounds similar to your experience laz mesa.

I would like to see that, can you post a Pic?

If it is stock specs then there is no porblem with springs or cam. Only thing I can dream of is maybe rockers were a little to tight and putting excessive pressure on lifters. On hydraulic, I always use 1/4 turn from 0.

Good luck next time. Glad you have a warranty.

lifter issue
 

i would like to see a pic too, i'll see if i can't get one from the engine builder....he'll give me the old pieces if i want them.....once he finds them!

Make sure that he does. They are in there somewhere. They usually hide in the coolers or lines, and when you think your back in the clear, WHAMMO, they come back to haunt you and blow up your next engine for you. :angry-smiley-044:

About a year ago, one of the car mags had an article about GM's special facility where they were hand assembling the Corvette Z06 and Cadillac hi-per engines. The article stated that they coated all the critical moving parts with "GM Camshaft and Lifter Prelube" (p/n 12345501) before firing the motors. They shipped them with Mobil 1 Synthetic in the crankcase. A 4 oz. bottle of the prelube is about $8 and my local GM dealers don't always have it in stock. They tell me that they often use the old standby-EOS. About the same time, I believe it was Hot Rod Magazine had an excellent article on cam failures. As I recall,for flat tappet cams especially, they recommended EOS in the crankcase until the first oil change. After that,they recommended a bottle of the Prelube to offset the concerns about ZDDP. Anyone interestested might do a Google search as my old memory ain't too good. I've been adding two bottles of the prelube to each of my 800SC's for two seasons now. 170 hours since a Sterling rebuild and the valve covers have never been off. Just tryin' to help....