Piston Rings for 351w

[FirstEliminator]

The 351w is back together and in the car. Getting ready to break-in the cam today. I've heard multiple people say that they paint a white stripe on the push rods to make sure all the lifters are turning. When do you view the turning of the push rods? Do you leave the valve covers off during break-in? I don't see any other time to view the push rods turning before it's too late. But, it seems like it'd be quite messy.  Or, would you see if they turn while the engine is at cranking speed? Seems the excessive cranking which would wipe off the lube.

    I've been pondering why this previous cam had a lobe failure. There are a couple things that I think contributed. The cam is a Lunati Voodoo with specs of 250/256 advertised with a 207/213 @.050. That seems like a really fast ramp for a flat tappet. I think this fast ramp is a bit more prone to having a failure or overall less longevity than a cam that had similar specs @.050 but with another 20 degrees advertised. But, those slow ramps look antiquated and less efficient. I like cake and like to eat it which is why I can't resist buying a fast ramp.

    The other thought is the springs that I had used to break-in the first cam with had about half the pressure that the cam card called for. After removing all those springs I noticed there were a couple that were shorter and probably weaker. I did not measure the pressure of those two and can only guess the pressure may have been around 40ish. Also, I do not know if one of those shorties were on the failed lobe/lifter. All 16 springs quickly went in the scrap barrel. Is the idea correct that for the cam to spin the lifter there has to be a minimal amount of friction present? Does the possibility exist that the spring was too weak to maintain firm enough contact between the lifter and lobe as to where it would not promote lifter spin?

    The springs are now just about what the cam recommends. Lunati calls for 115 @ 1.75.  The intakes set up at 110 lbs and the exhaust at 105 lbs. The tech at Lunati mentioned 90-100 would be sufficient for this cruising application. The cam and lifters are covered with a lot of Isky Rev Lube. The engine oil is 30wt non-detergent with a bottle of Lucas Break-in additive.

    Perhaps 3rd time is the charm? I had the original build back in 2010. Then the build where I replaced the block and the new cam lost a lobe. Now is the 3rd build and hopefully the last.


   thanks,
       Mark

     

[FirstEliminator]

    Tonight, I broke-in the new cam. Everything went pretty well. Here and there I'd hear a little ticking, but nothing like before when the lobe and lifter failed. Perhaps the ticking could have been fluctuations in the load of rpm, oil pressure and temperature affect on the lifters?  About 10 minutes into the break-in I shut down the engine. Removed the oil filter and cut it open. There was some metallic in the filter element. I am not sure how much is what would be considered "normal" on break-in with a flat tappet. I replaced the filter and topped off the oil for the remainder of the break-in. After the break-in, adjusting the idle mix and initial timing I had shut the engine off again. We put the hood on and made sure everything else was in check for a road test. Before going on the road test I had again changed the filter. I have yet to cut open the 2nd filter. The oil is sparkling clean and still has the break-in additive. I will put a few miles on the engine before doing an oil change and putting on another filter. So far, so good. Still curious about some of the questions I'd asked in the previous post if anyone has some comments. Having this cam failure on break-in is bothersome and I'd love to know where I went wrong.

    This 112 lobe separation came seems to have a louder exhaust than the 108. Why would that be? A later exhaust closing point?

    The car drives good and the shake at idle is gone. The shake is why I pulled the engine out in the first place.

   thanks,
     Mark

[machoneman]

The 351w is back together and in the car. Getting ready to break-in the cam today. I've heard multiple people say that they paint a white stripe on the push rods to make sure all the lifters are turning. When do you view the turning of the push rods? Do you leave the valve covers off during break-in? I don't see any other time to view the push rods turning before it's too late. But, it seems like it'd be quite messy.  Or, would you see if they turn while the engine is at cranking speed? Seems the excessive cranking which would wipe off the lube.

-The covers need to be on due to the large amount of oil thrown off at 2,000 and more rpms. So yes, it's too late if later one cuts up an old steel cover horizontally (i.e. top is cut off) to see the spinning p-rods or if all 16 moved at all.   

    I've been pondering why this previous cam had a lobe failure. There are a couple things that I think contributed. The cam is a Lunati Voodoo with specs of 250/256 advertised with a 207/213 @.050. That seems like a really fast ramp for a flat tappet. I think this fast ramp is a bit more prone to having a failure or overall less longevity than a cam that had similar specs @.050 but with another 20 degrees advertised. But, those slow ramps look antiquated and less efficient. I like cake and like to eat it which is why I can't resist buying a fast ramp.

-There may be some disagreement from others but.....I don't believe for one second a slow ramp is any better at break-in time versus a fast ramp. It's all to do with ensuring the lifters rotate, the springs are sufficiently weak, cam is well lubed, the engine starts immediately, etc. etc. Even then, if the lifters aren't correctly heat-treated (the still recent issues of American made Johnson-type lifters being supplanted by cheap Asian parts) it's all for naught! 

    The other thought is the springs that I had used to break-in the first cam with had about half the pressure that the cam card called for. After removing all those springs I noticed there were a couple that were shorter and probably weaker. I did not measure the pressure of those two and can only guess the pressure may have been around 40ish. Also, I do not know if one of those shorties were on the failed lobe/lifter. All 16 springs quickly went in the scrap barrel. Is the idea correct that for the cam to spin the lifter there has to be a minimal amount of friction present? Does the possibility exist that the spring was too weak to maintain firm enough contact between the lifter and lobe as to where it would not promote lifter spin?

-40 is pretty low but if you didn't drive it and the rpms were under say 3,000,  a too low spring pressure should not have impacted the break in. A bouncing lifter you would have heard unless the headers were unplugged! Keep in mind at installation it's key to hand 'work' each lifter in each hole to ensure they easily spin in their respective bores. Older, well-used engines often have gunk in the bores that limit lifter rotation with disastrous  results.

   The springs are now just about what the cam recommends. Lunati calls for 115 @ 1.75.  The intakes set up at 110 lbs and the exhaust at 105 lbs. The tech at Lunati mentioned 90-100 would be sufficient for this cruising application. The cam and lifters are covered with a lot of Isky Rev Lube. The engine oil is 30wt non-detergent with a bottle of Lucas Break-in additive.

    Perhaps 3rd time is the charm? I had the original build back in 2010. Then the build where I replaced the block and the new cam lost a lobe. Now is the 3rd build and hopefully the last.

-sounds like this is the same block (3rd time)? I'd be quite careful right afterwards and maybe even consider setting up a dial indicator and magnetic base (beg, borrow, steal?) to check lift at the p-rod end for all 16. Your recent issues are why many have given up on flat tappet cams and switched to a pricey yet reliable hydro roller cam set-up with no lifter spin issues. 

   thanks,
       Mark

   

[FirstEliminator]

  Thanks Bob. The 1st time (2010) was a different block. The engine was pulled to change the cam as it had a 108 lobe separation and I thought it may have been compromising a smooth idle. The block was replaced because of a rough spot in the middle of a cylinder. I didn't due any further checking, but my assumption is a tiny crack or pin hole causing coolant to wash oil off the wall. The rings were worn in that area too. That may have been the cause of the shake at idle I was chasing for a few years.

   Mark