installed this cam a few years back. Broke it in, etc.. used ZDDP oil changes twice a year. Used adjustable push rods. Had a lifter noise and pulled it apart . Bam. So what caused it. Set lash to zero on pushrod and went one more turn for preload
What spring pressure when you broke it in? Did you use non detergent ZDDP for break in? Necessary to build the ZDDP bond to the cam lobe surface, and detergent oil will reduce that to significant degree. Imperative to lower spring pressure and use non detergent oil and have ZDDP during break in. No dry starts, plenty of oil prime. No excessive cranking, and that assembly lube was used as well. Immediate acceleration and keeping it at or above 2500 RPM and vary RPM up to 3K periodically to ensure splash to cam. (correct timing is a must to prevent overheat from retarded timing.) And keeping car cool.
the last photo is about normal for a pointed nailhead lobe. they do round off a little. what are your cam specs and cam brand.
I use vr1 racing oil. Went through the whole breakin 20mins over 2500rpm . Cam was swapped used assemble lube . Pretty sure I set timing around 8-11.all in around 30-32 from memory. To much preload on the lifter? Went to zero and added one turn on the adjustable pushrod
The VR1 ZDDP content is really low for flat tappet setups. It was higher ten years ago. As for diagnosing, there are many reasons you flatten one lobe. -The break in as already addressed. -One soft lobe from production (they are heat hardened cast iron) -Valve could be sticking, from bad gas and varnish in valve guide. -Lifter failure or sticking in bore/bore clearance to tight. -Hard metal picked up and deposited/embedded in the lifter (but usually will show more wear over more of the lobe surface). You mentioned the lifter noise, when you pulled it apart, and inspected the lifter, did you find anything significant with it?
You need to check the valve guide-to-retainer clearance. If it's in adequate, the valve guide needs to be machined down. Clearance needs to be checked with oil seals, if they are used. Coil bind is unlikely to be a concern at those valve lifts. In regards to breaking in with only outer valve springs, I'm gonna say it's less critical with a Nailhead since we are not putting very stiff valve springs in. With the small valves and low rpm, stiff springs aren't needed. Stock springs are rated at 75# closed, 177# open. Many 'performance' engines are running 130#closed, 300+# open. TA offers various levels of valve springs ranging from stock 75/195#, to mild 90/230#, to Super 105/275#.... still less that other engines. I agree the 1 turn preload is a little on the high side. If your adjustable pushrods have 24 tpi, one turn is .042" which should be okay, but it depends on exactly which lifters you are using, and their specific recommendations. I've seen general recommendations in the 0.020 to 0.040" range. I don't know what is causing that lobe wear, I'd suggest checking all your clearances first.
When we were using a flat tappet cam at one point in time we had 140lbs. closed & just shy of 400lbs. over the nose with an open .660" lift. Never had that kind of wear pattern with ANY of the cams we used. Tom T.
Spoke with comp yesterday, said he said the same thing about the vr1 oil being low on the zinc. I always used addition ZDDP but didn’t use it the last oil change. I had the guides cut down and looks like a positive seal put on them. Intake only,none on the exhaust. Looks like the top of the valve seal is holding oil and allowing it to come down the guide onto the back of the valve. I looked in the intake port and really looks like the guides dropped .500 . I had the guides replaced when I replaced the camshaft but something doesn’t look right. I even noticed dripping down coming out the exhaust port. Will be pulling the heads off tomorrow night. Wanted to today but Between the heat and EEE I haven’t had the motivation. Think this is part of the reason. at the back of this valve how it is clean and soaked with oil. The other one looks normal with carbon. These have over 1500 miles on them.
Do you have lifters that are compatible with the cam? OEM cams had no taper. OEM blocks have no lifter offset. OEM lifters are about as flat as they can be made. Virtually ever other V-8 OHV engine uses tapered cam lobes, lifters offset from the lobe, and a "flat-tappet" that in fact is crowned. All three of these traits promotes lifter spinning when the engine runs. Buick Nailheads were NOT DESIGNED TO (intentionally) SPIN THE LIFTERS according to the SAE design paper. Aftermarket cams may be tapered--or not. Aftermarket lifters may be "flat" or "crowned". Mixing parts is not recommended.
