I've had it happen once before. Twenty minutes of breakin and the whole day goes south. I have the voodoo 60204 with the lunati lifters. Harold, can you pm me or give me lunati tec line or something. Summit will credit my account for a new cam and lifter set but I dosn't want to go through this again.

how does that happen?

When something like this happens, it is generally that the cam was too far forward.
Are all lobes down, or are there some left? If so, look at the front of the lobes.
If there is still phosphate on them, the cam was too far forward in the engine. If there are no lobes high enough, look at the distributor gear on the cam. If there is no wear on the front 3rd of the gear, same thing, the cam was too far forward.
We cannot tell exactly until we see the cam, but there is nothing in the design to cause trouble. I stayed .019" away from the edge, and almost all of my UltraDyne hydraulics were .017" from the edge. The VooDoos also have good nose radii.
Please send it back so we can examine it. You are the 2nd cam failure I have heard of, and we have sold 600-700 of them.
The cam should have no more than .010" end-play, and I prefer .006" to .000".
Sorry about your trouble......

UDHarold

here are some pics, I was curious why the lifters are bottomed out with no pressure on them? In these pics the cam is pushed to the back. The lifters are hanging off the front of the cam. Why are some square over the lobe while others are way off center?
I'm seriously thinking roller but was wondering if I can run a roller with my heads that were set up for this paticular voodoo? Stacey

Stacey,
This is all speculation, but as bad as that looks, I would have to take a serious look at the spring setup on the heads. If you used the correct Lunati spring, it really is not all that much pressure. You need to check the following things for sure:
1. Verify the spring installed hgt on your heads.
2. Check the spring pressures with the retainers you are using. (springs could have been boxed wrong)
3. Make sure that the retainer is not hitting the valve seal or the top of the guide at full lift. (I like to have at least .050-.060 clearance)

These are the three most common mistakes I have seen on heads.
4.

Thanks Bill, I just shot out to garage and looked close at an intake at full lift. It looks iffy as far as hitting. Another thing I notice is the machine shop used dual springs. What it looks like is an outer then dampner then a thin small spring. Now I know he used comp springs and retainers and locks but said he set them up for the cam. The color on the outer spring is yellow and the inner spring is blue. Can you tell from spring color if there is too much pressure? Now I'm starting to question his work. One question I have is WHY the lobes are so far off center of the lifters. Is this normal? AND, Why are most of the cups bottomed out inside the lifter and not springing back up?
BTW, I had 1/2 turn on preload. (and I know how to set valve lash).
I think I'm going to pull it with the intake off and show the machinist the engine and then let him explain to me how this could have happened.
One other thing. The machinist told me not to worry about the valve lift if it is under .600 as far as clearence problems. He CC'ed the heads and decked the block so I had 10-1 comp. I have closed chamber 215 heads and a .100 dome on the piston.
thanks, Stacey

Stacey,
The lifters are probably bottomed out either because they are worn all the way through the bottom, or they leaked down due to spring pressure. The fact that it is a double spring does not mean it is too much pressure, just depends on the particular spring used. You cannot tell anything by the spring color. Do you have the spring part number ? Should have been on your invoice. The lifters are supposed to be off center, thats what makes them rotate so they do not wear.
You might want to get a different shop to check the heads just to get an unbiased opinion.
By the way, I would see if you can send the cam back directly to Harold. I am betting that most of the returns sent back to the mail order houses just get trashed and nobody really gets to see them to figure out what happened to them.

Bill got the #'s comp springs 924, comp retainers 741, keepers 612. Any help?

Stacey, that 924 spring is rated at 115 on the seat at 1.900. Is your installed height that tall? 115 is not a pressure that's going to wipe all the lobes off a cam. Is there a shop near you that can measure the pressure at your installed height with your retainers?

There's another CC spring, 60924 that's 175 on the seat, that'll kill a normal hydraulic cam. Need to make sure you've got the right springs, the right pressure at the right installed height. Also need to check all the usual suspects on binding, retainer hitting the valve guide, etc.

1.900 is a fair amount for most SBC heads. I would bet it is less than that. You also have to look at the spring rate to know what open pressure is.

This is a big block right? If you did not cut the guides, you only have clearnace built in for about .540 - .550 lift with no extra margin. Lift for this cam is .553/.574 (??). Gauranteed retainer/guide interference. The 924's will give you 115 at seat and 290 - 300 open at that lift. With retainer/guide clearance out of the way, I would look into lifter bore clearance, binding at the rocker/stud or rocker/retainer interference also. Most flat tappet hyd cam failures I have ever witnessed came down to mechanical intereference problems.

>>......question I have is WHY the lobes are so far off center of the lifters.....

This is normal. The offset, plus taper on the cam lobe, plus the crown on the bottom of the lifter are what causes it to spin.

I'm sure your mechanic checked it by hand before it was assembled for lifter spin right? No pushrods, no grease (oil only), rotate the cam by hand, make sure all lifters spin.

" I'm sure your mechanic..." :rolleyes: What's this a Corvette board? ;) Stacey, sorry to hear about your troubles.

Gene, while you were away (few weeks ago wasn't it?), we changed the forum. Sorry. PS - If you want to get back in with the crowd, there is still a limited supply of those "Members Only" jackets inscribed with a Chevy SS logo available for 49.95. Also have a special starting May 1st on some kool sunglasses for 15.95. Send me a check and I will se to it you get reinstated.


PS - didn't mean to get off tangent - but he left himself wide open

Back to the topic. I would go through the entire valvetrain for binding and also check the oil galleries for obstructions.

In Chevy's "Power Manuals" (at least the early ones) , all dual spring combos should be fired with the inner spring removed, to lessen the chance of what happened to you. If you get in a spot where the engine doesn't kick right off for any reason, no spark, no fuel, anything at all, and you keep crankin' it while looking for the reason, you will lose the cam, period. Performance BBC's need 130#/140# and 360#/380# open, assuming a .600 lift, hence no inner springs during break-in. Many (many) years ago, when we first started, we often wondered how Chevrolet was able to deliver high-end "crate motors" with powerful (dual) spring pressures and have the cams broken in when they were delivered without ever "firing" and not a trace of fuel ever touched the engine. We could start these engines, and we're talking hundreds, and let 'em
idle (no 1500 RPM/20 minutes rule here). We were amazed! After we got
inside General Motors, we learned they "ran" the engine using sequentially
fired air pressure in the 8 spark plug holes. It was pre-oiled, brought up to
speed for 15 minutes (cam break-in), oil pressure checked, and crated after
draining the oil. Amazing! Thank's Gary in N.Y.
PS This is more prevalent on the BB's due in fact to the low cam rise
and the high valve lift, or in simpler terms, the 1.7:1 rocker ratio.

The retainers didn't bind, nor the springs. Rockers are comp roller tip and have plenty of travel. Machinist says he had 120 seat pressure, a little tight but no prob. as he can see. I didn't know he put dual springs in or I would have broken her in with just the outers. The weird thing is how the plungers on most of the the lifters have collapsed. There was plenty of oil up top too.

I doubt those particular dual springs casued the problem. The flat tappet I was runng was a 335 rate single spring with 120 on the seat and right around 300 overthe nose (your 924's are only 317 rate). Nothing against Lunati or any of the cam manufacturers, but there is no guarantee that the heat treat on the cam was correct either. Best bet on a flat tappet is to have it made on a Premium core (I think Isky calls it a P50??). Usually about a 50.0 upgrade. Just double check that the lifters spin freely also.

the spring in a lifter that pushes the pushrod seat up to the pushrod or retainer is in the bottom of the lifter. I'm guessing that heat generated scraping the lobes off killed the springs. Most springs are not very heat resistant, another good example is the relief spring in the oil pump. Braze the pickup in without removing the spring and it's "Hello no oil pressure." Pull one apart, I think you'll find the spring as flat as the proverbial pancake.