I just got done rebuilding my 390 this last weekend. We got it going Friday night. Saturday I was driving it around. After 50 miles I noticed the engine wasn't running right. I got it back to my mechanic right away. When I got there and lifted the hood the lifter noise was obvious. We tore the intake off and found that all of the lifters were damaged. The worst ones have over 0.25" ground off. My brand new engine needs another overhaul. There are filings everywhere. I put in CompCam's cam, lifters, and valvesprings. The cam has a .498 lift. We broke in the cam per CompCam's instructions. I haven't heard what the cam itself looks like yet, my mechanic is tearing it back down this weekend. Has anyone else had problems like this? Any idea what could have caused it other than a plain bad cam or lifters? The engine fired immediately, had good oil pressure, and never got hot. I'm not hearing anything positive from Comp Cam. They say the most they would pay for would be a new cam and lifters. I'm going to have at least an additional $1500 into it. The machine shop said the lifter galley's may be scarred beyond repair. I may need a new block too.

 

BUMMER!

Sounds like you didn't have any oil around the lifters/cam or your pushrods may be too long. Did the pushrods bend? The lift certainly isn't too much for a stock valvetrain.

Good Luck.

 

Did you torque down the rocker shaft assembly correctly?

#4 to #1
move to other side
#5 to #8

I used five steps:

snug
snugger
25 ft lbs
35 ft lbs
41 ft lbs.

At this point I would question if you have the correct pushrods for the application or if they were inserted the correct way if all the lifters are bad. Did you prelube everything?

 

I had this happen to my first 390 I tried to build. The block I used was from another rebuild where (suprisingly) it seems the cam rounded out. It did it again. I replaced it with a high-mileage 360 block that obviously had NO problems and it's been nice ever since. I should have used the one originally in the truck with > 150K miles

The block that rounded out the cam appeared to have a bad cam-to-lifter angle. I always wondered if it had been overheated and the block warped...

art k.

 

I found out last night that my block is ruined. I used stock pushrods in the engine. I put in new ones and checked against the old ones that they were the same length. None of the lifters were blue or scorched, so I'm pretty sure they had oil. Comp Cams said it just didn't get a good break in for some reason.

I got some good news though. My mechanic found someone to sell me a block for 50 bucks. The machine shop said they would machine it for free and clean out my heads. My mechanic said that he would donate his labor to rebuild it again. I'm still holding out hope that Comp Cams will refund my money for the cam and lifters. At least I'll only have to buy another gasket set, rings, and oil pump. I just pray that the 2nd attempt pans out. If not, my wife will probably want a divorce!

 

Is it possible that someone had blocked the oil gallery for solid lifters. You didn't say but are you using solid or hydraulic lifters? I am glad your mechanic is so willing to help out, I just really would like to know what caused this failure. I'd hope the camshaft company would be interested as well. Why is the block ruined? Metal in the oil will take out all the bearings and may even damage the crank but not the block!
William in Atlanta

 

I would also like to know what "ruined" the block. Why didn't the machinist discover that in the first place? I suspect that's why he is doing the re-work for free...

 

I used hydraulic lifters. The block was ruined because the new lifters I put in destroyed the lifter galleys when they mushroomed. The machine shop tried to hone them but they were too far gone. They were all scratched up. Comp cams should be getting the cam and lifters today to do their inspection. My new overhaul is in process, but I'm very nervous now that this will happen again. My dad has always had such good luck with his FE's. I'm hoping it was a fluke, but I would like to know what exactly happened myself.

 

At the rear of the center oil gallery are two plugs. One on each side. Pull these plugs out and look in these short galleries. Do you see another plug? Can you put a piece of wire in the lifter gallery and see the end of it in the short gallery you just removed the plug from? Mushroomed lifters! Geeze! What valve spring pressures are you running? Please respond this is driving me nuts!
William in Atlanta

 

It may have nothing to do with the original poster, but in my experience I listed above, some cam lobes rounded off and the lifters got beaten so badly that they would not come out the top of the block anymore. It did kill the lifter bores.

When my friend, a machinist and long-time engine rebuilder, looked at the surviving lifters and cam lobes (not all of them failed), he said it looked like the line bore of the cam was not perfectly perpendicular with the lifters. And, from the damage to the lifter being circular, they were still spinning.

The lifters themselves showed no wear or scoring except where the cam beat them to death.

It was a light Wolverine hydraulic cam. Since then, I used the biggest hydrauilic cam they made for the FE at the time. Now, with double springs and .554 lift, the cam is still hanging in there after 10,000 miles of very hard running. (292/292 - 230/230@.050 .554/.554 lift)

However, I do pray for the stock rocker arms every time I start it up - Even with the 10.5:1 compression and such a big cam, it'll spin the 33x12.50r16.5 tires at around 1500RPM. That machinist degreed in (advanced?) the cam for me for low-end torque and boy, does it. Took quite a bit of fiddling with an adjustable vacuum-advance and the Holley 750 vac-sec, but it's not too bad. still needs a bigger accelerator shooter (already at .040)

That same machinist was able to deck the block, mill the heads, redo the heads and come up with the valve train so close to OEM I only had to use two .030 under-length pushrods and one .030 over-lenght. With 428SCJ exhaust valves, OEM-sized intakes and all new seats. That nut also spent three days grinding metal out of the intake/exhaust ports.

art k.

 

I did have the block line bored, I hope that didn't cause it. I could have the machine shop check that out on my old block. These lifters were destroyed beyond belief. More than half of them were ground off a 1/4 inch! A couple other engine builders I talked to said that the cut on the cam must have been off so the lifters didn't swirl properly. I also checked the hardness of the cam. There were a couple lobes left that measured 52 Rc everywhere else was less than 40. I've, been told as long as its over 50 its ok.

I am using 940-16 comp cam valve springs. That is what they recomend for the cam I used.

I used stock pushrods. They showed no wear and were straight after we tore it back down. My mechanic said there was no reason to use anything else on a relatively small cam with only .498 lift. He has a lot of experience, so I trust him on that.

We did run the engine for about 5 minutes with no water to seat the gaskets first. Then we put the water in and broke in the cam. He does that to all his engines and hasn't had any trouble. Is there any way at all that could affect the cam break in?

 

No water for 5 minutes? Sounds like a long time. To seat the gaskets? eh? sounds fishy... or do you mean seat the rings? Well, I could see that, but with no water, the cylinders will heat up in spots, warp and cause more problems. I never heard of no water for 5 minutes. Anyone else?

Check the ends of the pushrods. If the lifters were not turning, you may see a straight wear pattern on the end of the pushrod. When my cam went, my machinist was very suprised to see the lifters with circular damage. The lifters were still turning almost all the way up to the end.

As for the rest of the stuff, I am using stock push rods with a .554/.554 lift and double springs (I forget the spring rate). While I try not to hit the 6000 RPM MSD rev limiter, I have gotten close to it a few times and so far no problems. My machinist said the same thing, the stock pushrods are pretty strong.

Line bored, or line honed? Isn't line boring where they set up the borer based on the main bearing journals? Line honing is when they straighten out the main journals (and MAYBE the cam journals). Or is this just semantics? Did you need oversized OD cam bearings or main bearings?

art k.

 

I have not heard of running an engine without coolant to "seat the gaskets". Back in the day we would re-torque head bolts after the engine had been ran to operating temperature and allowed to cool. Modern fasteners, sealers and gasket materials eliminated this requirement as well. Such a catastrophic failure of the camshaft and lifters after 50 miles is very unusual. I have had lobe failure and I have had lifters fail but never the complete failure the way it has been described. Maybe someone forgot to harden the camshaft? I am stumped! I'll bet the camshaft company will have answers. I hope they are willing to share them!
William in Atlanta