My buddy rebuilt a 1971 sbc for his 59 Studebaker . He had our local Napa machine shop bore it out , do the heads, install the cam bearings, machine the crank and so on, The machinist lives and breathes small and big block Chevy's and has for over 35 years. A**** other things my buddie order a Summit racing cam. He thought he had ordered a cam and lifters, but turns out he goofed and ordered just the cam. Our engine guy had a new set on the shelf so that's what my buddie used. Now we and most of our buddies have been doing this hot rod thing and building and firing motors for 50 plus years. I have never wiped out a cam or a lifter and neither has my buddy. the cam did not last 10 minutes on break in. We tore it down and several lobes where gone but the real surprise was that three lifters had notches machined into them by the cam lobes. I had never seen that before. Got hold of Summit and they said No Problem and he had a new cam no charge 2 days later. The motor was dis***embled flushed out and inspected. New cam bearings installed again. Machinist got another set of lifters from a different supplier and the motor was re***embled , lubed and primed. Fired right up ,set timing and ran for 20 plus minutes. Startup oil pressure was 70 psi and 40 to 45 at temp. Took it for a test drive yesterday and noticed a lifter rattle . Pulled valve covers and notice #1 exhaust rocker loose. Thought maybe lock nut backed off so he replaced it with another new one. took it for a drive and it was ticking again by the time he got back. Pull intake today and the exhaust lifter is recessed an 1/8 inch into lifter bore and will not budge or rotate. Needless to say he is Pissed ! Only common denominator is the Summit cam. Have any of you or anyone you know had this problem. Motor will come out again when he cools off . Larry
Mic the lifters, Chevy’s are .842 and I would not expect to see more than .0001 to .0003 variation on a quality set. Next try to locate a dial bore so you can check the lifter bores too, maybe the machinist has one, you just want minimal clearance. The good lifters should show a convex surface when you put two face to face. Next I’d mic some lobes that are still good, you are looking for taper from one side to the other. The radius on the face combined with the taper on the lobes is what makes them rotate.
It is not the cam's fault. Describe your break in procedure, we might be able to spot something. -Abone.
I used Summit cams years ago, I only had one go bad. Lots of talk these days about why cams and lifters are going out all the time. I haven't heard any definitive explanation. but I have been using rollers instead and they seem to work fine. Good luck with it...
Do you test fit the lifters before ***embly ? making sure they travel up and down and rotate freely. Then re-install them in the bores they were fitted to. That is what I have found to work. I always run a break hone through the lifter bore and you would be surprised at how much difference will be in the lifters checking them this way. Plus I still use plain old LUBRIPLATE white grease on the cam.
What @TA DAD said, and with all of the discussion here about wiping out camshafts and lifters, i always wonder about cam size, spring pressure, coil bind, things like that. I've never wiped a cam lobe on anything except a VW, and they are sitting in oil. But that was a cheap regrind. I had to beg my machinist to sell me a set of lifters, he was tore all to hell, worried, because they put a set of the same lifters in another engine and wiped 2 lobes. I told him to relax, everything would be fine, and it has been so far. I bought another set for the sbc that's on the stand right now. He's ordered a bunch of the Johnson high lift, he swore off the other brand lol
How much spring pressure? Do the lifters rotate when you turn the engine over? What oil was used for break-in?
Always leave the adjustment loose on new break in. Always use molly lube on the cam and lifters with break in additive can't be too careful Just what I've learned over the years after loosing a couple cams Go roller when ever you can Will worth the added expense
1971 350 4 bolt main block with factory heads. Harden seats,3 angle valve job , Napa replacement springs. Bored 30 over, line bored, hone lifter bores. crank 10 under. Cam was Summits own, what I would call an RV cam. Smooth idle, increase bottom end torque. Jon the machinist at Napa gets the lifters from a performance supply outfit he deals with near Green Bay. Randy used Valvoline high zinc 10ww30 and added a Lucus zinc additive Cam and lifters were lubed with what Summit sent and the ***embly lube from Napa. lifters were pumped up with motor oil with an oil can and then left to soak in a pan of oil over night. Rockers were set lite , resistance on the push rod plus half turn. We always go through them again after we break in the cam. engine was pre primed with my OTC priming tool and my Snap on high torque air drill un till we had oil flowing up into the heads and had 55 to 60 psi at the gauge. Once he had the the engine installed and before the plugs were in we spun the motor with the starter till we again had oil flowing to the heads and had pressure at the gauge. It was fired and idle was set at 2 grand and ran for a good 20 minutes. The same way we have done for 50 years. As I said in my first post, this is not our first rodeo. This motor was built to be a nice mild street motor to power up a nice street machine 59 Studebaker Lark Hardtop like Randy and I would have driven in high school back in 71. A lot of different car guys I ***ociate with in all different styles of builds from all over have been having a lot of problems with parts the last few years and like I said before I have never seen a cam lobe actually dato out a slot into a lifter before, HAVE YOU! Larry
Don't have any more to add for tips, but you asked about the lifter gouge, and I have seen that on SBC way back. Believe we replaced cam and lifters, no issues again.
Talked to my son today, SBC lifter problems in his new crate inboard engine. He told me there is a recall on GM lifters. Just read about it and valve spring service bulletin last September. QC issues with manufacturing from their unnamed sources since the Covid lockdowns. Mostly L87, LT1, LT2, and LT4. Don't know if supplier is same for aftermarket. Joe
Only thing missing : Isky Rev-Lube , after 3 cam failures , started using it 15 years ago , since then 5 successful cam. installations . Its a moly coating .
What is a Napa replacement spring? Seat presssure? Pressure at max lift? Height at coil bind? Installed height? Lifter bore? Lifter diameter? Lots of missing info that could have caused problems and no definitive answer unless you have done the math.
Hey, OB51M; Don't think you, buddy, or machinist did anything wrong, other than maybe too tight lifter in bore(s)? Can't tell you what, but things I'd look at before another rebuild: Some other posters already touched on some of the things, & some of these will be hard to check. ***uming flat tappets: Are the cam & lifters material-compatible? There are differences & those cannot be mixed. Have the lifter &/or cam materials been changed, esp w/o notice? Not unusual... ;( . Is the lifter properly hardened? & compatible w/that particular cam material? Is the lifter foot ground to a proper radius? Does the cam have the proper angle ground on the ramps n nose to promote correct rotation of lifter? Same mfgr lifter/cam is a slightly better bet than mix/match, but not guaranteed. Does the lifter spin easily in the bore? If the lifter has a dado cut thru it - it was *not* spinning, = instant junk. Hope your buddy gets that '59 Stude on the road soon, we need all of 'em that we can get. . Marcus... W/o testing, at least the Hardness, of the destroyed parts, would be hard to tell what caused the problem. The stuff that is still ok might test ok. ****s. But it'd be intersting to find out.
Read this today. As promised last month, when i went up to Ms. i would test several cams and lifters for hardness. The first test was a 6 to 7 yr old Comp cams hydraulic flat tappet cam that went flat in my street El Camino on 3 lobes. Tested 29/30 RC really soft in my opinion. I then tested the lifters that were on the cam. They tested 57/58 RC, not a problem i think. I then tested a 13 Yr. old Bullit solid flat tappet cam, still good after a couple hundred p***es on it. It tested 34/35 RC a full 5 points harder than the newer Comp hydraulic cam. I then tested a new never run set of solid flat tappets lifters They tested 60/61 RC I then tested a solid roller Comp Cams Cam It tested 58 RC I then tested a set of Comp Cams Extreme duty .180 offset solid rollers lifters. They tested 38/41 RC I tested all the lifters on the body portion of the lifters the Cam companys are saying the problem is with the lifters, I think that's BS, it's a cam core problem and they don't want to address the cam hardness problem, I doubt if they even have a Rockwell tester, of course the lack of Zinc in todays oils are a contributing factor also. They are now putting oil holes in the solid flat tappet lifters for an extra fee, i think howards cams started this. In conclusion they are using cheaper softer cam cores, and are not really interested in solving the problems, but would rather sell hydraulic roller cams which cost as much as $700.00/$800.00.
Well at this point, I have to wait for Randy to take a deep breath and tear it down again. Randy is on a budget just like me and everyone else. And at 66 we remember 50 years ago a couple hundred dollars could buy you one hell of a top shelf cam and lifter kit . Now it just gets you cheap **** in a white box. At this point he would have been money a head to spend 800 to a 1000 0n a good roller cam. The lifters were spinning by hand fine as we installed them in the bores. Now I wish we had left the intake off till we cranked the motor over with the starter to make sure the were spinning once the rockers were adjusted. But in 50 years of hot rodding I or anyone I know of have ever had that be an issue. Between built motors, crate motors and remans I have never loss a cam before. thanks everyone for your imput. Larry
This is the only thing that stands out to me as being potentially problematic. After you primed the oil pump with the drill and built up pressure, there's no reason for this step, other than putting the valvetrain under undue stress without adequate oil flow. Look up the cam break-in procedures and you'll see that they recommend bringing up the rpms and not allowing the engine to idle for a set amount of time. You've essentially idled the engine, at very low rpm no less, before breaking in the cam. This could have been the cause of your failures.
The holes in the face of the lifters which are apparently being promoted by some manufacturers are a waste of time. The hydraulic film pressure generated in the hydraulic wedge at the cam/tappet interface is, from memory, 30000 psi. Drilling a hole at the interface interrupts that film and the pressure actually allows oil to flow out of the interface, back into the tappet, making things worse. The cam manufacturers apparently need to brush up on tribology.
"the real surprise was that three lifters had notches machined into them by the cam lobes." These lifters were not rotating.
My question for when he tears it down would be: Are the lifters that went bad this time in the same location as the lifters that went bad the first time? If so, that might indicate a lifter bore problem in those locations. Second comment is: What steps were taken to get the metal out of the motor after the first cam failure? It sounds like maybe just changing oil and cam instead of dis***embling and flushing.
Just a wild guess . Has anyone compared cam lobe placement of a new cam versus and old 60-70s factory cam ? Heres my thinking on it . Most sbc cams today are roller , and rollers run directly under the lifter bore ( almost) older flat tappet cams had the cam lobe offset under the lifter bore to rotate the lifter . What if modern manufacturers just cast one cam for sbc and since most are rollers ,follow the roller spacing . Then grind and harden for flat tappet ? Just a wild *** guess knowing how bean counters can screw things up . Nothing to base this on as Ive got a supply of older nos cams and no new ones .
Roller cams are usually made from hardened or billet steel rather than the cast iron typically used with flat-tappet cams. Very unlikely that the same cam blanks would be used for the different lifter types.
Hey, OB51M; Hope your friend will fix it, one way or another. I sympathize. I'm the same age as you guys. Understand very well on costs & available funds - or rather - lack of them. If a technical post-mortum-testing/investigation is done, would you mind posting results? TIA. Marcus...
Hey Gary , The cam blank will not be the same . The roller has its lobes centered in the lifter bore,,,,,the flat tappet cam has it’s lobes offset to one side . That is to help make the lifter spin,,,,,,as the lobe pushes on the lifter . Imagine it p***ing by on the edge of the lifter face . The lobe still sees the entire lifter face,,,,,just part of it at a time . Also,,,,,,to another post,,,,,,there are millions of factory cast iron cams . And all cams are hardened,,,,even iron . Tommy
This is a common story from people that do everything correctly. There's a reason why so many have switched to hydraulic rollers. I realize this isn't correct for this site but the reality is that cam failures are as common as can be.
Hey, SW; Can you retest the lifters on the foot portion? It should be much harder, & tougher, than the body portion. Marcus...
I was thinking the same. Most likely washed the ***embly lube off the camshaft from the non-start rotation. You want the cam covered in ***embly lube prior to starting. Prime the oil pump to verify the pump is working, and to fill the galleries to verify pressure. Cranking the engine over without starting is not going to do you any favors. If you missed something at ***embly it's a bit late to try and find an internal engine problem now at startup.
Geez what pisser. Last year I put one of those cheapo no name 'white box' cam and lifter kits (about 100 bucks on ebay) in my 350, stock springs. Usual lube and break in procedures. Had the timing way off so it took awhile to get it started, cranked over quite a bit. Doing fine a year later. As other have said, I would check for lobe location, rotational taper and convex of the lifters.
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