Experience: Comp cams 268H in a stock 289

GT1966 · Aug 29, 2006

OK, so I installed a Comp cams 268H K-kit hydraulic flat tappet cam in my stock bottom-end 289. Replaced timing set, lifters, springs, went with Magnum roller rockers on a stock set of heads. The duration at .050 is 219 on both intake and exhaust; the gross lift is .456 also. This thing idles like crap (they described it as a "mildly rough" idle in the literature) and I'm not making any power. The top end is noisy, I've started from scratch and adjusted the pre-load about 8 times (I had too much initially) and at least it now starts right-up. Took it out and it "pops" under full throttle from the exhaust pipes..... timing too retarded? With the clatter I'm getting under the valve covers, I'm afraid something is gonna come un-done. Any help would be appreciated.
GT1966

Dano78 · Aug 29, 2006

Did you install the cam, straight up? (timing marks properly aligned, not advanced or retarded)

Is the intake properly sealed to the heads? (check by spraying carb cleaner or using Argon gas) Check for other vacuum leaks.

Are the valves set properly to zero lash +1/2 turn? (ensuring that the valve you set is seated and the lifter is off the lobe ramps)

Your timing may need adjustment. Stock specs are not usualy good enough, but great for a baseline. There are 2 sure-fire ways of getting the timing set without a spec. Let me know if you want me to elaborate.

fastdave · Aug 30, 2006

About 6 months ago I built my 289 with the same cam. Same problems as you. I tried everything. Took it back to the shop that built it and they tried everything they knew too. Finally they tore down the motor. Found that EVERY lobe was WIPED! I stared the motor for the first time. I have a old dist shaft that I put in the dist hole to run the oil pump to prime the engine. Vented the oil gauge and ran with good pressure for 10 minutes. PLENTY of time. Installed the distributor and started it up. It started okay. I ran up the rpm to around 1200 -1500 rpm to break in the cam. After about 3-4 mins it didnt sound right,still had good oil pressure - 60#. When the mechanics tore it down he thought I did something wrong and I thought the did something wrong. Neither of us could figure it out. I bought a new cam -different brand- and the shop rebuilt the motor again. Now it runs just fine. I HOPE that that is not what happened to you.

rbohm · Aug 30, 2006

dave, flat tappet cams need to be broken in at 2000-2500 rpm, NOT 1200-1500. they also need proper cam lube on them, otherwise you will wipe the lobes.

gt1966, check everything dano78 recommended, also set your intial timing at 10 degrees btdc. when you broke in the cam did you run it where comp cams recommended? did you use the lube that they recommend? did you use enough lube? too much is not a problem but too little is. did you use comp cams lifters or a cheaper brand? regarding the springs, are they the ones that comp cams recommends? are they dual springs? did you break in the cam with the outer springs only installed? are your valve adjusted properly?

mustangdave · Aug 30, 2006

Did you install screw in studs so they don't pull out of the heads?

fastdave · Aug 30, 2006

Sorry. My mistake on the rpms. I ran it at the rpm and length of time they recommened. And yes it did have plenty of cam lube. I bought the cam kit so that everything matched. Basically I did everything right and the shop mechanics said they did too. That is why we are still scratching our heads because we don't know why it failed.

GT1966 · Aug 30, 2006

Well, thanks everyone for the input....I've addressed pretty much all your points....plenty of lube, I primed the motor with the oil pump, the K-kit had new CompCam lifters and springs (single, not double), the kit claims you don't need screw-in studs for this cam / rocker combination. I only got through lashing the valves again, so I'll know a bit more tonight. Question: this might sound a bit basic, but should the amount of stud protruding from the adjusting nut at each rocker be approximately the same? I've got a couple which require a few extra turns compared to the others.... which may be an explanation if I wiped-off a couple lobes?.... OUCH! Wouldn't I see a ton of metal in the oil if the lobes were gone? Better check! Fastdave, I hope I don't have the same results as you!
GT1966

Max Power · Aug 30, 2006

If some studs need some extra turns, I would suspect those studs are pulling out of the heads, regardless of what the directions say. I would not run that cam and springs without screw in studs.

I am not sure you are getting your valves adjusted properly.

On each cylinder, when the exhaust begins to lift, adjust the intake. When the intake opens and then is almost closed again, adjust the exhaust. That way you will know you adjusted the valves when the lifter was on the base side of the cam lobe.

I am assuming you do not have the positive stop rockers where they are merely torqued into place.

66forfun · Aug 30, 2006

tall valve covers to clear the rollers?

1966conv · Aug 30, 2006

Is this the the Extreme Energy Cam? I installed the XR-268-R (roller) cam. This is basically a 351W cam and uses a late model spark plug configuration. (BTW I wiped out the cam early too)

Oldskool · Aug 30, 2006

Some engine builders now recommend NOT priming the engine with oil before starting it after a cam install. Priming the engine with oil can wash off the cam lube. One thing you should definitely do is fill the oil filter with oil before installing it. For high-lift flat tappet solid lifter cams, many engine builders (and Comp Cams) now recommend using Shell Rotella T 15W 40 diesel oil during breakin. (It's got a much more robust additive package.) Check with Comp Cams to see if they recommend Rotella T for flat tappet hydraulic cams. You can also add Comp Cams' engine break-in oil additive to the oil with any type cam. After you've run the engine at 2000 to 2500 RPM for 30 minutes, let it cool and change the oil and filter. Some ultra careful engine builders change the oil and filter again after 100 to 150 miles. Lastly, use a magnetic oil drain plug to identify excessive metal loss (usually from cam lobes) early on. Good luck!

Great68 · Aug 30, 2006

When I first put on roller rockers I noticed the increased noise, I thought something was wrong and I readjusted them 3 times before taking them to a shop. I was told everything was fine, so I learned to live with it.

Dano78 · Aug 30, 2006

Yeah it's possible that the factory studs are slightly un-even. That's not uncommon. I have to ask-
-Are these 3/8" studs or 5/16" studs?
-Are they torque-down style or do they have a locking nut?

I really wouldn't worry about studs pulling out of any SBF head. They are not at all like SBC heads where stock cams will fling a stud. I've run a .496/.512 cam with 120# seat springs on stock 5/16" studs and didn't ever break or pull out any studs. And that was with a teenager behind the wheel. (my younger days) That's not saying it'd last 60K miles like that but it proves that your more mild cam will be just peachy. I've got a couple other cars running just shy of .500 lift with 110# seat pressure springs, one at 230K miles (5/16 studs) and the other at just over 28K miles (3/8 studs). You you will be just fine. You know when the studs start to pull, and really it's not a big deal if they do. It'll drop that cylinder and run like ca-ca, and if it's just and intake stud, you'd be able to limp it home.
But I do need to know what style of stud/nut configuration you have as thet could be part of the problem. Depending on that situation, crane and comp do make special nuts to allow adjustability with the non- adjustable setups.

Max power has the valve adjusting down perfectly.

I noticed you said you were lashing the cam.... you're not setting any valve lash are you? (just checking) Remember... set to zero lash and give it 1/2 turn.

It may also come down to adjusting them with the engine running. This is old school, and IMO is the only correct way to do it. Although kinda messy. I save the mess by cutting the tip-top part of an old stocker valve cover off and bolting that down to keep the majority of the oil in the engine. Now thay can be adjust, running without much mess.

GT1966 · Aug 31, 2006

I guess I'm brain dead or severely challenged

The saga continues, but let's go back because there are a few details which I feel I covered, but I'll add the to the mix for a complete picture. When I assembled my 1966 engine, I went with 1968 heads using the "rail" rockers. That was a mistake 'cause the rockers were just touching the new spring retainers on their "forearm" at the same time touching the extended valve tip. I went and purchased the Magnum Roller rail rockers (side rails at the roller) along with new pushrods. Problem solved, or so I thought, 'cause I've got similar noise issues on the top end. Question: the noise wouldn't be valve to piston contact, would it? I figured if that happened, the engine wouldn't run after about a minute. The engine started right-up yesterday after I went thru and set the valve pre-load again, took it for a ride, and it runs pretty good, except for the TOP END NOISE! Drove it to my local shop; the guy raced Ford-powered Modifieds, so he knows Fords. He said it was valve lash noise and also check the valve cover clearance. I did, OK, no sign of cover contact. Now that engine was warm, I checked pre-load and added ~ 1/2 turn to all studs (is this wrong?), plus a couple were loose. Now car won't start (like too advanced). Back to square ONE. If this engine is going to be this noisy with this cam / rocker set-up, it's coming apart soon (yes, with a wrench)! HELP!!!!!!!!!!!!!!!! Are the '68 heads the issue? Ran fine (other than guide wear) with the stock cam and 66 heads now on the shelf. GT1966

65fast · Aug 31, 2006

did you ever degree it?

gsxrken · Aug 31, 2006

quote "I checked pre-load and added ~ 1/2 turn to all studs (is this wrong?), plus a couple were loose. Now car won't start (like too advanced). "

"Plus a couple were loose" worries me. If your cam lobes are disintegrating, this would happen. I'd drop your oil and check for filings, and cut open the oil filter to see what's going on there, too.

When you have valves too tight, they come off their seat and don't seal the chamber well- you will barely run or run like crap. You want to just take the up and down slop out of the pushrod. and then go 1/3 of a turn.

One last thing to check: sometimes the firing order is of the later 351W variety. Check that too.

zookeeper · Aug 31, 2006

I may be wrong, but I've always heard that small variances in valve adjustment on hydraulic lifters are not enough to lift the valve off the seat. What I mean is, some people adjust their lifters with 3/4 turn past zero, some go to 1 1/2 turns past zero. I think the problem is going to be more obvious. Not only that, but the 268h is a mild cam, so I think piston clearance is not an issue. I would first adjust the lifters as per Comp Cams instructions. Then run the car with the valve covers off, I know it may be a touch messy, but I've done it before, it's not that bad. While the motor is idling, listen carefully to see if you can find the source of the noise. I have a 268 XE cam with Magnum roller tip rockers in my motor and it's got no lifter/rocker noise at all. No hydraulic lifter should make racket, that's why they are referred to as "self adjusting". One thing nobody else mentioned is your oil pressure. If the engine doesn't have sufficient oil pressure, you're going to hear a lot of noise all the time. Get a good mechanical gauge and make sure you have 10lbs of pressure per 1000 rpms. Also, try to measure and note the height of each rocker stud, then drive the car a bit then recheck your heights. Don't be afraid to check for vacuum leaks as well, your poor idle quality may be a vacuum leak, bad plug wire, fouled plug or any number of things. Start by eliminating the easy stuff first. Good luck!

6T6coupe · Sep 1, 2006

It could still be a rocker problem. Had the same thing happen to me once. Turns out the heads I got were early style heads with rail rocker type valves.

Are the heads themselves the rail rocker type or are they the earlier stud type with the tight pushrod clearance slots? Running rail type rockers on an earlier style head will cause a pushrod bind that sounds horrible and will eventually fail. Same issue if you are running guideplates with rail rockers.

GT1966 · Sep 6, 2006

Back to square ONE

I almost hate to post this, but I'm defeated and I've got several questions to answer, so apart the motor comes. Thanks all for the input; this is where this thread will end until I tear it down. But I want to address a lot of the input everyone gave me: After adjusting the pre-load for the umpteenth time, I decided that I would run the motor and adjust them on the fly. I took a set of the old Bronco tall valve covers, cut one open and folded back a flap of steel so I could get a socket on the rocker nuts. Wow.... the upper clatter was almost completely gone! About 2 minutes into this wonderful idle, clack, clack, clack, one of the roller rockers turned a bit sideways and bent a pushrod.....damn. I truly believe that I wiped out a lobe (or two) early in the process and I've been attempting to chase a botched-up (by me) cam. The crankcase oil is extremely dirty.... with a nice silvery content, which tells me I gots plenty of cam lobe floating around. So, I'm plulling this baby apart.... an expensive lesson, but I've learned a ton. Funny, the stock rocker covers do not show ANY contact from the rockers, but thinking back, I would tighten the adjusters and the noise would get better, but then the idle would suck....back off, and the noise would get worse, but the car would idle pretty good. Lesson: early 289 valve covers don't work with Magnum Roller rockers on standard 3/8" studs.... I went and bought the Edelbrock tall alum covers for the next round. OK, what's my next street cam with stock heads, Performer intake, and Tri-Y headers? Thank you all. Member "66forFun" gets the prize for the valve cover suggestion!

D.Hearne · Sep 7, 2006

If you had to adjust the lash that many times, I'm pretty certain you wiped the cam. Too much lube for break-in is as bad as not enough. I only apply a thin film of cam lube to the lobes and lifter bottoms. No lube on their sides. Oil only there. Make sure the lifters spin freely in thier bores when you slip them in. Use either a diesel spec'd oil or a non detergent oil for break-in. Prime the oil system before startup. Run it at the recommended rpm's during break-in. Change the oil after break-in and again after about 500 miles.What happens many times at startup is the cam lobe fails to spin the lifter in it's bore. That is a gauranteed recipe for failure. Pull the lifters and inspect the bottoms. Wiped lobe, and the lifters will be gone too.

Experience: Comp cams 268H in a stock 289

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