antman89iroc

It is understood that as cam lobes become higher in intensity it can start making noise and causing component issues. It seems to me that rocker ratio would play a part in this regard.
For SBC motors I have read that even lobes like Comp XE are pushing the edge of the envelope. Is there a way to determine at what point a lobe is likely to start making noise? When at the edge of this point does rocker ratio make it worse?
I am running some Comp QNI/QNX hydraulic roller lobes with 1.6 roller rockers. It has always had "clatter" at idle and mid rpms. Probably at high rpms too but I can't hear it then. I have had pushrod/rocker galling issues, roller lifter issues and broken valve springs. Assuming I have correctly addressed geometry, coil bind, spring rate and related setups the only thing I can attribute it to is lobe intensity.
The lobes I am using are 281/291 229/237 dur and .387/.377 lobe lift. I have tried to use comparisons like hydraulic intensity, major intensity, comparing advertised to .050 duration and the like to try to compare the lobes to other family lobes but it is difficult to determine any significant difference. Or at least I can't recognize it.
I read about a "rule" that says .050 duration should be at least 47.5% of lift to be a "safe" intensity. Using that guideline almost EVERY performance lobe violates the rule.
I have compared my lobes to XE XFI Magnum & Voodoo and they are all about the same as far as the "intensity" numbers. Is there any rule of thumb to use here to know when a lobe is going to make noise? I don't really mind the mechanical sound I am just tired of beating up parts.

86LG4Bird

iTrader: (1)

Hey ant, I can't offer any explanation/theory of figuring this out based purely on the numbers, but having some experience with similar lobes to yours, I have a few comments/opinions.
1. Using these type of lobes with stock GM hydraulic roller lifters over 6500 rpm isn't a good idea. I ran a 280/286 228/234 .383/.383 cam with 160-165 lb on the seat with stock GM (pre-LS7) lifters, and upon teardown after a piston failure (running roadcourses at 7000 rpm shift points), the valvetrain had clearly been out of control. I suspect the HR lifters were compressing and contributing to slack in the valvetrain. I ran only 1/8 turn preload on the lifters to limit lifter pumpup in case of float.
For the new 383, I'll be running QNI lobes and solid lifters with about 170 lb on the seat. Low lash setup, about .004" cold.
Are you solid or hydraulic?
I briefly considered going short travel hydraulics this time around, but I'm a little skeptical of those too based on what I've observed. For street use and drag race, they'd probably be fine, but for extended high rpm on the road course, I'll sleep better with solids

I'm confused on your comment "almost EVERY performance lobe violates the rule". Your 229 duration is clearly more than 47.5% of your .387" lobe lift.

Where do you live in Huntsville? I visit my daughter frequently between Huntsville and New Market.

antman89iroc

Thanks for your reply and insight. I am running the Comp short travel lifters on this motor. I have mixed thoughts on them. They do seem to address the bleed down issue but by the time you combine a Hyd lifter, roller and link bar it is quite a heavy package. This in turn demands a lot of spring and along with the aggressive lobe just magnifies the issue. I have tried adjustments from "0" preload up to 1/2 turn (.025 with 7/16-20 studs) with little distinguishable difference. I am interested in your plan to run these lobes with a mechanical roller lifter. At least it would be lighter. Not sure how that would work for a "daily driver" application but may be worth a try.

The comment about violating the rule is- if you apply it to catalog lobes- almost all the XE XFI Magnum lobes go under that 47% figure. IOW they have a lot of lift for their duration. Some of the really low lift lobes are around that level. And these are roller lobes and I believe the rule was originally for flat tappet. I'm not suggesting the rule is an appropriate one to apply, just hoping there is SOMETHING out there that says "if you go over this intensity level, expect to have a noisy valve train".

Do you remember if the previous setup was noisy? Again, I don't mind a mechanical sound but there a difference between the sound of a solid lift cam and what sounds like a lifter out of adjustment. No matter what I have tried it is always there. As the motor is approaching 50K miles it is getting worse so I am planning to address it but don't know how much to give up (performance wise) to keep it reasonably quiet and more durable. With around $1900 in the cam/valve train that's a high price for 50k and I have had problems along the way. Besides sounding like it needs a tune up at stop lights lol.

Another culprit may be the Comp Pro mag roller rockers. At this lift/duration they may be loosening up and adding to the noise. I always felt they had a lot of side play in the trunions and wondered if Crane, Crower, Scorpion were any tighter.

Lastly, I live just outside of Huntsville. New Market is on the other side of town but only 15-20 mile away. PM me when you are in town again.

Orr89RocZ

iTrader: (20)

The rocker pushrod galling sounded like oil supply issue which could be because of lifter bore length and cam base circle. Short lifter bore length with a small base cam might allow lifter to drop below oil band.

That aside, hyd rollers will get some noise with aggressive lobes. Nature of the game. I would call your lobes pretty aggressive at those lifts on a small base circle. Thats alot of lifter speed/acceleration and gonna be harder to control. And make noise.

Hard to say what will make alot of noise and what wont. Imo i try to look at durations from seat opening to .050 and to .200" and then compare lobe lifts. More lift you have combined with more duration at .200, and less degrees from seat to .050, the more noisey and hard to control it will be. But you really need to compare the entire lift curve with a cam doctor program and plot the velocity, acceleration, and jerk curves to get an idea on the lobe. These will tell you how fast the valve/lifter will move and thus you can tell its gonna be hard on parts and noisey


The highest quality hyd roller stuff is what you need to get for best performance. Morel lifters and maybe even the short travel stuff. The short travel stuff is basically a solid roller lifter with some give to simulate some lash. For street duty i kinda dig the conventional style. Morel 4602 lifters. They are what i ran. .400" cam lobe, .640 net lift. 7200 rpm with a 2.100" valve and 30 psi boost. Dont get much better than that. 185-190 lbs seat and nearer 450 open. Thats stout hyd roller stuff. Lobes are magnum hi lift. Definitely smoother than some of the other stuff out there. Near standard sbc base circle

You want to keep the base circle large as you can. If not, you will want a lobe design that is meant for that small circle and make sure its not too hard on the lifter wheel.

antman89iroc

Thanks J. You've heard me talking about this combination before. It runs great aside from the issues. And the "noise" isn't really my problem, it just concerns me because I don't really know if it is indicating a more serious problem. You are likely right in that I may have more than one condition creating a variety of symptoms. I do suspect oiling since it only dribbles at the rocker. But it does dribble on each side about the same. Dart SHP block and/or the comp race lifters something is restricting oil vs stock. No squirting with the valve covers off.
We did grind a new cam with a few minor changes and on a .950BC. They lobes were selected with this BC in mind. Lifters are lined up with the oil supply hole for certain.
I just spoke with my guy (Brian) at Comp earlier. He has been involved with most of what I have done although I am only one of thousands of people he probably deals with. He said it would likely have some mechanical sound but everything "should' work together nicely. Lot's of similar combinations running out there. Don't misunderstand I am not having a failure right now, it's just starting to get more noisy than usually so I want to look into it before something else comes up. If I can make it quieter I will.
I an planning to inspect everything and go from there. If I get as deep as lifters I will likely try morels or other dog-bone LS style HR. Brian did mention the link bars I am using make some sound of their own. Damned if I find out that is what I am hearing. If it isn't "coming apart" then I will run it til it really is worn out. Just don't want to drop a valve or have a lifter come apart and cause catastrophic bottom end problems.

antman89iroc

Oh and what do you think about the side play on the roller rockers?

Orr89RocZ

iTrader: (20)

What oil weight you using? Link bars do make some noise as well. Usually sewing machine sound.

As long as rockers arent loosening up and preload seems to be holding consistantly, everything should be fine. Also need to keep in mind valvesprins might need to be replaced every 10-20k miles depending on the aggressiveness. Need to measure them for pressure to make sure they are holding true value and not fatiguing

Stud rockers always seem to have some play. Another reason i like shaft rockers, valvetrain rigidity is inportant in making aggressive valvetrain last. Deflection leads to geometry changes and could contribute to wear

NoEmissions84TA

iTrader: (1)

I do suspect oiling since it only dribbles at the rocker. But it does dribble on each side about the same. Dart SHP block and/or the comp race lifters something is restricting oil vs stock. No squirting with the valve covers off.

You have already identified your problem - your valvetrain is lacking the proper oil supply. I suspect your lifters. You can test easily - install a known good lifter in any bore and run the oil pump with your preluber shaft and drill motor. Watch what happens at the rockers. I'll bet you get the proper amount of oil at the 1 known good lifter.
Other clues you yourself pointed out: NOISE = increased wear and lack of lubrication, pushrod/rocker galling issues, roller lifter issues and broken valve springs = the oil is the only thing that cools the valve springs - tried adjustments from "0" preload up to 1/2 turn (.025 with 7/16-20 studs) with little distinguishable difference - the oil cushion in the lifter is not working.
How do I know? I have actually been through this before.
Are you using oil restrictors to the lifter galleys?
The Dart block has priority main oiling, so your bottom end has oil. Troubleshoot why you either don't have oil to the lifter galleys, or why the oil is not getting out of the lifters and to the rockers. Again, I suspect the lifters.
Good luck.

antman89iroc

I'm running 10-40 oil and recently (5k) changed the valve springs.

I agree the oil supply is in question. I just pulled the valve covers and ran the engine to be able to pinpoint the noise. The oil came to each rocker on each bank by the time I got to the engine. What I describe as a dribble is pooling at each rocker pivot fairly well. When I bring the rpm up it doesn't "squirt" like a stocker but does sling to the tips and springs in an amount that seems sufficient. It's really hard to say if it is enough but I am less concerned than before. I did not assemble this engine and don't know if there are restrictors. It was build by a reputable company for hydraulic lifters and they didn't mention it. If I had it to do over again I would have used a LS or moral stock type lifter.

Using a stethoscope and then a piece of vacuum tubing I was able to identify 3 or 4 which have more of a clacking sound than the others. Both rear, exhaust valves and a couple others. Listening down into the lifter valley (as best I could) didn't have any obvious noises from the link bars but I could hear a lot of mechanical sound.

The lifters I am using are limited travel. .050 and with my 7/16-20 studs works out to 1 turn. With the engine running I could adjust the loudest valve down to almost 1 turn and the noise was greatly reduced. I pulled that rocker and it seems ok overall. Of course there is side to side movement and a little up and down at the trunnion. Some, but not a lot. It does not feel rough or especially loose. It seems the noise is coming from slack in the rocker or at least it is minimized by tightening it down.

So, what does this tell me? Should the oil pressure be keeping the valve train tighter? I may try adjusting them all close to the bottom of the travel and see what happens. I don't think I can quite bottom them out since it may hold the valves open when cold. It would at least give me an indication.

NoEmissions84TA

iTrader: (1)

Your engine's oil pressure has NOTHING to do with the lifter's internal metering. And assuming you are using an oil viscosity within normal usage parameters, the viscosity will not affect the lifter operation either. The internal clearances for the pumping mechanism inside the lifter is .0003" max. That is 3/10s of 1 thousandth. Even at a 500 rpm idle, the lifter is moving way too quickly to be able to see any difference from thick or thin, or hot or cold oil.
If you adjust to the bottom of the plunger's travel, you will have less oil spurt to the rocker arms. And you NEED that oil to cool the valve springs.
Keep investigating.

antman89iroc

Will do. Thanks for the advice. Adjustment seems to have no real affect on noise. Even at ~.010 from bottom. When i get down to ~0 it does reduce some clatter. I presume by keeping some tension on the valve train.

NoEmissions84TA

iTrader: (1)

Yes, but at ZERO, you essentially have a solid lifter running with NO clearance.
You can try the lifter substitution test for proper oiling WITHOUT REMOVING THE INTAKE MANIFOLD. How, you ask?

https://www.grainger.com/product/PRO...ing-Tool-5C598

I have used this exact magnet to change out an entire set of hyd flat tappet lifters on a SBC and had the car back on the road in 1 hour!
Goes fast when you do not have to drain the coolant and remove the intake.
My engine was Gen 1 SBC with carb.

If your heads will allow the magnet to go through the larger holes in the cylinder heads between the pairs of pushrods, then you can do this: it is all done through the distributor hole. Obviously the valve cover(s) are off.

1. Remove the distributor (preset engine to where you can reinstall it without having to figure anything out later).
2. Stuff a rag or paper towel in the hole in the lifter valley to cover the oil pump intermediate shaft so things don't fall down there.
3. Remove the necessary rocker arms and pushrods.
4. Use the magnet to pull the lifters out of their bores. "Walk" them back towards the distributor hole for removal.
5. Do the reverse to install new lifter(s).
6. Put the pushrods back in place (make sure they are seated in the cups of the lifters). You do not need the rockers in place.
7. Remove the rag covering the distributor hole. Use your drill motor and preluber shaft (one that seals the oil passage at the bottom by the gear) to run the oil pump.

Observe and compare the amount of oil coming out of the pushrods/rockers.

I cannot guarantee this will work for every setup, but it certainly did work for mine.

antman89iroc

This is a very interesting technique. I wouldn't have thought if it so thank you. It may take some time fishing things around but it's possible. I'm running link bar lifters so that adds some difficulty but still possible.

Yes, running the lifter down to "0" or close to that does essentially make it solid. The problem I ran into was thermal expansion when cold made it run rough until warmed up. I can back it off some to compensate but then it allows slack and defeats the whole purpose. Plus, it shouldn't be necessary. I am going to investigate to see if possibly the engine has oil restrictors. That could explain some of it. I ran it again with covers off and the amount of oil seems adequate and does splash over to the springs with some rpm.

I suspect I have a combinations of things. Very intense lobes, possibly low oil supply, roller rockers with some bearing slack and stiff springs all working together to make more noise than I would like.