Acceptable lobe variation?

chris wilson · Jul 9, 2017

I was out for a drive the other week and shifting through the gears at 5500 when the motor seemed to lose compression on one cylinder and back fired and came to stop. I had just been working on carb prior to run as carb was flooding itself. There was a strong odor of fuel when i got under hood to see what was going on. Car refused to start.

I was only a block from house so pushed car back. So i pulled the intake and checked lifters and pushrods and found one pushrod to be slightly bent and the rocker arm showing signs of heat. (Comp roller tip rockers). Concerned, i pulled the heads as this motor has less than 800 mi on it and found no issues with the cylinders. Cylinder #5 appears to be fine.

Drained oil and cut open filter but found nothing alarming.

I further pulled the AFR heads apart and found the valves to be straight although signs of overly rich conditions seemed to confirm my suspicions.

So ordered new replacement pushrods , lifters , and 7/16 full roller rockers ( Comp ultra Pro Magnum) and head gaskets and stick her back together thinking it was nothing more than a collapsed "Rhodes lifter" but thought having gone this far I should error on side of caution and pull the the cam and have a look. It all appears well visually ,still has lube from install a year ago on it. (Schneiders Cam)

Was able to rig up a dial indicator on some metal steel "V" supports and took some readings. Highest were .320 on cyl # 8 intake/exh lobes and the lowest .313 the intake lobe on cyl #7 cylinder . My question is if this a concern or can i still run this cam or should i replace it? The funny thing is this was not the lobe with the bent bushrod or lifter that failed.

Your recommendations and or thoughts appreciated.

1).316
2).316
3).320
4).320
5).318
6).318
7).317
8).316
9).315
10).316
11).317
12).318
13).318
14).317
15).313
16).316

Grumpy · Jul 9, 2017

theres always some variations in cam lobe height, especially on flat tappet cam lobes ,CONGRATS on taking the time and effort to accurately measure, so many people never bother or assume if an engine runs at all, its just fine!
because the cam lobes are ground too shape then coated and hardened,and the machine grinding the lobe tends to wear a bit as it profiles the lobes ,
but that listed chart seems to indicate rather excessive wear for an engine with only 800 miles on some lobes.
now Id like to see clear detailed pictures of each lobe ,
but the basic rule here is if your in doubt its generally cheaper in the long run to install a new cam and lifter set than run what you suspect is a cam with a lobe or two that you think is wearing,
or too chance excess metallic trash from lifter or lobe wear getting into the bearings if a cam or lifter is showing signs of rapid wear.
on that other issue, of bent push rods, Id suggest you look into that as it takes hundreds of lbs of force and usually some component in the valve train or piston to valve contact to bend a push-rod and if that much force was applied somethings binding or somethings been badly clearanced.
before, you start reading through the thread and links below, Ill point out that I,ve done the forensics on quite a few failed cams over the years that guys have brought to my shop and Id say about
60% of the failed cam lobe & lifter problems were traced to a failure to check clearances or correct valve train geometry issues , like coil bind, rocker to rocker stud, or rocker to adjustment nut clearance, retainer to valve seal, clearances or rocker geometry, use of the wrong spring load rates for the application,or failure to check valve train or push rods binding issues like rocker to retainer, push rods binding on guide plates or heads,etc. before they became an issue.
about
10% were traced to failure to remove metallic or other trash, generated by a previous cam failing from the engines internal oil passages, or failure to carefully clean the engine before installing the new cam, and components, ( use of shrapnel screens and magnets help a great deal in this but can,t remove all trash as some is non-magnetic)
5% to low quality components, or miss matched parts, like the wrong spring load rates for the application, and perhaps
15% of the failures due to using the wrong lubricants , or not nearly enough moly cam lube on the lobes and lifter bases or setting up the oil supply system correctly, or use of a high quality oil and filter, and a failure to change that oil and filter regularly after the first few hundred miles , the remaining
1o% were from unknown causes but more than likely due to a failure to correctly break in the cam,or properly adjust the valves before the engine break-in process or carefully check and re-adjust the lifters rapidly during the break-in process
BTW a couple magnets help reduce the potential damage should you decide to continue to run a cam thats potentially loosing a lobe or lifter
if you have doubts why not call the manufacturer and ask if you can, pull the cam and send it to the tech / engineering department at the cam manufacturer for their inspection
(obviously get a engine disassembly board so you can label each lifter so it goes back on the exact lobe it came from or if it was my engine Id have installed a new set of lifters.

its generally a very good idea to keep all the cam, lifter,valve train and cylinder head components in matched sets, keep components in labeled matched sets, if you intend to reuse used parts in a rebuild. as each wears in, or laps in to its matched components a bit differently thus random assembly increases the chances of future parts
failures

http://www.summitracing.com/parts/pro-66830/overview/

https://www.harborfreight.com/multipositional-magnetic-base-with-fine-adjustment-5645.html

https://www.harborfreight.com/catalogsearch/result/index/?dir=asc&order=EAScore,f,EAFeatured+Weight,f,Sale+Rank,f&q=indicator+stand

keep in mind all that metallic trash, cycles through the oil pump BEFORE it reaches the oil filter

https://www.summitracing.com/search?SortBy=BestKeywordMatch&SortOrder=Ascending&keyword=POW735002

Loves302Chevy · Jul 9, 2017

Grumpy said:
if you have doubts why not call the manufacturer and ask if you can, pull the cam and send it to the tech/engineering department at the cam manufacturer for their inspection

The "old" Crane cams examined a camshaft I bought from them, found strange wear patterns, and replaced the cam no charge.

You said that the carb was flooding itself. Your bent pushrod could have been the result of hydro-locking that cylinder.
But at 5500 rpm, who can actually say?

chris wilson · Jul 10, 2017

I will talk with Schneiders cams tomorrow in regards to variables in lobes, but suspect i know the answer. I agree 100% i would not run the lifters again and yes i have every thing organized for each cylinder.

I will run through the springs again and see if everything is ok there. So off in search of next cam. great reading on roller vs hydraulic flat tappet cam.

Indycars · Jul 10, 2017

Don't forget to verify all your valved train clearances. You might be on the verge of coil bind and only one cylinder was bad enough to actually bend the pushrod. Or the slot may not be long enough and hitting the rocker stud. With the new rockers ( Comp ultra Pro Magnum) you won't have any trouble with the slot binding of course, since they don't have a slot.

chris wilson · Jul 10, 2017

Talked to Schneiders Cams they advised that .004 are the acceptable limits for variation in lobes and advised to send it in and they would refinish it. Great that they offered.

chris wilson · Jul 10, 2017

Well i guess i will look into a roller setup. Am i correct to avoid the cheap $300 roller lifters and go straight to the $700.00 I presume staying with a 288 cam in a roller is going to be fine from a 288 flat tappet. I will look into whether solid or hydraulic fits my requirements.

Grumpy · Jul 10, 2017

yeah I figured they might! but you can,t ever be 100% sure
yes theres at least some potential for all the cam lobes too be worn once the metallic trash from even one lobe enters the oil flow, and circulates thats one great reason to install the magnets I've suggested, you might be amazed at the volume of metallic trash these magnets can prevent from circulating through the engines oil passages that the oil filter failed to catch.
remember the oil filter is located after the oil pump, so the gears in the oil pump are not protected from ingesting that metallic trash
you should be easily able to use a caliper and measure each cam lobe's base circle vs lobe lift to see the wear.

http://garage.grumpysperformance.com/index.php?threads/acceptable-lobe-variation.13654/page-2

http://garage.grumpysperformance.com/index.php?threads/metallic-debris-in-filter.12364/#post-61283

IVE typically used these magnets in an engine, one in the rear oil drain on each cylinder head, one near each lifter gallery drain and 4 in the oil pan sump
proper magnets trap metallic debris
SmCo Samarium Cobalt Disc Magnets
http://www.magnet4less.com/
many magnets lose their magnetic pull if heated to 200F
these below won,t

proper magnets trap metallic debris
SmCo Samarium Cobalt Disc Magnets
http://www.magnet4less.com/

http://www.magnet4less.com/product_...ucts_id=254&osCsid=ckl4nevgdrmireotnegg7jcf36

http://www.magnet4sale.com/smco-magnets-dia-1x3-8-samarium-cobalt-magnets-608-f-temperature/

Strictly Attitude · Jul 10, 2017

I like morel or isky for roller lifters

Strictly Attitude · Jul 10, 2017

What engine is it?

chris wilson · Jul 10, 2017

It is a sbc 355 with afr 195 ported heads. Is it best to find a kit or purchase individually? I guess i just need the cam. lifters, springs, retainers, locks, cam button and pushrods.?

Grumpy · Jul 11, 2017

generally its best to purchase all the listed components in a cam installation kit (cam, lifters,valve springs, etc. ) from a single manufacturer as mixing parts, sources or brands,
allows the cam manufacturer to void the warranty, even if the parts in the kit they sell are either identical or inferior to,
the individually purchased components you individually sourced. keep in mind most manufacturers will have tested parts compatibility ,
so they are reasonably sure the components they sell in the kit will work, that can,t be always assumed,
with randomly matched parts even if those parts are good quality.

Strictly Attitude · Jul 11, 2017

depends on the age of the AFR heads and if you know the history of the heads whether you would need springs or not the newer style AFR with AFR casted on the side not the big A castings came factory with hydraulic roller springs that can be used for an up to .600 lift again take nothing for granted. If you are iffy on any components on the heads I would go with a kit but make sure the springs will work with those heads the newer 195's spring pockets are not very wide. Again I am not sure of the history on your heads.

Strictly Attitude · Jul 11, 2017

My 195's ate my old cam as I was not aware of oil issues of todays oils mixed with the heavy pressures from the springs that came on my 195s. I ran an Isky solid in it after that ran great no issues till I spun a bearing.

chris wilson · Jul 11, 2017

So my understandings ,please correct me if i am wrong, the Solid Roller cams seem to be cheaper than the Hydraulic Rollers. However the solid rollers seem to be a great deal harsher on the roller lifters. Most recommend the hydraulic rollers for the street maybe because they require no maintenance. Personally i have no problems setting valve lash but understand how others might want to avoid doing this. The biggest concern seems to be that if one wants to take things over 5500 rpm they are out of luck or they are going to have to spend big dollars to keep things from jumping all over the place. I saw Hot Rods article on the 8500rpm but that was no cheap endeavor! I was curious why i read so many post from individuals claiming they would not be exceeding 5000-5500 rpm. I guess i have my answer, it's to expensive!

So my question is what roller lifter are people running here with their retrofit kits. They seem to start at $159.00 and go to $1300.00 Plus? Which ones are included in the kits and are they any good? I hear of one manufacture that dominates the retro kits on flea bay that people claim is not American made and are absolute Junk, contrary to what you would expect from the individual. True they are cheaper than the others and offer more kits than most.

Grumpy · Jul 11, 2017

I can easily see why you might be confused, if you read enough internet commando posts you'll very quickly get the idea that hydraulic roller lifters will last a great deal longer than solid roller lifters. (thats frequently the case mostly because solid roller lifters are run with much higher valve spring load rates and spun up to much higher rpms thus operate under much higher stress, if both types of valve trains were run under similar stress and rpm limitations both styles would have similar life expectancy)
but what the vast majority of the posters fail to mention is that the valve spring load rates and peak rpm expectations , plus the basic cam core materials, and valve train quality, all can vary a great deal, and in general, the solid roller lifters are generally lighter in mass(weight) so that they can and will operate safely to slightly higher rpms with identical valve spring load rates, compared to the heavier hydraulic roller lifters, but remember you'll need to match the valve spring load rates too the intended inertial loads the valve train will be expected to see, during its intended operational rpm band.
if you run an engines rpms up to the point the lifters loft, of FLOAT, ( or leave the cam lobe surface due to inertial loads exceeding the valve springs ability to maintain lifter to cam lobe contact, valve train damage will usually quickly follow)
your generally going to see stock O.E.M. valve springs start to not be able to control hydraulic rollers at about 6000 rpm, and remember valve springs have a tendency to loose the load rates as the stress and age of the valve spring in use is extended, so a new set of O.E.M. valve springs that controlled the valve train very effectively for the first 10K-20K miles will no longer have anything like the original resistance or load rates after 20K miles in most cases.
any time your building a new engine youll want to talk to several engineers at several cam manufacturers to discuss, carefully matching...
the cam and valve train components youll want to use and the limitations of the parts you'll select, discuss the cams intended operational rpm range the cars weight, drive train and rear gear, tire size, basic lobe lift, duration, lobe separation, engine displacement and compression, along with the valve spring load rates lifter design, rocker ratio, and the potential use of a billet or hardened cam core.

Strictly Attitude · Jul 11, 2017

I have never used a hydraulic roller personally the solid ISKY was a solid flat tappet I used there good solid lifters which are about $200. You have to look at what you are going to run cam wise to make a sound decision here. If you get into an aggressive cam profile with a large amount of lift it is going to me harder on your parts period. Yes if you want to spin rpm it gets expensive. Good solid rollers are more expensive also. I would recommend on a street hot rod mild/mid performance which is most street builds where some one is unsure of the parts to get a kit.

Loves302Chevy · Jul 13, 2017

chris wilson said:
So my question is what roller lifter are people running here with their retrofit kits. They seem to start at $159.00 and go to $1300.00 Plus? Which ones are included in the kits and are they any good? I hear of one manufacture that dominates the retro kits on flea bay that people claim is not American made and are absolute Junk, contrary to what you would expect from the individual. True they are cheaper than the others and offer more kits than most.

If you are talking about Skip White - DON'T DO IT!!!!!

chris wilson · Jul 14, 2017

That is Funny! No not a chance no worries. I have realized a great deal from reading posts around the internet and the hours of reading that Grumpy has provided to me that just does not end! Just as i think i am through it the next page has 20 more links that each has 20 more links. Thankfully some actually double up on past readings. So i have grown an 18 inch beard sifting through it all.

It appears that one can buy these kits at $500.00 cam and lifters. (obviously garbage) kits $800.00 that have springs, retainers camshaft , pushrods ,lifters. keepers, timing chain, (more garbage)
and than $1500.00 that give you lifters and cam that will actually handle over 7000 rpm, but you still need springs, retainers, keepers, pushrods, stud girdle, and odds and ends.

The lower end kits with the $350.00-550.00 lifters seem to be were the majority of the problems stem from unfortunately. It is also the most profitable for vendors and the most affordable for the general public. This roller stuff done right may be worth visiting but from a performance stand point you have to put some serious coin into it to do it right or not do it at all.

I am starting to believe that one is better off to go Solid Roller than invest in these mediocre hyd roller kits that limit performance and appear to be great for puttering around but that is it. The durability is indeed questionable unless you keep things below 5500rpm. Not really what i have in mind from a performance standpoint.

Grumpy · Jul 14, 2017

the hours of reading that Grumpy has provided to me that just does not end! Just as i think i am through it the next page has 20 more links that each has 20 more links.

this may help
http://garage.grumpysperformance.co...-the-rabbit-hole-with-alice.10933/#post-66925

Acceptable lobe variation?

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