Roller Cam Bearings?
 

Just wondering if anyone has any real world experience with roller cam bearings? Good or bad... Brand used ect. ect.

I fell across a deal on a new block I couldn't pass up. Unfortunately I already purchased a cam and it will not fit in the block unless I go to a roller bearing. At this point that's what I'm doing just wondering if anyone has any usefull experience with roller bearings in a marine application.

We use roller cam bearings. Don't see or have any issues. They may make a small amount of HP but ther aren't generally used in a normal marine application. Roller cam bearings are generally used if you are going to run a 55mm to 60mm cam core. Not sure that standard cam bearings are even used with the larger cam cores. The larger cam cores are stiffer and allow you to be more aggressive on lift (and maybe duration?) and still provide valve train stability. The right push rods are the key to long term valve train stability. I am not an engine builder, but just smart enough to hire experts.

Do you know what brand bearings they are using? Coated or uncoated?

I would talk to a couple of engine builders, they are really designed for drag race pro stock style engines looking for every HP. Not sure how that would work in endurance apps, also may not oil the rockers/springs enough to keep from killing springs due to overheating...but just speculating here...

What do the cam bearings have to do with oiling the rockers and springs?
I have rarely seen roller bearings in a drag race motor. Most of the ones I've seen have been in circle track stuff.

[QUOTE=Black Baja;4386830
I have rarely seen roller bearings in a drag race motor..[/QUOTE]

I see them in an SBX small block all season,actually,3 seasons and before that in an SB2.2 engine.
If the cams bearings are hard enough,I see no reason why the roller bearings won't last.Think of all the 2 strock cranks and rod bearings that are out there.

How many millimeter are you talking? I don't see why a machine shop could not make a sleeve to step it down to a Babbitt bearing. Probably run the roller bearing since it is machined for it.

2.478 new block housing bore
2.282 old block housing bore
Before I got into shimming cam bearings I would just spend the money on a larger cam. At this point I really don't see any downside to using a roller bearing and I already have the cam. Roller bearings are a little extra money but it is what it is.

Probably oil bleed off I would have to think, like the rest of bearings oil is limited to them, not sure how that works with roller cam bearings though as far as keeping oil in them and still provide for rockers and springs.

Why changing the block to the new one?

I don't think they have oil holes in them fed from oil splash.

.600 raised cam = no grinding rods.
10.6 deck = a lot less side loading on the piston with a big boy crank
Donovan pan rails = much better windage
And if you ever seen a Dart Race series block you would know it's a bad mofo and I just had to have it.
At this point I'll have a clean slate blank hull so it just made sense to to purchase the block. Machine shop bought it for a guy and the guy stuck them with the block. So I purchased it for a lot less than WD cost.

That is correct. So it would improve oiling to the top end.

I was going to do just what your talking now. But the two of everything oil pans belt drives and new connecting rods I had to stop.
Sounds like a nice build does it have keyway lifter bores? And now what crank and rods you going to use?

I feel your pain. I'm probably going to run the .937 Jesel tall bodies i already have (probably). Callies Crank and rods. Was considering the Molnar rods but having a set of pins that are almost double what the price of the rods are didn't sit very well. Everything was already bought and ready to go into the 10.2 block. I'll just buy a new belt and plate for the belt drive. Luckily the pan I had made has the Donovan pattern on it. All in all the change isn't to hard on the wallet. But if I had two motors I wouldnt even consider making the change.

I think those pan rails are spread apart on that block so you might need a wide pan rail pan for that.

withe the reg bearing oil travels around cam and thru hole in bearings(why the oil holes must lined up) and that is the feed to the heads for rockers etc, roller bearing loose oil pressure at the cam it would seem to me and not supply as much up the the heads, now in drag race apps some engine builders run no oil to heads and only pour enough to lube everything for 1 run and know the valve covers are coming off after every run to ck springs etc...

A lot of guys have e gone from roller cam bearings back to babbitt because of valve train harmonics.. I personally have never seen any gains from the roller bearings. I know that in some cases babbitt bearings have shown more power. I would also not consider shimming cam bearings.
The heads are fed oil via the lifters which is a different oil circuit than the cam bearings. Cam bearings are usually fed after the mains and that's the end of that run and should have no effect on oil going to the top end. Also, roller cam bearings are splash fed, not pressurized like a babbitt bearing. Personally, I wouldn't lose a lot of sleep over a roller cam bearing as long as everything else is right like spring pressures, a forgiving cam lobe, the biggest push rods you can run and spot-on rocker geometry. Don't get caught up in thinking that just because you already have something, it's a good idea to use it just to save some $$$. If it's the wrong part, the money you think you might be saving could end up costing you way more in the long run. I will also add this: upgrading to the larger cam journal (and larger base circle)is one of the best upgrades you can do to an endurance engine. It would be a shame to have the potential of this new block (they made the cam tunnel that size for a reason) and not use it. Problem may be that you aren't running a big enough cam to really take advantage of it and in fact, there may not be a large journal core with a lobe small enough for you to use. What are your current cam specs?

I already have a 55mm cam with a 60mm barrel on it. Sourcing a 60mm cam core is not a big deal. I could have the cam in my hands tomorrow if I wanted it. But what really is to gain? .472/.465 lobes

The Race blocks actually come with a DRCE2 housing bore which is smaller the 55mm I had it opened up and was going to run a 60mm cam then my brain started working and I asked myself is it really worth it...

If you're starting with a round lobe core then the lobe size isn't really an issue. The only real benefit is stability and I don't think you can get too much of that in these off shore deals, especially in something high end like you're building. If the bore is already there and the 60 is in your budget, then I'd say go for it and use a babbitt bearing. What size lifter are you running? Might as well go .937 at that point.

.937 Jesels
What would be the benefit from the larger core and what if any would be the pitfalls?

who's block did you get??

Dart

time for A 5" crank!!

And #6 Drive

I almost went 5-1/2" but when is enough enough?

#5 unless I hit the lottery again

Larger base circle and lobe circumference. More rigid and the lobes can be ground much more precisely. Combined with the larger wheel on the lifter it reduces pressure angle and lifter side loading. No pitfalls.

Here is what bothers me at this point. Increased bearing journal diameter at some point has to become an issue. Why? More surface area... More surface area = more heat. At this point the Pro-Stockers are going to a 68mm cam but they are using Clam Shell bearings. Why? Well that's above my pay grade but based on my experience I would have to say for two reasons. The first one is obvious. But I believe the second one is to free-up some of the bearing surface area. Largest motor I ever worked on had a 96mm cam yes 96 not 69. It had roller bearings in it. When you hold a cam of that size in your hands and you think 9,500 rpm how much heat is this baby going to generate?
The other thing that's going to happen with this build is the lifter is going to be moved up higher and the oil galley for the lifters will have to be addressed with possibly bushing or cutting a groove in the lifter.
So instead of buying an $800 cam and scrapping what I have it's going to turn into $2000 before all is said and done. And again I ask myself when is enough enough?

The larger the bearing, the bearing speed slows down yes....? I always was under the impression that was true. Slower bearing speed, less heat, then higher rpm durability.

More load carrying area too...?

Regarding cam questions it might be worth your time to contact somebody like Cam Motion in Baton Rouge, LA. They are a high end custom performance cam grinding company. (Truth be known I bet many of the custom cams on this site are ground by them). They are very knowledgeable and willing to spend time with you explaining the nuances of these cam aspects. Check out their web site and you get an idea of their pedigree.
Keep in mind that I personally don't know squat about anything but I can get it figured out.
Regarding 9,500 RPM, cam RPM is Engine RPM/2 (4750). My Harley Davidson uses roller rod bearings with dry sump oiling at 7,500 RPM (not a typo) and bearing failure is at the bottom of my concerns. Just saying.
And enough is always just the starting point for improvement.

No, larger bearing means more surface area and more surface speed for the same RPM. I think the differences between cam journal diameters is moot (regarding heat) as compared to the gains in valve train stability, but we're also not turning 10K rpm here. PS and cup guys are also running 9 journal cams, so I don't think heat is the issue. Everything in an engine is a compromise and there is always a give and take to consider.

what is the intended use of the boat this engine is going in?i,m not being a smart azz,i am just curious as it looks like you are building a pro stock style engine.

Mike I don't really look at it like building a pro stock style engine. I look at it like modernizing a BBC. When I started all this I had I couple goals. Make as close to 1000hp N/A on pump gas as I could. Secondly get the boat over 100mph. And lastly beat up on the guys that I boat with. We are a pretty close bunch. Talk a lot of crap to each other you get my drift. So we will see what happens. This isn't some thrown together project. Each part of this build has been carefully looked at and at the end of the day I have a lot of confidence that it will turn out great.

Seeing how companies such as Isky are moving "away" from roller bearings in their lifters, I think I'll stick with regular bearings.

ok,i understand now.you have set some goals and i hope you can get it done.looking forward to seeing progress on your build.i totally understand talking smack with the buddy,s.

Is there really any reasoning on how most of us do things? We are all nuts. :bong:

I think a good start to finish build thread on your piece would be in order when completed.

Plain babbitt cam bearings in my experience are junk above 750 hp with a SOLID ROLLER cam . When a plain babbitt or conventional non roller bearing fails you will see a loss in oil pressure above 5000.00 worsening exponentially. If you don't catch it in seconds you will cause rapid oil starvation and boom
Goes your 35000.00 1000 hp motor. It's insurance and if I were to go racing boats I would endure the maintenance required for abating solid roller cam demons. My boat has a hyd. Roller
I have no problems running 4800 for 70 miles non stop.
solid roller. Roller cam bearings ain't hard or expensive and you can turn the motor by hand and insure proper cam alignment under a load the bearing ain't tin like babbitt. If you intend 7500 + rpm and a 1000 hp don't be afraid if you don't know ask a real engine builder. Sure as **** I blown 6 540s in 4 years . My learning curve.

This was never intended to be a Babbitt vs roller thread. At this point it's going to be roller. I'm sure there are plenty of solid roller experience that will discredit your post.

What I was trying to find out from the guys who have ran rollers is who's bearings is everyone using. Are there any to stay away from... That sort of thing.

But putting up a post saying your stuff blew up because it had a Babbitt bearing in it. I'm sorry but there has to be more to the story.

how does an engine ^750 hp destroy cam bearings?i have never heard of that and have built plenty of engines way over 750 hp and solid roller cams with no failures.