mech Roller vs Mech flat tappet cam Q

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tooslow

tooslow

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RB"s have the large diameter lifter bore-.902 With this in mind would there be any advantage of going to a Mech Roller vs a standard Mech flat tappet in the .590 lift and 240 dur at .050?
The car is not a drag racer it is driven on road race tracks and consistantly in the 2500RPM to 6200RPM range
 
The advantages are minor. The expense out weighs the benefits, for the most part. However, I still vote for a roller since today's oils are not up to spec on there content and ability to protect Hyd. and Mech. cams like it used to be.
 
rumblefish360 said:
The advantages are minor. The expense out weighs the benefits, for the most part. However, I still vote for a roller since today's oils are not up to spec on there content and ability to protect Hyd. and Mech. cams like it used to be.
Click to expand...

I AM AFRAID TO GO HERE BECAUSE I KNOW WHAT CAN HAPPEN:eek:ops:
BUT HERE I GO(the oil addative debate)

I am running Brad Penn 10w-30 which has the most Zinc(Zddp) of any of the
racing oils including VR-1 and all the others from what i have read. So I should be OK am I right?
Also The large bore of a BB Mopar makes it a little easier to spin a Mech Flat tappet vs like a .78 BB chevy lifter- Am I right that the load is disapated more with the the RB .902 lifter
 
Question one; You are correct.

Question two; This is something you worry not.

The larger .904 lifter has the advantage to handle a steeper ramp, quicker rise rate cam. AKA, bigger more aggressive cam. Load handling ability is a combination of parts and material used. AKA, proper valve springs and acco. parts on the head. Pushrod strength, good metal in the making of the parts and of course, lubrication.

While I'm sure a larger diameter tappet can handle more load, I have not noticed the smaller diameter tappet engines having any problems. Of course, when they get super serious, there tappet diameters go to 1 inch.
 
tooslow said:
RB"s have the large diameter lifter bore-.902 With this in mind would there be any advantage of going to a Mech Roller vs a standard Mech flat tappet in the .590 lift and 240 dur at .050?
The car is not a drag racer it is driven on road race tracks and consistantly in the 2500RPM to 6200RPM range
Click to expand...


All mopars have the largest factory diameter. The limit imposed by lifter diameter is rate of lift. That's it. Once you make the change to a roller tappet (solid, not a hydraulic roller tappet) there is no real restriction. So the exact same duration at .050, or at .200 lift, can still be an overall larger area under the curve with a roller lifter. If this is the oldschool .590 MP solid, there are major improvements over that just in solid flat tappet cams. If you want to post all the info on your build (including car, gearing, trans type, and P/S and A/C or not) we can help be more specific.
The "surface area" is really a non issue. Yes, technically, it's larger. But, it's not really relevant because the load capacity of the oil wedge on even the narrow Chevy lifter face well exceeds the force applied through the valvetrain by the springs.
 
in my opinion if you purchase a custom solid roller cam for your hotrod your will be amazed at the additional power you get and will never use a flat tappet cam again.
 
SuperShafts; I say spend the extra money on the roller and not to worry about break in and oils without zinc....
It seems to change weekly on the zinc content as to who has what content or what article you read --Mind Boggling for me!!
 
Road Racer --RPM is 2500 to 6200RPM Want as close to 600HP as I can get--60MPH to 150MPH for 20 sometimes 30 minutes depending on the track
I drive it around country roads on occasion
2900lbs
3.23 gear

496 CI stroker
440 source heads 72 cc's I am around 10.75 to 1 CR
Flat top pistons w reliefs
dual plane Hi rise manifold
850 Demon
headers dual exhaust
MSD ignition
8 quart
Accumulator

The cam and valve train has to hold up to typical 20 minute sessions every 2 hours twice a month


Thank you
(i get alot of neg comments cuz its a BB but thats what it is and if you guy's drove it I dont think you would say that BB SUCKS and rather be a Craft SHow??) could be wrong
 
Now that the build is known, and a far from stock build it is. I'd go roller.

People all ways give unwanted opinions and advice. This is what I call asshole-ism. It comes from when they think they know it all.
 
rumblefish360 said:
Now that the build is known, and a far from stock build it is. I'd go roller.

People all ways give unwanted opinions and advice. This is what I call asshole-ism. It comes from when they think they know it all.
Click to expand...

I apologize, I just couldn't resist.

[ame="http://www.youtube.com/watch?v=9hynzB459Jc"]Spaceballs Asshole Family - YouTube[/ame]
 
Put a full roller setup in there and never look back (if you think about it if you stuff a roller cam in roller lifters are required and only the roller rockers are the last step). You won't have to worry about that additive crap and you'll get the benefit of that the power curve will come sooner and stay on longer then a flat tappet cam
 
Technical question here: how does the roller lifter negate the effect of low zinc content in present-day oils? Is it strictly due to the roller lifter not needing to spin?
 
bOb shingler said:
in my opinion if you purchase a custom solid roller cam for your hotrod your will be amazed at the additional power you get and will never use a flat tappet cam again.
Click to expand...

............I'm with bob on this 1...............roller u go...............never look back.............kim..................
 
There are quit a few articles that say roller lifters are not safe for a stock RB block on the street. Easy to lose oil pressure to the main bearings
ARE THEY SAFE AND WHO MAKES THE GOOD ONES???
 
Rollers are great if money is no issue. I have NEVER had a flat tappet ruin a lobe or lifter. I built my first engine in 1963. If you are you are young and making decent money, Why not? Rollers are the future.
 
I recall something about bushing the first two lifter bores on the right bank when using a roller but I can't for the life of me remember why. I haven't touched a BB in decades.

There are now pressurized pin oiled roller lifters on the market so using them in a street car isn't that much of problem anymore. It was the excessive time spent at idle that would cause problems.
 
For your build you can get away with less expensive parts.

Under .650 lift.
Hughs lifters $250
0902001018a.jpg

Hughs lifters and Crane rockers
Crane roller rockers $400

Over 650 lift and 700 lbs springs
Comp lifters $1050
2011-04-14_09-37-13_743.jpg

TandD rockers $1250
Unknown.jpg


For your combo you should be right at the .600 lift to get 600 hp.
My 10.70's pump gas street car I'm running a Hughs .590 lift solid flat tappet cam at about 490 hp per Moroso's slide rule,so about 600 flywheel hp.

Total cost for the over .650 lift came in at just about $4300 including more head work.

I've lost 3 flat tappet cams in the last couple of years.

Hope some of this helps.
 
Not that we didn't try other rocker combo's.
0902001018.jpg

We just couldn't get them to work on the Indy SR heads.

We couldn't get the roller tip to sweep over the valve stem right.
This also shows the problem of Nextec 1.65 dia springs,not the correct 1.55 dia springs needed on SR heads.
0901001021.jpg
 
tooslow said:
There are quit a few articles that say roller lifters are not safe for a stock RB block on the street. Easy to lose oil pressure to the main bearings
Click to expand...


Umm,
you can put a orfice in the oil channels that runs up each side of the block in the lifter galley from the cam journal through the head. Many folks have done this. this stop the crank from getting robbed of oil pressure on that main.
 
As far as bushing the lifter bores or restricting the oil, my original set of Isky lifters required bushing the bores because the roller wheel cutout was flat across above the wheel and would open up the oil galley to drain all the oil pressure. I bought a set of Lunati rollers and the cutouts tapered around the wheel which keeps the oil pressure up and look like the comp rollers in the above pics ( at least where the roller wheel is ). I have been running my same roller cam and lifters since 1991 or so and drive it on the street all the time. .570 lift and 270 duration @ .050 lift. Never had any trouble with the setup. I would like to step up to roller rockers one day though. I have been using the Isky 1.6 iron rockers with this setup the entire time too. I'd go with a roller.
 
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