getting a new cam in my sb 1975 tomorrow. My question is what is the notieable difference in a roller versus a Hydraulic. Any more power. I'm tring not to go so big as to have a vacuum problem and don't want to change stall. Can I get more HP out of a roller than a hyd and still meet these 2 issues. Going with an Erson cam. Any word on these cams? Thanks

 

I'm not sure what you are asking. Are you asking flat tappet vs roller cam (both can be either hydraulic or solid) or are talking about roller rockers (full fulcrum or roller tip) vs a stamped rocker?

 

A hyd. roller cam will be easier on the valve train than a hyd. flat tappet. The down side is the cost to up grade is often 600-1000 dollars. Roller cams tend to retail around 300 on up and the lifters are 300 on up. Most of the lifters I prefer such as Morels run around 400-600 dollars. I think a hyd. roller is great for a street car and offers more smoother running and reliability vs a flat tappet.

 

Say you have a hydraulic flat tappet cam and a hydraulic roller cam. They both have a 270 advertised duration. They both have the same intake valve opening and closing point. The difference will be the lobe design. The flat tappet cam has a flat bottom lifter. This meens the lobe has to be designed for the flat bottom to slide on the lobe without digging in. This requires a slower ramp design than the roller that has only the thin contact point at the roller lobe interface. The roller cam can snap the valve open and closed faster. This allows the valve to be open longer (more duration @ .050 and .200) and lift higher without increasing overlap (More power without negatively affecting vacuum). This allows for better cylinder filling and more power and torque. It also increases valvetrain life expectancy, reduces friction and lets you use conventional oils. The down side is the Roller lifter is heavy. This combined with the faster ramp will allow the lifter to launch off the lobe and not remain in contact with the cam lobe (valve float) at a certain RPM usually 6000 to 6500 RPM with a hydraulic roller. This can be addressed by increasing spring pressure but a hydraulic roller lifter is only designed to take so much spring pressure on the internals before collapsing the lifter. There are also "rev kits" that are secondary springs that mount beween the head and lifter that load the lifter body instead of the lifter internals. You can also increase RPM capability by reducing weight in the valvetrain with beehive springs, lighter valves, lightweight retainers and roller rockers designed to reduce weight "seen" by the cam on the valve side. Or just don't wind it past 6000 RPM (rev limiter)

 

With a roller cam, you are far less likely to say "Dang, I wiped a lobe."

 

If you are considering going to a "solid roller" setup, you should probably read below to see what us Big Block guys are having to deal with. I'm not sure how much this affects small block guys, but I don't think they are immune to the same issue.

Some folks think that if they choose the right oil, they can keep their solid roller lifters in good shape. But the fact is, that no matter what oil you run, even all the way up to the high zinc/phos Royal Purple XPR Racing Oil (which costs $16.00 per quart from Summit), your solid roller lifters will still fail at a time/mileage that most of us would consider premature.

Solid roller setups do make the most power, but they also decrease the valvetrain’s life expectancy. Failures as early as 5,000 miles, or even sooner, on street driven BBC Hotrods is not that unusual if you run the needle type lifters which are by far the most vulnerable. So, the best oil money can buy, cannot and will not save you here. That's because these lifters typically do not suffer from oil related failures (more on that below).

Of course there are some reports of solid roller lifters lasting a decent length of time, with their owners wondering what all the fuss is about. But reasonable longevity is mostly just the luck of the draw and not something that you can really count on with any regularity. At the end of the day, there are only two kinds of solid roller users. Those who “have” had failures, and those who “will” have failures.

So, a couple of years or so ago, to get to the bottom of this problem, I decided to investigate this all too common premature failure issue. To that end, I collected a few sets of failed standard diameter .842" BBC pressure fed, needle type solid roller lifters. The lifters were different name brands, and had used different name brands and viscosities of high zinc/phos oils. And they were from different performance level engines, ranging from relatively mild to relatively wild.

The engines’ specs are:

*** 408ci BBC, 243*/249* duration at .050, .663"/.655" valve lift, .024/.026 hot lash, 210 lbs on the seat valve spring pressure, 567 lbs on the nose valve spring pressure, 15W40 Chevron Delo motor oil, Isky Redzone lifters, 6300 max rpm. These failed at about 3,000 nearly all street miles.

*** 540ci BBC, 266*/272* duration at .050, .678"/.688" valve lift, .016 hot lash, 260 lbs on the seat valve spring pressure, 650 lbs on the nose valve spring pressure, 20W50 Redline motor oil, Crower HIPPO lifters. These started to fail at about 5,000 nearly all street miles.

*** 632ci BBC, 277*/292* duration at .050, .848"/.824" valve lift, .026/.028 hot lash, 325 lbs on the seat valve spring pressure, 875 lbs on the nose valve spring pressure, 20W50 Mobil 1, Redline, and Royal Purple XPR Racing Oil, Crower HIPPO lifters, 7200 max rpm. These failed after 1 1/2 years. Mileage and driving style not documented.

Careful failure analysis revealed that they showed no sign of oil related failure at all, but they had all failed from the EXACT SAME root cause – METAL SURFACE FATIGUE FAILURE. This failure comes from excessive loading (these lifters are way too small for the loads they typically see), and in particular excessive shock loading/hammering. Not only had the needles/axles failed, as is normally the case, but the roller OD's had also failed or were starting to fail, depending on the set in question. And the larger the lash had been, the worse the lifters had failed.

Spintron testing has shown that the lifters can bounce up and down on the cam's base circle, within their lash slop and even beyond, and can even bounce the valve up and down off its seat as well. In so doing, the lifter isn't always going to be in a position to follow the lobe’s clearance ramp as intended, but instead it will hit hard somewhere on that ramp. So all the effort the cam designer put into designing that clearance ramp, will have no effect at all on how hard the lifter hits, at the point of actual contact. This being the case, the larger the lash, the more severe the shock loading/hammering can be.

So, no matter what Super Duper brand or model of lifter you run, due to this repeated shock loading/hammering, you will still almost certainly end up with prematurely failed solid roller lifters, especially if they are the needle type.

Once I determined once and for all, what was going on here, I pulled the Crower needle type HIPPO lifters out of my 540ci BBC and put in a set of Isky bushing type EZX's. They are still subject to roller OD surface fatigue failure, but at least the highly vulnerable needles are gone.

SUGGESTIONS:

1. DO NOT run needle type solid roller lifters, no matter what brand, and no matter what their marketing hype says. Because the needles and their axles are by far the most vulnerable to premature metal surface fatigue failure, even if they have high pressure pin oiling. If you run needle type solid roller lifters, you are simply playing Russian Roulette with your engine. Instead, use a non-needle type solid roller lifter. A popular one is the Isky EZX bushing type lifter.

2. Run a rev kit if that is reasonable for your application. If you can’t do that, then run the smallest amount of lash that you can live with. Because reduced lash will help to somewhat reduce the shock loading/bouncing/hammering that the lifters will see, no matter how well your cam lobe ramps are designed.

3. Replace/rebuild the lifters at frequent intervals to head off failure before it catches up with you. A fairly reasonable interval for street driven Hotrods is to consider 5,000 miles as the maximum use limit. But that could vary for any given combo.

4. Beyond what is mentioned above, just keep a close eye out for any unusual changes in lash, to try and catch a failure in its early stages, before too much damage is done.

Only “hydraulic” roller setups, that don't have such radical lobes, don't have such high spring pressures, and have no lash, thus no bouncing/hammering/shock loading, seem to have a reasonable life expectancy in most cases.

So, if you want to go to a roller setup, you'll probably enjoy life more if you choose to go with a hydraulic roller setup.

 

Go with the hydraulic roller if you can afford it. No question it makes more power than a comparable hydraulic flat tappet set up.

 

Very interesting perspective, thanks for sharing.

 

why solid roller, stay with hyd or go solid flat tappet which produces nice power and can turn 65-7000rpm . Just because it is big does not make the performance better.

 

With the thousands of wiped lobes this century, of flat-tappet cams due to the newer oil recipes (with reduced wear aditives) and aggressive ramps of the cam companies, there's no way I'll ever use another flat-tappet cam.

Go with a roller.

 

Too much pressure on the small contact area of the lifter.
The big blocks use the same size lifter as the small blocks. The spring pressures required to control the really heavy big block valvetrain at high RPM, faster ramps to get the big lift numbers and the lash needed with a solid roller reduces the life expectancy substatially. The solid roller small blocks with lightweight valvetrain components throughout do better but are not immune to the above issues. A hydraulic roller valvetrain can be designed to run 7500 RPM redlines but they involve expensive, lightweight components throughout and, again life expectancy is reduced. Speed cost money, RPM kills engines. Hydraulic rollers are the answer for a street driven small block if your not planning on spinning it up past 6000 RPM.

 

Yes sir !!!!

 

We deal with alot of roller lifters and we have seen alot of lifters under size for some reason both with ISKY and Crower lifter measure right at .841 that being said GM lifter bores are .8438 to .8443 and most GM lifter bores are mostly righ at .844 and now you have .003 clearance which is to much clearance and I can see why lifters are failing because they are rattling around in the bores. Most flat tappet lifters are right at .8425

85% of the blocks we machine both OEM and after market we go to the .903 lifter which has a bigger body, bigger wheel going from a .750 wheel to an .810 wheel plus they have a bigger axel as well.

Also we find the Morel lifters to more to the OEM size.

There are a lot of guys out there buying lifters and putting them in bores with way to much clearance and expecting them to last and when something breaks then they always blame the lifter company but don't have a clue what the clearance is!!!!

We don't send any blocks out the door with out having the lifter to fit the bore or if a shop has the lifters they give us the size of the biggest lifter and we clearance to the biggest lifter.

We measure each lifter for size and taper we found a set of EZ rolls that measured .9019 to .903 and being .0011 differance we could not use them, ISKY wants .0016 to .002 for bore clearance and one lfter had .0005 taper for some reason.

Proper bore clearance is key to having lifters live and most guys don't have the proper bore gauges for measuring bores.

One way would be to measure the flat tappet lifters to the roller lifters and they should measure the same if you want a good fit.

 

So you feel the .903s would have a better life expectancy by means of the additional surface as well as stronger? I'm putting a set in a little M 4.145 bore. Looking at a mild solid roller for a customer.

 

Just make sure who is ever doing the work fits the lifters to the bores and they do a honed finish VS just using a reamer to finish with as the reamed finish is to coarse.

We use a lot of the .903 lifter in alot of our builds and where we can we so use bigger base circle cams as we go to the BBC cam jounal or the 50MM and some 55MM cams as well.

Lifters hate samll base circle cams.

Dart has the SHP Pro block which comes with the BBC cam jouranl and .903 lifter bores and all billet 4 bolt caps from front to rear. Which seems to be very popular.

 

there's a large weight difference between a roller and a flat tappet, be it hydraulic or solid. that extra weight demands more spring tension, which means more wear and breakage. be realistic about what you expect from your engine. "old fashioned" hydraulic lifters will spin to 6000. that's plenty for a street engine and occasional red light burn-outs. spend that extra money on $4 per gallon gas!

 

As usual good info Carl.

SO many rebuilders choose to overlook this, they just do a quick hone IF that and give it back to the customer;most dont know any better

Think these are made right on the budget Ebay motors everyone raves about?

Had a friend get one of those $1000 cheapo rebuilder jobbies for his Iroc I think they cleaned up the lifter bores with a screwdriver, some were very loose and yes he complained about lifter noise, rebuilder wouldnt do anything about it so he kept replacing lifters hoping that would fix it.


No need to spin that stock bottom end 65-6700 unless you want to sweep up a pile of parts.

 

Some of our circle track engines with hyd. falt tappet run up to 7200 with no problems

Also our blower engines run spring pressures 1250 over the nose and 460 at the seat have not busted a .903 lifter yet.

What would wear with good parts?????

 

I respect Blockman's opinions and contributions. He is one of the valuable contributors on the forum. Race and street are two different build parameters, uses and have very different maintanance expectations. Circle track engines are thoroghly inspected and freshened on a regular basis. Blown pro stock engines are many times torn down, inspected and rebuilt as needed every week during the season, many times between runs. The OP is asking for advice for his needs. I still think the best option for a durable, low mantainence moderate performance street build is a hydraulic roller hands down. If you want a little more RPM, better valvetrain stability and not break the budget a beehive spring upgrade when intalling the cam would be my advice since you need to buy new springs and setup the springs anyway. Too many guys try for maximum power on the cheap with a fast ramp flat tappet and end up having to replace a cam with a wiped lobe soon after. Hydraulic lifter valvetrains can be setup to run 7500 RPM but are cost prohibitive for many. Just my 2 cents.

 

Think in many cases the whole fast ramp thing is a waste.

If its race only or very mild possibly worthwhile but for something thats going to be hammered on the street/high rpm it just beats things up, personally Im done with them.

Is it really worth the claimed 5-10hp , guessing not.
At least going by what my parts replacemement costs are for these things taking a dump/premature wear.