[Will]

SD Performance sells the "Old Faithful" roller cam. It's nothing more than a custom spec'd Comp hydraulic roller. If you knew the lobes used you could order it from anywhere but Dave's a good guy and I'd give him my business.

In order to achieve the higher ratio of 1.65+ ratio rockers the pushrod cup is moved closer to the trunion centerline on the rocker. This pulls the top of the pushrod in closer to the rocker stud. The pushrod passages in stock heads need to be clearanced/opened up to accomodate the pushrod location with such rockers.

If you go roller you really don't need to run 1.65 rockers, but if you go flat tappet I definitely would.

[panhead59]

I am also running that Lunati Voodoo flat tappet hyd cam. #704. With 1.5 roller rockers. I love it in my 455 30 over. Don't really know what 1.65 rockers would do, but I beleive it raises the lift. To late now, but I am very happy with this cam.

[GRX]

Far as clearance goes ... in addition to what Will said about push rods & 1.65 rockers, be sure your machinist cuts the valve guide tops enough so the spring retainers do not hit at full lift. That includes taking into account height of the valve seal.

[pontiacman63383]

So if im going with roller lifters can I go with 1.6 rockers and not have to mess with the head?

[68WarDog]

Originally Posted by pontiacman63383

So if im going with roller lifters can I go with 1.6 rockers and not have to mess with the head?

If you invest in HR, why not spend the little money required to open up PR hole? If you don't have the money, simply run a cam with approximately 10% more lift,basically what you receive using 1.65 versus 1.5. Solid rollers will differ depending on lash, don't want to go into that

[Will]

Doesn't matter what lifters you use. The higher ratio rockers change the location of the pushrod cup in the rocker, moving the top of the pushrod closer to the rocker stud which creates a problem with clearance at the top of the pushrod hole in the head.

Most roller cams give you plenty of lift with 1.5 rockers. The gain in performance going to a 1.65 rocker on a roller cam will be less than the gain going with them on a flat tappet.

The higher ratio rockers on a flat tappet produce valve motion that's closer to what you get with a roller. Depending on the roller grind, the heads and how they flow, and your performance goals, I wouldn't bother with high ratio rockers on a roller cam unless you're after every last little bit of power. Since the higher ratio rockers produce more lift, and rollers generally have more lift to begin with, it makes spring clearance more of an issue as well.

[ponyakr]

All this talk about running a roller instead of a flat tappet, brings up a question, in my mind, which I'm quite sure many on this forum will consider absolutely ridiculous. But, I'm use to that by now.

I don't think there is anyone who does not agree that roller cams can make a lot more power than flat tappets. A flat tappet lifter simply will not work on the aggressive shape of a roller cam lobe.

And, most everybody agrees that when using the best roller cam components, in good condition, the roller cam set-up SHOULD last longer, with less wear and less chance of failure. I assume this is the reason that most car makers switched to roller cams years ago.

But, since NOT EVERYBODY who is building a street engine, is looking to make absolute max horsepower, or to build an engine that will produce the quickest ET possible, why do most who post, seem to recommend cams that will do exactly that ? Having done quite a bit of racing, I understand wanting to make more power and go quicker.

But, what about the guys who never plan to take their car to a track at all ? What about those who just want a mild street engine, which has a smooth idle, and plenty of vac and low end torque, but at the same time want the reliability, longevity, and other advantages of a roller cam--similar to what most folks want from any new vehicle's engine ?

Has anybody ever ordered a roller cam with specs similar to the popular flat tappet grinds ? Some might say--what advantage would there be in doing that ? Well, the 1st thing that comes to mind is that the reduction in lift and effective duration, from what most roller cams have, would eliminate the need for the high spring pressures, and all the possible negatives and problems associated with higher spring pressures.

One of the problems with the hyd roller seems to be the longevity of the lifters. So, wouldn't less spring pressure, put less stress on the lifters, thus preventing premature failure, in most cases. Less spring pressure would also put less pressure on the cam lobes, which should also decrease wear and increase longevity. There would also be less pressure exerted on the valves, rockers, pushrods, and most every part of the valve train. There are lots of vehicles nowadays that get 200,000 + miles, with their factory roller cam engines--right ?

So, could this be a POSSIBLE solution, for the guys who just want a mild street engine, with a reliable, long lasting valve train ? Could you just order a roller cam with the exact lobe specs of one of the flat tappet cams mentioned in this thread, and use the same springs and associated parts ? If so, what would be different ? Cam core material, lifters, dist gear, pushrod length ? OR ???

Any positive ideas along this line ? Or, does everybody think you should go for max streetable power & lowest ET your budget will allow ?

[Will]

There would be nothing at all wrong with running a mild roller cam and yes, it should last longer.

To my mind the cost/benefit analysis comes into play. A cam costs what it costs regardless of specs for the most part.

A mild flat tappet is far less expensive than a roller and if properly broken in, using quality parts and good oil, it will last a good, long time. So why spend all the extra money if you don't need the other benefits?

If you have the money, by all means, go roller, but I'm not sold on the integrity of currently available hydraulic lifters. These are aftermarket parts used in a retrofit application, not an OEM application designed from the ground-up to use rollers. Maybe there are some that are just fine, I just don't know and for the money spent I'd rather spend it on the tried & true for my mild cruiser.

[ponyakr]

"...A mild flat tappet is far less expensive than a roller and if properly broken in, using quality parts and good oil, it will last a good, long time. So why spend all the extra money if you don't need the other benefits?..."




"...in the last two years I haven't pulled out a flat tappet cam that I would have put back in - all were showing signs of failure. Some might have lasted another 10,000 miles, but there were a few where I don't know why they were not making noise yet. Everyone swears that they stuck to recommended break-in procedures, and were running a ZDDP additive..."

[berniearlta]

I have been exactly where you are right now not that long ago. No matter which style of cam you end up selecting, make sure you know exactly what your compression ratio is going to be. DO NOT ASSUME.

[dataway]

I might be missing something ... but seems to me, in stock applications that flat tappet cams and lifters have reliably done hundreds of millions of miles in total. I first took the OEM cam out of my GTO when it had 100,000 miles on it, still ran well, didn't make much noise ... and even had a lifter worn to the point that it had a pinhole in the bottom.

Without a doubt a roller setup is superior in just about every way, specially in OEM applications. But I would expect any properly installed, quality flat tappet system to do 60,000 miles no problem.

Is there a problem with current aftermarket flat tappet cams and lifters that is causing some drastic change in durability? I'm talking stock or very mildly built engines, not high lifts and high spring pressures.

In the vintage race motorcycles engines I've built (OHC), camshaft and rocker wear was a tremendous issue when running spring pressures probably twice stock, and rpms probably 30% higher than stock redlines. But the OEM valve trains in the stock engines would last many thousands of miles in stock, non racing scenarios. So I realize a performance valve train is under many times the stress of a stock valve train.

Hard to believe than any current flat tappet system properly installed is destined to fail in short order. Seems like people have been running them for many, many years without problems. Is there some major difference between current aftermarket quality and the quality and durability of a 60's era OEM parts?
JohnnyB

[ponyakr]

"...Is there some major difference between current aftermarket quality and the quality and durability of a 60's era OEM parts?..."



That's a great question. Most of the guys who build lots of engines seem to think so. Some say the cores are made of inferior material. Because of this, some recommend some sort of treating process to increase the longevity of flat tappet cams. Comp and others, offer such a process, call nitriding.

http://www.compcams.com/nitriding/

http://www.enginebuildermag.com/2011...er-technology/

There are lots of discussions of this, online.

http://www.fordmuscleforums.com/all-...cess-cams.html

Also, some have sited the use of inferior quality Chinese lifters, by many vendors. Then some simply blame the modern oil, for all the problems.

Here's a good explanation of why a flat tappet lifter won't work on most roller cam lobes.

https://www.lunatipower.com/Tech/Cam...tOrRoller.aspx

[Will]

American made Johnson lifters would be the only ones I'd trust. Any lifter from China or wherever, no thanks.

The heat treating of the cores is also an issue as ponyakr mentions. Do none of the cam companies heat treat their own cams?

[dataway]

You guys are making me think I should reinstall my 35 year old CC cam. It only has about 5,000 miles on it and looks as good as the day I first installed it.

[gtofreek]

I've only had 1 flat tappet cam failure in the past 10-15 years, or more. So, I don't feel they are failure prone. Most of the street engines[and, by far, Pontiacs] we build still get HFT cams. Nothing wrong with them if broken in correctly. I even have many out there that are running 130-140 lbs. on the seat, and 340-350 lbs. open, without problems. I don't feel it's a cam core quality issue.

[Steve C.]

Just a fwiw here, and nothing new. A tid bid for interest and not a recommendation ....

Clearly, there are many important traits to consider when looking for the perfect flat tappet camshaft, but none more important than durability. Addressing this concern, COMP Cams® pioneered the use of pulsed plasma nitriding to solve today’s flat tappet camshaft durability concerns.

http://www.compcams.com/nitriding/


.

[dataway]

Interesting, they seem to indicate it's a modern oil issue rather than a core quality issue.

[track73]

As far as cams go for a .030 over 455 with 9:1 (96 heads) compression I just installed an 041 with Rhodes and 1.65 rockers. I idles fine with a slight lope and has a ton of power. I hit the throttle in first gear and it got to 4500 so fast I couldn't get to the shifter quick enough.

[Karck]

Originally Posted by ponyakr

But, what about the guys who never plan to take their car to a track at all ? What about those who just want a mild street engine, which has a smooth idle, and plenty of vac and low end torque, but at the same time want the reliability, longevity, and other advantages of a roller cam--similar to what most folks want from any new vehicle's engine ?

This is what im considering for my engine alot. I want my engine turn effortlessly whit minimum friction to have it last long! But the price and rumors about lifter problems keep me at bay. Also already mentioned that it needs more spring pressure means that other valve train parts are gonna wear faster, is it worth trade off after all? Could i use same springs as in flat tapped if i just used flat tapped specs ?

[gtofreek]

You cannot run hydraulic flat tappet cam springs on a roller cam of any sort that you can buy for a Pontiac. They need more spring pressure due to their lobe design. Without that pressure, you will due far more damage to your valve train, and engine than the spring pressure will ever do.