Looks like another old thread on another forum. Evidently morels were most consistent.

It may seem like splitting hairs. But remember we are dealing with 16 lifters. So when you start looking at .0001x16= .0016 or .0002x16= .0032 or .0005x16= .008 The numbers start looking a little more interesting. Now let's say .001x16= .016 When you look at it like that and think of the leakage in the motor it really makes you think that it's worth splitting hairs in the lifter department. It's probably one of the most important clearances in the motor. Jesel recommends .0018-.0022 as I stated. We run them in the middle at .002. And we have found this works very well in the Marine environment. We have one motor that has 4 World Championships on it with the same Jesel lifters. Over .800" lift 6500rpm and every time the lifters are pulled for inspection they look like they have never been run... Should they be tighter? Based on our track record with them we will continue to run them where Jesel Rocomends. Now with that said we don't run everyone's lifters at those clearances.

On the .904 lifters and the .937 I run them on the low side as with the bigger bore more bleed off.

I did this build years ago for Kjell Adams Drag boat set National and World records ran for four years and it was called the Swiss watch. That had the Morel .904 roller lifters, Machined the cam tunnel to 55MM.
http://www.performanceboats.com/gn7-...is-straub.html

Using .904 lifters with an .810 wheel and .937 lifters with a .850 wheel keeps the wheel speed down and less revolutions around the lobe compare to a lifter using a .750 wheel.

Jesel Roller lifters are my first choice second would be Morel. Morel and Jesel there sizing seems to be a lot better then other companies selling roller lifters.

since we are splitting hairs,jessel wants .00188 to .00220.just saying.

Whats your thoughts on a .700 wheel in a .842 body

I think at that point we are going to need to know what temperature we need to take that measurement at. Elevation and the moons relationship to the earth is going to affect it as well.

Those are a Hydraulic roller lifters considered a stock replacement compared to a lifter with a .750 wheel is more for a performance applications.

Going to bigger cam cores and bigger rollers effects pressure angle in a good way. Less pressure angle happier lifters!!

http://performancetechnician.com/pdf...a-Lifter-2.pdf


Here is an interesting article about lifter bore truing, Look on page 52 Also having the cam tunnel to blue print should be considered.

http://digital.enginebuildermag.com/...1-ae5dfcff4c38

Whos valve springs where you using in the marine motors with 800+ lift? Was it a 55mm camshaft and 937 lifters? Thanks

I should probably read your attached links before asking however what is the rule of thumb with .904's and .937's on std core cams.

Great links btw but now my head hurts so I went to page 53...

Standard cam standard lifters. I believe it was a Pac 1326. I will check and let you know for sure tomorrow.

Any time you can reduce the pressure angle of the lifter is a big plus, More lift equals reduced base circle, Smaller base circle increases pressure angle which does not make for happy lifters.

Bigger wheel lifters pick up on your .020 .050 and all your numbers quicker and its a good to get with your cam grinder so they can grind the cam according to your wheel size being used.

Some of my engines I build their are classes where certain cams must be used and going from a .750 to .850 wheel makes a difference because it pick up on your numbers quicker.

What kind of power have you seen on a dyno going from a standard core camshaft to a 55mm and big lifters?
And one more question do you put .937 lifters in a dart BBC with out doing a bushing for the oiling? On a 55mm cam.

[QUOTE=CNC BLOCKS;4511360]Going to bigger cam cores and bigger rollers effects pressure angle in a good way. Less pressure angle happier lifters!!

http://performancetechnician.com/pdf...a-Lifter-2.pdf


Once you’ve made the move to roller
lifters, your choices and options get better.
Obviously, friction is reduced because you’re
rolling over the lobe instead of dragging over
it. Where the flat lifter is velocity-limited, the
roller lifter is acceleration-limited. You can
only achieve so much rate of lift before the
pressure imposed by the wheel on the lobe
initiates contact failures. The pressure angle
is the angle formed as the roller impacts the
lobe. The advantage of a roller is that you can
shorten duration while maintaining high lift, but
in doing so the wheel almost gets driven into
the side of the lobe on the opening ramp. By
necessity, the first point of contact has to be
something above the centerline of the cam
core, otherwise the lobe just tries to knock
the wheel off of the lifter. If you look at some
of the photos, you can see where the roller
wheel marks the lobe. There is considerable
side thrust generated and this will be seen
as increased wear in the lifter bushing, often
in an hourglass pattern, wide at the top and
bottom and at or near specification in the
center of the bore. Using a larger diameter
cam core helps reduce pressure angle, as
does using a roller lifter with a larger wheel.
If you use a larger wheel, remember that
while the lift will be unchanged, a larger
wheel will increase the effective duration
of the cam, opening the valve earlier and
closing it later. You will need to account for
this when you talk to your cam grinder.

should full force read this? seams like the answer to his 193 page cam lobe question........ thoughts anyone?

disregard my post didnt see you had already posted it a little earlier MT...
very interesting read though. kinda sums it up

Saw Joes thread, interesting info that answers things.. short duration high lift was the question from beginning....

My builds over .800 lift I do go to a 55MM cam core and .904 lifters. I have not done a A to B test between the two.

I machine a lot of blocks for other builders and engines shop can only go by their feed back.

I have a customer in Hawaii that has two Dart SHP Pro blocks with a 55MM cams and .904 lifters and no bushings one engine is 3 years old.

The only problem with bushings there is no way to clean the oil galleys out once installed.

Dart BB's have tall lifter bores and so far no problems, Never done a 55MM and .937lifter yet.

World blocks have to short of lifter bores to go to a 55MM cams some blocks the lifter bores are counter bored so much they are only 1.250 in length.

The 55MM cam and .904 lifter in BBC seems pretty common now.

I had some custom cam bearings made for the 55MM cam with one hole and a groove to control bleed off. All the 55MM cam bearings I have seen have 3 oil holes for that size housing bore it creates a lot of windage problems. I use these in SBC, BBC and SBF.

Here is a link on those cam bearings
http://www.yellowbullet.com/forum/sh...d.php?t=999434

I rarely see blocks to machine roller cam bearings any more seems to be a thing of the past. More HP with babbit bearings and less harmonics through the valve train.

Out shear curiosity, what happens when you reduce cam size and increase ratio on rocker? Whats the tradeoff? More spring or less .idk. Are there gains to be made or just moving issues elsewhere?

Dumb questions? ?? Or no real definitive answer.:offtopic::readinghelp:

Kinda funny you mention that buck. I think you will get to many different answers that will be debatable yet not an easy question to answer as build components etc will vary especially the cam itself. Some will say it will throw off the geometry and create problems. Others might suggest it's like a band solution for a poor cam choice. Others will say it just simply works great but chances are haven't even done back to back testing. In regards to trying to achieve a short duration high lift cam this is my opinion is or can be a better solution and easier on the lobes. I've personally done it in several different engines with some noticeable gains and some not. By going to 1.8's you also change duration slightly as well. So again I think every application will vary.

Assuming the heads flow well at net lift and if I was wanting a short duration high lift cam I would certainly go this route. I've personally seen engines run hard and get thrashed on with 1.8's with good valvetrain geometry run for hundreds of hours with no lobe wear or issues what so ever. Example custom cam from comp with 236/242- 667 lift with 1.8's nets at like 707. Now as we know with a bob cam that would never last.

So in a nutshell with example of cam lift and duration above I highly doubt a 236/242-707 endurance cam would last however with the 1.8's achieving the lift it definitely takes some wear issues off the lobe. Provided you have a good stable well aligned valvetrain I'm all for it. Again much what may work one cam certainly doesn't mean it will work with another. Lots of variables but nothing ventured nothing gained.

Thanks for the reply, im certainly no engine builder but I try to read and absorb as much as possible on here. Theres a lot of math for sure in the answer, was just wondering if adding to the fulcrum instead of the cam lobe to achieve the same result on a build would be easier on the valve train or harder.

There is no change in geometry with different ratio rocker arms. The distance from the trunnion to the valve stays the same. This distance is what influences geometry (longer arm better geometry). Longer arm sweeps less (think about it).The way to change the ratio is from the pushrods cup to the trunnion. The closer the cup is to the trunnion the higher the ratio (does not affect Geometry) But nothing changes from the trunnion to the valve. Because the cup moves closer to the trunnion the pushrod/lifter/cam lobe loose there mechanical advantage and put more force on everything from the trunnion to the cam lobe. If you look closely at the rocker arms being made there is no change in design to help compensate for the added load on the rocker. Higher ratio rockers DO NOT add duration. They DO however open the valve faster. Which is a ++. The faster you get the valve off the seat the more power the motor makes. Doesn't matter if it's 400hp or 4,000hp. So, it does have some advantages. you have to be careful when changing ratio that you don't run out of room for the pushrod. Higher ratio pushes the pushrod towards the exhaust. For the little bit of added lift you get stepping up to a 1.8 I don't think it's worth the added stress on the cam/lifters and pushrods. If you want that little extra bump in lift just put it on the cam lobe. Now if we're talking 2.0 ratio now we're doing something and at that point I think the +'s might out weigh the minuses.

NEVER said it would change the geometry. RE: duration increase... MEANT to say it will change duration once off the seat. I've personally seen it and had a degree wheel on an engine a time or two also. Should have clarified the duration.

Here's what my cam software shows, showing a 5500rpm, 540ci with AFR 325 heads. For the intake lobe. using a hyd tappet

1.7 rocker 1.8 rocker Degree of change
296.9 .006 296.9 no change
268.5 .020 267.5 -1*
242.0 .050 240.5 -1.5*
212.0 .100 209.0 -3*
161.0 .200 155.5 -5.5*
103.0 .300 90.0 -13*
.372 lobe lift .352
.622 valve lift .622
.158 lift at tdc .158

Thats the cam being designed around the rocker ratio that will be used. I can only speculate as to why the program does what it does, but my guess, is that there is a given valve movement rate that one may think is ideal. Lets say you had a cam designed for a 1.6 Rocker. And you go and put on a 1.9 ratio rocker. On a symetrical lobe. There's probably a good chance, you're gonna slam the valve off the seat on the closing ramp. That leads to valve bounce, tons of spring psi needed, and , prob beat the fuk out of the valve seats. As well as put more stress on the lifter and lobe. What certainly would change, is the timing events from a rocker change I would think. Not at the seat measurment so much, but at the .050, .100, .200, .300 etc. Plus lifter wheel diameter plays a role too.

I think thats why a cam grinder wants , or should want, to know what lifter wheel you are using, as well as what rocker ratio, when he is designing your camshaft.

very well said bb.as the rocker ratio increases so does the ware on the parts.it,s just the law of physic,s.

Anytime you increase ratios the biggest issue you have is the closing cycle , the increased valve lift acceleration also brings a parallel acceleration in closing . This most always induces seat bounce for the valve.

[QUOTE=dunnitagain;4512307]Anytime you increase ratios the biggest issue you have is the closing cycle , the increased valve lift acceleration also brings a parallel acceleration in closing . This most always induces seat bounce for the valve.
This was the focus of my question, that if you ruduce lift while increasing ratio to achieve basically the same thing, whats the tradeoff. Slamming the seat was my thought but wasn't sure. 1.7 seems the magic number on ratio, just curious what happened when you switch things up a bit.
Mt , thanks for spending your time to run that. Like I said previously, I'm here to read and learn, and occasionally ask a not too stupid questions. :stooges:

X1000000000000 Higher rocker ratio's eat up HP as well and do put more of a strain on cam, lifters and there is more valve acceleration as mentioned .

I knew there would be controversy over this and that's ok. I completely get why some may choose not to do and in some applications the HP rewards aren't worth the potential valvetrain issues. Yes I agree it may potentially add some strain. Done deal!!! Does it work and last on certain applications? Yes it does... I wouldn't expect everyone to agree however it is what it is. It can also just be used as a simple test to see if your engine likes the extra lift or not. Then order new cam accordingly. I've personally seen the cam specs and engine in question in earlier post get the livin dog chit beat out of it for years with worthy gain and no issues. So back to individual preference, build and components.

Anyone ever wonder why some cam companies even bother with different rocker ratios while advertising net lift? Even on BBC's.

I've used 1.8's permantly and flawlessly and I've also only used as testing purposes. Right wrong indifferent... I'd rather concentrate on the thread.