not that a SR cam is good for everybody (hell, I didn't use one in my turbo motor, nor my blower motor) but the 2 things to make a SR live on the street is correct spring pressure(most people go overkill here) and oiling (on the roller).. lots of ways to do this.

 

What are the tricks to keep the lifters alive over the long run on a street engine which has to idle and low RPM cruise for long periods?

 

jordan show us the way. i want to run a solid roller, shaft rocker, cc 943 spring, custom intake, afr headed daily driven street monster w/ 500++ rwhp rwtq and 10sec NA passes! i know it can be done!

 

[QUOTE]Originally posted by OldSStroker

FWIW, and LT1 in a MGB? My MGB buddy would have a coronary! We're trying to get him to bolt in a T5 transmission. Geesh, 10X the hp would do him in.

Not quite 10X the hp of a stock MGB but 350 RWHP in a car that weighs less than 2300# - ought to be exciting. It looks a little strange also since there is an additional 11.5" added down the center of the car, gives it the proportions of a pumpkin seed. Hopefully, the 315/35/17 Kuhmo Victoracers will give it enough traction to use most of the power.

 

I knew you sounded familiar.

http://web.camaross.com/forums/showt...threadid=52084

Been thinkin' more about your chassis. I'll get back to you via PM.

 

You might want to fix that combo if you want it to live!

A street SR is a fine balance of things.

One of the reasons I said to fix that combo above.

SPRING PRESSURE!!!!, lobe profile and lifter quality are the 3 keys to making a SR street motor work.

Bret

 

those are a bit too much spring :-D

 

I'm going to chime in here with a voice of experience.

I personally broke three lifters running SR cams and also scored a roller on a camshaft. I sold my last (unused) SR cam and lifters to a friend and he also had problems.

All I say is be sure someone has figured out the bugs before you leap. These were all high dollar setups w/o cutting any corners.

Sure cost me a bunch on engine rebuilds. Excuse me but no more SR's for me untill someone has all the answers.

 

Aren't those the same springs you were using?

Considering I have the 943 Pacaloys in my engine at the moment, I'm very interested to hear people's thoughts on why they constitute "too much spring" for a street SR. Jordon, you were a long-time proponent of SR cams on the street and (at least I thought) the Pacaloys, so your change of opinion is somewhat puzzling also. What gives?

 

I've heard the excuse that I was running too much spring pressure also. However, other people have said spring pressure didn't have anything to do with it and they were also running the same springs w/o problems.

I've also ran oil restrictors and removed the oil restrictors, still with the same results.... broken lifters. Tried so many things and so many people had input, I honestly can't remember everything that was done, but for sure two of the broken lifters were Crane. The lifters I sold my buddy were Comp Cams and he had problems.

The only thing consistent is all the cams were done by Cam Motion.

Until someone has some real definitive answers besides luck....... it's HR time.

 

Well Jim the quality of a 943 Pacalloy is not in question here, it's a great spring, but at no point a decent budget spring since it costs about 100% more than a traditional SR spring.

The key here is lifers and springs, I think Jordan has seen too many SR setups destroy themselves due to too much spring pressure. Long periods of idleing and low RPM work will cause a lifter setup to have a lack of oil and that will cause roller needle bearing failure. There are a few ways around that, one is to not stress the needle bearings as much and the other is to rebuild the lifters every once in a while.

From what I have seen guys who have broken a SR lifter in a motor did so because they were using springs that could have gone on a Busch Series Car (not Nextel since they run flat tappets)

Now on the other end of this, the cam manufacture. Well that is partly the fault of the guy who picked out the camshaft. The lobe design (i.e. aggressiveness and ramps) and the lobe profile of the cam are going to be big determining factors to what else you need to run in your valvetrain. One of the nice things about Comp is that they have designed on the spintron, lobes that are ment to work on the street and live for a long time, most race lobes can't cross over and do that unless they have been put thru serious testing, it looks like to me that the testing has been done just the guys were paying to do the testing, not being paid for it.

One more thing, the springs guys have had to run are causing them problems and they over spring the application. To me it's the choice between to evils; have broken springs (which is the point for Pacalloys) or to have a broken lifter. Well once a lifter goes the block needs work so you have a tear down, new camshaft, new bearings and a set of lifter bushings to be installed. If a spring goes and you are running a rev-kit you can pretty much save a lot of the parts mentioned before if you shut the motor off fast enough. I know that I would rather replace a set of $130 springs than replace a set of $440 lifters and a $300 camshaft along with a rebuild and getting the lifter bores done at $500.

It's not that big of a mystery, but you really need to be honest with whoever is working on your camshaft design. If the car is going to be used on the street AT ALL then the camshaft is totally different, a race SR camshaft and a street/strip camshaft and valve train are more different than similar.

Bret

 

Well, it turns out that my cam is an "off-the-shelf" piece from Comp Cams (PN 07-000-9), and I'm running Crower Extreme Duty lifters (PN 66292). My build sheet says that my installed height for my Pacaloy 943s is 2" with 260 lbs. on the seat and 675 lbs. open, for what it's worth.

I guess I don't understand why the roller bearing of a hydraulic roller lifter and the roller bearing of a solid roller lifter would be any different at low rpm and idle. If solid roller lifters fail because of the high spring pressures involved, that's one thing (although they should be designed to work with those spring pressures, so I'm still puzzled), but to say that they fail because they don't get enough oil at idle and low rpm doesn't really make sense to me.

 

Ditto...

 

PN 07-000-9 is a Billet Cam designation for any "off the shelf" custom cam. I would be willing to bet that with the duration you are running on your cam lobes are most likely not a street lobe.

943's are not 260lbs @ 2.000" installed height, my guess is that if they are 943's then they are at 1.900" and have a 240lbs seated spring pressure.

The needle bearing material and heat treatment might differ in the bearings of your roller lifters but they are pretty close in design. What we are talking about is a big percentage increase (over 50% more load) at the seated spring pressure and over the nose on a SR setup like yours vs a HR setup. The load is what kills the lifters, and since you can't make the parts physically bigger (unless you go to a Ford or Mopar size lifer and increase the roller bearing size) so you are operating at the edge of the physical limit of the parts and material envolved. That's why they break. My guess is that there is a point where the pressure on the lifters is so great that the low oil pressure and low RPM don't allow the lifters to get oiled enough and the roller basically runs itself out of oil, they are not going to work very long once that happens. You can't change physics, you can change the parts and work with physics but you can't change them.

Bret

 

Is this your off the shelf cam #s......260/267 @ 0.050", 0.686"/0.686