1) Theory - Assuming stock lifters are in good shape, how much pressure/revs can they take before its time to pick a different cam/spring combo?

2) Real world - Could a stock lifter take 420lbs pressure along with 7k rpms in a drag race application (short bursts) for any length of time? IOW, tearing it down and inspecting every ~10k miles or so.

TIA,
Ryan

 

I've run 150/430 on hydraulics before without too much fuss. Wasn't a factory lifter so I don't know what to tell you there. I'm thinking they'll be just fine but I'm hoping someone with actual experience will chime in too.
What spring diameter are you working with here?

The problem with lifter collapse isn't really about the spring pressures as much as it is about making sure the oiling system is up to the task. Any aeration of the oil is gonna cause serious problems. A good anti-cavitational oil pump would be a necessity... eliminating windage, etc.. You have to look at the oiling system quite a bit more when your aim is to make 7k sprints.

-Mindgame

 

Mindgame: Springs are 1.460" OD. They are Comp 977s.

This combination is going to be on a stock LT1 shortblock. A good friend of mine ran healthy rpms (< or = 7000) in his stock shortblock for a while without any problems. He seems confident about my setup being ok as-is. With this in mind, I'm going out on a limb and assuming that the stock shortblock's oiling system is up to the task?


Ryan

 

I'm following you Ryan.

I'd want an aftermarket oil pump or at a minimum, I'd blueprint the factory unit to make sure everything is up to snuff. I mention oil aeration because I know there are quite a few guys in here who like to use oil additives, some of which are notorious for 'foaming'. Those are a no no..... they've caused some problems for people at the track.
There's no dount that factory oiling has gotten better over the years and for 7k are probably up to the task.

Your game-plan sounds good to me though. Just keep a close eye on things... check the valvesprings routinely and examine your oil filter for signs of excessive wear. An oil filter can tell you a bunch.... as can a routine oil analysis.

Best of luck!

-Mindgame

 

The CC #987 (138@1.750", 344lb/in) will work with factory lifters. The #977 (133@1.850", 441lb/in) seems borderline to me, but I have never tried it. I have always used the conservative rule of thumb that hydraulic lifters should be limited to 350# open. I know people using #985 (164@1.750", 333lb/in) to get more seat pressure. This is still <350lb open though: 348lb@1.200" and I wouldn't hesitate to use them either. #977 hits 350lb at just 1.400" if installed at 1.850". Seems high to me.

Mindgame is more inclined to push the limits, from what I have seen

Rich Krause

 

LOL,
Yes, I've done some off-the-wall stuff over the years but keep in mind that most of this was carried out on dirt cheap bracket engines that I could care less about breaking. Just lots of head, lots of cam and the cheapest bottom end parts I could throw in there.
They didn't have to get me to work the next day.

On that note, I much prefer the more conservative approach like alot of you guys who drive your cars daily. Same thing for my "drivers".

-Mindgame

 

Your cautionary statements concern me.

Like many, I have the dual Crane springs (99893) that they recommend on their Lt1 cams. Seat press. is 130lbs @ 1.850, open 402@1.150. They are rated at 391lbs/in. It would appear that according to your advice we are on the risky side. I just hope my new Comp 850 lifters are up to the job.

 

I (and many, many others) have used the 99893 spring set without problems for a very long time now... I run .576" lift on an installed height of 1.850" on the stock roller lifters - that works out to ~348# at my max lift of .576", which is in Rich's acceptable range with a hyd. roller lifter... do you plan on running more lift than that with a hyd. roller cam? If not, the crane dual valve spring set is a great package.

 

Mindgame: thanks so much for the info .

Rich: re: springs. This is a strange topic for me. GTP recommended 140-145lbs of closed pressure, and "double that" much open pressure. However, Craig himself said I needed the 977 springs which supply almost 420lbs of open seat pressure. When I asked how they select valvesprings for a camshaft I quickly got the idea that there is more to it than matching up a few specs on Summitracing.com . I think listening to the camshaft designer would be beneficial for me.

The cam in question is the GTP6 grind - 235/242 .568/.592 114 LSA. This is a bit of an experiment for me. Although this is my daily driver, I am willing to make a few sacrifices (more maintainence) to gain a few more hp .

Somewhat off topic - I have seen the effects of improper valvespring selection and what it can do to a billet camshaft. After calling MTI about cleaning/smoothening down a tracked out camshaft they told me "they didn't know, because they only use billet camshaft and billet camshafts don't track out." I beg to differ .

Thanks for the help guys. Unless Comp puts out more 875 "R" lifters in the next couple of weeks I plan to go forward with the stock ones - or someone gives me a good reason NOT to use them.

Ryan

 

Oh sure, I agree on that!

A billet cam is a bit tougher but they'll die just like anything else. The diagnosis is hard to determine though. I don't doubt that it could be the product of excessive spring pressure but I'd be looking elsewhere first. Namely the tappet bore relation to the camshaft. Or maybe oiling problems in that area.
Alot of this kind of 'on-the-edge' performance stuff really calls for professional-level-competition-type engine work. If you can keep the tolerances to nil, everything lives a happier life and you can get by with stuff that is more 'abnormal'.
The thing about springs is that they store energy.... yeah, there's energy exerted on the opening ramp but there's equal and opposite energy on the closing ramp. So everything is in a balance there.
One thing that is well worth the money, is a rev-kit. Granted, they don't make magical 30 hp gains like alot of the makers want you to believe, but they are well worth the hassle. Not only do they help the springs, but they keep the lifters in the bore. Break a link-bar and you've got a big mess cause the lifter is gonna break or come out of the lifter bore (or both)..... there goes your oil pressure.

Got off on a tangent there, sorry.

Thing of it is.... stuff doesn't udually just break all of the sudden. It usually shows signs of destruction along the way. I go back to the oil anylisis and oil filter inspection. That in itself has saved me alot of $$$$.

-Mindgame

 

Have you tried calling Comp lately? Are they out of stock already? I posted this a while ago stating that comp R's are now available straight from Comp. They were on my doorstep 2 days after I called

 

allmotor: I am calling them tomorrow! I missed your thread. Thanks for the heads up!

Mindgame: Thanks a ton for the help thus far! How often would you recommend popping the intake off for lifter/spring inspection or having the oil analyzed?

Ryan

 

Ryan,
It depends on how often you make the 7k sprints.

I would take a look at the valvesprings every 6k. Seems like alot of valve cover pulling but its well woth the hassle. Understand that you will lose pressure after the first heat cycle so take that into account. If you find a loss of 10% or more, after the initial cycling, then you need to shim (providing there is adequate clearance) to get back to spec.

WRT oil analysis,
I perform oil analysis every oil change in my daily drivers. Using full-synthetic (Royal Purple) and making oil changes at 6k... filter changes at 3k. The cost for the analysis... another ~$20. On the more radical street cars I've owned, this has helped me find quite a few problems before they became disasters...... abnormal bearing wear, camshaft lobe wear, to name a couple. The analysis can spot every type of metal in the oil and compares that to a normal wear condition. So, its pretty obvious when something is out of wack.
The oil filter is something I check every 3k and I always cut the thing open to see what's in the filter element. You can buy a cutter from Powerhouse Products that does a very snazzy job of cutting a filter open... highly recommended. Maybe overkill on the checking I do but it has kept me from having failures for some 20 years now. I learned these tricks from an old racer I hung out with when I graduated from college. School of hard knocks kinda guy and one of the sharpest engine guys I've ever known..... but long gone.
If you're gonna be edgy, then it's best to be "over-observant" of things. Normal wear is cool and there will always be more with a hi-po engine but at least this way you rebuild when you get ready.

Best of luck.

-Mindgame

 

Mindgame: I have no problem popping a valvecover - especially the driver's side - which takes all of 5 minutes. I will definitely look into the oil analysis. Sounds like a great idea and a resource most of us should be using.

I would say a 7k blast (1st-4th gear) would happen maybe 2-3x a week in between the 350miles a of weekly driving (mostly highway).

Ryan

 

Ryan~ I run the Crane 99893 Springs and I love them..I also picked up some Comp "R" lifters from Craig when I was down there in Houston. I was recommended to use these springs from a couple of engine builders. I havent spun it above 6400 yet but I guarantee you it doesnt drop any power to the rpm..Ill get it on the dyno so I can verify that and also my a/f ratio. Glad ya finally decided on the GTP-6 cam..Ive had it for 2 yrs and its great..It hits fairly hard if ya remember
Gluck bro!

Cody