BBC .904 lifter

When is it time to step up to the 904 on a bbc ? I've been killing lifters 20-25 psi boost 350# on the seat conv. head manton 7/16 rods T&D shaft rockers 7500 rpm.
Made 1 pass and killed another new Morel have tried Isky and Crower ?? & how much will it cost to make them fit. Thanks Craig

 

comp cams severe duty with high pressure oiling

 

Craig, we've had really good luck with the 66291H from Crower. ( .842 dia )

We use close to the same spring, maybe a little more, but, we run it in a circle boat at 7000-7500 rpm for longer races than the drags ?

 

We are having the problem on the exhaust,11.5:1 compression 20-25 psi depending on the tune. Was also wondering if the xdi waste spark ignition may play a part in this it fires on the exhaust stroke as well ?? We have ran the hippo crowers but still killed them.WTF Thanks Craig

 

Well hmmm, we are 10.25 at 25 lbs. Knock on wood, two years in the circle boat now ?

 

Lifter issue

How stiff are your pushrods? Need to be .160+ wall thickness.
Run crower BBC lifters to 10,000+ with a scew blower, no problems.

 

I went with the .904" Morels in by BBC just because it was a fresh build and in Edmonton it cost me right around the $1000.00 mark to have lifters bored and bronzed bushed.

 

I have been using the crower lifters for years without an issue at 45# of boost

 

I'm not sure how thick they are they are 7/16 manton Terry RIP said I'll never bend one.

 

I think Robert has the best thoughts so far !

 

lifter

probably something is pissed off in the combo. Big ignition timing lead will load the exhaust side harder. We had an Oddy cam that murdered valvetrain even with .904's unless you ran pretty slow timing. We had the exhaust side reground and it was happier.

 

"the Crane lifters are now produced on new precision machining centers that hold much closer tolerances than previously possible with the former equipment. That's enabled more consistent outside diameters, and better concentricity. Materials have been upgraded, and the same wheel/needle/axle assemblies come from the same recognized bearing supplier as previous. The folks assembling them have better fixtures and are familiar with the processes and quality needed. Overall, a higher quality part than previously supplied. Are they unbreakable, no. If the lifter bores are not sized properly, or not perpendicular to the cam, or if the cam lobes have any taper, this can quickly cause issues. If a stable cam lobe is not used, as has been noted with a number of the "just like Crane" grinds we've seen, that can also lead to problems. Any broken roller lifter, regardless of brand, can easily be the result, not the cause. Regards, Chase"

 

That was my first thought also. I had issues with the exhaust side on a wedge combo before and a change of the camshaft helped out the situation.

 

Another set of variables that have to be considered nowadays are the resonanant RPM points of the valvetrain. This traditionally has not been much of an issue in drag racing, as the RPM's are pretty much constantly changing (passing quickly through these points), and are not being maintained at any one level. However, more folks are using a starting line rev-limiter, where your engine is held at a very steady RPM for a few seconds. If this RPM is at one of the resonant points, you now have the potential to really tear up valve train parts. During this time, valve train separation will usually occur, basically causing a severe hammering of all of the components. Valve springs/retainers/locks, rocker adjusters, and the lifters are the most common victims. Your damage will be initiated before the vehicle even moves. These RPM points can be calculated by knowing all of the specifications of the exact cam grind, weight/mass of each component, rocker ratio, inertial value components of the rockers, exact valve spring specifications (wire diameter, number of coils, diameter of each coil, etc.). Just changing the valve spring pressure will not shift these points, but going to a different spring having different characteristics might. Some folks just use the cam profile and valve spring information to approximate these points, which can certainly be of help. It may just be a matter of raising or lowering your staging RPM by two or three hundred RPM's to avoid these areas, and reduce or eliminate potential permature failures. Regards, Chase

 

Craig... sorry I didn't get back to you on the phone. Been swamped..
Anyway... it is time. What lift are you running with what open pressure? Your pushrods still may be marginal, but your lifters are. I had this discussion with the big boat guys a couple weeks ago. Personally crower or morel. The Hippo or hppd or whatever oiling is a must. Also, when starting I immedialty bring rpm up to 2500 to 3000. Your lifters immediately get oil via splash if nothing else. Not restricted oiling with my dart block way less need than back in the day.
Our stuff sits so long between starts (weeks at a time) oil has drained down, off, etc.
Find someone with a cnc piece. NOT the older BHJ block true fixture. It was more than adequit in the day, way better stuff now. Rottler makes a killer CNC piece. I think Peterson does also, or maybe Rottler bought them... anyway.
Oh, what are you running for oil?
Wags

 

50wt Penn heated. Pulled it down lifter stuck in bore all the others still like new. We did hydraulic it on the back 2 cyl's with alk. once & Jeff (we call him Bam Bam the driver ) cranked it through the hyd. lock that may have been the end of it there. I'll know more when I get the time to pull the pan & look at the upper in that rod. The push rods are Manton 7/16 I paid Terry (RIP) over $600 smackers for them they are the least of my worries. Thanks Craig

 

Does this hold true for for a swap feet leave where you are holding the engine at a certain RPM and dumping the clutch also or is this more of a two-step related problem?

 

Yes, it would also apply to a "manual" (footual?) stage if you were holding it at a consistent steady RPM. Thanks, Chase

 

We do hold the same rpm for 8 seconds. This problem is KILLIN me !! This is the 3rd time. Each time I thought we had it solved.It's in a different spot every time. Thanks Craig

 

You never did say, is it killing the lifter on the intake or the exhaust side or is it random? Is it hurting the cam also? Is it possible that you are sending it into valve float?