2276cc, 12:1 CR, Roller-Cammed Daily Driven Oxyboxer

[Wally]

Very interesting!
So, what would be the solution in your opinion? Shorter lifters? Longer sleeves to support the lifters more upwards?

[Piledriver]

Fascinating...

I wonder how the V8 folk get away with it, the spring pressures and pushrod angles are far more jacked up in many cases.

Curious if it is just a matter of oiling...

I'm also wondering if GM uses sleeves in their aluminum block V8s lifter bores (stock) , Google hasn't found a definitive answer yet. (If so, what material?)

Good point, Wally, I vaguely recall seeing a Pauter block awhile back with extended lifter bores/sleeves... Pushrod tube mount blocks covered the whole affair, bolted to the sides of the block. (standard?)

[Stripped66]

Very interesting!
So, what would be the solution in your opinion? Shorter lifters? Longer sleeves to support the lifters more upwards?

The appeal of the Isky lifters (besides the severe-duty design) was the fact I could run a 9.3" pushrod. However, my initial thoughts are that if the pushrod cup were within the body of the lifter, like most conventional lifters, this wear may have been minimized.

As I mentioned in the previous post, what surprised me is that the wear was not consistent with side-load from the valve opening event. However, if you calculate the forces "levering" on the lifter from the pushrod angle, those are not terribly great, either...so I wonder if the wear may additionally be attributable to start-up, where the oil layer may have thinned. I dunno...gonna chat with Rocky about this one later this morning.

[Stripped66]

Fascinating...

I wonder how the V8 folk get away with it, the spring pressures and pushrod angles are far more jacked up in many cases.

1) Mileage.
2) Spring Pressure.
3) Pushrod geometry.

Production engines that see high mileage do not run high spring pressures. The Corvette, with it's huge titanium intake valve, uses a spring that puts out about 100 lbs on the seat. The lifter is probably a recessed-cup design.

Race engines that use similar spring pressures as what I'm using, or much much more, will never see the mileage that my engine saw in 9 months. This is equivalent to years and years of drag racing. Additionally, similar tall lifters for V8's offer offset pushrod cups to correct some of the pushrod geometry.

Curious if it is just a matter of oiling...

If so, I would've expected the 1/2 side to have more wear. This was not the case.

I'm also wondering if GM uses sleeves in their aluminum block V8s lifter bores (stock) , Google hasn't found a definitive answer yet. (If so, what material?)

I don't know if GM does this on production engines, but silicone bronze sleeves are not uncommon when using hi-po, keyed roller lifters.

[Piledriver]

Good points all.

Another thought is many/most V8 roller cam setups run 1.6-1.7:1 rocker ratios, so there may be a little less cam lift/lifter motion???
(On production engines, anyway)

[Stripped66]

Update:

I didn't snap any pictures of the lifters or bores. My camera was dead and I had to pack up the case and ship it to Rocky this afternoon.

Rocky's going to check out the lifter and bore wear and the plan is to remove the current sleeves, install new sleeves, and run the lifter that Pauter currently has made to their spec's by Crower. This lifter will have the pushrod cup in the body of the lifter and should alleviate the wear we are experiencing...this is, of course, if my theory that the side-loads reflected by the pushrod angle are, in fact, the cause.

This also comes at a great cost to Rocky's personal time, as much of the work will occur after business hours. I can't emphasize how grateful I am that he's agreed to tackle this problem given my rediculously short time-frame. It will truely be the difference between having a running car when I move to Delaware at the end of the month, and letting the car sit for 2 years after my research position has ended.


Now, update on the heads:
The intake valve seats have indeed sunk; the exhaust seats appear fine. We are moving forward under the premise that they may have stopped sinking/shifting around. For now, that assessment is fine with me and we'll continue to keep an eye on it as the engine accrues more miles. The intake guides are also toast, so Darren is going to replace the guides and perform a valve-job. We're not sure if the valve guide wear is due to the seats shifting around or running the Scat rocker arms when I initially ran the engine (the "swiper" style rocker tips can cause significant side-loads on the valve stem/guide, especially with this much spring). So, maybe this wear would've been minimized if I simply ran my roller-tipped Pauter rockers from the start.



Hopefully, the end result will be a combination that is not only streetable, but daily-drivable for me and future customers. I knew from the start of this engine project that we were blazing a new trail, and understood the risks...from premature wear to complete and catastrophic failure. To get to the answer, you have to work on the problem. The wear is acceptable considering the knowledge we had at the start of the project. So far, I like what I see, and I'm pretty confident that these small changes will give us the desired outcome!

[Stripped66]

I spoke with Rocky today, so here's a few updates from my recollection of the conversation:

-the lifter bores were not in too bad of shape. They were about 0.0002" (2 ten-thousanths) out of round. Unfortunately, simply reaming the bores would not clean up the deep grooves on a few of the bores.

-some of the deeper grooves *may* be the result of the roller wheel having too little chamfer; combined with the sideplay of the wheel on its axle, the edge of the roller wheel was able to wear a deep groove into a couple of the bores. This may be a problem with a few specific lifters in my set.

The plan is to remove the lifter bushings and press new bushings in. The new Pauter lifters should arrive at his shop tomorrow; check the depth of the flat-cut on the side of the lifter and see how much clearance we have with the current guide-block. I should see the case early next week!

So, I feel this is good news as I expected worse based on the wear patterns on the lifters and bushings. I suppose if it were not for the deep grooves cut into a few of the bushings, this might have bolted back together without complaint. Nonetheless, I'm hoping that the shorter Pauter lifters will alleviate the wear pattern that developed with the taller, Isky lifters...at least for the outlook of longevity on the street.

On the strip, where mileage is low and a 9.3" pushrod has a great advantage, the Isky's should fare well.

[Wally]

Thanks for your report!

A groove is probably not even bad for oiling either

Any data/pics of those Pauter rollers? Is their only advantage that they are shorter?

[Stripped66]

Thanks for your report!

A groove is probably not even bad for oiling either

Yes, and an extra bonus is that they are "self-clearancing"!!!

Any data/pics of those Pauter rollers? Is their only advantage that they are shorter?

There are some pictures of the Pauter's lifters about half-way down this page: http://pauter.com/super_pro.htm

I imagine that they are also going to be lighter than the Isky lifters, and the recessed pushrod cup is going to straighten the pushrod angle a bit (albiet, while running longer pushrods).

The Pauter lifter is actually less expensive when you consider the modifications that have to be made to the Isky lifter. The modifications are nearly the same, but Pauter has 'em made that way from Crower, while Rocky charges a unit or two of 'shop-rate' to modify the Isky's. Hopefully, the end result of these changes are less expense and less time for the modifications necessary to run a roller cam.

[Stripped66]

Case will be shipping tonight and I should have it back on Monday

[Stripped66]

Thought you guys might like this next pic...



New silicone-bronze bushings, new Pauter lifters. Rocky had to shorten the T-bars to fit the depth of the flat surface that is ground into the side of the Pauter lifters; the Isky's were retained the same way.

[Unkl Ian]

Excellent,thanks.

[redbluebug]

Nice! Thanks for sharing. Sounds like very good service from Rocky

[Passatman]

I have been reading this post for sometime now but forgot to ask, strippe what are the sleeves like do they still have any signs of the cross hatching on the sleeves.

[Unkl Ian]

...; the Isky's were retained the same way.

VW did basically the same thing on the 36 hp.

Only their lifters were not real rollers.
There had a rad like a roller,but there were solid.
An odd hybrid.Must have had wear problems.