I’m running the Crane “High-Performance” HD roller lifters w/ the Comp XFI-292 cam, 918 Beehives, 3/8" pushrods and 1.6RRs. I’m experiencing some high RPM problems (slight miss, or flutter) as the engine RPM approaches the shift point in second gear (problem seams to occur around 6100 RPM) then the shift completes (2-3) at 6400 using the PCM programming. When I built-up the engine, the lifters were initially adjusted ½ turn preload past 0-lash.

In discussing the problem, one person I talked with (who is very experienced) though ½ turn past 0-lash was “too much” lifter preload. So before doing anything, I decided to call Crane’s tech line. The tech person at Crane told me I needed more preload (3/4 to 1 full turn).

Now I’m not sure which way to go with the lifter adjustment (more, or less preload), or if the lifter adjustment is actually the cause of the high RPM problem I’m having. Does any have experience with the Crane High-Performance HD lifters and what is your recommendation on the adjustment?

WD

 

Hey Warren,
I am dealing with an up top problem too, so keep me posted. I am running oem lifters roughly 1/4-3/8 past 0. Probably not enough on my part.

Replaced multiple optis, wires, plugs several times. New coils, two icms. Swapped valve spring once already. Going to get an ignition box next for s&gs.

I really don't think mine is float, its like it misses a plug or two then pics right back up and pulls higher.

 

1/4 turn is OK but your problem is most likely tune or valve springs,valve springs being the most likely.

 

Can you be floating just 1 valve? I always thought that valve float was like hitting a rev limiter and it wouldn't spin higher?

 

Yes you can and that would prove the rest were marginal.
Nope just a miss.

 

First, thanks for your input on my problem.

The 918 beehives are the valve springs Comp recommends with the XFI-292 cam. Also, the springs are new and they were professionally set-up by an experienced machinist on the AFR 195 heads. However, anything can happen???

On the tuning, Brian Herter (PCMforLess) did the tuning and from the beginning everything seemed perfect with the tune and the car was running great. Then the high RPM problem started and it now seems to be getting worse.

I guess I could also talk with Brian to see what he thinks. I don’t think it is an opti problem, as the opti is only about a year old with no street miles (weekend street-legal bracket car only). Again, I’m not sure the problem is the lifter adjustment, or valve train, just where everyone I talked with pointed to. Can the ICM cause a high RPM only problem?

Also, I'm running 12.2 to 1 compression, I wonder if plugs could be the problem (used up quickly)?

WD

 

I know crane claims they gain power with their lifters going with more preload. But I'm with everyone else on this, 918's probably can't handle that cam past 6k.

 

Pull the plugs and check the gap. If your using NGK plugs they wear quickly and may have opened the gap too far for a 12.1:1 motor. Second guess would be valve springs, the XFI grinds can be hard on 'em.

 

Loosen your lash and see what happens.

 

When you installed the 918 springs how close to coil bind did you come?

 

Man I don't wanna say it but for a while I have said that over 6000rpm and a XFI lobe just don't mix. I honestly think that's your issue.

Bret

 

I hear what you are saying and I know you're an expert on cams. However, after I assembled the engine and Brian did the tuning it ran “really great” then this problem slowly evolved and got worse. Therefore, if there was some inherent problem with the XFI cam lobe design, or valve springs I don’t think it would have ever run like it did (without any problems). Also, the engine was finished in October of last year and doesn’t have many runs on it.

I need to try some course of action to fix the problem (short of changing the cam and springs) and the 0-lash adjustment will be my first step. As Shoebox has pointed out, reducing the lifter preload is the “conventional school of thought.” Although, the tech guy at Crane told me to increase the preload for the Crane high-performance lifters (???). I also talked to Chad Golen and he said, “typically less lifter preload is what works.”

I really respect Shoebox’s knowledge and experience on LTs (plus he is from a neighboring state, for what that’s worth), so I’ll start with less preload and T-n-T this weekend and see what happens.

The first points bracket race is the following weekend (March 10), so I’ll still have a week to go the other way (more preload) if less preload makes the problem worse.

Additionally, I looked at plugs on the driver-side bank last night and they looked perfect.

WD

 

Shoebox, I forgot to ask. What is your lifter preload recommendation (thousands and what that equals in fractional turns) for my particular application.

Comp 292-XFI, w/ 918 Beehives and 1.6 RRs (I-242/E-248, I-.584/E-.579 w/ 1.6s)

Thanks
WD

 

Ya know that springs will loose pressure after break in. Some as much as 25lbs.
If ya adjust at small preload the recovery time is less when ya float the valves,they have less distance to pump down. With 1/2 or larger the will hold the valve open farther and longer causing ya to notice a miss.
Just because ya don't notice it with "0" lash don't mean it ain't happening. It just goes through it so fast ya don't notice.

Get some springs.

 

I guess the only way to check for a weak one though is to pull them all off and test them again?

I hate pulling springs with the heads on the car.