Thread:

Running 454 BBC

ttt

Originally Posted by Need4Speed77

Not enuff info on the cam. What is it? solid roller or flat tappet? Compression? Thanks

Comp 292H Hydraulic Cam w/ Solid Lifters Maybe they are beat out on the bottom by now.

the letters on the pass. side w/p pad tells hp & model

Originally Posted by OC2Vegas

Hey, thanks for trying to put something down that you obviously know very little about. Maybe you should do some research about the combo.

When the manufacturer is ok with the combo and National Automotive magazines have written about the benefits of using this combo maybe you dont quite know what your talking about?

I will even do the research for you... From: Hot Rod Magazine

Putting solid lifters on a hydraulic-cam will gain about 500 rpm on the top-end over hydraulic lifters due to the solid lifters' improved valvetrain control-unlike the hydraulic, solids have no bleed-down/pump-up problems. Some hydraulic-roller cams-particularly smaller grinds with 220-240 degrees duration at 0.050-are quick off the seat, but this tends to cause more instability on top. Using solid lifters, even with the existing hydraulic springs, enhances top-end stability and fights the onset of valve float.

Successfully running solid lifters on a hydraulic profile requires some amount of valve lash (a solid lifter cannot run at zero lash or be preloaded). This lash effectively reduces cam duration, especially at low lift off the valve seat (see table). With less duration, peak torque and power occur at lower rpm than would normally be the case for the given combo when running a hydraulic lifter-in other words, the cam acts smaller.

Exactly how much lash is required varies with the specific cam profile, as well as the material the block and heads are made from. Too little lash and you could burn a valve; too much and the valvetrain gets very noisy. Generally the amount of hot lash will vary between 0.004 and 0.015 inch. Such tight hot-lash settings cause problems with aluminum blocks and heads, which see considerable thermal expansion between cold-start and normal operating temperature, so running solids on a hydraulic profile isn't recommended with all-alloy engines. Generally, aluminum heads on an iron block work out OK, with lash expanding about 0.012 inch from cold to hot. With iron heads, expect about 0.008-inch growth.

The more aggressive the lobe, the tighter the lash needs to be. The tighter the lash, the more thermal expansion problems must be taken into consideration. For example, Comp Cam's older Magnum hydraulic-roller grinds usually run fine with solid lifters at 0.012-0.014-inch hot lash. But its newer, much more aggressive Xtreme Energy hydraulic rollers get very noisy over 0.010-0.012 hot lash, so Comp recommends 0.006-0.010 lash settings. When lashing the valves, set them at 0.004 inch cold, then warm up the engine, and recheck it hot. Fine-tune lash settings within the preceding recommendations if the valvetrain is too noisy. Once satisfied, let the engine cool down again and recheck the lash. In the future you can accurately cold-lash the motor.

Some classes restrict competitors to hydraulic lifters. Cheaters have been known to run hydraulic lifters on a solid profile. Because they have no quiet lash ramps, solids make for better race profiles. If you take hydraulic lifters and put them on a solid profile, they generally run better than they would on a roughly equivalent hydraulic profile, generating more area under the curve. Hydraulic cams in general are quicker in low-lift, low-rpm, high-endurance applications. Race motors don't care about vacuum and throttle response; they care about area and rpm. Putting hydraulic lifters on a solid grind raises the rpm points at which peak power and torque occur compared to using solid lifters on the same solid cam. However, the actual power and torque peak numbers at the higher rpm points will be lower using hydraulic lifters. That's because the hydraulic lifters installed on the solid cam are slower off the seat, even though they develop more overall duration. Effectively, the hydraulic lifters installed on a solid grind act like a bigger (but slower) cam with very little increase in flow capacity (no more air, but more time to breathe). In terms of numbers, this means a 249-degree-duration (at 0.050-lift) feels like a 255-degree cam.

To successfully run hydraulic-roller lifters on a solid-roller profile generally requires that the solid cam be a tight-lash (under 0.020-inch hot) profile in the first place, with less than 30 degrees difference between the 0.020- and 0.050-inch duration specs.

Duration Vs. Lash
This shows the change in effective duration at the valve from different valve-lash settings on a Comp Cams Xtreme Energy No. 3315 lobe profile. It assumes1.5:1 rocker arms.

	Valve Duration at Lash
Lift	0.004"	0.008"	0.012"
0.006"	279.7	273.6	268.6
0.020"	262.5	258.9	255.6
0.050"	240.9	238.6	236.5
0.200"	183.2	181.9	180.6

Comp Cam's older Magnum hydraulic-roller grinds usually run fine with solid lifters at 0.012-0.014-inch hot lash

Like how it say USUALLY. Been there and done it. Never worked for me or some others I have seen. Maybe you got lucky. Good Luck.

Originally Posted by EVILFORCE

Comp Cam's older Magnum hydraulic-roller grinds usually run fine with solid lifters at 0.012-0.014-inch hot lash

Like how it say USUALLY. Been there and done it. Never worked for me or some others I have seen. Maybe you got lucky. Good Luck.

Maybe I got lucky or maybe you set it up wrong?

I noticed you did not support your BS statement with any data about what you were running that was either setup poorly, with cheap components or just a bad understanding of what you were trying to do.

Either way, good luck with sticking your head in the sand when it comes to there being multiple ways of doing things!