Another cam q: solid vs. hydrualic

Solid lifters are noiser and require adjustment occasionally. They are best suited to high RPM applications. A flat lifter is a hydraulic lifter that has collapsed and requires replacement.

Personally, "sounding cool" is NOT a good reason to have solid lifters. BTW, lifters are either hydraulic or solid.

a flat lifter is flat at the bottom where it rides the cam as opposed to roller or mushroom

If you plan to drive the thing on the street at all, don't even consider a solid. They like to break rocker studs, bend push rods, and you have to get ungodly high spring pressure to run it. Which they wear out quickly, solids are not kind to valve springs Although they do make great horsepower....no...stop...ingore that last comment.

As SD said, solid lifters are noiser and require regular adjustment, while hydraulic do not. Now, if you do want the run up in the higher RPM range, but don't want to deal with the regular adjustment of solids, then you can get variable duration hydraulic lifters, also know as rapid bleed lifters; however, there is some extra info about them that you have to concider. At low rpm they leak down quickly and shorten the duration and peak lift at the valve. It is easy to assume that they simply reduce the duration at the valve, but there is more to it than that. The opening points of the valves remain the same; any duration reduction comes off the end of the lift curve. So if these lifters reduce the valve duration by 10°, the valve will open at the same time and close 10° sooner. If rapid bleed lifters are used on both intake and exhaust, it not only makes the cam act smaller, but also advanced. A good solution is to run the cam straight up (or 2-4° more retarded than optimum with regular lifters), which would build better top-end hp, and the variable duration lifters will cause valve timing to be more advanced at lower rpm, so the engine will not be as peaky. You can also run rapid leak down lifters on the exhaust side only. This would only advance the exhaust valve. If you had a cam that had a narrow lobe separation to build top-end power, and need some more bottom-end to use a lower stall converter, advancing the exhaust at low rpm would widen the lobe separation and reduce overlap. This would give more vacuum and more low-end torque.

-Shaun

streetstang67 said:

People talk about how solid cams sound cool? and hydrualic cams run smoother? I dont know anything about the difference between the two. Can someone explain? Which do you suggest for my engine?

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Most basic difference....solids can be run with a cam that has steeper ramps. Hydros require a little less steepness on the ramp. What that equates to is with a solid lifter setup the valve will be full open longer than with a hydro setup running the same lift and duration, which equates to more usable power at the rear wheels. Solid lifters however are noisier than hydro as stated previously and require a little closer attention to proper torquing and valve lash on the lifters.

If you think you are having fun trying to decide between hydro and solid now....wait till you find out that you have solid roller and hydro roller lifters too then you will really be confused what to run in your car

Streetstang67, if you dont mind a little adjustment once in a while runa solid lifter cam. I have one in my daily driver and I have no problems with it. I was also able to keep my valve springs. The cam I have is a comp custom grind thats 236/236 duration @50 with .528/.528 lift on a 108 lobe. I personally dont see what the big deal about mechanical solid lifter cams is, I mean, I only have to adjust it about once a month. Yes there is noise, its much like a ticking sound, but it is barley audible over my exhaust system. I hope this helps.

I am with hummer on this one. I have built three different V-8 Mustangs, and each one had a solid cam in it. The Hi-Po 289 also came with a solid lifter cam, and I know a guy who has the original engine in his 65 Shelby, and it runs HARD to this day.

I have never broke a valve spring (and as a matter of fact, the spring rates aren't much different than a hydraulic) bent a pushrod, or anything else. With todays locking nuts on the rocker arms, adjusting the valves is really not something you would do very often.

It IS a fact that hydraulic lifters bleed down after 5500 rpms, and you are not getting the full lift and duration of your camshaft when you are pushing your engine above that number.

I put a solid roller in my current 393, and will probably continue to use solids until a better design comes out.

My 2 cents.

87

blkfrd said:

I'm going to chime in on the side of flat tappet mechanical cams too. The same valve springs called out for a 280H Comp Cam are called out for 282S Comp Cam. I'm running a 282S in a 331 and I love it. The lash is adjusted tight at .019 instead of the advertised .022. Comp told me that it could be run as tight as .016. They also said the lifter would not dig into the cam lobe until the lash was adjusted to a rediculous .006 or .008 so therefore I felt safe adjusting lash to .019. I experimented with the lash from .018 to .022 and found that it ran nice at .019. The duration is effectively extended by doing this. It also quiets things down. I'm using Comp Pro Magnum true roller rockers.

Adjustment would be recommended every 3 to 6 months under normal conditions. More often if it is raced a lot. If they require adjustment frequently, than there may be something wrong with the valve train...geometry (pushrod too long or too short) is one cause. No one would buy solids if they broke rockers, bent pushrods, etc.

Solids will give more HP than a hydraulic cam with similiar duration and lift.

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Amen on the solid cams. How do you like that 282S? What does it idle at and what RPM does the engine pull to? That is a cool engine combination, I am intrigued by the 289 rods with the stroker crank.