CamarosRUS

im clueless on cams and have researched my butt off but am still pretty confused. are they 4 different types of cams or more? hydraulic roller, solid roller, hydraulic flat tappet, solid flat tappet???
also are flat tappet cams the same as mechanical cams?

and after that is quickly cleared up what are the actual differnces in the differnt types, maily between the flat tappet (mechanical???) and roller.....
also do hydraulic cams benefit over solid ones???

sorry for my ignorance and thanks in advance, to some this is second nature but i am still young and learning. i know there are many others in my situation that this thread would be of major use to as well.

dankhound

Those are the 4 basic types of cams. Mechanical cams are what is considered solid lifter. Flat tappet cams are cams that dont use roller lifters. The benifit of a hydraulic is that it doesnt require as much adjustment as a solid lifter because it takes up the slack that occures from wear in the cam and lifter.

Review
Flat tappet- Non roller lifters so there is limited lift capabilitys and more friction
Roller-Steeper lift profiles and less friction but more $$$$$$
Hydrolic-Less adjustment but cant, generally, be used for more than 6k rpm
Solid/Mechanical-Requires more adjustment but can handle higher rpms

CamarosRUS

ok so i guess i had it right (well kind of?)

there are two main categories:
Roller and Flat-Tappet


and two subcategories for each:
Hydraulic and Solid/Mechanical


which equals hydrualic roller, solid/mechanical roller, hydrualic flat-tappet, and solid/mechanical flat-tappet

now a few moew questions for anyone willing to help

when was the cut off date for roller blocks to start production. was it when they started the 1 piece RMS in 86 or for some reason a year later in 87???
and in my 1 piece RMS roller block i can use either a hydrualic roller or a solid roller cam right??


thanks very much dank that helped me emmensley (SP)!!!!!

dankhound

The roller blocks did come out a year later in 87. It was originally a hydraulic roller so i would stick with that. The cam may be more expensive but the lifters are cheaper. If you get a set of rhodes lifters designed not to pump up then you can extend that 6k "rev limit" higher.

CamarosRUS

rhodes??? is that a brand or type of lifter in general? as far as the hydraulic or solid cam is there a specific reason i should stick to the hydraulic? my engine will max its power at probably 6500 due to my stealthram but if you say so then ill stick with it for sure

ME Leigh

You can actually use any type of cam and lifter in any SBC. But you can only use the factory hydraulic roller cams in the factory equiped blocks which started in 86 IIRC.

Your 91 will have a factory hydraulic roller setup. I'd stick with that if i were you.

CamarosRUS

so i could use a flat tappet cam in my roller block? and IIRC to use the roller cams in older blocks some machining has to be done


another question i just thought of while i have everyones attention .......is there a specific type of head i ned to use for a specific cam? like a roller head or flat tappet head???

ME Leigh

The heads are the same but different springs are required to work correctly with the type of cam and lifters.

Stekman

I'm bored, so here it goes:

Tappets refer to the lifters themselves. mechanical or hydraulic refers to the method of tension applied to the pushrod via the seat and internal mechanisms. Solid, the pushrod seat is resting against a inner step which prevents any movement, thus making it "solid." Hydraulic on the other hand has an internal spring and a series of valves which allow the pushrod seat to be depressed. Of course, then the flat or roller part refers to the cam mating surface of the tappet. flats are just that, flat. While rollers have, well rollers.

You don't HAVE to stick with hydraulic, you can go solid. however, hydraulics are generally have a low maintanance "Set it and forget it" approach, while solids need to be readjusted every so often. This reflects back to the pushrod seat. Solids need a small running clearance whereas hydraulics do not. Over time this lash setting will change on solids and you need to readjust it. For some that is no big deal, for others, its annoying. Also, because of this little internal adjusting mechanism, hydraulics can be set at any engine temps because the internal valving compensates for thermal expansion whereas solids do not.

As for the Rhodes fast bleeds, i am not really a fan of those, or any "Fast bleed" design. TO me, the are reserved for the people who over cam their engine and dont match the cam with the compression and use too large of a cam. The fast bleeds can improve vacuum and increase cyl. pressure/engine performance in the lower RPM's. They are also a bit noisier. IMO, they should be left to the people who have poor cam selection and think "bigger is better" in terms of camshafts, when the cam requires more compression than what the engine really has.

You dont have to machine the lbock to use a roller cam in a pre roller block. They have what is called a retro fit roller setup. However, retro fit kits are a tad on the expensive side.

passenger vehicles got roller blocks in 87, trucks got them in 96.

Expanding off of dankhounds price thing, yes roller cams are more expensive because they are usually made on steel blanks whereas flats are cast on iron blanks. factory hydra roller lifters are cheaper, yes. Cheaper than hydraulic roller RETRO-FIT lifters. Not cheaper than flat tappets.

Yup, heads are the same, springs are different. Springs differ, to a point. Hydra flat tappets can get away with the lightest springs (lightest in terms of the 4 tappet variations, NOT in overall spring pressure). Hydraulic rollers use a bit more pressure, but still not a lot as you do not want to collapse the lifter. Mechanical flat tappets can use the same springs as hydraulic rollers. They have slightly more aggressive ramp rates, but nothing roo radical that requires massive spring rates. SOlid rolers have crazy spring rates. I have a solid roller and springs. The springs i have are Isky 9965 springs which have about 245 lbs of seat pressure and 585 lbs open with a 570 lb/in spring rate. Massive springs to control massive ramp rates.

Thats my 2 pennies on the issue, for now.

CamarosRUS

whoa thats a lot of good info there...im glad you were bored
it seems all the heads i look at dont have springs that can handle the lift i think i want and i will have to change them anyway so i guess i can pretty much open my head selection again.

thanks for the info guys, keep it coming!!!

Stekman

What heads are you looking at?

Perhaps more importantly, what lift are you after?

z92maroman

Keep in mind, you dont want to use a mech. cam, roller or flat, in your efi setup, unless you plan on deleting the knock sensor thru reprogramming the ecm, etc. The solid lifters will trigger the KS, and the comptr will retard the ign timing...no pwr!

Stekman

Uh, he's long since selected a cam...Comp hydra roller.

CamarosRUS

yea i went ahead with a lt1 version custom comp..........cant disclose the ever important specs since its such a power secret but i can tell you its got the 3315/3316 lobes 230/236 dur with .544/.555 lift.......oops that was everything