[zachscc]

Stoned, you can run moster lift cams with solid lifters if you want BUT you better make sure the rest of your valve train is made for it ie..rocker arms,valve springs and locks etc.. The chain is as strong as the weakest link right?

[nicefrog]

Thanks Ohio Dan, the XS268 is almost spot on for the duration and lobe seperation I want but I wanted less lift, I'm building everything around getting the most I can out of the 1.84/1.5 valves on my 305's heads and trying for peak power at 6000 rpm with peak torque not long before that (trying for 5000) I should be reaching the limits of the valve size before .5 lift so I wanted about .46 and .48 I'll see about getting a custom one made, 9 more sleeps untill Christmas (I'm getting David Vizard's budget chevs book for Christmas wohooo )

[stonedchihuahua]

yeah aren't the rockers the big thing... I know a guy who had a big lift cam and had a box of rockers in his trunk cuz he was young and poor... he started notching the rockers to get more life out of them... still broke them all the time though

[zachscc]

Rockers are usually the first to go with a big cam. Especially if you have a small block chevy as the studs are pressed into the heads and pop out like crazy when you increase lift. You should get the screw in studs if this is your motor(they are cheap ins.). The big blocks already have them stock. As you go up in lift you need to worry about piston to valve clearance so you don't bend your valves on the tops of the pistons.(Another mistake I have made before) You can usually put some silly putty or clay on the piston and then put the head on and roll the motor around and check, but I am not the one to be telling you exactly how to do this as it has been a long time since I have done this trick.

[stonedchihuahua]

well... shouldn't I have a shop cut the valve reliefs in some dome pistons for me??? or should i buy ones with them already in, and make sure they are deep enough

[zachscc]

Either way will work fine, you can have the pistons Fly cut for your cam or buy pistons all ready check with the tech guys at summitracing or where ever you buy your pistons I have put some pretty big (comp cams 292 Hyd) cams in and not had to have any fly cutting done to the pistons it just depends on your motor. By the way if you are shopping for piston you want 10.5 to 1 Compresion at a minimum if you want to run a big cam as the bigger the cam the more comp you need. I wouldn't go over that unless you want to run race gas.

[mustang66maniac]

solid lifters will not give you as good low end torque, they open the valve all the way, all throughout the RPM band.

Hydraulic lifters bleed off oil at low speeds so they take away some duration and lift at low speeds while filling up with oil at higher speeds to restore full cam lift and duration. This makes more velocity at low speeds, which means more low end torque.

The bad thing is that a good hydraulic lifter will start to pump up at about 6500rpms causing valve float. A solid lifter will never pump up and thus, has a unlimited rpm capablilty as long as the rest of the valve train is up to it.

This is why racers use solid lifters. If its primarily a street engine, i would definately use hydraulic lifters. Generally speaking, if you take 2 engines, one with a performance hydraulic cam, and one with a performance solid cam, the one with the hydraulic cam will probably make peak torque at around 4000rpm. The one with the solid cam will make peak torque around 5000rpm. There is a 1000rpm spread here which is definately noticable when you drive. I guess driving a solid lifter motor is like driving a 4 cylinder honda. Not much on the low end, but as soon as you get going, your really going.

I think I would rethink your decision to get solid lifters if its going to be mostly driven on the street.

[stonedchihuahua]

I was thinking 10.5:1 compresion with 4:11 gears with my current tranny (4.56s if I ever get a t-56) So yeah I'm split now

[nicefrog]

Alright now I'm really confused, even the most famous hydraulic camshaft maker here in Australia says that a biggest advantage of a solid camshaft is that it will make more low and mid range torque than any hydraulic cam, they have several times built and raced the fastest street car in the world so I had taken their word as camshaft gospel

This is the solid cam I've decided on for my 305

C.O.M.E Racing CSBS 900

Advertised duration
int 286
exh 319

.050 duration
int 242
exh 254

Cam lift
int .305
exh .320

Valve lift
1.5:1 rocker
.458
.480

Lobe seperation 116

[engineczar]

Don't be confused frog. First of all, low end torque is linked to the cam profile in connection with the rest of your engine combination and not neccesarily the lifter type. Solids allow a more aggressive profile without the sponginess of a hydraulic. That sponginess, as minor as it is can be like the face of a golf club and could launch the valvetrain into valve float. But you'd be surprised how aggressive you can get with hydraulics. Rollers allow even more lift per degree of rotation without the danger of the edge of the lifter gouging the cam.
Second, hydraulics don't pump up on their own above 6500rpm's. The reason they pump up is due to valve float and the lifter is just doing it's job and taking up the clearance.
The biggest downfall with flat tappet lifters regardless of whether or not they're solid or hydraulic is that the life of the lifter is tied directly to the combination of spring pressure, lifter rotation, and lubrication.

[ December 17, 2002: Message edited by: engineczar ]</p>

[stcam427]

lifter profiles that include hydraulic uses oil pressure to maintain zero clearance between the valve stem tip and rocker arm... solid lifters have no internal valving so you maintain a constant clearance at the valve stem tip to avoid clearance in the chamber and to allow for metal expansion...they feed oil thru them to the rocker for lubrication only...a quite solid lifter is bad news... roller designs keep the cam lobe from being scuffed by the lifter face thus allowing more hp by reducing friction and heat build up...not to mention the extended life of a roller cam.. both applications apply to rollers and maintenance on both types of lifters is still required...pushrods are different length,, and the difference in parts to install a roller tend to get pricy ,,, off set to more durable power..
unless practiced on alot of routine engine upkeep,,, best to run hydraulic and after initial break in and setting, should be low maintenance...

[stonedchihuahua]

The more I read the more I get confused <img src="confused.gif" border="0">