Just bought a 1969 350ci short block for my 1970 coupe. The engine is a 4bm with raised pistons and a solid lifter cam. I have taken the engine to a local V8 builder. He is rebuilding the block and supplying a pair of 1971 double hump heads. He said that I should put in a hydrolic cam as it would not be as noisey. I am looking for good performance and good driveability. What is the benifit of a solid cam to a hydrolic I am not very mechanically minded but I know the LT1 had solid lifters and put out 370 bhp. The suffix on the block is CEOA 08625 which a believe could be a warranty replacment engine.
Thank Mark.......

 

The Hydrualic lifter cam will be maintainance free and will work well to 6000 RRM(maybe a little more). The Solids will need to be adjusted periodicly and are capable of much higher RPM. The amount of noise will depend on the specified lash setting required for any partcular cam. Mine calls for .022" lash and is audible most of the time, but not too loud. When you start getting lash specs up around .030", it will be much louder. Personaly, I like the noise and it's more or less music to many of us. Generaly, the solid lifter cam will have a more agressive ramp design that is geared towards upper RPM power, but that will really depend on the cam chosen. If you are as you say "not mechanically minded", then you will probably be happier with the maintanence free design of the Hydraulic.
As far a choosing the cam itself, it will depend on what you are looking for. Top end power, or low end torque? Also, what is your rear end gear ratio and what tranny are youy running? What intake manifold do you plan to run?

Tom

 

A hydraulic cam is maintenace free but at higher spring pressures and high revs it will not work as well. A solid needs adjustments about once a year if your lucky and will outrev the hydraulic. If you want to install it and forget it go hydraulic. To me the slight tick of solids is music.
Regardless of which you install go with the recommended springs.
Are the double hump camel heads drilled for accessories? There are alot of better heads out there.

 

Solid Lifters are the simplest lifter design there is. All things being equal they provide more horsepower than hydraulic lifters. They also give more RPM before valve-float sets in(6000 RPM +/-500). Valve-float happens when the lifter closing velocity is too fast for the valve spring pressure. This causes the lifter to bounce. However, hydraulic lifters must have a certain amount of lash(space) between the pushrod and the rocker arm. This prevents the valve-train from binding. Lash must be set periodically every few thousand miles due to lifter wear. Hydraualic lifters also prduce a distinctive engine noise that has to be heard to recognize. Some people prefer this noise, others do not. In general a solid cam also shortens the duration compared to a hydraulic lifter by about 5 degrees.

Hydraulic lifters are used to make a quieter more "user friendly" valve train. They do this by using enigine oil to pump up a diaphram in the lifter. This in turn pushes the push rod up agaist the rocker arm. The valve train does not bind because the diaphram is allowed to partially collapse. This has the effect of creating a "hands free" lifter. They have zero lash and require little attention, if any, for up to 100,000 miles. By their nature however, they are prone to valve-float much sooner (~5000 RPM +/-500).

Solid Lifter: more hp, more RPM, more noise(music), more work.
Hydraulic Lifter: less hp, less rpm, less noise, less work.

 

Did you hear that they are coming out with a solid roller cam that will outlast a hydro roller on the street? That might be something to consider when it comes.

 

Solid lifters are for people who like to tweek their cars twice, or more, a year.
They are old technology. Yes they are better than Hydrolic lifters for all out performance. But if you are not running at WOT most of the time whats the point?

Roller cams are better. A Hydrolic roller cam will outperform the solid lifter in everything except high RPM and will never need adjustment.

 

MARK,Just my 2 cents , on an on going cam controversy.... & reference to April 1998 Issue of Super Chevy magazine.....they took a ZZ4 350 chev engine , with 190 cc Air flow reaserch heads, Endlebrock Perf Rpm intake, 750 holley....the following cams are all hydralic..... A 252 comp cam was dynoed at 348 hp @ 5000 rpm ,398 ft lbs @3800............the 268 comp cam = 380 hp @ 5400 &402 ft lbs @ 4100 rpm, ....280 comp cam =404 hp @ 5600 & 403 ft lbs @4400 rpm .... Finally the 292 comp cam = 431 hp @6700 rpm & 400 ft lbs @ 4500 rpm.....Comp cams now has the extreme energy series that out pull all the cams tested above, all hydralic, throughout the rpm range.........anyways Tourque IS KING & for a street driver the 268 seems perfect to me :crazy: just the thoughts of an old fart.............


[Modified by StrayDog, 10:44 AM 2/26/2002]

 

StrayDog-
The ZZ4 is hydraulic roller, not hydraulic flat tappet. Add the benefits of solid to a roller setup (mechanical roller) and you'll have a motor that does quite serious business.
Hydraulic roller is the way to go for a daily driven street car, especially someone who doesn't want to push thirty pounds of smog equipment out of the way every time he needs to check the valves. :) Hydraulic roller is different than hydraulic flat-tappet, and in terms of power is slightly better than a solid flat-tappet, but not as good as a mechanical roller.
-Steve

 

I went through this decision process a few times. I talked to engine builders who specialized in small blocks like the ones I built. I have also been through several iterations of cam/lifter hardware myself, including trying off beat stuff, such as Rhoads lifters.

Hydraulic lifter-based valve trains rely on oil pressure to pump up a small piston in the lifter and keep the valve train tight. This system works well, yielding a valve train that needs no lash adjustment virtually for the entire life of the engine. However, it places some limitations on how strong you can make the springs, because too strong a spring force would defeat the hydraulic pressure on the lifter piston. However, stronger springs keep the valves in contact with a rapidly reciprocating rocker arm to higher RPMs. Thus there is a tradeoff, and this is why the choice of lifter type helps determine the maximum RPM you can expect from an engine. You really don't want the valve train separating (called valve float).

Another consideration besides "hydraulic vs. solid" is "roller vs. flat tappet". This is perhaps a more important choice from a perspective of engine performance, because the maximum rates at which the valves can be opened and closed differ greatly between roller and flat tappet lifters. Plain and simple, roller lifters can slap valves open and slam them closed more rapidly than their flat tappet counterparts. In real-world terms, roller lifter engines generally idle better, have better torque, and have perhaps give a bit better top-end as well. Think of it as widening out the driveability. Roller tappets are partly why more modern engines have flat torque curves across a wide range of RPMs.

Given all the above, I opted to build my valve train around a solid roller arrangement. That is, the lifters have rollers on the bottom, but are solid inside - no hydraulic pistons. One engine builder I spoke with said "if the hydraulic rollers made as much power the racers wouldn't be using solid rollers". To offset the need for frequent valve lash adjustments, I use big block rocker studs (they're thicker and don't deflect as much) and of course matching rocker arms.

People talk about quiet engines, but a quiet engine has no place in a 'Vette, IMO. Hearing the valve train (it really isn't all that noisy) tends to elicit knowing nods and grins from other car nuts who know engines. I like those nods. :)





-Noel

 

steve..........I didnt reference hydralic roller / or flat tappet....only hydralic cam....the article was written in 1988............ :boxing , the magazine stated they began with a ZZ4 350 crate motor......as a starting point , the possibility exhists that in 1988 the ZZ4 then available , was a flat tappet cam,,,, anyways the dyno numbers were outstanding .....the 268 , was part # CS 268H-10, acordingly the Comp cam XE series has more aggressive ramps & is available as roller , but also as basic hydralic lifter....obviously the technoledgy has changed since 1988 & the XE series now available & roller series will produce even more H/P & Tourque. than the hydralic cams referenced in the 1988 article.......anyways Super chevy has good tech info................THE DOG :cheers:

 

Thanks for the advice,
The heads are drilled for accessories, and I have an edelbrock preformer intake to put on. Not sure what the rear end is but I think about 355.1 (3000rpm @ 60mph) Looks like I will go with the hydrualic. I am doing this on a budget or I would go for some nice new aluminium heads. At present my car is running a 307 block so this new set up should be a vast improvment on that.
Mark......

 

IF you are small CU IN , Suggest a 252 cam remember tourque is king ,,,,,,,,,, ref the 1988 articl4e i referenced ......again the 252 is wirth 1 hp per cu in , or possibly the 262 xe energy ,,,,,,,,, :seeya


[Modified by StrayDog, 4:29 PM 2/26/2002]