not to sound like a dumbass, but I've always been confused by cams. I have an 87 trans am with a cc q-jet 305 engine, what is in my car. and whats the difference between a roller cam and a hydrolic cam. and is there a difference in the lifters? what is solid and hydrolic and whats best.

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neko
'87 trans am
car in the making
angelfire.com/fl2/neko

 

A roller lifter has a little roller on the bottom of it, it's about ¼" in diameter and rides on a pin that goes through the bottom of the lifter. A "flat tappet" has a slightly convex surface, and the cam lobe is slightly tilted, such that the cam only contacts the lifter at one point, which is near the edge of the lifter; this is supposed to force the lifter to rotate in its bore as the cam moves underneath it, rather than just sitting still and getting worn in one spot.

A hydraulic lifter has a little chamber of pressurized oil that gets trapped by a check valve, thereby allowing it to take up a considerable amount of tolerance. A solid lifter is just that, a solid piece of metal; although most of them have a little "piddle valve" that meters the correct amount of oil through the push rod to the rocker.

Both flat tappet and roller lifters are available in either solid or hydraulic designs. In general, all-out racing applications use solids, and most street builds use hydraulics. Solid lifters allow more aggressive ramps, due to the lack of need for dealing with the check valve in the design of the ramp. Roller designs can be extremely aggressive because they do not have the geometrical limitation on ramp slope that flat-tappet ones do, that results in a compromise between valve action and longevity. Roller cams allow for a much greater "area under the curve" of valve motion without reliability concerns, and are the way to go when possible. They're always more expensive.

The cam is designed to go with the lifters; that is, you can't put roller lifters on a flat-tappet cam, or vice-versa; and you can't put hydraulic lifters on a cam designed for solids. Sometimes it's possible to put solid lifters on a hydraulic cam but usually this is not an optimum setup.

Your car has hydraulic lifters, and probably a roller system. Stick with it if it does even though the cam will cost twice as much. It's worth it.

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"So many Mustangs, so little time..."
ICON Motorsports

[This message has been edited by RB83L69 (edited December 03, 2001).]

 

ok thanks, so if my car is really a roller engine then my lifters have 1/4 inch rollers on the end. can these be reused in a new engine if not its goin to cost me huh?

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neko
'87 trans am
car in the making
angelfire.com/fl2/neko

 

Yes, if they are in good shape, they can be re-used. They do wear out, but they last a long time. You just need to make sure when you buy a cam that you get a roller one.

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"So many Mustangs, so little time..."
ICON Motorsports

 

I hear a slight ticking from my engine, is that a bad lifter, or rocker, or is that my carb, I haven't dealt with carbs much so I don't know thier sounds yet

 

the ticking in your engine could be an exhaust leak or maybe a bent pushrod, but i would check for an exhaust leak first. i had that problem not too long ago.

 

RB,

Aren't the rollers more like 1/2-5/8" in diameter? Just a detail.