Roller lifter: cheap trick?
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|Ashley P |
I'm building a chevy LS series engine and comparing it to the Pontiac. I got to thinking about the cost of roller lifters for a Pontiac. Consider these interesting *facts:
-the lifter diameter of Chevy and Pontiac is the same.
- each PAIR of lifter bores are spaced about 2" on center (Pontiac and LS Chevy)
- LS lifters use a plastic "tray" that keeps the lifter from rotating.
- this tray could be cut to compensate for the different spacing between lifters of different cylinders.
The largest question to me is oiling. I know old Pontiac and old Chevy hydraulic lifers were different yet somewhat interchangeable.
I wonder if anyone else had explored this idea?
*facts: I have only a few minutes comparing these parts. All my claims need to be put to a micrometer.
|Steve C. |
|A Chevy style lifter has a lower oil band than the Pontiac lifter. But it can make a difference on the base circle of the camshaft lobe. Specifically when you get below a certain base circle O.D. as is necessary with cams above a certain lobe lift to achieve further lift, the oil band can be exposed on the bottom side of lifter boss with common Pontiac lifters, even factory GM Pontiac lifters.
That said many years ago I needed a solid roller lifter with a offset pushrod cup to be used in conjunction with offset intake rocker arms on my T&D shaft system being used. We used ISKY Small Block Chevy solid roller lifters with a 0.150" offset pushrod cup. Both Chevy and Pontiac use the same .842" diameter. For this use the oil ring situation was compatible with the base circle on the high lift camshaft. The one thing we had to change was the guide bar, also often called a tie bar, since the length on a Chevy and Pontiac are different. The type of SBC lifter we were using had interchangeable guide bars rather than encapsulated.
We encountered no issues with this Pontiac engine that made 699.9 hp at 6900/7000 rpm.
Related. GM engineers lengthened the lifter bosses in late-model small-block and big-block V8 engines to accommodate hydraulic roller lifters. The switch from flat tappets to roller lifters was primarily intended to reduce friction and to improve fuel economy on the highway. It had the additional benefit of allowing faster, more aggressive camshaft profiles that boosted horsepower in high-performance street engines like the LT1 and LT4 small-blocks
|Steve C. |
|Deleted- duplicate post|
|Ashley P |
|Steve C, thanks for that info.
Pontiac lifter bore is 1.2" long, the LS is 1.8". (Rough measurement.)
|Steve C. |
In the LS family, the plastic “buckets” register the roller lifters to prevent rotation. Other methods of preventing roller lifter rotation (on other OE and/or aftermarket applications/engine types) involve either a pair of lifters connected by a pivoting tie-bar, or more commonly, each pair of lifters being guided by a twin-cavity “dogbone” plate, with these dogbones being held down by a common sheet metal plate that features tensioned “fingers” that prevent the dogbones from moving.
Note that some aftermarket performance lifters may be a tad longer (to allow for higher lift cams) and may require the use of a 6mm-diameter spacer washer between the lifter bucket and the engine block. If required, these lifter bucket bolt spacers will likely be supplied with the lifters.