Oil restrictors?

[Guest]

I wanted to install oil retrictors in my olds 455, but the machine shop told me with hydr. lifters that I should beware, does anyone have any information on this subject.

Thanks

-bob

<img src="http://www.aaca.org/ubbthreads/images/graemlins/confused.gif" alt="" />

[NTX5467]

When an engine's oiling system is designed, there are certain priorities as to how much oil goes where, when, and why. In a street oriented engine that seldom sees higher rpms and has hydraulic valve lifters, the lifters and cam area can get oil just before the main bearings do. Therefore, when the oil level gets to the danger level, you'll hear the valve lifters clicking and know to check things. Other engines will feed the crank first or at the same time as the lifters and cam area. These engines typically will have greater performance potential as the crank receives oil with a higher priority than other engine areas.

Perhaps a good illustration might be the small block Chevy and the Chrysler 350/361/383/413/426Street Wedge/440 big block engine families. In the Chrysler orientation, the cam area receives the oil first and then down to the crank. The possible orientation MIGHT have been that a typical Chrysler customer might hear the clicking of a valve lifter before they'd notice the THUMP of a main bearing. While these engines proved themselves worthy higher rpm motors in law enforcement duty for many decades, they typically did not see more than about 5500rpm for extended periods of time (that was typically enough to allow for approx 140mph to speeds in the police cars they were installed in with 3.23 gears).

For higher performance build-ups of these motors that would have mechanical lifters for upwards of 7000rpm capabilities, there would be a reduced need for oil in the camshaft area due to the solid lifters. Therefore, restrictors could be placed in the oil feeds to the cam area to reappropriate additional oil to the crankshaft area. If it didn't go to the cam/lifter area in quite so large volumes, then it would be forced to go to the crankshaft area. There was also a complimentary machining operation to enlarge the oil feed to the oil pump and install a larger oil screen in the pan.

The small block Chevy motor was a natural for higher rpms and had factory versions with solid lifters for the Corvettes, from the factory. Therefore, in the orientation of "no cost" modification to cover all engine choices on the engine assembly line, the Chevy engineers designed an oiling system which would feed the crankshaft area first and still put plenty of oil to the cam/lifters to supply the needs up there. As a result, one block casting would work for a 283 4bbl Power Pack or a solid lifter Fuel Injection Corvette. Plus, if the owner desired, the Corvette's solid lifter valve train could be put in the existing passenger car engine with appropriate changes to the fuel induction system for increased performance without any machining operations.

I'm not sure what the oiling priorities are for the Olds engine you have, but I hope my information might help you understand why it might be advised against to put oil restrictors in an engine with hydraulic valve lifters.

If oil to the lower end of the engine is a concern, you might consider putting in a high volume oil pump, but with regular pressures, instead of oil restrictors. Why not increase the oil pressure with the high volume pump? The oil pump is an internal power consumption item of the engine. Therefore, what power it doesn't take to run it can get to the flywheel for greater performance--not to mention fuel economy. Similarly, using an oil heavier than 10W40 or regular 30 -- with modern oils being what they are -- probably should not be necessary and will similarly load the oil pump more with a resultant power decrease.

It is a known fact that the bottom end of those Olds engines was probably the strongest one in the whole GM engine family line back then. The old 394s were the basis of many blown fuel race engines in the '60s too, so I suspect that what's in those blocks, even the later versions (which spawned some awesome experimental "future production" engines that never saw the light of an assembly line), might be plenty fine for a strong street engine, but I'll defer to the Olds experts and their recommendations on that.

Just some thoughts,

NTX5467

[Guest]

Thanks for the info. That did clear up my concern. This motor will not see more than 5500 rpm, as it will be a daily in town driver.

-bob <img src="http://www.aaca.org/ubbthreads/images/graemlins/smirk.gif" alt="" />