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Hydraulic tappets

Posted: Sun Jan 06, 2008 8:27 am
by pixbo
Hello! I am a Swede who is putting a Rover v8 from an early Range Rover into a MGB GT-69. The car is going to be a race car looking like an old racer from that time.

I am doing an overhaul and just noticed that half of the tappets are solid, they don´t give after when i put pressure one them, but the other does.
The are new, but have been stored for about seven years.
Since I have never worked with hydraulic tappets before, I better check.

I know howe they work in theory, and that oil eventually comes into the annular grooves, but what about when I start the engine fist time?

Posted: Sun Jan 06, 2008 9:24 am
by ChrisJC
You might be able to take them apart to see if they are free?

Chris.

Posted: Sun Jan 06, 2008 9:27 am
by winkle
Hi pixbo,

I think it would be an idea to leave them in some thin oil overnight just to make sure none of them are seized/rusted inside after being stored for that long.

Are they standard lifters or a performance type?

Posted: Sun Jan 06, 2008 9:34 am
by pixbo
Okay! They are standard tappets. Should I try to fill them with oil?

Pixbo

Re: Hydraulic tappets

Posted: Sun Jan 06, 2008 11:00 am
by sidecar
pixbo wrote:Hello! I am a Swede who is putting a Rover v8 from an early Range Rover into a MGB GT-69. The car is going to be a race car looking like an old racer from that time.

I am doing an overhaul and just noticed that half of the tappets are solid, they don´t give after when i put pressure one them, but the other does.
The are new, but have been stored for about seven years.
Since I have never worked with hydraulic tappets before, I better check.

I know howe they work in theory, and that oil eventually comes into the annular grooves, but what about when I start the engine fist time?
If the lifter is full of oil you can not press the centre section down at all, it is quite likley that some have leaked out their oil as they were under pressure from the valve springs, these are the ones that you can press down.

If you are doing a full rebuild I would dismantle each lifter and clean them out, re-assemble them with NO oil in them. When you re-assemble them you need to place the internal spring on the centre piston and hold it in such a way that the spring is pointing upwards, then lower the outer sleeve over the spring and piston. Push the two parts together so that the spring is under some pressure, then fit the snap ring. This method ensures that the inner spring is located correctly.

You need to put each lifter back in the same hole that it came out of if you are re-using them.

The reason for not using oil is that you can now check the pre-load using varrious pieces of wire. 40-60 thou is the usual given range but if you want the motor to rev well over 5k then 20 thou is better. When checking the pre load you can push down on the pushrod end of the rocker to help gauge the preload gap.

To prime the lifters you can spin the oil pump using a drill, you need to do this anyway on a re-built motor. To prime all the lifters spin the pump for 30 seconds then crank the engine 1/2 a turn and spin the pump again, do this 4 or 5 times.

HTH,

Pete