Reply to "Adjusting Solid Lifters"

> I was told that when the prior owner re-built the engine, he discovered
> that it was a 351C H.O. - so it has solid lifters like the '71 351 Boss
> engine.

Verify this is true for yourself. Some owners will see that there
cylinder heads have been converted to Boss style adjustable valve
train (screw-in studs and guide plates) and assume they have solid
lifters. That is not necessarily the case. You can run hydraulic
lifters with an adjustable valve train. If it turns out to be a
solid lifter cam, it may not be an HO part. Without looking at
the part number on the cam, you can set up a dial indicator and
measure the lift. The HO cam should be 0.490" lift on intake and
exhaust (with zero lash). I don't have the lash handy for the HO
cam. If you can get your hands on a Ford Mustang shop manual from
'72 or '73, it should have the lash ifo in it. Also, Crane makes
exact copies of the the Boss and HO cams in their Blueprint Series
cams. If you get an HO cam card from them, it'll have the lash info.
Be aware that some manufacturers provide valve lash at the lobe so the
lash figures must be multiplied by the rocker ratio (1.73:1 for a stock
351C) to give the valve lash at the valve. You can fine tune the cam's
performance with more or less lash.

Given that you don't know for sure what the cam is or what the
lash should be, prehaps the best course of action is to set lash
0.025" cold then see how noisy it is and adjust the lash from
there until you get the sewing machine sound. You can set one
cylinder hot then let the engine cool and see what the actual
difference is hot to cold.

The valves must be set when their lifter is on the base circle of the
lobe. At this position the valve is closed and there is no lift taking
place. The SAE method (a.k.a. the EOIC method for Exhaust Open, Intake
Closed) is to:

1. Warm the engine. Once you know the difference between hot and
cold lash, you can set the lash cold.

2. Follow the firing order. You can pick any cylinder but I usually
start with number one and have a copy of the firing order and
cylinder numbering in front of me.

3. Crank the motor over by hand (socket on the balancer bolt), set
the intake lash just as the exhaust valve begins to open.

4. Watching the same cylinder, crank the engine over some more and
then set the exhaust lash just before the intake valve closes.

In more detail,

1. Remove the valve covers and pick the cylinder you are going to adjust.
If your cam is already broken in, do this with the engine fully warmed up
(takes thermal expansion into account). If installing a new cam, use the
cold specs before firing the engine, then re-lash after cam break0in with
the engine hot.

2. Hand turn the engine in its normal direction of rotation while watching
the exhaust valve on that particular cylinder. When the exhaust valve begins
to open, stop and adjust that cylinder's intake valve. When the exhaust is
just beginning to open, the intake lifter will be on the base circle of the
lobe, ready to be adjusted.

3. With a solid cam, use a feeler gauge to set the correct valve lash.
Place it between the tip of the valve stem and rocker arm. Turn the
adjust until you arrive at the proper setting then lock the adjuster in
place. In my TR8, with hydraulic lifters and adjustable pushrods, I
shortened the pushrod until I got zero pre-load (lengthended pushrod
until free play was gone), then went one turn on the adjuster. I used
a thread pitch gauge to verify my adjuster was 32 turns to the inch.
1/32 = 0.03125" or 31.25 thousands (with the Buick/Rover aluminum V8
30 thousandths cold is a good goal with a high performance hydraulic
flat tappet cam). If I'm feeling paranoid, I also used a bent wire
gauge under the lifter clip to verify the pre-load.

4. After the intake valve has been adjusted, continue to rotate the engine,
watching that same intake valve. The intake valve will go to full lift and
then begin to close. When the intake is almost closed, stop and adjust the
exhaust valve on that particular cylinder. When the intake valve almost
closed, the exhaust lifter is on the base circle of the cam. Follow the
procedure in step 3 to set the lash or pre-load.

5. Both valves on this cylinder are now adjusted, so check the firing
order and move to next cylinder and repeat the procedure.

The SAE method is more accurate than the 90 degree method described in the
Ford manual and the more overlap the cam has or the less piston-to-valve
clearance you have, the more important this method is.

Dan Jones