My builder is dragging *** and I need to know
cause I know ya'll do!
Blocked is finally ready, 17 months later
what's the new pushrod length?

1977 FORD 400 BORED .030 OVER
Heads Decked -.010 UNDER
Block is decked -.010 UNDER
New Howard's Cam Lift 496/.496 Duration @ .50
213/213, centerline: 106

How much adjustment is in the Rocker Arm after Lash and then preload ,once everything is pumped up and "ready" to continue to prime Engine/Oil repeatedly

 

On a 351m or 400, you don't typically "adjust" rocker arm "preload". You use empty lifters, well lubed ... & not dry. Set the pushrods in, then install the rockers on the studs and tighten them, checking to be sure they don't bind on the bases. Once the engine is started and running in, oil pressure will pump the lifters up only enough to take up slack when the lifter is on the lobe base, and the lift happens fast enough in a running engine that the lifter can't collapse. Result is no "preload", but no excess clearance either on the lobe base circle. The lifters take a time to fully adjust up because the oil path in is small to prevent collapse. Oil to other lifters passes each lifter via the recessed wide channel around the lifter.

Good lifters take a while to pump up which is why they don't collapse while the vehicle is parked & not running.

Some lifters that are resting on the base of the cam lobe will pump up some during a drill driven pre oil. Some lifters will be under load and will not pump up during pre oiling.

If running solid lifters, then you need adjustable rockers. Solid lifters never use preload either, they use a clearance adjustment.

You might end up needing shorter push rods, but then you might not. I'll leave that for others.

 

I take it you have adjustable rockers? and flat tappets? your geometry needs checked first if so. then measure with zero lash. adjustable or not you need a pushrod checker.


Pumping the oil up doesn't mean anything because zero lash is found with just the spring in the lifter anyway.

 

But that spring will not open a valve against it's stronger spring until the lifter is pumped up too. Before then, it'll tick as the lifter plunger bottoms, then it'll open a valve part way. The tick is the plunger bottoming out internally ... no? Just my experiences.

 

I haven't worked on a 400 or a 351M but I if you have non adjustable rocker arms it should be the same as the other Ford engines of this era I have worked on. When you assemble an engine, best to check before the hydraulic lifters are pumped up if hydraulic lifters are used. If they get pumped up they can be bled down.

Anyway you need to place the engine in a certain piston and valve position to check the clearance with a feelers gauge on certain valves, but you do have a range. If the clearance does not fall with this range, you need to get different length push rods. You can usually figure out the difference you need by figuring a 1.6 rocker arm ratio. The entire engine likely won't need the same size different push rods if required. Hope this helps.

 

That's true, so that's why it must be checked on the base circle of the cam so there's no load on the lifter. even with oil unless it's running the lifter will partially collapse. when you spin the pushrod with 2 fingers and start to feel resistance that's zero lash.

The tick is usually the excess slack in the valve train since the lifter is out of travel. or the lifter is bad.

The other thing lots of people don't think about when they do home valve jobs or have a hack machinist do their work is the variation in stem height. if they vary you can check 16 valves and get 16 pushrod lengths. add that to deck and head surface work, head gasket thickness and cam base measurements and you can have a mess. then adjustable rockers are about your only hope.

 

I haven't looked for them for a series 335, but used to use some locking nuts to adjust rockers on my Pontiac, was a long "deep" nut with a socket head set screw in the top to "lock" them.
I knew one guy made his own using hardware store bought threaded rod coupling nuts and hardened set screws in the end ... I guess that would that be a hack? .

I know they are a common deal, but Pontiacs didn't come with them as I recall, unless a solid lifter engine maybe.

 

It would probably be more trouble than it's worth, you'd need guide plates so if you're going that far it would be best to just go adjustable rockers.

I use Posi locks on Pontiac and it works , that's probably what you're talking about. but the pushrod holes in a Pontiac are designed to give the pushrod a guide. for high performance most guys do put guide plates in though.