Valve Lash On '92 7.4l

[moonlite]

hi,

could you please advise me as to the proper way to set valve lash on a '92 7.4L with the positive stop shoulders. thank you

[Shu]

Aren't the 92's hydraulic roller lifters? Are they independent rockers that are adjustable or at these the ones that are on a shaft or non adjustable fulcrum? If adjustable, rotate engine to where both valves are completely closed, tighten to zero lash (where the pushrod just begins to have resistance when twisting it between your fingers and thumb) then tighten 1/2 to 1 turn. I usually go 3/4 turn. If non adjustable you have to detemine if you have the proper preload once the rocker assembly is tightend to spec. To do this use a straightedge on the head where the vavle cover gasket go. Mark the pushrod, then loosen the rocker and wait a minute or so and mark the pushrod again. I think you want between .020" and .060" preload (distance between two marks on pushrod). I don't think the 7.4L had mechanical lifters but if it does there is another procedure for setting the lash.

[gmtech4]

you should get a book.

[moonlite]

you should get a book.

 

 

i do have a book, the chilton manual, all it says is that on 7.4 engines with the positive stop shoulders you simply torque them to the required torque which is supposedly covered later in the chapter, the only torque setting i could find that is even remotely related is the lifter torque which i assume is the same, just thought someone on here might know for sure

[moonlite]

Aren't the 92's hydraulic roller lifters? Are they independent rockers that are adjustable or at these the ones that are on a shaft or non adjustable fulcrum? If adjustable, rotate engine to where both valves are completely closed, tighten to zero lash (where the pushrod just begins to have resistance when twisting it between your fingers and thumb) then tighten 1/2 to 1 turn. I usually go 3/4 turn. If non adjustable you have to detemine if you have the proper preload once the rocker assembly is tightend to spec. To do this use a straightedge on the head where the vavle cover gasket go. Mark the pushrod, then loosen the rocker and wait a minute or so and mark the pushrod again. I think you want between .020" and .060" preload (distance between two marks on pushrod). I don't think the 7.4L had mechanical lifters but if it does there is another procedure for setting the lash.

thanks for the thoughtful reply, this engine has the positive stop shoulders, consulted with a knowledable tech today, he set me straight, just torque them to 12 ft. lbs. and forget it, no need to properly position the valves or the crank supposedly, i did it even though it goes against everything i ever knew about setting valve lash, quess i'll find out when i start it in a few days, now i need to find someone with a '90-'93 with the same engine to give me some pics of the engine compartment so i can figure out where all this stuff goes, i bought it already completely disasembled, just boxes of parts. once again, thanks a lot.

[Shu]

mauro,

 

If you have made other changes, like has the heads resurafaced, block decked, etc. then the method of described for scribing the pushrods with rockers torqued and un-torqued will give you the lifter preload amount. On those engines with non-adjustable rockers, you would then need to order special length pushrods to get the preload within specs. Provided no resurafacing in the engine, then by all means torque to spec and call it good as this will preload the lifters properly:)

[moonlite]

mauro,

 

If you have made other changes, like has the heads resurafaced, block decked, etc. then the method of described for scribing the pushrods with rockers torqued and un-torqued will give you the lifter preload amount. On those engines with non-adjustable rockers, you would then need to order special length pushrods to get the preload within specs. Provided no resurafacing in the engine, then by all means torque to spec and call it good as this will preload the lifters properly:)

 

thanks a million fot the reply, no machine work done other then cleaning up the heads, you put my mind at ease, just went against everything i THOUGHT i knew, now if i can get some under hood pics i might figure out where all these parts mount(LOL), thanks again