Pushrod length

veggiemike · Aug 19, 2008

What exactly determines the required pushrod length for our engines? Is it the entire combo of rockers, lifters, cam, and head? Or just one or two of those? Just trying to figure out all the other parts to go along with my H/C/I swap.

95-stang · Aug 19, 2008

You can buy pushrod length checking kits, when i had afr 165's the standard length pushrod was perfect, but that can depend on a lot of combinations.
The idea is to get the tip of the rocker to "strike" the head of the valve dead centre, something you dont want to be guessing at.

Sorry its not dead clear, but you can see the faint line in the middle and thats just after running in which is where you want it.

veggiemike · Aug 19, 2008

Can you use the kit to determine the length prior to actually assembling everything? I'm trying to avoid tearing down my engine, and then having to wait for a missing part to arrive before I can put everything back together.

95-stang · Aug 19, 2008

You need to have everything ready beforehand i'm afraid to mock it up. A single solid lifter helps too for accuracy [as it does'nt compress], but i had to make do with stock to gauge it.
You really need to build it up with everything your going to use, then use the kit, maybe if you say what your going to use, someone might have used similar stuff and know the length required, but there's a lot of variables.

http://store.summitracing.com/egnse...checking+tool&searchinresults=false&N=700+115

Cheap but worth it.

LAFENATU · Aug 19, 2008

Pushrod length is influenced by many things: The deck height of the block, the type of cylinder head that is being used, the brand of rocker arm that is used, the camshaft base circle, the lifter height, the valve stem size, the thickness of the head gasket, the thickness of the guide plate, the height of the valve job relative to the deck of the cylinder head..

What heads and cam are you using?