choosing a cam?

[1961 slickwilly]

i never fully understood everything about changeing cams as far a lifters and rockers go any help would be great apreciated, the motor is a 78 400 it will be driven on the street as well as offroad and i would prefer it not to be so choopy that i have to run a stall in the trans

[mikewirth]

There are many factors in choosing a cam, some questions that should be asked and are usually forgotten are:do you have need for engine vacuum for power brakes and etc as you may need a vac res. Is it a manual or auto trans, what type of driving are you doing, do you want bottom or top end performance, what is the rear end gearing, how tall are the tires, what other mods are you doing or will you do, I strongly suggest you never take the word of the "guy that built it when he says it has this or that in the motor" always verify personally the compression ration bore, stroke etc. this sounds like alot of work for just changing a cam but it will make all the difference in getting the cam you want and getting the results you expect. When changing the cam I always change the lifters and the valve springs to the cam grinders specs as this is a matched assembly. You also want to check the pushrod length and the rocker arm action to make sure nothing is binding on you.

[64 f100]

Consider also, the cam timing was retarded on the 400 engine, so a new timeing chain setting the cam where it needs to be will help wake up the engine. Most engines used for road driving in a truck would bennefit from an RV cam, but not much more to speak of as far as usage.

Rich

[Greg D]

For how you want to drive it like Rich said - RV cam with a straight up timing set should do you just fine.

[Uncle Skip]

As a general rule and warning to everybody.

Always change lifters when you change a cam. Always.
Use a lot of engine assembly lube on the lobes and on the bottom of the lifters.
Always put a bottle of engine assembly lube in your initial oil change.
You can get this from a lot of different sources, including your cam manufacturer.
And as another general rule, I use about half a quart at every other oil change "because the new oil formulations have eliminated zinc from the oil". Blame the EPA and the ecology nuts for this one.
Even my personal favorite, Shell Rotella-T has the zinc gone.
Failure to do the things above WILL result in wiping out at least one lobe on your new cam.
U@ss

[1961 slickwilly]

its a 400 and a c6 i plan on running 38.5 tall tires and the gearing will be 3:50 or 3:55 i plan on driving it everyday to work and the ocasional off road but i live 1 mile from work. the motor is bone stock so is the c6