i need help setting valve lash - 3.1 MPFI

[TurboSedan]

i just got my heads back from the machine shop yesterday and i have them bolted to the engine. now it's time to install the lower intake manifold and set vavle lash.

only problem is, i have never set valve lash before....

i've done a few searches on this subject but i still have a few questions. it sounds like the lifter for the valve i'm adjusting needs to be on the base circle of the camshaft (valve fully closed). but how do i know when the lifter is on the base circle of the camshaft? obviously the new lower intake gasket must be in place before i start setting valve lash, so i won't be able to look directly at the camshaft to see

also, when i do get the lifter on the base circle, how much do i tighten the rocker arm nut? do i just tighten it enough so the pushrod starts to become difficult to spin and then tighten it one full additional turn?

any help really appreciated, thanks

[SappySE107]

RE: i need help setting valve lash - 3.1 MPFI

The aluminum head setup is simple...torque them down to spec and you are done. You would have to go with a different rocket setup to adjust lash, or have some custom pushrods made for the proper length.

[TurboSedan]

so i can just tighten the rocker arm nuts down to the correct torque spec regardless of weather the valve is open or closed?

also, my Haynes manual lists the torque spec at 18 ft/lbs....is that right? i just want to be completely sure.

thanks Ben

[SappySE107]

I thought we had the specs on the site...but they don't seem to be there anymore for the gen 2 motors. 18 sounds right, as I know it wasn't super tight.

I think the nut is supposed to tighten down 3/4 - 1 1/2 turns with the lifter on the base lobe of the cam. With a stock cam and just some head decking to make it flat, you should be fine.

[TurboSedan]

I think the nut is supposed to tighten down 3/4 - 1 1/2 turns with the lifter on the base lobe of the cam. With a stock cam and just some head decking to make it flat, you should be fine.

yeah that's what i'm worried about...how do i know if the lifter is on the base lobe of the cam? will i be able to tell just by looking at the valve spring? IOW when the rocker arm is not compressing the spring at all?

this is all new to me

[SappySE107]

Its going to compress the spring. Easiest way to tell is to just look at the lifter:P Rotate the crank until the lifter you are going to measure is sitting the furthest in the bore. You just need to check 1 intake and 1 exhaust.

[firechiken]

With the engine in the number one firing position, ex 1-2-3 and in 1-5-6. Turn engine one revolution, then ex 4-5-6 and in 2-3-4.

[TurboSedan]

Its going to compress the spring. Easiest way to tell is to just look at the lifter:P Rotate the crank until the lifter you are going to measure is sitting the furthest in the bore. You just need to check 1 intake and 1 exhaust.

ahh i see now. so after the lifter is on the base lobe, should i just tighten the rocker arm nut down to 18 ft/lbs and that's it? or do i turn it 3/4 - 1&1/2 turn past 18 ft/lbs?

[TurboSedan]

With the engine in the number one firing position, ex 1-2-3 and in 1-5-6. Turn engine one revolution, then ex 4-5-6 and in 2-3-4.

cool thanks! that will save me some time.

[SappySE107]

Nope, the 18 foot pounds should come out to 3/4 to 1 1/2 tuns once you feel tension. Im guessing on the 3/4 to 1 1/2, though I did see 1 1/2 for the iron head motors.

[TurboSedan]

Nope, the 18 foot pounds should come out to 3/4 to 1 1/2 tuns once you feel tension. Im guessing on the 3/4 to 1 1/2, though I did see 1 1/2 for the iron head motors.

cool, that's exactly what i wanted to know. time for me to head out to the garage and get to work on this 3.1

thanks again!

[geoffinbc]

Yea Ben I am still working on all the Gen 2 stuff and some of the Gen 1 stuff
All specs for every engine will be up soon.

[SappySE107]

Ok cool

[TurboSedan]

ok i just got done setting the valves and installing the LIM and i want to be sure i did this right before i do anything else...

first i rotated the engine until piston #1 came up to TDC (i just looked through the spark plug hole). then i checked to see that exhaust lifters 1-2-3 and intake lifters 1-5-6 were furthest down in their bores. all of them were so i tightened the rocker nut while spinning the push rod until i felt some tension. then i torqued the rocker arm nuts for those six valve to 216 in/lbs (my ft/lb torque wrench only goes down to 20 ft/lbs so i used my in/lb wrench instead). 216 in/lbs turned out to be around 3/4-1 full turn after i felt tension spinning the pushrods. i then rotated the crank 360' degrees and made sure exhaust lifters 4-5-6 and intake lifters 2-3-4 were furthest down in their bore and torqued them down just like i had done with the first six.

is that right? please don't tell me i have to take this back apart!

[Invasion1]

Thanks for that question Josh........im at the same stage as you in the assembly process.....

lots of good info guys