Hydraulic cam lash settings ?

[Nassau1969]

Ok I put Edelbrock heads on my 440 motor with a mild Hydraulic cam with Comp Roller Rockers. Problem I cant find the spec sheet on how I should set the lash on the rockers, some say tighten it until there is no lash then go a half turn or a 1/4 turn more, some say you need a little lash because the engine will heat up and expand, so what is it. Anyone no.

[Cooter]

You need to "Pre-load" the lifters in a Hydraulic Lifter engine...I'd tighten the adjusters until you can't spin the push rod anymore..Then, 1/2 turn to pre-load the lifters...

[John_Kunkel]

I am of the opinion that aluminum heads need more preload than iron heads because the aluminum will "grow" away from the block when warm and open up the lash. I'd go 3/4 or 1 full turn.

[Nassau1969]

When the engine to cold correct.

[Nassau1969]

Ok so the Hydraulic push rod needs to stops spinning with no lash, then set the preloaded by a half turn, Ok Thanks. If I need to do a little more i will after I test this one out first. I'll do that cold then check it after its hot to see if the push rod turns. Thanks guy.

[BSB67]

"Ok so the Hydraulic push rod needs to stops spinning with no lash, ..."

If you do this you might bottom out the lifter plunger, as the push rod will likely still spin as you tighten the adjuster and the plunger bleeds oil.  Just watch the plunger and once it starts to move, that will be zero lash, then turn a half turn.  Of course the lifter needs to be on the base circle of the cam when you do this.

[elacruze]

Depending on your valve spring pressure and oil pressure, your engine may want a little more or less preload.
On my 440, I have double valve springs (170# maybe?) 70psi oil pressure and a Mopar .509 hydraulic cam. When I set the preload to 1/2 turn, the engine runs very rough at idle, and hard to start. When I backed them off to zero lash, it runs great but is a little noisy. I ended up adjusting them by the old Chevrolet method, that is loosen each rocker while running until it clicks, then tighten just enough to make quiet. Minimum preload. You'll want a set of rocker covers with the top cut out to do this so oil doesn't run down onto the exhaust. Bottom line is, set the preload where your engine likes it best, but remember that the more you preload the more potential for pumping up the lifters and holding valves open.

[Nassau1969]

Ok reason why I took off rockers was that one of the push rods feel off. So I redid the lash and re torqued the rockers. Ok well I went to start the car today and same push rod fell off. ?? Confused. Any one have any idea whats up hear motor is new 2700 miles and it ran fine when I put the rockers back and redid the lash on the problem push rod the other day. I don't think a cam lob is whipped out, could a lifts maybe bad ? It ran good the other day when I put the car way after fixing the problem.

[Nassau1969]

Well the answer seems to be the one Lifter has gone bad. I tightened it a few more times did the 1/2 to 3/4 turn and it just taps at start up and after about 5 road trips and a cold start it fell off again. Just ordered another liftere from Jeggs $5.99 well it better be the problem tried everything else.  Also the advice on the aluminum expanding more than cast heads, about 1/2 to 3/4 turns on the rockers was right on the money it worked for a while on the bad lifter but it must of have gave up. It worked like a charm for the other lifters, rough Idle at start up but when warmed up perfect, Until that same lifter failed. Thanks again for all the help.