Roller rockers and pistons Valve slap?

[74bigblock]

I'm worried that when I swap my heads I will run into valve slap issues. I'm going to pick up some edelbrock BB Chevy aluminum heads complete with springs, valves and locks. I'm planning on transferring the roller rockers over... and just want to make sure they will not extend the valves into the pistons. I have no idea what make or size the roller rockers are... they were installed before I purchased the vehicle.

Thanks all!!
Dave

 

[Tom Bryant]

Dave,

If they didn't cause any problem with the old heads I can't see that they would with the new ones. Are you running a very high lift cam? The only way to know for sure is to measure.

If you want to check, go to an art supply store and get some modeling clay. Dont try to use your kid's play dough or anything like that because it is elastic and springs back. Modeling clay will stay where it is pressed. Put a layer on the piston top and install the new head with an old head gasket. Torque it down, adjust the valves on that cylinder and turn the engine over by hand past where both valves completely open and close. Remove the head and measure the thickness of the clay where the valves indented it. That's your clearance.

Tom

 

[74bigblock]

Dave,

If they didn't cause any problem with the old heads I can't see that they would with the new ones. Are you running a very high lift cam? The only way to know for sure is to measure.

If you want to check, go to an art supply store and get some modeling clay. Dont try to use your kid's play dough or anything like that because it is elastic and springs back. Modeling clay will stay where it is pressed. Put a layer on the piston top and install the new head with an old head gasket. Torque it down, adjust the valves on that cylinder and turn the engine over by hand past where both valves completely open and close. Remove the head and measure the thickness of the clay where the valves indented it. That's your clearance.

Tom

Interesting idea there Tom! I wish I knew what cam was installed... the only thing I have to go on is an Edelbrock 425HP kit... but that could be any number of cams.

 

[gmjunkie]

Interesting idea there Tom! I wish I knew what cam was installed... the only thing I have to go on is an Edelbrock 425HP kit... but that could be any number of cams.

Us old Timer's have been do'n thing's Like that for Year's!!!! Dave you wont have a Problem!! junk!!

 

[74bigblock]

Us old Timer's have been do'n thing's Like that for Year's!!!! Dave you wont have a Problem!! junk!!

Junk...

You sa'in that I should slap 'em on and cruise, or should I double check with the modeling clay as Tom suggested?

-Dave

 

[gmjunkie]

Junk...

You sa'in that I should slap 'em on and cruise, or should I double check with the modeling clay as Tom suggested?

-Dave

No !!, I would ck them!! Tom's Way is as GOOD of way of checking as any!! And it will be accurate!! I'm just Say'n you wont have a problem them, if you don't have a problem Now!! The Aluminum head's are gonn'a Look and measure very close to the same as cast Iron!! There just aluminum !! Unless you are getting Custom made Billet Head's and then there mite be a problem I don't know!! junk!!ps I meant us old Timers have been checking clearances with thing's Like modeling clay, Soft Bees Wax, Hell I've probably used a turd before,Just can't Remember!! BTW Nice Hat!!

 

[glenkov48]

If you use a turd, what size would be best?

 

[gmjunkie]

If you use a turd, what size would be best?

You just pinch off what ya need!! otfl junk!!