"coil bind" of a head???

[Boxxbanger1]

im reading a back issue of MM&FF mag. they have the cylinder head test article. they have a column listed as "coil bind"??? what is that. is that the max lift you can run on a particular head? they show the AFR 185's as having a .700, but afr rates these at a max lift of .550

 

can someone explain this to me?

[Buckeye1647545503]

Dude I have no clue on your answer but I just wanted to say that is one sexy stang in your sig

[Lustalbert]

coil bind is where the coils of the spring start to touch each other. this is where pushrods start to bend, rockers break, and other bad shit happens

[SupraGlue]

Yes, it's the maximum lift that you can get to before the spring coils contact each other. In terms of the head design, it's directly related to the depth of the spring seats. Deeper seats allow for more lift before you hit coil bind. Depending on how much metal is in the casting, you can sometimes machine the seats deeper.

[rl]

Originally posted by Corvette Envy:

Yes, it's the maximum lift that you can get to before the spring coils contact each other. In terms of the head design, it's directly related to the depth of the spring seats. Deeper seats allow for more lift before you hit coil bind. Depending on how much metal is in the casting, you can sometimes machine the seats deeper.

What he said.

[desperado]

Originally posted by Corvette Envy:

Yes, it's the maximum lift that you can get to before the spring coils contact each other. In terms of the head design, it's directly related to the depth of the spring seats. Deeper seats allow for more lift before you hit coil bind. Depending on how much metal is in the casting, you can sometimes machine the seats deeper.

Right, you can also get valves with a longer stem, if you looking the performance catalogs, you will see valves that are + .100 or + .200, those are long valves, then you can run a stiffer spring, or a longer spring and get better lift numbers without the coil bind. As far as going to a .700 lift, you are talking about new valves, springs, aftermarket rockers and possibly a different length of push rod to ge that to work right. I have heard more than once of someone going out and buying a cam with silly ass lift like that and putting it in a otherwise stock engine and it tearing the shit out of there valve train. BTW, the other thing that you will need to do is run guides for that sort of lift and make sure that where the push rods come up through the head, that there is enough clearance for the rod. With that much lift you will get some side to side movement of the rods and if ther isn't enough clearance then you will bend your rods. There is alot that goes into running that sort of lift in a motor. And that doesn't cover the piston to valve clearances, and other things like where the flow increases with lift stop with a specific set of heads. Basically what I am saying is this, there is a level that you have more lift than the rest of the motor can take.

 

Also, speaking of sky high lifts od .700 or so. This is serious drag racing motor stuff, and not for faint of heart or those without deep pockets. It will make tons of power in the upper RPM's but the low end streetablity will pretty much suck.

[Boxxbanger1]

thanks for the reply's. i really was not sure of what they meant. so now i guess im ok to go with a bigger lift cam. im anxious as hell to get this engine back together.