Valve guide & spring seats on Stock heads.
 

The rule book says that "Any valve spring permitted provided no modifications to head is performed."


It sounds like dual springs are allowed. But does that mean the guides and "step" on a Mopar small block head can't be modified anyway? (For different seals/inner springs/guide - retainer clearance.)


(I hate the rule wording where it sounds like you can use something, but you can't change anything to make it fit!)


Any insight here or via PM would be appreciated.

Re: Valve guide & spring seats on Stock heads.
 

That's a good question ! I thought you were not allowed to make the spring seat larger, but they have allowed you to modify the guide to install valve stem seals. I think you could make a case that any guide modification was to allow for those seals to be installed.

Re: Valve guide & spring seats on Stock heads.
 

Myron,

Please check with your tech guy in Div 2. I don't think you can put bigger Dia springs in a stock head.. If your engine came with 1.440 dia. springs, you can't open the spring boss to run 1.550.. Just like you can't match ports to gasket openings, No-grinding at all ??? So, save time & money, check withyour Tech guy & he will help you out ... You are right about the rule book being vague ...Hope you are doing well...

Re: Valve guide & spring seats on Stock heads.
 

I wasn't looking to put bigger springs in. But wondering about something that would modify/cut away the step, especially if dual springs were used. Can't go too big on diameters because of rocker interference. I'll direct my inquires to NHRA as well and hope for a "clear" answer..

Re: Valve guide & spring seats on Stock heads.
 

I don't think removing the inner step is a problem, they don't want to see grossly oversize springs. The step is typically about .100" deep and before you remove it, see if it works to your advantage as coil bind won't be a problem with a stock cam lift.

Re: Valve guide & spring seats on Stock heads.
 

I don't see where this is vague. It says no modifications. How is that subject to interpretation?

Re: Valve guide & spring seats on Stock heads.
 

What's the point of changing the rule to allow "any" valve spring if nothing is changed to accommodate "any" valve spring? (Within some structured reason, of course.) While there may be a way to incorporate some Frankenstein combinations within the letter of the rule, the creativity of it can lead to other questions of legallity, interpretation and expense.

I've seen simialr rule changes pop up which just confuse the situation. I may not go to dual springs that would "normally" require elimination of the step. But I have a good, otherwise legal, set of heads that happen to have had that step machined away by the previous owner. With the valve spring rule change, it would seem that a change allowing the use of the available spring options would make sense.

Re: Valve guide & spring seats on Stock heads.
 

Myron, have seen the step removed before when new guides are being installed on the cylinder heads. Your other option is to use a spring with a damper in lieu of a dual spring.

Re: Valve guide & spring seats on Stock heads.
 

Might want to try a beehive spring and a hard spring cup.

Re: Valve guide & spring seats on Stock heads.
 

I did found a beehive spring I'd like to use. A standard spring with or without a damper wouldn't change anything. I'm just trying to get some sort of consistency as to what to expect in tech with the machined-off step - considering the rule change. Or if it's an "it depends on the tech guy". Hate to discard otherwise good heads if it's actually been allowed before.
I wish I remembered the person and configuration I saw with Chevy small block springs on a Mopar small block Stocker.

I've seen other similar rules discussed here allowing something new, but being unable to use it without doing posted illegal mods. The Edelbrock small block Mopar heads come to mind.

Re: Valve guide & spring seats on Stock heads.
 

The small block Chrysler has a better foundation for springs than a small block Chev, not sure why anyone would do that, it would be a step backwards.

Re: Valve guide & spring seats on Stock heads.
 

You could machine a "Seat" to fill the void in the step, creating a flat surface for the spring, spring seat, ect. Basically a washer to just sit in the lower step and be flush with the upper step.

Re: Valve guide & spring seats on Stock heads.
 

After more research and talking to some people "in the know", the heads may not be legal because the spring seats may have been opened up (unnecessarily) during the guide & step machining. My engine guy will double-check, but I'll be looking for another set.

I'll get use to interpreting the rules as time goes on. But that's part of what this forum is for. Thank you for the opinions and suggestions.

Re: Valve guide & spring seats on Stock heads.
 

I was always under the impression that any spring including a beehive spring can be used so as long as no machine work of any kind can be performed to make a particular spring fit. We are using a beehive style spring on our BBC that fits using the original factory machined seat.

Re: Valve guide & spring seats on Stock heads.
 

Yes, I'm under the impression that is as as you describe. I was just a little surprised that they allowed "any" spring but no macining at all. I was hoping to use the otherwise good set of heads. OEM Mopar spring seats do accept certain beehives very well.