What are safe valve spring bind specs pls?

[70Hardtop]

Does anyone know what tolerance value constitutes coil bind on a valve spring? Please see attached pictures. This is the spring I have installed and the valve is shown fully open - at max lift at the lobe (using a solid lifter for accurate measurements). The coils are not touching in three places (middle and the two next coils) and the max I can measure is about 30 thou (0.030") between middle coils. Coils are tight at the top and bottom. I read that there is no hard and fast rule with binding tolerance, it all varies between spring types and materials. From 0.020 to 120.

This is a hydraulic cam but I think these springs might be a little close for comfort (lift is advertised at 0.525/0.525). What are other people's thoughts on using these springs for running in this new cam? Thanks

 

[Steve340]

That spring is not right.
The spring should be able to handle full lift plus 100 thousands.

 

[moparleo]

Are you just using various parts on a set of standard cylinder heads ? A proper machine shop doing a valve job would use your cam specs to setup the installed spring height, measure for coil bind and seat pressure. If you don't know or have the proper equipment to do these things, have someone who does, do it for you . Otherwise it can cost you much more in parts damage.

 

[TC_Cuda]

In the picture I don't see any shim's under the springs, not that you HAVE to have them but, it doesn't look like it has been "set up" properly.
I would NOT run an engine if my springs looked like that. Your using a hydraulic cam and if a lifter "pumps up" that .030 we disappear and then....well I hate to think about it.
If it were me I would take the heads to my machine shop, as to Me it looks like the spring seats need to be machined to get proper spring height and pressure.

Also I only see a single spring and at .525 lift I know its recommended to use duel springs

just my 2 cents

 

[70Hardtop]

Are you just using various parts on a set of standard cylinder heads ? A proper machine shop doing a valve job would use your cam specs to setup the installed spring height, measure for coil bind and seat pressure. If you don't know or have the proper equipment to do these things, have someone who does, do it for you . Otherwise it can cost you much more in parts damage.

Well this engine (1969 340 X heads) was a newly built engine in a Challenger I bought. So I have no idea how well it was built. But I do suspect it was not done as well as it could and should have been. For one thing, several of the main cap bolts were not properly torqued. It was probably assembled by what we call down under, a "Backyard Bob". We do have several machine shops in this city that I would trust to set it up, but it is not like the States, and Mopars are quite low in number, so these guys who have adequate experience in them cost a lot of money. The cam that was in it was an unbranded cam - so I pulled it out as I had no idea what it was. Now I am using this Comp Cams 0.525 /0.525 hydraulic (XE275H I think)

 

[70Hardtop]

In the picture I don't see any shim's under the springs, not that you HAVE to have them but, it doesn't look like it has been "set up" properly.
I would NOT run an engine if my springs looked like that. Your using a hydraulic cam and if a lifter "pumps up" that .030 we disappear and then....well I hate to think about it.
If it were me I would take the heads to my machine shop, as to Me it looks like the spring seats need to be machined to get proper spring height and pressure.

Also I only see a single spring and at .525 lift I know its recommended to use duel springs

just my 2 cents

Thanks for your input. Yes I know it doesn't look overly pretty, these are only old OEM 318 springs so I don't care about correct pressure (the lower the better) and height as I was only wanting them for 15min to break in the new cam, without worrying about heavier springs loading up the lobes too much. It's a good quality CC one so maybe I am worrying unnecessarily. I do have some TrickFlow springs but I think they are about 285lb open which is still too heavy for my liking. Special light valve springs just for the purpose of breaking in new cams have even been manufactured, so obviously doing this has some merit. But even though I have made up a solid lifter to do the measurements, that is a good point about the hyd lifters pumping up to take up that 0.0 30. And then disaster. I do have shims if I need them, for the correct Comp springs which I will put on when the cam has been broken in. Yes they use dual springs for this cam , but even without the inner spring, open pressure is still about 300.

 

[moparleo]

So you are saying that the set up that you have now is only for cam break in ? What about after the cam "breaks in " ? Are the heads already machined for the new springs ? Are you sure what the open and closed seat pressures will be or about what you think they will be? True rocker arm ratio ? Installed height will be different for different types and brands of valve springs.................

 

[70Hardtop]

So you are saying that the set up that you have now is only for cam break in ? What about after the cam "breaks in " ? Are the heads already machined for the new springs ? Are you sure what the open and closed seat pressures will be or about what you think they will be? True rocker arm ratio ? Installed height will be different for different types and brands of valve springs.................

Yes that's correct, I am only wanting these old springs installed for 15 or so minutes to break in the new cam. But of course I still need them to work for 15minutes without breaking or causing anything else to break. But as someone else pointed out, these old OEM springs with this high lift cam (0.525) will be forced to work in a much higher compression range than they are used to and combined with 30 or so years of use, who knows how the metal will react, we just don't know what is going on inside the metal. No these heads have not been machined at all for any springs. Only the valve seats have been cut for the stainless valves. I bought the new cam and the recommended springs (dual). So before I install these new springs permanenty I need to pull all the springs off and check each one for installed height (between spring pad on the head and bottom of retainer)

 

[IQ52]

The Comp 995-16 valve springs suggested for that cam requires the heads be machined for those springs.

 

[moparleo]

Wow........

 

[70Hardtop]

"The Comp 995-16 valve springs suggested for that cam requires the heads be machined for those springs."

Yes you would be right, although I have just been looking all over the Comp Cams website info and can't find anything on that. If you have a link handy with that info, that would be appreciated. But with this high lift cam, the installed height will need to be correct and maybe even the tops of the guides will need machining. But really, it is not that much of high lift, 0.525, sure it is bigger than stock but closer or more than 0.600 is high lift. And the heads are all bolted on so I hope I don't have to pull them off again. But in the morning I will check all the heights without the springs, and also check the distance between the top of the stem seal/valve guide and the bottom of the retainer as per these CC instructions shown here.

 

[TC_Cuda]

If you look up the cam, on Comps site where it lists the springs, it has a note 2 beside it, and that denotes ... 2 [2] Requires machining on cylinder heads.

Complete K-Kit K20-227-4
Cam & Lifter Kit CL-Kit CL20-227-4 [7]
Rocker Pushrod RP-Kit RP1322-16
Lifter Kit 822-16 / 867-16 [37]
Timing Set 2103 / 3103
Rocker Arms 1322-16 [23] / 1074-KIT [23]
Push Rods 7958-16
Valve Springs 995-16 [2]
Steel Retainers 740-16
Valve Locks 626-16 [24]
Valve Seals 505-16 [2]
Camshaft Break-In Lube 159
Installation Notes (These notes apply to the above recommended components with the trailing installation note numbers)
Note Description
2 [2] Requires machining on cylinder heads.
7 [7] Stock springs cannot be used.
23 [23] Includes special shafts & spacers.
24 [24] Special 10º 4 Groove Lock. Single Groove use part #612-16.
37 [37] Adjustable valve train required.