Spring Height Question

I bought some DOVE heads from a guy at a machine shop who did all the machine work for larger valves. They came with Ferrea valves, but no springs or retainers. Spring heights are measuring about 1.99in. These heads will go on a street strip 460 with a Comp Cams XE274 cam, which on the old heads, I used Comp Cam 924 springs @1.88in. Do I need to get some new springs that set up at 1.95 or ? I don't need must spring pressure with this cam, but most of the bigger springs have a high spring rate I don't need.

Thanks
Mark

Use a locator / Cup and some shims to get them where you need them.

Wouldn't that be too much difference to make up? I would need about 0.11 to get my old springs height at 1.88 in.

No not to much some shims are .060 thick

Between the Locators / Cups and a shim of two it will be fine.

If your worried that much about it some Locks and Retainers are avaliable in Minus sizes Like -.050.

What it sounds likeis you have +.100 valves.

What it sounds likeis you have +.100 valves.

Yep thats what I have. I was worried if I shim too much I will lose the boss which locates the inner spring.

Locators or Cups.

Mark460 wrote:

What it sounds like is you have +.100 valves.

Yep thats what I have. I was worried if I shim too much I will lose the boss which locates the inner spring (for the Comp Cams XE274 cam -- PK).

Generally, most any +0.100" valve on a D0VE head with the 2.00" installed height will require a valve spring that would dictate the inner spring perch being machined off the head for the fitment of the big double/triple valve springs.

Incidentally, the XE274H also calls for a dual valve spring (924-16 or 930-16, flat tappet application) and so inner-spring pad machining of the cylinder head would still be required with those springs. Once the inner-spring boss is machined away, I suppose you can stack shims if you want. Also, there is a single spring available that would suit the need of the camshaft and engine application and you wouldn't need to machine the inner-spring bosses, but you would still need to stack shims.

Regardless.........the wise thing to do is get a more suitable (read: correct) length valves for this combo. This is because at 0.100" long, the valve-cant angles end up putting the tip of the valves closer to the rocker studs and may be cause for some frustration when setting up your D0VE heads with your particular, combined selection of valve train parts (rocker arms, studs, retainers, 0.250" tip length, etc). In the end, you will have stacked shims and a roller tips outboard of the valve tip. It can be made to work alright, but if you are going to be concerned with the roller tip of your rocker arms being way outboard of the center of the valve tip, then get the shorter valves which will address roller tip location; this will also (all but) eliminate an inordinately high quanity of valve spring shims on your heads. Lastly, your pushrods will end up being shorter (stiffer) as well.

Paul

Just to clarify, the valves I have are the same length as stock valves, but the groove is .100 higher, so I would assume these wouldn’t change where the roller tips hit the valve tip, vs. my old valves, but I’ll be checking it anyway. The inner spring boss was already machined for a dual spring like the 924s. After running some numbers, seems like the 930 springs, with .060 shims will get me close to where I need to be with this cam, trying to keep the 924 springs would require just too many shims. I wanted to keep the valves in case I decide to swap out with a higher lift cam later.

Thanks
Mark

Mark460 wrote:Just to clarify, the valves I have are the same length as stock valves, but the groove is .100 higher, so I would assume these wouldn’t change where the roller tips hit the valve tip, vs. my old valves, but I’ll be checking it anyway. The inner spring boss was already machined for a dual spring like the 924s. After running some numbers, seems like the 930 springs, with .060 shims will get me close to where I need to be with this cam, trying to keep the 924 springs would require just too many shims. I wanted to keep the valves in case I decide to swap out with a higher lift cam later.

Thanks
Mark

It sounds as though you have standard length valves with the 0.250" tip. With unmachined heads, this typically gives a 1.900"installed height....not 1.990"-2.000". And so assuming that you do have standard length valves with a 0.250" tip the additional 0.099" must be coming from the deeply machined spring pads and/or +0.XXX" retainers.

If you definitely have standard length valves with the 0.250" tip...but still measure a 1.990" spring height...then you can certainly use a 0.060" spring cup as dfree noted. The final 0.030" may be handled at the retainer, or with a single 0.030" shim.

Glad you have the correct valves (but verify that),

Paul

p.s.: Ballpark length of the usual OEM replacement valves should be approximately 5.280" +/- 0.010" Intake and 5.070" +/- 0.010" Exhaust. (<----those are not OEM lengths they are dimensions that cover the various lengths of most of the aftermarket replacement valves).