But the kit doesnt include spring seats for my alu head. So as my question, do i need those cup formed seats to hold the buttom of the springs, or is it enough with shims? I know im going to setup height for 1.750
Any idea what the current springs are? The recommended springs have a fairly high spring rate for a 1.25 diameter spring. A larger diameter spring with the same rate and install heights will last longer.
You have to have some way to positively locate the bottom of the spring. If left unchecked the spring will dance all over, which can cause the valvetrain to lose control(valve float) at an earlier rpm than it should, or it will wear out the spring itself(lost poundage).
You can use either a cup to hold the O.D. of the spring, or a spring locator that has a step that holds the I.D. of the spring. Choice is yours, just make sure that whichever you use is a fairly close fit to the O.D. of the valve guide itself.
On an I.D. locator, the inside step needs to be a close fit to the spring, but not a tight fit. Same with cups on the spring O.D.
Ok thanks. The springs are 1.266 OD, and .883 ?D, it seems there is none for sale on ebay to fit these, guess i have to write to summit, maybe they have. For me it doesnt matter if its id or od type, as long as the valvetrain doesnt blow
It is a real PITA to find sprig cups or spring locators that fits the head and spring.
The easiest way is to choose locator that fits the ID of your spring and then machine the valve guide to fit the locator. The spring to locator ffit should be .005" to .010". Machine the valve guides to .630" OD with a guide cutter and choose a locator that fits the guide and the spring.
Example:
Spring ID ....... .750"
Locator ID ..... .630"
Comp Cams 4773 spring locators
No idea, but i have written to the seller. The springs are so big im afraid it will make too much work for the lobes. And i would rather use the cam card recommended springs.
All that being said to get the correct setup what you need to do is remove the current springs and any shims/spacers that are there.
Measure the height from the spring seat to the underside of the retainer. Measure the spring seat diameter. Measure the valve guide outer diameter at the base.
There are couple of things to remember. New retainers may give you a different assembled height than the old retainers. Also spring cups and locators are usually .060 thick so take that into consideration. Adding cups sometimes will make the stack less than the desired installed height. This is where +.05 locks come in.
More than likely there will not be enough room between the I.D. of the spring and the valve guide on stock heads for an I.D. locator but all heads are different. If you have aftermarket heads you might be fine.
When ordering shims get shims to fit the valve guide. There are several types and having a shim with a center hole that is too large will allow the shim to slide around under the locator.
Lastly the shims go between the locator and the head not between the locator and spring. I've seen a few heads with the shims on the wrong side and this gives the cup/locator less of a wall to capture the spring.
But the kit doesnt include spring seats for my alu head. So as my question, do i need those cup formed seats to hold the buttom of the springs, or is it enough with shims? I know im going to setup height for 1.750
For aluminum heads you need to use spring seats. Without them the hard steel of the springs will chew up the softer aluminum of the head.
The spring seats come in two types:
1) Locates on the valve guide and has no raised peripheral edge that would trap the spring's outside diameter. However the base needs to be as large as the spring or the spring pocket.
2) These have a raised peripheral edge the traps the spring's outside diameter. This works if the spring used is a smaller diameter than that of the spring pocket.
A hard spring shim that fills the spring pocket from the valve guide outward is suitable.
This is an area where you need careful dimensions. The guide centering spring seat most likely needs a specific diameter of the guide and also need to extend outward to support all of the spring. A spring seat that supports the spring with a peripheral cup needs to fin into the spring pocket, support all the of the springs if a compound set up to the guide. These may limit or be limited by the spring's OD as well as the pocket diameter. A simple shim is subject to the same fitment requirements.
Comp Cam 4785-1 valve spring locator is probably what you need. The bronze valve guides on aluminum heads do not have a valve guide boss and the locator registers directly off the .560" OD bronze valve guide. The Comp Cams 4785-1 locator is 1.550" OD to fit the spring seats as is, without machine work.
You can buy one locator and check the fit. The locator is .060" thick so take that in consideration when you shim the springs. The locator will increase the coil bind height and reduce the seated spring height from the suggested 1.750" to 1.690" which is still good for stock length valves. The locators will raise the seat pressure by about 20 lb. Don't worry about that because aluminum heads have hard valve spring seat inserts.
Unlike stock cast iron heads, most aftermarket aluminum heads have spring seats that will accept more than 1.600" OD valve springs and register the spring from the .560" OD bronze valve guide.
That will probably work. It appears that the 4705 locators will have .005" clearance on the bronze valve guides and the valve springs will have .005" clearance on the locator valve spring registers.
.
Order Comp Cams 4705-1 to test fit one locator. If it fits you can then order a full set of 16.
I believe these are good to go. The stock ones i have pulled out is 0.020 in oversize from the guide AND the from the springs
Fortunately there are 3x0.020 shims per spring, so im well prepared
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