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Old 01-07-2008, 04:13 PM
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Valvespring shim question

I've got a question for you all. My 350 with Dart aluminum Pro1 heads have several valvespring shims that are destroyed after 5k miles. The valvesprings are 1.250 diameter, nothing special, just a stock type. The shims are 0.030" thick.

Now my question here is this. Can I run these Trick Flow Valvespring cups?
http://store.summitracing.com/partde...0&autoview=sku

The biggest thing I am wondering about is that the cups are 0.060" thick. Will this make that much of a difference in my engine? It's only got a Comp Cams XE268H, with .477/.480 lift. It's not a radical engine. Just a weekend hotrod. Thanks in advance.

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Old 01-07-2008, 05:46 PM
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Check the springs with .030 less instaled hight and see if you have the extra room (PSI at X amount of installed hight). I would guess the shim got hurt because of valve float or not enough spring. How do they fit in the spring seat, do they have excess room to move around side to side?
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Old 01-07-2008, 05:47 PM
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Quote:
Originally Posted by fastrehotrods
I've got a question for you all. My 350 with Dart aluminum Pro1 heads have several valvespring shims that are destroyed after 5k miles. The valvesprings are 1.250 diameter, nothing special, just a stock type. The shims are 0.030" thick.

Now my question here is this. Can I run these Trick Flow Valvespring cups?
http://store.summitracing.com/partde...0&autoview=sku

The biggest thing I am wondering about is that the cups are 0.060" thick. Will this make that much of a difference in my engine? It's only got a Comp Cams XE268H, with .477/.480 lift. It's not a radical engine. Just a weekend hotrod. Thanks in advance.
Seems young for this kind of a problem, how hard do you push this engine and how often? What about top end lube to the rockers and springs, is it oiling them?

Did you deburr the springs before installation, the sharp edges left from machining the ends of the springs need to be softened, otherwise they can really carve up the shims and the retainers.

The cups you sight are quite good at positioning the spring, especially when used with an aluminum head. Often the guide is used as a means to position the spring, for an aluminum head, this material is too soft or the springs aren't sufficiently restrained from sideways movement, especially on a head that anticipated the use of dual coils so the gap to the guide tends to be a bit wide allowing single coil springs or single coil with flat wound damper too much space in which to slide about.

However, these cups double the thickness of the shim from .030 to .060. These should be followed up with measuring coil to coil clearance at max lift. There should be at least .050 inch between coils when the valve is fully open.

Bogie
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Old 01-07-2008, 10:06 PM
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Well the shortblock is rebuilt, and the heads are brand new. Oiling is not an issue with this engine, as the gauge goes up to like 80+ psi at 6k, which is also about as high as I've pushed it. I've brought it to 6200 a couple times, but I threw belts, so I put the 6k pill in my MSD box. It's a street car, once in a while I'll stomp on it. It has only been to the track once.

I didn't assemble the head. My "local trusted engine builder" had that task. But that is the one thing that had me wondering. All that there was under the spring was the shim. There was nothing else in this large span of the seat to hold the spring. And with a non-hardened shim to boot.

I don't know if there would be much interference at full lift. My cam only has 0.480" of lift, plus there is an uncompressed height of 1.880" for the spring so it looks like it's one of the taller springs. But I guess I'll just turn the engine over and check it at max lift just to be sure.
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Old 01-07-2008, 10:08 PM
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Forgot to add. Here is a pic of my head. Disregard the shim my engine builder gave me to put in, since "this happens all the time" as he put it. The O.D. is the same as what I had, but the I.D. is much larger than what I had. Anyways, so just the shim is all I had on there. No locating device whatsoever. Wouldn't a Dart head have something like that? Or maybe not since I have the smaller valvespring?

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Old 01-09-2008, 10:45 AM
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A couple things, first the oil pressure was not my first concern, whether or not oiling to the top end being terminated or reduced was. There is or was a popular move to insert a gadget into the passages that feed the lifter galleys from the main galley to reduce or eliminate oil flow to the rockers via the pushrods. This results in overheating the valve springs in street or circle track engines and starves the rockers if they are not roller types.

The second thing, from the picture, the spring is being located by the pocket machined in the head. However, aluminum is quickly abraded by a piece of steel ridding on it. The shims used should be hardened and should not be so thick as to fill the locating hole. The spring should have nearly the same external diameter as the pocket's ID to prevent the spring from sliding around.
The cup shim will provide the necessary hardened surface and the rim will keep the spring from eating the sides of the pocket. If youre running a smaller OD spring the cup will also help fill the extra space. The cup must fit to the bottom of the pocket when installed, so check this and machine the pocket if necessary.

Bogie
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Old 01-09-2008, 11:27 AM
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Quote:
Originally Posted by fastrehotrods
It's only got a Comp Cams XE268H.

How does that cam act in your 350, how is the idle, the lope, are you running a higher stall converter. I am just curious because I just ordered one for a mild 383 I am building. I was thinking about running it with 1.6 rockers if it was not enough Cam.
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