Sunshine Guy

I have a set of Flo Tek Windsor heads; they are GT-40X clones. (Hold the tar and feathers; an assessment of these heads is not the question).

These heads were made with an aluminum shoulder around the valve guide where it rises through the valve spring pocket. That shoulder is about 1/4" tall and .890" in diameter. It was used to locate the valve spring cups that came with the heads. See attached photo.

The valve guides have about one inch of interference fit engagement in the central "meat" of the head, plus are also supported by that extra 1/4" shoulder on top.

My question: Can I machine away that 1/4" tall shoulder without unacceptably weakening support for the valve guide?

I've had three people tell me it should or would be fine, including Tri-State Cylinder Heads who is the distributor for these heads. However, my local machinist thinks it might be a bad idea. I really need to do this to accomplish my planned goals, but then my goals don't include ruining a new pair of heads, either. Any thoughts?

.boB

These are my Windsor head (Dart-195). I don't see any reason not to cut down that shoulder.

tbone heller

First off, I am not a machinist nor do I claim to be one, but I have removed thousands of cylinder heads. What are you trying to accomplish that this 1/4" shoulder is preventing? In order to remove that material, the valve seals & guides will most likely have to be removed, but at what cost? Will they have to be replaced with new ones, or can they be reused? Will the machine shop reinstall them correctly? Will they be straight & leak-free? Will you have to have a valve job done on a brand new set of heads after all of this work is completed?

I have run into issues trying to install large valves into a set of cast iron BBC heads. Only after the first machine shop destroyed 2 sets of heads attempting this, the second "race engine shop" was able to make it happen. Unfortunately, a valve seized in the guide on it's maiden voyage, bent valve & damaged piston.

The point is, yes, you should be able to remove the 1/4" material, but you may find that you are better off buying the heads that you "need" instead of trying to make something "work".

Sunshine Guy

I'm with you, Tbone, if the guides have to be punched out to remove the bump, it won't be a good idea. Might be opening pandora's box, as we all have experienced all too often. That's what I've been thinking, and your input makes me adamant...I just won't do it.

However, my local machinist says it is a no brainer for him to use a cutter that indexes on the bore of the valve guide and just cuts that little bit of material down flush with the valve pocket. That process is what is pictured on those Dart heads in the post right above Tbone's.

Why I need to do this: Cam maker recommends two springs. The primary recommendation is a spring with 130# seat pressure and a 430 lb/in rate, which would give me 357# over the nose with my .527" lift. NOW...Howards, like most companies, recommends the same spring for all their "streetable" series hydraulic rollers. Those cams range from about 4600 rpm to 7200 rpm power peaks, and from around .470 lift to ~.600 lift. There's no way I believe the same spring is the best choice for all those cams; my belief is, it is a matter of convenience and profitability that they recommend the same spring for everything. It will WORK for all, but puts much unnecessary wear and extra frictional power loss into the cams on the milder end.

My cam is much closer to the lower end of the range with a 5500 rpm power peak and .527" lift. The springs that came with my heads are 122# on the seat and about 290# over the nose. Those "might" be enough for my engine with its 5700 rpm rev limiter, but "might" isn't a good idea with valve train control. The springs themselves are the typical aftermarket, big and beefy (read: heavy), and the big, steel retainers weight about as much as garbage can lids. Takes a lot of spring pressure just to control its own mass.

The other, manufacturer-recommended spring option is an upgrade to an ovate beehive spring. Because of their much lower spring weight, relatively tiny, light retainer, and lack of harmonics issues, these beehives are recommended for all the way up to their big, ratty, 7200 rpm/.600" lift cams. Yet they only give a slight pressure increase from my OEM springs, at 130# seat and 295# over the nose. So you get the best of all worlds: Low wear and friction with reliable valve train control. You LSx guys know all about this.

However, because no one makes a valve spring seat cup that indexes on the outer 1.29" diameter of these springs, they require a locator that indexs on the inner diameter which is about .885". That leaves a center hole on the locater only the size of the valve guide, which is why the shoulder has to go.

There must be some shorter way to explain that, but obviously I don't know what that is.

Gator Bait

Please don't go looking for shorter explanations. I enjoy the technical chat and learning something while goofing off at work.

tbone heller

I would just use the springs that came with the heads if you are not planning on using a radical cam.

523-LSX-NB

I agree w/ above, unless the cam lobe has an aggressive ramp rate. No way you need that much spring on most cams w/.527" lift @ 5500 RPM. They just aren't normally designed w/ aggressive lobe ramps. Need cam specs including lobe profile.

IDK, about the whole guide wear claims either. We've run very aggressive, high lift, long duration cams on stock LS rockers (LS rockers make a wide wipe pattern on valve tip) & have never experienced excessive valve guide wear. Maybe valve guides spec'd. for Ford heads are of a softer material? Would guess not, but, maybe. Would be good to find out what material & treatments, if any, are applied to the valve stems.

Sunshine Guy

Really the only question I was asking was regarding removing that 1/4" high shoulder that surrounds the valve guide (as was done in the photo in the second post in this thread). I'm not worried about internal valve guide wear' that's more a function of proper valve train geometry, which I'll handle. Wear shouldn't be affected by removing that shoulder. I've already decided on upgraded springs and am confident in that choice; I was less than confident the OEM springs in the heads would have been adequate.

My concern was vertical support for the valve guide body, i.e., how it locks into, and is supported by, the head. The valve guide body engages the head with a press fit over a distance of about one inch, plus that little 1/4" shoulder that sticks up in the valve pocket. My question was whether removing that 1/4" shoulder, which represents about 20% of the total engagement between valve guide body and head, would result in insufficient valve guide support.

I have since talked with two other machinists that gave the green light on this, as well as two other guys who have actually done this and run their cars this way for 1 and 3 years respectively. The 3 year guy races his car a few times a year, so it looks like this plan is okay. Glad I asked though; better safe than sorry.

Picking them up from the machinist tomorrow, then off to Total Engine Airflow to cure their asthma!

523-LSX-NB

Yes, but you also brought up the cam & springs which appear to have discrepancies.

Sunshine Guy

Reading my statement regarding, "I only asked about the shoulder around the valve guides," I can see how that might come across as harsh or condescending. Not so intended! I always welcome input from anyone on anything they see that might affect what I'm doing. That's why I post; hoping someone will see something I don't. Finding out sooner is always easier and cheaper than finding out later!

I think my cam has fairly brisk ramp rates as far as street hydraulic rollers go, similar to a Comp XE profile. The springs that came on my head would be right on the edge of "maybe enough," even, "probably enough" at 5500 rpm, but I just feel more comfortable with the new beehive springs which actually are a recommended upgrade option for this cam by the manufacturer.

Honestly, my decision was partly influenced by my desire to try a set of these springs ever since I first read about them probably 10 years ago. I really like the concept of better valvetrain control with less pressure. Less friction, less wear, less effect from harmonic resonance, no retainer to rocker interference, and less absorbed horsepower.

Naysayers point to the fact that if you break a single spring set-up, the valve can fall into the engine. True, but I point to the fact that GM runs them as OEM on plenty hot LS motors with a factory warranty, and those engines typically see plenty of duty above 5500 rpm.

Remind me of all these odds in my favor when I am picking pieces of my broken crankshaft out of the cracked main saddles in my block, LOL.

523-LSX-NB

Similar to XER lobes explains why the cam vendor wanted the heavy (strong) springs. Beehives sound good. Am a$$uming that it's something in the low to mid 300 #/in range. The springs that jumped out as too much were the 430#/in rate springs. Keeping in mind that spring pressure eats power too. More spring force, more energy lost to the valve train.