errr Rb

2.02" is the diameter of the head. 1.60" is the typical exhaust that would go with that.

.100" longer means they're about 5.011" long. That, all by itself, would take your installed height from 1.700" (stock) to 1.800", with the spring pocket cut to the stock depth. .050" offset keepers on top of that would take you to 1.850". That's pretty close to enough for .600" lift solid roller cams.

You don't necessarily need the same length on both I & E. For example, imagine the situation of a nitrous cam, with a HUGE exhaust lobe; you might need the longer valves there, but not on the intake. But it's not necessarily "better" to do that, I only use it as an illustration that it's possible. If I was going to lengthen one side, I'd do the other side too, and use 16 identical springs set up identically.

Personally, if I have to buy valves anyway, I tend to get longer ones than stock; that way, there's room to grow. I can always stack more shims under them to take up space for now, and then if I want to go bigger later on, I have room to put in more spring, and take out shims. It's alot harder to go the other way.

Don't forget, if you lengthen the valves, you'll most likely need longer push rods too; since the whole rocker will have to move upwards by the valve height difference.

That's a tiny head, I thought you were beyond RC helicopters!!!

Yes, I knew you meant the valve. Happy hellicopering!

Maybe for the "big head", but for the "little head", it's adequate. The little one does all the thinking anyway. The big one is useless, basically just an 8-lb tumor sticking out the end of my spine.

ROTFL!

You have a better sense of humour than I ever imagned!

Always knew the brain stem did more than keep our hearts beating.

Don't get me started on ABS modules.

Alright so I'm looking at manley

Man-11823-8 Exhaust, 1.6, .100 longer 160$ for set of 8
. So that will work for the exhaust correct? Then the .050" offset keepers so i dont run into problems and get all the lift i can.

Now the intake? Do you know by chance the typical intake head?

2.055?

BTW all of the porting thats going to be done to these heads, none of the valve heads size will be changed will it? I dont think so.

The exhaust seat is directly under the exhaust valve and is what the valve seals against when it is closed. I suspect some port work would fix that problem.

Is what this guy told me since 10239906, which has a modified exhaust seat and loses 20 percent of its flow at 0.120-inch lift."

I guess this is correct info? But when the guy goes to port all this out will it effect the valve head size?

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Porting doesn't change the valve size. You use a cutter to cut in a new seat for that.

AFAIK the seats on the 2 Vortec head castings are the same. There was an article in some one of the hot-rod mags where they said that; they published a retraction a month or 2 later. But the original comment seems to have stuck.

For what you're doing, you should get your machinist to cut a seat and mock it up with a stock length valve of the correct diameter, and see what installed height he comes up with that way. Then go from there. You might need only the longer valves, or only the offset keepers, or both, or neither, to get it to the point you need which is 1.800".

Ths stock intake valve head diameter on those heads is 1.94". 2.02" is about as large as they'll go. Any larger, and the exhaust & intake valve heads will touch; and the metal between the ports will be foil-thin, and tend to crack. Personally, I've found that you get more bang out of 1.94" valves with undercut stems, than out of straight-stem 2.02" valves. And with less risk of problems. It depends on whether you're going for broke on the flow, or being conservative inteh interest of longevity and low risk of failure (cracking etc.). That's a decision only you can make, with competent informed help from the machinist that actually is laying hands on your castings and warrantying his work.

"For what you're doing, you should get your machinist to cut a seat and mock it up with a stock length valve of the correct diameter, and see what installed height he comes up with that way. Then go from there. You might need only the longer valves, or only the offset keepers, or both, or neither, to get it to the point you need which is 1.800".

1) Are you referring to the seat of the valves or the seat as in the guide seat for the valve springs?

2)When you said "The stock intake valve head diameter on those heads is 1.94". 2.02" is about as large as they'll go."

I just looked in summit and all the valves in there that come in 1.94 are not .100 longer. I only see 2.02 on the intake side for .100 longer and thats with Milodon-undercut stems. I didn't see any manleys in the description that stated they had undercut stems.

So from that research, it looks like the valves on the intake side are going to have to be machined open more on the seat to suffice for a 2.02 diameter valve. And the exhaust i think you stated above on these heads are 1.6 and those do come in .100 longer. Thats a good thing that i dont need both machined. So am i on the right track?

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Go to www.manleyperformance.com, and look in their catalog, and type the part #s you find into the Summit part search. There's lots and lots of them in the catalog that aren't in Summit's list you can browse through. Make sure as you look through the catalog that you pay attention to the stem diameter; you need stock diameter which is 11/32" (.3415").

You'll find though, they tend to be REAL $$$$, because that combo (1.94" dia, 5.011" long, .3415" stem) is usually only available in NHRA super stock legal stuff, which is way overkill for a street motor.

If you don't need the longer stem, there's no reason to pay $200 more for valves than you have to, just to get it. If it works out that you can't get the spring you need to fit any other way, or you're going to buy some kind of the more $$$ valves anyway, then that's one thing; but if the stock length and the less expensive types of valves will work, which will be WAY cheaper, then go that way.

Let your machinist tell you if you need the longer valves. If you don't, then don't go to that expense. Here's a few all-around best choices in stock length for a stret motor, for example; IF you can go with the stock length, which only your machinist can tell you if they'll fit the springs in. http://store.summitracing.com/partde...AN%2D10722%2D8 http://store.summitracing.com/partde...AN%2D11522%2D8 or if he can cut the heads for 2.02" diameter for cheap (although it's not necessary), these http://store.summitracing.com/partde...AN%2D10766%2D8

Ok so i'll buy my valve springs, and retainers. Have the machinist cut a guide down and see if he can get an installed height of 1.8 with my stock lenght valves. If thats the case then yes i'll just tell him to wait and i will get better valves then stock.

If thats not the case then oh well. I'll go .100 longer. I kinda understand it now. Its just I dont know this guy and the communication with the "engine world" i'm just learning so i dont want to sound like some kid who doesnt know what hes talking about. Does it seem like i have it down? as for the valve train?

To get the valve springs installed alls I need is the comp cams retainers correct?


Valve locks? I know they lock the valve stem up top of the valve spring. Whats that at the top called? spring cups? or are those at the bottom.

good job understanding the valve train "crash course" so far!
man!where was this site when i was 17?
just to clarify,keepers and locks are the same thing.they lock the retainer to the valve,the retainer"retains"the spring at the top.spring cups also do exactly that they say,they are a cup the spring sits in.you shouldn't need em unless the springs are smaller than the valve spring pockets(where the shims go),they won't be.
now for valve train geometry....................

Eric B

than you

I'll refresh your memory. I'm getting the 987 comp valve springs which need an installed height of 1.8 on my vortec heads. For my machinist to determine the height he can get out of my heads what does he need? Just my heads , a micrometer (which he probably has), Should I buy the retainers or locks yet?