How far to trust LS 5.3 OEM valves?

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PackardV8
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How far to trust LS 5.3 OEM valves?

Post by PackardV8 » Tue Oct 30, 2018 11:57 am

FWIW, we've been using OEM LS 5.3 valves, springs and retainers in Studebaker V8 builds; larger intakes, better springs at lower cost.

We've got a build going the customer wants to be able to turn to 7,500 RPM and use dual valve springs. Are OEM LS valves even safe at that RPM with higher spring pressures? If not, who makes good 5.3 valves?
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Re: How far to trust LS 5.3 OEM valves?

Post by Newold1 » Tue Oct 30, 2018 8:21 pm

The Manley Race Flo LS1 (5.3) high quality stainless 2.00" intake and 1.55" exhaust are both available from Manley in sets of 8 each for about $150 set retail.

My advise is these valves will do 7500rpms reliably if a nice set of lighter weight conical valve springs and lightweight tool steel retainers are used and they are not overstressed with big heavy fat dual or triple springs You only need about 125-150lbs on the seat and about 250-300lbs open to spin these valves all day long at 7500rpms. Keep the weights down and Don't kill them with "overspringing"
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Re: How far to trust LS 5.3 OEM valves?

Post by peejay » Tue Oct 30, 2018 8:36 pm

I'm a bit scared of LS1 valves, since it seems like anyone who open-tracked an LS1 back when they were common would blow an engine up sooner or later, more sooner than later. The carnage would be incredible and total. One of the most memorable photos I've seen was some piston ring chunks on the control arm of a CTS-V. Another was an FD RX-7 that had been LS1-converted, blew up at a track day, and removing a head showed that one of the cylinder liners was just gone, along with the piston etc.

In all cases, valve heads were missing. And, I suspect this is why I have to say things like "Back when LS1s were common"

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Re: How far to trust LS 5.3 OEM valves?

Post by PackardV8 » Tue Oct 30, 2018 11:08 pm

We need the LM7 1.890" intake valves; can't use the 2.00".

I have cut down 2.00", but it's not cost-effective.
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Re: How far to trust LS 5.3 OEM valves?

Post by PackardV8 » Wed Oct 31, 2018 1:14 pm

These 1.890" intake valves were used in "706" heads on the 4.8 and 5.3 LS up to 2007.
My advise is these valves will do 7500rpms reliably if a nice set of lighter weight conical valve springs and lightweight tool steel retainers are used
For true, but the customer isn't familiar with beehives and I've not found it profitable to argue with customers. Maybe I can get him to read up on conical springs.
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Re: How far to trust LS 5.3 OEM valves?

Post by Newold1 » Wed Oct 31, 2018 3:37 pm

Qualcast in Tennessee makes a 1.890" makes a 1.890" exhaust valve for the 5.3L a part #10-1934. They make some good valves and you might be able to get them in the nitrided versions

Just how many Studebaker heads are you doing for this application, as cutting down 8 valves from 2.00" to 1.890" is a quick trip on a trained lathe operator.

As for conical springs, I know you are working "antique" heads but come out of the antique mode and have your customer take account of the newer valve and spring technologies.
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Re: How far to trust LS 5.3 OEM valves?

Post by BillK » Wed Oct 31, 2018 4:02 pm

I would call Ferrea and ask them how much they would charge to cut down a set of the 2 inch ones. They have been very reasonable in the past for things like this. Their 6000 series valve should be fine.
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Re: How far to trust LS 5.3 OEM valves?

Post by Keith Morganstein » Thu Nov 01, 2018 8:17 am

PackardV8 wrote:
Tue Oct 30, 2018 11:57 am
FWIW, we've been using OEM LS 5.3 valves, springs and retainers in Studebaker V8 builds; larger intakes, better springs at lower cost.

We've got a build going the customer wants to be able to turn to 7,500 RPM and use dual valve springs. Are OEM LS valves even safe at that RPM with higher spring pressures? If not, who makes good 5.3 valves?
There are almost no offering for that 1.890 size intake valve. Brian Benson at Dakota parts warehouse will make you custom Ferrea. From what you post, its more than you want to spend.

IMHO, the stock OEM valve is very good in that size. Many people turbo, NOS and beat the crap out of 5.3's

If your just wanting inexpensive, you are using the best valve for the $$$ already.
If you are regrinding old used valves, that's just rolling the dice in a HP application.
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Re: How far to trust LS 5.3 OEM valves?

Post by PackardV8 » Thu Nov 01, 2018 11:55 am

Thanks, Keith, et al; we're buying new valves. Since you all assure us the 4.8/5.3 valves are good enough and affordable, that seems the way to go.

FWIW, a couple of years ago, we bought eight sets of takeout 6.0 valves, springs, retainers and keepers from a shop which specializes in stepping up new LS heads. A friend with a CNC lathe cut the intakes to 1.875" for us just zip/pop and they were so smooth, there was no touch-up grinding necessary.
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Re: How far to trust LS 5.3 OEM valves?

Post by Keith Morganstein » Thu Nov 01, 2018 9:34 pm

PackardV8 wrote:
Thu Nov 01, 2018 11:55 am
Thanks, Keith, et al; we're buying new valves. Since you all assure us the 4.8/5.3 valves are good enough and affordable, that seems the way to go.
What are you paying for a new 12564494 valve?

SI does have that size in their port flow series. I’m not sure if it’s a better/tougher valve than the OE.
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Re: How far to trust LS 5.3 OEM valves?

Post by novadude » Fri Nov 02, 2018 10:53 am

peejay wrote:
Tue Oct 30, 2018 8:36 pm
"Back when LS1s were common"
Now I feel old. I thought LS1s were still common. I guess I'll stick to my stone-age Gen 1 SBCs.... can't keep up with all this new-fangled technology. LOL :lol:

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Re: How far to trust LS 5.3 OEM valves?

Post by PackardV8 » Fri Nov 02, 2018 4:00 pm

Now I feel old. I thought LS1s were still common.
For true. When I started using the 1.890" 4.8/5.3 LS valves and springs in Studebaker V8s, they were the latest and greatest. By 2007, they were obsolete and now difficult to find.

A bit of trivia - in my search for the valves, I turned up an old test of four different OEM LS heads on 5.3s. They made much of the shocking result. The original 1.890" valve heads made more horsepower than any of the 2.00" intake heads.
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Re: How far to trust LS 5.3 OEM valves?

Post by WPH » Fri Nov 02, 2018 5:54 pm

PackardV8 wrote:
Fri Nov 02, 2018 4:00 pm
Now I feel old. I thought LS1s were still common.
For true. When I started using the 1.890" 4.8/5.3 LS valves and springs in Studebaker V8s, they were the latest and greatest. By 2007, they were obsolete and now difficult to find.

A bit of trivia - in my search for the valves, I turned up an old test of four different OEM LS heads on 5.3s. They made much of the shocking result. The original 1.890" valve heads made more horsepower than any of the 2.00" intake heads.
Propably due to new larger valve size not matching the size of the port or the shape of the short side radius

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Re: How far to trust LS 5.3 OEM valves?

Post by peejay » Sat Nov 03, 2018 9:07 am

novadude wrote:
Fri Nov 02, 2018 10:53 am
peejay wrote:
Tue Oct 30, 2018 8:36 pm
"Back when LS1s were common"
Now I feel old. I thought LS1s were still common. I guess I'll stick to my stone-age Gen 1 SBCs.... can't keep up with all this new-fangled technology. LOL :lol:
They made "SBC"s for thirty or fifty years depending on who you ask, they only made LS1s for five or six years.

How common are DZ302s or LT-1s?

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Re: How far to trust LS 5.3 OEM valves?

Post by HDBD » Sat Nov 03, 2018 11:42 am

Why not use a 7mm valve in those engines? Manley blanks can be cut to length and used with no lash cap or hard tip. Need the lock groove cut too.

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