Qualfast valves?

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blackford
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Qualfast valves?

Post by blackford »

So I got Promaxx 180 heads for a 331 SBF. I disassembled them to do some port cleanup and i'm going to change the valve springs.

I've been doing some research on the part numbers on the intake and exhaust valves to determine what they are and i've determined they are Qualfast valves. It appears that Qualfast is a large automotive parts distributor located in the Nashville TN area. These are not expensive valves by any means. They can be had for about $10 each. Does anyone know anything about these valves?

The valves in general look good (see pic). The one thing I dislike is the large .080 margin on the exhaust valve. As a result, I can't install my new springs and locators because the exhaust valve seat is so high. I'd like to have the valve seat re-ground .030 lower. Would that be OK or should I buy new exhaust valves? Cost would probably be comparable to just buy new valves vs. machining the valve seats lower.

These heads are going on a 331 SBF. It's a street/strip motor, and it will be revved to 7000 just like it was before I took the old heads off. HP will be around 475. Spring pressure will be 130 closed and 284 open (PAC 1286 ovate wire beehives or equivalent). I kinda wish I bought the heads bare, but if I need to get different valves, then so be it.
Promaxx Valves.jpg
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65 Mustang FB, 331 custom built with 289 H beam rods and 383W piston, 282S cam, Ported Maxx 180s, T5z, 9" 3.89 gears. ~460HP@6500

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Re: Qualfast valves?

Post by PackardV8 »

Maybe QualCast.

https://qualcast.net
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Re: Qualfast valves?

Post by BillK »

Just get some +.050 locks and be done with it. Seems like almost every set of aftermarket Ford heads I see requires it. I keep them in stock. Its not the margin on the valve its the tip length from the groove to the tip. I certainly would not sink the valve seats !

http://www.pbm-erson.com/Catalog/Erson/ ... BM205%2b50
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Re: Qualfast valves?

Post by blackford »

BillK wrote: Sun Jan 29, 2023 7:25 pm Just get some +.050 locks and be done with it. Seems like almost every set of aftermarket Ford heads I see requires it. I keep them in stock. Its not the margin on the valve its the tip length from the groove to the tip. I certainly would not sink the valve seats !

http://www.pbm-erson.com/Catalog/Erson/ ... BM205%2b50
That's a good idea. The exhaust valve is 4.930 long...should be long enough, but the big margin makes the distance between the valve spring pocket and the underside of the retainer a bit too short for my new springs and locators. The intake valve, although .020 shorter overall, is just fine.
65 Mustang FB, 331 custom built with 289 H beam rods and 383W piston, 282S cam, Ported Maxx 180s, T5z, 9" 3.89 gears. ~460HP@6500

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Re: Qualfast valves?

Post by blackford »

PackardV8 wrote: Sun Jan 29, 2023 7:15 pm Maybe QualCast.

https://qualcast.net
Yes. Qualcast uses the Qualfast name for some of their parts
65 Mustang FB, 331 custom built with 289 H beam rods and 383W piston, 282S cam, Ported Maxx 180s, T5z, 9" 3.89 gears. ~460HP@6500

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Re: Qualfast valves?

Post by 6.50camaro »

Blackford, so what is the difference between the intake installed height and the exhaust installed height. what is the installed height you need for the springs you are installing and how close is that to the minimum height by the spring manufacture. The thicker margin on the exhaust valve is not a bad thing IMHO. Dan
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Re: Qualfast valves?

Post by blackford »

6.50camaro wrote: Sun Jan 29, 2023 8:16 pm Blackford, so what is the difference between the intake installed height and the exhaust installed height. what is the installed height you need for the springs you are installing and how close is that to the minimum height by the spring manufacture. The thicker margin on the exhaust valve is not a bad thing IMHO. Dan
Distance from valve spring pocket to underside of spring retainer on the Intake is 1.820. Exhaust is 1.780. Spring locator is .060 (thinner locators appear to be uncommon). Installed height of spring is 1.750. If I leave everything as-is, the installed height for the exhaust will be .030 less than manufacturer installed height with no shims. I suppose it's not a hard fast requirement to be at the manufacturer installed height...seat pressure may be more important. It's just that I don't have any wiggle room on the exhaust side. Maybe i'll use +.050 offset 10 degree keepers or i'll get new exhaust valves. It sounds like lowering the seat on the valve by .030 (decreases margin to .050) may not be the way to go.
65 Mustang FB, 331 custom built with 289 H beam rods and 383W piston, 282S cam, Ported Maxx 180s, T5z, 9" 3.89 gears. ~460HP@6500

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Re: Qualfast valves?

Post by 6.50camaro »

blackford wrote: Sun Jan 29, 2023 9:29 pm
6.50camaro wrote: Sun Jan 29, 2023 8:16 pm Blackford, so what is the difference between the intake installed height and the exhaust installed height. what is the installed height you need for the springs you are installing and how close is that to the minimum height by the spring manufacture. The thicker margin on the exhaust valve is not a bad thing IMHO. Dan
Distance from valve spring pocket to underside of spring retainer on the Intake is 1.820. Exhaust is 1.780. Spring locator is .060 (thinner locators appear to be uncommon). Installed height of spring is 1.750. If I leave everything as-is, the installed height for the exhaust will be .030 less than manufacturer installed height with no shims. I suppose it's not a hard fast requirement to be at the manufacturer installed height...seat pressure may be more important. It's just that I don't have any wiggle room on the exhaust side. Maybe i'll use +.050 offset 10 degree keepers or i'll get new exhaust valves. It sounds like lowering the seat on the valve by .030 (decreases margin to .050) may not be the way to go.
I'm assuming then you are at max lift at the valve of the spring, on both intake and exhaust?
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Re: Qualfast valves?

Post by blackford »

6.50camaro wrote: Sun Jan 29, 2023 9:32 pm
blackford wrote: Sun Jan 29, 2023 9:29 pm
6.50camaro wrote: Sun Jan 29, 2023 8:16 pm Blackford, so what is the difference between the intake installed height and the exhaust installed height. what is the installed height you need for the springs you are installing and how close is that to the minimum height by the spring manufacture. The thicker margin on the exhaust valve is not a bad thing IMHO. Dan
Distance from valve spring pocket to underside of spring retainer on the Intake is 1.820. Exhaust is 1.780. Spring locator is .060 (thinner locators appear to be uncommon). Installed height of spring is 1.750. If I leave everything as-is, the installed height for the exhaust will be .030 less than manufacturer installed height with no shims. I suppose it's not a hard fast requirement to be at the manufacturer installed height...seat pressure may be more important. It's just that I don't have any wiggle room on the exhaust side. Maybe i'll use +.050 offset 10 degree keepers or i'll get new exhaust valves. It sounds like lowering the seat on the valve by .030 (decreases margin to .050) may not be the way to go.
I'm assuming then you are at max lift at the valve of the spring, on both intake and exhaust?
I'm not sure what you mean by that.
65 Mustang FB, 331 custom built with 289 H beam rods and 383W piston, 282S cam, Ported Maxx 180s, T5z, 9" 3.89 gears. ~460HP@6500

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Re: Qualfast valves?

Post by mag2555 »

That tall margin ( which should have nothing to do with the installed height) is a big plus for exh flow !

You never want a exh valve margin of less then .050”

Whatever valves you do get be fully sure they have chrome plated stems like Manley valves do.
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Re: Qualfast valves?

Post by 6.50camaro »

blackford wrote: Sun Jan 29, 2023 10:12 pm
6.50camaro wrote: Sun Jan 29, 2023 9:32 pm
blackford wrote: Sun Jan 29, 2023 9:29 pm

Distance from valve spring pocket to underside of spring retainer on the Intake is 1.820. Exhaust is 1.780. Spring locator is .060 (thinner locators appear to be uncommon). Installed height of spring is 1.750. If I leave everything as-is, the installed height for the exhaust will be .030 less than manufacturer installed height with no shims. I suppose it's not a hard fast requirement to be at the manufacturer installed height...seat pressure may be more important. It's just that I don't have any wiggle room on the exhaust side. Maybe i'll use +.050 offset 10 degree keepers or i'll get new exhaust valves. It sounds like lowering the seat on the valve by .030 (decreases margin to .050) may not be the way to go.
I'm assuming then you are at max lift at the valve of the spring, on both intake and exhaust?
I'm not sure what you mean by that.
if your spring has a .550 max lift and your cam is only .520 lift you are safe. or what ever the numbers are from your combo. as long as the cam lift does not put you past the max open spring height.
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Re: Qualfast valves?

Post by Walter R. Malik »

blackford wrote: Sun Jan 29, 2023 6:14 pm So I got Promaxx 180 heads for a 331 SBF. I disassembled them to do some port cleanup and i'm going to change the valve springs.

I've been doing some research on the part numbers on the intake and exhaust valves to determine what they are and i've determined they are Qualfast valves. It appears that Qualfast is a large automotive parts distributor located in the Nashville TN area. These are not expensive valves by any means. They can be had for about $10 each. Does anyone know anything about these valves?

The valves in general look good (see pic). The one thing I dislike is the large .080 margin on the exhaust valve. As a result, I can't install my new springs and locators because the exhaust valve seat is so high. I'd like to have the valve seat re-ground .030 lower. Would that be OK or should I buy new exhaust valves? Cost would probably be comparable to just buy new valves vs. machining the valve seats lower.

These heads are going on a 331 SBF. It's a street/strip motor, and it will be revved to 7000 just like it was before I took the old heads off. HP will be around 475. Spring pressure will be 130 closed and 284 open (PAC 1286 ovate wire beehives or equivalent). I kinda wish I bought the heads bare, but if I need to get different valves, then so be it.

Promaxx Valves.jpg
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Re: Qualfast valves?

Post by blackford »

6.50camaro wrote: Mon Jan 30, 2023 7:12 am
blackford wrote: Sun Jan 29, 2023 10:12 pm
6.50camaro wrote: Sun Jan 29, 2023 9:32 pm
I'm assuming then you are at max lift at the valve of the spring, on both intake and exhaust?
I'm not sure what you mean by that.
if your spring has a .550 max lift and your cam is only .520 lift you are safe. or what ever the numbers are from your combo. as long as the cam lift does not put you past the max open spring height.
Yea i'm good there. Neither the spring max lift or coil bind are being approached. I have 1.7 shaft rockers and gross lift is .561 and net lift is .543 with .018 lash subtracted from gross. Valve spring max lift is specified as .600 and coil bind is 1.060 (actual bind is much less than this but PAC doesn't recommend compressing the spring more).
65 Mustang FB, 331 custom built with 289 H beam rods and 383W piston, 282S cam, Ported Maxx 180s, T5z, 9" 3.89 gears. ~460HP@6500

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Re: Qualfast valves?

Post by blackford »

So I went back and measured everything very carefully. With the valves I have, I can set the installed height of the spring to 1.720, .030 less than recommended. We're talking about 8 more lbs of seat pressure...not much. Coil bind and max spring compression are non-issues. Should I just run it like this? Thanks
65 Mustang FB, 331 custom built with 289 H beam rods and 383W piston, 282S cam, Ported Maxx 180s, T5z, 9" 3.89 gears. ~460HP@6500

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Re: Qualfast valves?

Post by 6.50camaro »

IMHO, you should be good to go at that installed height. after it all together roll it over with a dial indicator on the retainer to double check max lift with lash and deflection. Dan
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