Who does valves?

[Ondonti]

Or just get custom valves for 30+ a valve. Get exactly what you want. Valves do not have to be off the shelf. The issue is whether the company you work with actually has interest since the money is in the valve and not in the custom part with the way custom valves are priced.

SI refused to make valves for my machine shop years ago but Ferrea said yes. It was purely to do with the engine requested (snob) and probably who was on the phone. Machine shop said SI had done complete oddball valves for them on tractors and other old stuff so they were a bit mad at the refusal.

[tryingbe]

Shelgame have a set of rules to follow, I'm sure not using stock valve is not allowed.

[ShelGame]

Shelgame have a set of rules to follow, I'm sure not using stock valve is not allowed.

Aftermarket valves are allowed. They just have to be stock sized.

I'm not worried about an undersized neck, in general. The Manley 'Pro Flow' valves are 2"+ diameter with the same size stem as ours, and they don't break. Not sure I want to do this to stock valves, though.

[turbovanman²]

Last thing you need is to drop a valve being cheap/frugal. This could be the result and I wasn't even racing,

[ShelGame]

If it can be broken on one of these, Simon, I'm pretty sure you've broken it at least once. You're kind of like Evil Kinevil. Being a 'stock' enigne, I don't rev this ting hard at all. It simply doesn't flow above 5500 rpm at all. I shift at 5100. I'm not stressing the valvetrain. I'm just trying to optimize the efficiency of it all as much as possible.

That being said, I'll give up on the undersize stem for the time being. When I can afford all new valves for head #3, then I'll look again. For now, I'll probably just send the stock valves I have to AJ to be back-cut.

[turbovanman²]

If it can be broken on one of these, Simon, I'm pretty sure you've broken it at least once. You're kind of like Evil Kinevil. Being a 'stock' enigne, I don't rev this ting hard at all. .

Why thank you, lol.

That damage as done at 3000 rpm, cruising, in vacuum, no boost.

Good and wise idea.

[Ondonti]

If it can be broken on one of these, Simon, I'm pretty sure you've broken it at least once. You're kind of like Evil Kinevil. Being a 'stock' enigne, I don't rev this ting hard at all. It simply doesn't flow above 5500 rpm at all. I shift at 5100. I'm not stressing the valvetrain. I'm just trying to optimize the efficiency of it all as much as possible.

That being said, I'll give up on the undersize stem for the time being. When I can afford all new valves for head #3, then I'll look again. For now, I'll probably just send the stock valves I have to AJ to be back-cut.

On the high end you are looking at 300 bucks for custom valves. Thats me guessing 38 dollars a valve. I think its a very good value for your race class plus you have a worry free valve. Maybe you could get away with a larger undercut based on some agree'd upon maximum rev that takes into account your cam profile.

[ShelGame]

On the high end you are looking at 300 bucks for custom valves. Thats me guessing 38 dollars a valve. I think its a very good value for your race class plus you have a worry free valve. Maybe you could get away with a larger undercut based on some agree'd upon maximum rev that takes into account your cam profile.

Spring pressures also come into play, and I'm trying to reduce that as much as possible. Since this engine doesn't rev, there's no reason for insane spring pressures.

[turbovanman²]

Spring pressures also come into play, and I'm trying to reduce that as much as possible. Since this engine doesn't rev, there's no reason for insane spring pressures.

True, but you have to take into account the boost your running. When I ran the 3.3L V6 conicals, they were being opened by boost.

[ShelGame]

True, but you have to take into account the boost your running. When I ran the 3.3L V6 conicals, they were being opened by boost.

The 8v intake valve is 1.4in in dia. That gives it 1.54sq in face area. At 20psi boost, that's only 30lbs pushing on the valve. At 30psi, that goes to 45lbs. I could see that being an issue if the closed seat pressure was less than 100lbs...

[Reaper1]

As already has been said, be careful just plopping parts in the engine because they seem to be what "everybody else" is using. I have heard before that exhaust valves on our cars flow better if the backsides are left alone. It has to do with guiding the flow into and out of the port. Remember that the valve acts as the bottom of the port in that area, so while having a huge sewer pipe sounds like a great idea (back cut valve stem), if the flow separates and stalls in that same sewer pipe then you are not flowing anything close to what it *can* flow.

In your class/case, Rob, I think investing in testing off the car is going to be beneficial so you don't waste money and time (and maybe more important is wasting test/tune and racing) on parts and combinations that don't play nice with your needs.

[ShelGame]

Found what I was looking for on eBay. Unfortunately, there were only 3 of each in the set. They appear to be brand new stainless valves. No markings of any kind. They're stock size, and very nice. I want to find out who made them and get another (full) set. Any ideas who made these?

[Pat]

Didn't MP make stock sized back cut valves? Not sure if they were stainless or not, but I could swear I had bought and used some way back when.

[ShelGame]

I should correct my statement above - these were brand new stainless valves; they are certainly used. What I meant was, they were new stainless undercut valves. Not modified stock valves...

[Ondonti]

As already has been said, be careful just plopping parts in the engine because they seem to be what "everybody else" is using. I have heard before that exhaust valves on our cars flow better if the backsides are left alone. It has to do with guiding the flow into and out of the port. Remember that the valve acts as the bottom of the port in that area, so while having a huge sewer pipe sounds like a great idea (back cut valve stem), if the flow separates and stalls in that same sewer pipe then you are not flowing anything close to what it *can* flow.

In your class/case, Rob, I think investing in testing off the car is going to be beneficial so you don't waste money and time (and maybe more important is wasting test/tune and racing) on parts and combinations that don't play nice with your needs.

The hard thing about testing is that flowbench time that you actually have to pay for will eat into the budget that already doesn't exist for custom valves. I am sure the data is out there but people here keep all that stuff secret.