OEM style valves - SBI vs Melling

-
Charlie_es_cool

Charlie_es_cool

Well-Known Member
Joined
Sep 6, 2020
Messages
59
Reaction score
55
Location
Puerto Rico
Hello everyone. I have a Melling v0548 valve and an SBI 00548. I have noticed there are some differences between them.

The SBI valve has a step on the underside of the valve head, and its finish is different than the Melling. (SBI on the left, Melling on the right in the first and second pics)

IMG_4041.jpeg


IMG_4042.jpeg


SBI:

IMG_4043.jpeg


IMG_4044.jpeg


Melling:

IMG_4045.jpeg


IMG_4046.jpeg


IMG_4053.jpeg


I also noticed the Melling has a fatter margin and a wider seat surface than the SBI. My question is, would it be worth it running one over the other? Or I could go either way without much difference? The main thing that’s throwing me off is that step on the SBI which seems to me to be the biggest difference. I’m thinking it’ll be a sharp edge in my combustion chamber. Don’t know if I’d like that.

IMG_4051.jpeg


IMG_4052.jpeg
 
Charlie_es_cool said:
Hello everyone. I have a Melling v0548 valve and an SBI 00548. I have noticed there are some differences between them.

The SBI valve has a step on the underside of the valve head, and its finish is different than the Melling. (SBI on the left, Melling on the right in the first and second pics)

View attachment 1716091187

View attachment 1716091188

SBI:

View attachment 1716091189

View attachment 1716091190

Melling:

View attachment 1716091191

View attachment 1716091192

View attachment 1716091200

I also noticed the Melling has a fatter margin and a wider seat surface than the SBI. My question is, would it be worth it running one over the other? Or I could go either way without much difference? The main thing that’s throwing me off is that step on the SBI which seems to me to be the biggest difference. I’m thinking it’ll be a sharp edge in my combustion chamber. Don’t know if I’d like that.

View attachment 1716091193

View attachment 1716091194
Click to expand...

It will darn sure hurt flow !!!
 
I'm FAR from a flow expert, but I fail to see how the step on the chamber side of that intake valve could in any way impede flow. Since the intake flow is coming from the other side, that step has no bearing on flow, IMO. So I'm not sure I would include the step in my decision process. Maybe @MOPAROFFICIAL will chime in. He's forgotten more about cylinder head flow than a lot of people will ever know.
 
They all have to meet a certain spec so however they do it is on them apparently one has a little deep dimple while the other has a lesser deep dimple but kind of a cutout on the other side. Between these two no it's not going to matter at all.. this is kind of like .."which turd is the shiniest".

If you're even considering flow increases by Valve change ...you should really buy a good valve instead of buying replacement stuff.

Hope that helps somebody.
 
@pittsburghracer comes to mind, too. But in the world of replacement valves, I like what I've seen in several different melling stainless valves I've purchased from eBay. I've not seen nearly as many SBI valves that I thought would be viable for a performance upgrade. Well, as much as a 3/8 stem exhaust valve would be for an upgrade, but good for a moderate heavy duty engine and a means to the end of eliminating the exhaust rotators.
 
Last edited:
I'll also throw you this one.
The valve with the wider margin allows you some more room to do a back cut which might just leave you better ..
Now here's the but...
If you can't back cut it yourself and have to pay somebody... well ****... by now you could have bought yourself some good valves lol
 
MOPAROFFICIAL said:
They all have to meet a certain spec so however they do it is on them apparently one has a little deep dimple while the other has a lesser deep dimple but kind of a cutout on the other side. Between these two no it's not going to matter at all.. this is kind of like .."which turd is the shiniest".

If you're even considering flow increases by Valve change ...you should really buy a good valve instead of buying replacement stuff.

Hope that helps somebody.
Click to expand...

Understood.

I actually did consider getting Mancini 2.08/1.74 valves but settled on replacement stuff since I’m not going crazy on my current build and want to keep budget creep in check.
 
RustyRatRod said:
I'm FAR from a flow expert, but I fail to see how the step on the chamber side of that intake valve could in any way impede flow. Since the intake flow is coming from the other side, that step has no bearing on flow, IMO. So I'm not sure I would include the step in my decision process. Maybe @MOPAROFFICIAL will chime in. He's forgotten more about cylinder head flow than a lot of people will ever know.
Click to expand...

You would be surprised at what can actually impede flow , I`ve helped my head man and long time personal friend (18 time national record holder) on 3 diff. sets of heads , (mine) , all flowed after and before , a little thing the size of a hangnail can affect flow a bunch !!
 
The valve head angle,shape, thickness all majorly impact flow.

The tulip vs the nail head ...
It's not the stem 3/8 vs 11/32 vs 5/16 -8mm... so much.. it's the door thing called the satellite, under head..
Is it 12 degrees? or is it .500 thick and 45-60 degrees like a tulip.

The magic trick of the Charlie 302 vizard show , for instance , was a nail head valve in place of a tulip...its worth over 12 cfm.
Too bad they're shorter by .110 stock 4.87 vs 4.98, meaning you need to put them down more and use pop ups ...or buy 200 dollar per 8 .150 longer race valves... or cut .050 off the spring seats/pads..etc..
 
You must log in or register to reply here.
-

Back
Top