to fast over SSR

[Carnut1]

Which lt1 head is that?

[GARY C]

How are you guys measuring throat %'s? Using seat OD.. or ID?

Why would you ever use seat od?

ONCE AGAIN; you show little clue about what is going on ... you need TWO factors to derive throat percentage.
Most people use Valve O.D. as one of the factors which should be close but, not really correct.

So what do you guys consider correct?

[mag2555]

Forgiveness asked for, in my picture it's a Vortec head.

[steve cowan]

165 flow 001.JPG

165 flow 003.JPG

bench checked for calibration by my plate and leakage accounted for,all electronic
i put in exhaust probe to the bend of the 10 inch pipe to get velocity ,i dont know if this is correct procedure.
mag i made a template last night for the stock SSR,i will make another template for the modified SSR.
i want to recheck a stock port after the valve job and see where i am at

[Frankshaft]

Forgiveness asked for, in my picture it's a Vortec head.

I think they are both correct technically. It's such a small difference anyhow. There is just some tension between the 2 that they try to one up each other. Headguy is saying you use the valve diameter x .9= 2.025. That would be 90% of a 2.25. Walter is saying I am assuming, he is talking about the max od of the actual valve seat that is cut on the head. Say it's cut .010 smaller than the actual valve diameter, which for a 2.25 valve would be 2.2275, then use that number to calculate the throat % which would be 2.005 throat at 90%. This reply was meant to quote Gary C's question, of who is right, headguy or Walter

[Walter R. Malik]

So what do you guys consider correct?

The outside edge of the actual valve seating is my choice. Sometimes, that is quite a bit smaller than the valve O.D.
Other people can figure whatever they want.

[Biteme]

On the sbc dart heads is there a water jacket under the short side?
How far down is it?

[GARY C]

Forgiveness asked for, in my picture it's a Vortec head.

I think they are both correct technically. It's such a small difference anyhow. There is just some tension between the 2 that they try to one up each other. Headguy is saying you use the valve diameter x .9= 2.025. That would be 90% of a 2.25. Walter is saying I am assuming, he is talking about the max od of the actual valve seat that is cut on the head. Say it's cut .010 smaller than the actual valve diameter, which for a 2.25 valve would be 2.2275, then use that number to calculate the throat % which would be 2.005 throat at 90%. This reply was meant to quote Gary C's question, of who is right, headguy or Walter

Just curious, I have seen people say "% of valve diameter" and others say "% of valve seat".

[user-17438]

Matt, those the EQ vortec?

Factory iron LT1 from a B-body.

[Rick360]

% of valve diameter is what most are referring. For a given valve size you can do the seats a hundred different ways that could give you different throat % if using a valve seat reference. Typical conventional seats has the seat OD the same as valve OD so it wouldn't matter. Throat % of valve od makes sense to use since that indicates how much room you have to make your valve seat and bottom cuts in any manner you want.

I had not heard/seen anyone mention throat to valve seat % before reading it in this thread.

Rick

[GARY C]

% of valve diameter is what most are referring. For a given valve size you can do the seats a hundred different ways that could give you different throat % if using a valve seat reference. Typical conventional seats has the seat OD the same as valve OD so it wouldn't matter. Throat % of valve od makes sense to use since that indicates how much room you have to make your valve seat and bottom cuts in any manner you want.

I had not heard/seen anyone mention throat to valve seat % before reading it in this thread.

Rick

Valve diameter is what I was taught but the I wonder about the exhaust where the seat is not on the outer edge of the valve?

[xanadu]

G'day Steve. Just wondering what flow bench you have. Thanlks

[steve cowan]

G'day Steve. Just wondering what flow bench you have. Thanlks

FLOWBENCH MANUFACTURING AUSTRALIA
there website has a bit of details or you can ring Warren and have a chat,4-8 weeks for a bench to be made to order

215 pro 1 014.JPG

Ok guys,
i am at 89.5% throat which is 1.94'' - 10.5 % = 1.73'' which is what i have,
i am going to lay SSR down from 1.130'' off deck down to 1.050'' and test,and if i am heading in the right direction keep working from there,
any feedback appriciated

[mag2555]

Just work slow and make a flow test ( keep good notes and take photos ) after every .030" you remove to get a good grip on how things are trending.
Keep a close eye on your Intake flow numbers @ .200" and .550" , you would be doing well to have 140 cfm or better@ .200"@ 28".
Clay can be your great friend as you can add it in at places to see how fast flow numbers change / go down and by doing such you can then judge with good certainty what parts of the port will thru rework provide the most flow gain for the least amount of port enlargement.

Steve, those heads have real good Exh numbers at .100" and .200" for a 1.50" valve with also coming close to the ports peak flow at around .400"!
Let us know before you go head long into reworking the Exh ports.

Whenever port a head 98% of the time I am doing a valve job to some extent just to get the main seat out to with in .010" to .005" of valve OD so valve ODis what I judge the Throat percentage off of.

[Frankshaft]

Then do you add area to account for the stem? After all, it is taking up area. Add roughly .010 to your calculated throat %.