bodhi

I just spoke with Brian @ TEA- very nice, knowledgeable and helpful. During my chat with him, I told him that I was interested in a 5.3 StgII, 2.055-1.60, dual springs, Ti retainers and 11.5CR. He agreed with almost all of this except the CR and the exhaust valve size. He said that to reach that CR, I would have problems with PVC (which I expected), and the 1.60 exhaust valve was too big.
From what he said, the stock 1.55 valve will flow better due the 24 degree "tulip" back angle. Is this correct? He said that this was the best way to go and that there were no issues with the stock valve..
From what he told me, the Ferrea and Manley valves only come in like a 20? degree slope and the only ay to go above the 24 was to go titanium.
So what's the deal? will the 1.55 stock valve work better because of the shape or will the 1.60 Ferrea work better due to the size?

What kind of CR can I go with and not have any major PVC problems? He told me about flycutting the pistons myself with the Isky jig (and that he would loan it to me for free), but I don't think I'm gonna pull the motor to do the swap.

Phil99vette

iTrader: (11)

You can run a thinner head gasket and pick up more compression than milling. Try a thin cometic gasket and 60cc chambers....should be more compression than you need.
Phillip

bodhi

Okay- BUT WTF is the deal Brian is talking about with the valve? Is he for real? Why would the stock valve flow better than a Ferrea?

mobius

I have heard that the stock exhaust valves flow better...

Nine Ball

iTrader: (38)

A "tulip" shaped valve has a tapered stem diameter near the disk of the valve, where a standard shaped valve is more like a flat disk with a stem. The tulip is smoother in transition between the disk and stem.

The tulip valve will give a bit better numbers out of a 1.55 and 1.60 size difference. I learned this at one of the cult meetings we had :p

Colonel

2001CamaroGuy

iTrader: (6)

a tulip 1.55" would flow more than a "standard" 1.60....but you should be able to get tulip 1.60" valves so that would flow even better....

bodhi

Thank you Tony. When I can afford the dues, I'll be there. Until then I'll come here for assistance.

I understand that the valve is tapered, but what's this deal about the stock valve working better than an aftermarket Ferrea (assumably tapered to the same degree as a stock 1.55" valve) 1.60"?
Brian brought this up and it doesn't seeem to make sense, but if it works- it works.

TEA Brent

The stock exhaust valve with its 20 or so degree back angle flows better than the Ferrea 1.55 (F6232) with its 12 degree back angle or the REV 1.57 with its whatever degree back angle and better than the Ferrea 1.60 (F6233) with its 12 degree back angle. The Ferrea 1.60 (F6234) with its 24 degree back angle will out flow the stock exhaust valve, but at the price of $100+ for the valves and $100 for the seat removal and reinstallation for the bigger valves. The kicker is we have seen LESS power with bigger exhuast valves on N/A engines. I know people don't believe some of this but we have tested it, and thats what we found, this is not our opinion. Thats why I brought up the fact that 900 HP Prostock Trucks have 2.200" intake valves and 1.58" exhaust, if you want to look at the sizing from a ratio aspect then the percentage of exhaust sizing to intake is 71.8%. If we use this math on our 2.05 intake valve then the exhaust valve would be 1.47 Things that make you go hummmmmmmm.
Hope this helps
Brian

needmoremoney

So bigger is not always better.

Cheatin' Chad

iTrader: (3)

You can also swirl polish the valves and/or have them fully radiused for flow.Full radius for the most part works best on exhaust valves while a 3 or 5 angle tends to work best on intake valves.Engine builders for quite some time now have been using a 30* backcut on valves for a solid low lift(.100-.300) increase in flow.Differing degrees of backcuts will see differing amounts of increase at different lifts.Therefore the degree of backcut should be tailored to the camshaft being installed.
Intake to exhaust ratio(expressed in percentages here) is highly dependent on the type of motor you are building.While N/A motors tend to work best with an exhaust valve 65-75% of the intake.A supercharged(chemically or mechanically) motor will usually see the best numbers with an exhaust valve 70-85% of the intake. A higher C/R will often allow the use of a smaller exhaust valve.

BTW a "tulip" valve has a concave face making the valve lighter. This valve treatment does not affect flow at all to the best of my knowledge.