Which valve seat do I need

[RedogOnyx]

OK I spoke to my mech, and it's possible that the reason I'm losing coolant is I have combustion gases in the cooling system. In other words, a $1200 head gasket job



Anyway, the mech wants to put the new heads on the motor. I'm looking to put the LS6 springs on and the 3500 valves in.



I'm going to buy the the retainers and keepers from Ben but IDK what to do with the valve seats? do I need the stock seat or do I have to modify for .553" OD Guides

[SappySE107]

What heads? If the stock seat/seal is on there, look at the color of the seals. Blue are .553", Orange are .520". If not, look at where the seal would go on the guide. If its not cut down, its .553" The seats are out of stock but I have 100 on order and they should ship to me this week.

[mfuller]

OK I spoke to my mech, and it's possible that the reason I'm losing coolant is I have combustion gases in the cooling system. In other words, a $1200 head gasket job



Anyway, the mech wants to put the new heads on the motor. I'm looking to put the LS6 springs on and the 3500 valves in.



I'm going to buy the the retainers and keepers from Ben but IDK what to do with the valve seats? do I need the stock seat or do I have to modify for .553" OD Guides

If you are talking about my old heads, they have stock 3400 valves in them with stock valve seats (except they have a valve job; 5-angle maybe?).
The valve seals are from a 3.1 Vin T motor. You have LS1 springs and seats with stock 3400 retainers/locks.