I am looking to freshen up my heads. I have ported Ga heads with 2" intakes and 1.68 exhausts. I want to up the intake valve size since I have to buy new valves I might as well go big as I can . Can a 2.125 be installed into a iron head. I have seen some posts that it has been done to edelbrocks. also what is everyones feedback on this upgrade.

 

Yes the 2.125 valve will fit just fine. But keep the 1.68 exhaust, no need to increase that.
Make sure you blend the bowl area to the new valve size, otherwise the benefits will be minimal.

And welding the exhaust center divider and filling the crossovers is always a good idea as well.

 

Cutlassefi,
Sorry to hijack grampy's valve thread, but you mentioned filling the exhaust crossovers, and I've read some very conflicting opinions on the benefit of this. I've read many of your previous engine posts and you really know your stuff. What is the benefit of filling the crossovers for a daily driver? Would an electric choke on a Q-jet work just as well as the stock air riser tubes? (I live in south Texas with pretty mild winters).

Some people have said that the intake manifold needs to be warm to keep the fuel atomized in the incoming air/fuel mixture, and a cool manifold will cause the fuel to condense out of the air and onto the the cooler surface of the port runners. In principle, a cooler air temp means a more dense air/fuel mixture, but maybe blocking the crossovers is only a good idea for race motors, and not daily drivers. I look forward to your "schooling". Thanks!