gen 1 heads with bigger valves

[sharkey]

how much different is a 3400 intake valve from a gen 1??? im looking at putting some bigger valves into my ironheads and i think about all i can get into them will be a 1.76 intake.

does anyone know the leangth and stem diameter of a 3400 valve???

[RacerX11]

I don't have the dimensions handy, but I know the gen2/3 valve stem diameter is smaller by about 1mm compard to the iron heads. I went with Buick 3.8 valves on my iron heads several years ago. They had pretty much the same stem diameter and length, with a slightly larger head (I think around 1.76"). The other advantage is the valve face is flat intead of concave, so you gain a couple tenth's of compression at the expense of slightly heavier valves. I don't have the part numbers or specs handy on these 3.8 valves...I basically just sat down with my machinist and went through his catalog looking at differnt valves that were close in size, and picked some that worked.

Marty

[oil pan 4]

There the same length as stock SBC valves I thought that was strange, there 8mm but I got 11/32 for my mesurement.

[RacerX11]

OK, I did a little digging around the garage and measuring my valves. Here is what I have installed (specs from Sealed Power?s site, which also match my measurements):

Intake: Sealed Power V3916, 1.71? head diameter, 4.727? overall length, 0.3405? stem diameter.
Exhaust: Sealed Power V3915, 1.487? head diameter, 4.727? overall length, 0.3405? stem diameter.

These are from a ~1990 3.8 Buick. The 1.71? intake sounds smaller than the stocker, but all of my stock HO valves measure right at 1.71? as well. Go figure. These valves have a flat face compared to the stockers, so they bump compression.

FYI, the stock valves are as follows (specs from Sealed Power?s site):
Intake: Sealed Power V2290, 1.7181? head diameter, 4.705? overall length, 0.3413? stem diameter.
Exhaust: Sealed Power V2291, 1.4252? head diameter, 4.737? overall length, 0.3413? stem diameter.

Here is a nifty site Sealed Power offers where you can search for valves (and other engine parts) by size to find something that will work: http://www.21cgt.com/FMWebCatalog/default.htm Click on SPECIFICATION, select SEALED POWER, then VALVES, then INTAKE or EXHAUST. Once you find a part you want, it will list the application they are associated with.

As an added note, there is a Methanol conversion application listed for the gen2 3.1?s on Parts America?s site that shows a 1.50? exhaust valve, PN V4240. This PN doesn?t come up on Sealed Power?s website. If this is still available, it might make a nice combination with the 3400 1.76? V4571 intake valve for gen2/3 heads, if they would fit. Happy searching

Marty