I have a set of slightly modified 601 heads that I'll be using on my 350 in the spring. They are rebuilt and unused, with 1.94/1.50 valves, screw-in studs and guideplates. They still have the stock ports and combustion chambers, completely untouched.

What I'm wondering is this... how good are these heads as they are now? I've heard from many people that the 601 heads are a good set to use on a decent street/strip 350, but compared to what? What other heads are these comparable to, aside from the 416 and 081 castings? Does anyone have any flow numbers for these heads?

 

I flowed a set of mildly worked 601s, with their stock 1.84/1.50 valve size.

Lift----Intake---Exhaust
.050---35.60---15.00
.100---72.40---47.00
.150---105.8---72.50
.200---133.4---98.00
.250---154.1---117.5
.300---180.6---137.0
.350---195.5---145.0
.400---209.3---153.0
.450---217.4---155.0
.500---224.3---157.0

 

Thanks man! Thats exactly the kind of info I was looking for

What do you mean by 'mildly worked' though?

 

if you've installed bigger valves you really need to unshroud the combustion chamber on these heads. they dont have the standard "D" shaped combustion chambers from what i've seen on TGO. thats a good thing, but it really needs unshrouded to take advantage of the bigger valves.

while you've got the grinder out you may as well smooth out the ridges from the bowl cutters, on the short side radi and bowls and straighten up the common wall atleast. thats probably 5 hours of work.

 

Thanks guys, I appreciate it

This will be my first time porting a set of factory iron, so any info is appreciated!

Doom - How much do I want to deshroud around the intake valve? It is quite a tight fit do the chamber wall, but how much do I want to open it up there?

 

wow those numbers are better than I thought for 601s, very cool info.

 

adam, bolt the heads to your block with a few bolts, and rotate the engine upside down (block is on a stand right?)
then use a sharpie, or a scribe, and scribe the cylinder wall onto the heads
remove the heads, and open it up by the valves, up to that line or so. Lay it back, and smooth it out. between the valve and the spark plug, nowhere else. do it mostly for your upsized valve, but a bit on the exhaust can't hurt, the decrease in cr is less of a power drop change compared to the increase in flow.

perhaps a few pictures here will help too, from a vizard book, I think that includes some info on deshrouding the chamber (or maybe it's just valve mods..)
https://webdisk.ucalgary.ca/~jmknopp...c_html/vizard/

 

Actually, while the engine will be on a stand when I do this, the shortblock will not be disassembled. These heads will be installed on an already running shortblock. I'm redoing the whole top end (heads, intake, cam, valvetrain, ignition) but I'm not going to touch the bottom end.

Looking at these heads... they have been machined off (not by hand, too cleanly done for that) on the chamber wall right beside the intake valve. Was it GM that did this, or perhaps the machinist that rebuilt the heads? I've only seen the heads after the work was done, so I don't know what was there originally.