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More head questions for the head gurus, seen 305 heads with 2.02's

6K views 10 replies 9 participants last post by  4speed57 
#1 ·
I've seen on the net several places that advertise high performance heads with either 60cc or 64cc chambers and 2.02 valves. After looking closer the heads are 305 heads that have had the larger valves installed. There has been no port work done. I have heard the 305 ports aren't the best, so would adding the bigger valves help at all? I'm no cylinder head expert and I was wondering what is more restrictive in a head, the valve size or the ports? I know vortecs have 1.94 valves and they outflow any other GM head even ones with 2.02 valves.
I guess in my search for heads, these 305 heads caught my eye since they have 2.02's, but if they haven't been ported then would they flow any better than if they still had the small 1.84 valves? Would a set of 882's or 993's with 1.94's be better than the 305 heads?
 
#4 ·
I dont think its a good idea to put that big of a valve in a 305 head. If you open up the pocket area anywhere near what it needs to be the walls will be too thin for any kind of reliability. Pin holes & cracks are likely, now its a really pretty piece of junk.
I would use a 1.94 and 1.6 but not get carried away with the throat cut or porting on intake on exhaust theres enough metal shouldnt be any problems, those sizes I would trust.
 
#5 ·
They also re-machine the combustion chamber to get the CC's up and to unshroud the valves. For an inexpensive replacement head on a torque type engine, they will work for the guy on a tight tight budget. Best bang for the buck is to get a set of Iron Eagles/SR Sportsmans or some Vortec's.

Chris
 
#7 ·
I've prepped plenty of these heads, which are most likely going to be either the 416 head, or the earlier 601 head.

I'm going to assume that you have been shopping around on Ebay, and seen a few of these guys peddling these, so-called performance heads.

The 601 head actually has very tiny 53 CC chambers in stock form. The intake valve size is 1.84" and the exhaust is 1.5"

In all reality, even stepping up to a 1.94" intake valve on this particular head presents chamber wall shrounding issues, so what I have done on many of them is to cut a 1.94" intake valve down to about 1.900" and cut the chamber, then port the head for good form and lay a slick multi angle seat that blends well into the port. I've gotten some pretty good flow out of them, but I've always used them on smaller engines like 327s and smaller. I usually avoid them on 350's because of compression issues.

I can guarantee you that the guys on Ebay are just slapping some bigger valves in them and maybe some are cutting the chamber to de-shroud and maybe some aren't. In either instance, you aren't buying a whole lot other than a set of orange heads with some shiny valves in them.

I would prefer to buy a good set of Vortec cores, re-lap the valves in and change the springs. You can get that done for about $275.00 and they'll blow those so-called "performance" heads away.
 
#11 ·
Thanks for all the replies and helpful insight. I figured the heads wasn't what they claim to be. I had heard before that a bigger valve in a 305 head could actually hurt it. The guys on ebay make it sound so good with the 2.02 and high performance, and stuff like that in big letters.
Thanks again.
 
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