Heads for the 305 (part 2) - Chevy Impala SS Forum
 
LinkBack Thread Tools Display Modes
post #1 of 6 (permalink) Old 03-12-2001, 11:55 PM
UltraZone
Guest
 
Posts: n/a
Post

Ok, so I'll be having valve problems with 350 heads. Why is that? Are the oversize valves going to hit the side of the cylinder? Or are you talking about the valves hitting the piston? If so then that could be fixed.

Also, i'm looking at a compression ratio of about 8.5 or 9. I'm planning of running about 9 or 10 psi. Can you guys recommend a head that will work with that and also the valve size that will notrun me into problems?
Sponsored Links
Advertisement
 
post #2 of 6 (permalink) Old 03-13-2001, 10:22 AM
Sleeper
Guest
 
Posts: n/a
Post

Valves hitting the deck, flame travel, swirl, just a few of the problems. Not advisable to run 350 heads on a 305.

I believe World Products makes a decent head specifically designed for the 305. Car Craft had an article on 305 build-ups a few years ago, included the sources for their parts. I think they used the World Products heads.
post #3 of 6 (permalink) Old 03-13-2001, 11:25 AM
kdrolt
Guest
 
Posts: n/a
Post

<BLOCKQUOTE>quote:</font><HR>Originally posted by Sleeper:
Valves hitting the deck, flame travel, swirl, just a few of the problems. Not advisable to run 350 heads on a 305.<HR></BLOCKQUOTE>

If someone HAS to stay with the 305, then I will disagree --- you can use 350 heads. But I'll be specific, because you don't want to waste time/money on crummy 350 heads. You ONLY want to use good ones if you are going to the trouble of a head swap.

At least one magazine, a number of Fcar owners, and Mark Grave on the 9C1 list, that have used GM L31 Vortec heads using 1.94/1.50 stock valves, on the 305. The valve-to-piston clearance is an issue of the lift you choose, and you'd need a big cam to have this problem. The valve-to-cylinder deck issue is ok for stock diam valves and for anything but extreme lifts. I won't even attempt to explain the geometry involved.

The flame travel and swirl are largely provided by the heads, and the Vortec is designed to optimize them. The only real hiccup, if you can call it that, is that the Vortecs have a 64 cc comb chamber, so using them will cause a drop in the CR on a 305. So you can either have the heads milled to gain a smaller comb chamber volume, or eat the slight loss in CR and the few hp that go with it.

<BLOCKQUOTE>quote:</font><HR>I believe World Products makes a decent head specifically designed for the 305. Car Craft had an article on 305 build-ups a few years ago, included the sources for their parts. I think they used the World Products heads.<HR></BLOCKQUOTE>

That's probably true. So then it would boil down to (a) cost and (b) performance of the World Product 305 heads vs the L31 Vortecs. I think CHP tested BOTH of these heads in their (?) Oct '99 cylinder head flow test supplement so the flow data is available. You'd also have to factor in the cost of the Vortec-friendly intake manifold as well. FYI.
 
post #4 of 6 (permalink) Old 03-16-2001, 06:43 AM
kdrolt
Guest
 
Posts: n/a
Post

<BLOCKQUOTE>quote:</font><HR>Originally posted by kdrolt:
.... So then it would boil down to (a) cost and (b) performance of the World Product 305 heads vs the L31 Vortecs. I think CHP tested BOTH of these heads in their (?) Oct '99 cylinder head flow test supplement so the flow data is available. .... <HR></BLOCKQUOTE>

ok, I found the 305 World heads tested. They were tested in a GMHTP article (not the CHP one) along with the Vortecs and the Fastburn. IIRC the 305 WP went 195 cfm intake and around 129 cfm exhaust, both at 0.40" valve lift. The Vortecs on the same test, same bench, same conditions and at 0.40" valve lift went 211 cfm and 150 cfm i/e. So the Vortecs are MUCH better choice, and probably cheaper too. FYI. - Ken


post #5 of 6 (permalink) Old 03-16-2001, 06:31 PM
UltraZone
Guest
 
Posts: n/a
Post

If the CR drops that's ok, cause i'll be supercharging the 305 if I go with that. So i'm looking at an 8:1 CR.
post #6 of 6 (permalink) Old 03-18-2001, 05:03 PM
Mike454SS
Guest
 
Posts: n/a
Post

What kind of blower are you going to go with on that 305. If I'm correct that engine is a TBI system, and I'm curious to see the blower you are going to go with. I'd also love to see UltraZone's blown 305 caprice with over 200k on the clock spank a stock and even some modded LT1 B-Bodies

------------------

95 9C1 LT1
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevy Impala SS Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome