SI Stainless / undercut valves for Series II L36 n/a? - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


Performance, Brainstorming & Tuning Talk about modifications, or anything else associated with performance enhancements. Have a new idea for performance/reliability? Post it here. No idea is stupid! (please use Detailing and Appearance for cosmetic ideas)

Reply
 
 
 
Thread Tools Search this Thread
Old 07-23-2007, 07:23 PM   #1
Senior Member
Posts like a Corvette
Thread Starter
 
Join Date: Jan 2007
Location: San Diego, CA
Posts: 1,451
Thanks: 0
Thanked 0 Times in 0 Posts
agrazela is on a distinguished road
Default SI Stainless / undercut valves for Series II L36 n/a?

Thinking about valves for my n/a Series II L36 project heads:
http://www.bonnevilleclub.com/forum/...ic.php?t=77163

zzp (and others) sell stock-diameter SI stainless steel valves for the Series II 3800; about $80 for either intake set or exhaust set (so about $160 all around).

(Note: Up-sizing valves is completely out of the question budget-wise)

Pros: Compared to stock valves, these are one-piece, all stainless, undercut, swirl-polished.
Theoretically, this should make them stronger, better able to withstand/conduct heat, and have better low-lift flow (or so goes the marketing...)

Cons: Compared to stock valves, these valves cost money

So, are they worth it? Maybe just on the exhaust side?

A local machine shop claims they can undercut the stock valves for a reasonable cost...given our valves are two-piece friction-welded design (I think), I'm a bit wary of this idea; should I be wary?

Is this all overkill for a lightly modded n/a?

Please discuss...
agrazela is offline   Reply With Quote
Old 07-23-2007, 09:27 PM   #2
Senior Member
Posts like a Camaro
 
Join Date: Oct 2006
Location: montreal canada NEBF07 ONBF07
Posts: 987
Thanks: 0
Thanked 0 Times in 0 Posts
firebuick is on a distinguished road
Default

well i don't think so i think the head and the cam are the 2 most important factor in the n/a engine to get more air in so youre asking if you should buy these valve or spend the money for a 3 angles valve job on the stock one .for steet use i think the stock valve are ok whit a 3 angle valve job they should flow well ,that whit a light porting and cleaning of the port that what im looking to do for this winter[/quote]
firebuick is offline   Reply With Quote
Old 07-23-2007, 09:36 PM   #3
Senior Member
True Car Nut
 
95naSTA's Avatar
 
Join Date: Feb 2003
Location: Philly
Posts: 4,508
Thanks: 0
Thanked 0 Times in 0 Posts
95naSTA is on a distinguished road
Default

For a lightly modded n/a I don't really think they are worth the price.
If you’re keeping the EGR, the valves will get carbon build up and negate the swirl polish. And over time the exhaust valves will have build up on them as well.
On my Milzy heads with the SI valves, the exhaust valves definitely lost their polished finish after 10k miles. I saw this when I pulled my motor out.
The under cut part will still help out though since the area around the valve is still opened up more.
And as far as undercutting the stock valves...I would be wary of doing so since they weren't designed to have material removed.

I think you may get the most hp/$ wise if you just cleaned up and polished your stock valves. Carbon will build up eventually build up with if they are polished it will take a little longer.
95naSTA is offline   Reply With Quote
Old 07-24-2007, 02:51 PM   #4
Senior Member
Posts like a Corvette
Thread Starter
 
Join Date: Jan 2007
Location: San Diego, CA
Posts: 1,451
Thanks: 0
Thanked 0 Times in 0 Posts
agrazela is on a distinguished road
Default

OK, so for safety'* sake the idea of having a shop undercut the stock valves is out.

The shape of the stock intake valves, IMO, looks pretty darned good...for now, the plan will be to just polish and reuse those.

However, I maybe could see some flow benefit to having undercut exhaust valves. I could also see some potential benefits to having exhaust valves that can "take the heat" better, especially as I am formulating some ideas on the EGR system in the n/a engine.

Anyone else have any opinions on valves?

(I realize this is kind of uncharted territory, since there aren't all that many dudes out there hopping up their L36'* :P )
agrazela is offline   Reply With Quote
Old 07-24-2007, 06:23 PM   #5
Senior Member
Certified GM nut
 
Join Date: Dec 2002
Location: plattsburgh NY
Posts: 2,037
Thanks: 0
Thanked 0 Times in 0 Posts
TJ'sblackbonne is on a distinguished road
Default

Andrew you just keep the ideas FLOWING (play on words haha)
TJ'sblackbonne is offline   Reply With Quote
Old 07-24-2007, 06:37 PM   #6
Senior Member
Posts like a Camaro
 
Join Date: Oct 2006
Location: montreal canada NEBF07 ONBF07
Posts: 987
Thanks: 0
Thanked 0 Times in 0 Posts
firebuick is on a distinguished road
Default

Quote:
I realize this is kind of uncharted territory, since there aren't all that many dudes out there hopping up their L36'* )
well where not many but you have all are attention on youre work progress keep it up
firebuick is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
The time has come... Do GN valves work? J Wikoff Performance, Brainstorming & Tuning 53 08-15-2005 12:23 AM
SERIES 1 STAINLESS VALVES Performance, Brainstorming & Tuning 9 01-25-2004 02:04 PM
Okay, what's the secret? (Proportioner valves continued) Icebound 1992-1999 2 09-22-2003 07:14 PM
Rear Brake Proportioner Valves. Icebound 1992-1999 2 09-08-2003 01:49 PM
ROLLER ROCKERS AND STAINLESS VALVES FOR SERIES 1 Performance, Brainstorming & Tuning 13 02-27-2003 10:53 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 11:52 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.