2.02 vs. 1.94 valves - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 11-06-2002, 04:25 PM
stfinney's Avatar
Member
 
Last photo:
Join Date: Oct 2002
Location: Vero Beach, FL
Age: 41
Posts: 387
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post 2.02 vs. 1.94 valves

I really need to know this. What difference will there be between the two valve sizes in the TQ and HP department?? Is there even enough to worry about with 170cc runners?

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 11-06-2002, 04:40 PM
BOBCRMAN@aol.com's Avatar
Member
 
Last photo:
Join Date: May 2002
Location: Holly, michigan
Posts: 8,131
Wiki Edits: 0

Thanks: 25
Thanked 267 Times in 250 Posts
Post

the 1.94 valves in a stock chevy head will give the best hp.& torque below approx 5000 rpm better driveability, nore response. properly installed 2.02 valves with a relieved combustion chamber will give better hp above 5500, both are dependant on cam specs.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 11-06-2002, 04:44 PM
stfinney's Avatar
Member
 
Last photo:
Join Date: Oct 2002
Location: Vero Beach, FL
Age: 41
Posts: 387
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post

I've heard people talk about relieved combustion chambers. What are they exactly??
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 11-06-2002, 06:20 PM
johnsongrass1's Avatar
Race it, Don't rice it!
 
Last photo:
Join Date: Jul 2002
Location: Columbia, Mo
Age: 38
Posts: 4,080
Wiki Edits: 0

Thanks: 0
Thanked 10 Times in 10 Posts
Post

When big valves are so close to the combustion chamber side wall the valves become "shrouded" or in other words, they are so close to the chamber side wall that air flow is diminished. Chamber relief, or cutting and rounding the area closest to the valve will give the added
room the air needs to flow around that part of the valve.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 11-06-2002, 06:44 PM
stfinney's Avatar
Member
 
Last photo:
Join Date: Oct 2002
Location: Vero Beach, FL
Age: 41
Posts: 387
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post

I have a pair of 487X heads with 2.02 valves. They came that way. Would they already have the reliefs built-in?? What about valve reliefs on the piston?? Do most pistons have these??

It's for a 350 SB with I think stock pistons. I would think a 350 would handle a 2.02 valve with ease.

[ November 06, 2002: Message edited by: stfinney ]</p>
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 11-06-2002, 07:15 PM
BOBCRMAN@aol.com's Avatar
Member
 
Last photo:
Join Date: May 2002
Location: Holly, michigan
Posts: 8,131
Wiki Edits: 0

Thanks: 25
Thanked 267 Times in 250 Posts
Post

487x heads only came with 1.72 or 1.94 valves if you have 2.02's someone put them in there, is the intake real close to the side if the chamber? or is there about 3/16 clearance.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 11-06-2002, 07:42 PM
stfinney's Avatar
Member
 
Last photo:
Join Date: Oct 2002
Location: Vero Beach, FL
Age: 41
Posts: 387
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post

Every site I have looked at shows different, not to say your wrong. Here are a few:


<a href="http://www.chevytalk.com/tech/engine/SBC_Heads.html" target="_blank">www.chevytalk.com/tech/engine/SBC_Heads.html</a>

"487" 3973487, OR 3973487X. The regular casting was found on the 1971-1972 350 LT-1 engines, had 1.94/1.50" valves, 76CC combustion chambers, DO have accessory holes, intake port volume should be 161CC's, exhaust port volume should be 65CC's. The 487X had 2.02/1.60" valves.

<a href="http://www.chevellepages.com/numbers/SBlock-head_Numbers.htm" target="_blank">www.chevellepages.com/numbers/SBlock-head_Numbers.htm</a>

3973487, 1968 / 79, 350, 1.94 / 1.5 or 2.02 / 1.6



<a href="http://www.ammotorsports.com/chvheads.htm" target="_blank">www.ammotorsports.com/chvheads.htm</a>

3973487X, 75cc, 2.02 1.60, 1971-72, 350
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 11-06-2002, 08:50 PM
Member
 
Last photo:
Join Date: Nov 2002
Location: Tennessee
Posts: 56
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post

1.94 inch valves as apposed to 2.02 inch valves--humm really depends on the cam, if your cam is going to be less than .5inch lift stick with the 1.94's these will help your heads swirl better at low lift(after all-your valves are at lw lift twice in the cycle as apposed to max lift only happening once-so swirl is deffinatly a good thing).although a 2.02 inch valve wth 30degree seats will accomplish the same thingif you have a high lift cam then 2.02 is well worth the money spent to help out with high lift flow. or you could use the 2.02 inch valves and smooth out the short side if you deside to portand polish the heads and this will give you the of best worlds.
---just my opinion
P.S. dont know about this where your at but here its only about 50 bucks to have the head releaved for 2.02 inch valves
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 11-07-2002, 09:49 AM
Member
 
Last photo:
Join Date: Oct 2002
Location: USA
Posts: 54
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post

In addition to the other great information on this subject I am submitting the following as described by a friend.

"All this means is that in this particular application that you need valve
reliefs in the piston so that the valves will clear the piston. Why? There
can be many reasons for the need of this, some contributing reasons can be
raised C.R., larger valves, change in valve timing (cam shaft), increase in
valve lift (cam or rocker arms). One or many of these things can cause the
need to have valve reliefs (i.e. cutouts on top of piston where the valve would
possible come in contact if it weren't cutout) on the piston."
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 11-07-2002, 02:29 PM
stfinney's Avatar
Member
 
Last photo:
Join Date: Oct 2002
Location: Vero Beach, FL
Age: 41
Posts: 387
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post

I have a Comp. Cams 4x4 Xtreme Energy cam with a duration of 250/258 and a lift of .432/.453 and a duration @ 50 of 206/214 which puts out alot of torque and a Brodix HP-1 Intake Manifold which is great for low end torque. I also have .500 lift Z28 springs with hardened retainers and 7 deg. keepers. With the engine making alot of torque, would the 2.02 valves hurt me that much? Do stock pistons with reliefs have enough of a relief to accommodate 2.02 valves? I guess that is my main question!! Thanks for all the info!!!!
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 11-07-2002, 03:53 PM
BOBCRMAN@aol.com's Avatar
Member
 
Last photo:
Join Date: May 2002
Location: Holly, michigan
Posts: 8,131
Wiki Edits: 0

Thanks: 25
Thanked 267 Times in 250 Posts
Post

your stock pistons have plenty of clearance for 2.02 valves at the lift that your cam has. I checked your web listings and copied them, they are sure not gospel! lots of errors, if i can i will find an AERA listing which is used by all the machine shops . if there were 2.02 xheads i stand corrected, but i have never seen any in 35 years of rebuilding cylinder heads. neither has my employer. he showed me two sets in the warehouse and both were 1.94s. thanks bob
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 11-07-2002, 04:16 PM
stfinney's Avatar
Member
 
Last photo:
Join Date: Oct 2002
Location: Vero Beach, FL
Age: 41
Posts: 387
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post

I am not an expert on heads myself. Not even close!! LOL I was just going by what I have heard and saw, so, who knows, maybe your right! Anyway, I could use these heads without any problems then, right??
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 11-07-2002, 04:24 PM
BOBCRMAN@aol.com's Avatar
Member
 
Last photo:
Join Date: May 2002
Location: Holly, michigan
Posts: 8,131
Wiki Edits: 0

Thanks: 25
Thanked 267 Times in 250 Posts
Post

YES
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 11-07-2002, 04:27 PM
stfinney's Avatar
Member
 
Last photo:
Join Date: Oct 2002
Location: Vero Beach, FL
Age: 41
Posts: 387
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Post

Thanks a bunch! I feel a little better now. I didn't really want to have to buy another set of heads, if these would work fine. How much usually does it cost to have hardened valve seats installed?
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 07-03-2005, 12:25 PM
Registered User
 
Join Date: Jul 2005
Location: vt
Posts: 2
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Rpms

What is the redline for one of these 487x 1972 350 chevy engines? one of my friends with a MT said he got his to 6700, but i'm sketpical.
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may 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



All times are GMT -6. The time now is 06:53 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.