Valve timing??????? - 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 04-25-2005, 09:17 PM
Member
 
Join Date: Apr 2005
Location: Cincinnati,ohio
Posts: 67
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Valve timing???????

On my 350 I hooked up a vaccum guage when i adjsuted my carb and noticed that it read at 15, steady. They say and engine should pull between 17-21, and says that it is a valve timing issue. I just built the motor, and the cam is in right, I know for a fact, I even double checked by making sure each valve on #1 was clsoed at TDC, what could be causing this problem?

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 04-25-2005, 09:23 PM
DoubleVision's Avatar
Not Considered a Senior Member
 
Last photo:
Join Date: Oct 2002
Location: Heart Of Dixie
Age: 40
Posts: 10,654
Wiki Edits: 0

Thanks: 15
Thanked 58 Times in 55 Posts
there may not be a problem, is the cam stock? if it`s stock it`ll read around 20 or so, if it`s a performance grind it`ll read lower. low spark timing can cause low vacuum readings, excessive slack in the timing chain will alter the valve timing events and will also effect vacuum, as will vacuum leaks, high idle, etc.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 04-25-2005, 09:32 PM
Member
 
Join Date: Apr 2005
Location: Cincinnati,ohio
Posts: 67
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Now that i think about it, it was idleing around 1000 when i checked it, i then bumped the idle down to around 800, and yes it is a comp 274 w/ .490 lift and like 236 duration at .050. I also jsut have a stock HEI with lighter springs and a stock style coil and wires, but the wires checked out as far as resistance went at like 2,000 ohms, and the plugs are gapped too much, like .55, shouldn't they be at like .35? Should i upgrade to better wires and a high voltage coil? I can get pertronix stuff at cost so that's not a problem
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 04-25-2005, 09:47 PM
DoubleVision's Avatar
Not Considered a Senior Member
 
Last photo:
Join Date: Oct 2002
Location: Heart Of Dixie
Age: 40
Posts: 10,654
Wiki Edits: 0

Thanks: 15
Thanked 58 Times in 55 Posts
I`d just run the plug gap at .045, and yes, a ignition upgrade with spiral core wires along with a matching coil and module is always a good idea, but it won`t help vacuum any. with the cam your running your lucky it has 15 inches. My 350 has a crane cam with 210, 216 duration and it only pulls 15 inches at 800 rpm. If memorey serves me right the overlap figure is what effects vacuum, but don`t quote me on that.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 04-25-2005, 10:00 PM
bracketeer's Avatar
489 Lemans
 

Last journal entry: Street Legal
Last photo:
Join Date: Dec 2004
Location: Courtenay, BC, CehNehDeh
Age: 55
Posts: 2,139
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
vacuum

My last 350 had a Comp 268H with the perf/rpm package and I only pulled 8 inches of vacuum.
__________________
[URL]http://members.shaw.ca/g.body.building[/URL]
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 04-25-2005, 10:06 PM
Member
 
Join Date: Apr 2005
Location: Cincinnati,ohio
Posts: 67
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
cool, sounds good, yea, i have a 274 with the performer rpm and vortech heads, it runds great, but i haven't really cracked it yet since i only got about 15 miles o nthe motor, i figured i'll give it at least 500 before I beat on it. I was jsut worried when i saw that the guage said 15 and in the red it said valve timing. But that makes sense b/c i've ehard of plenty of guys only pulling 8
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


Similar Threads
Thread Thread Starter Forum Replies Last Post
ignition timing bad502 Engine 21 02-20-2006 06:57 PM
Variable Valve timing 69 chevelle SS Hotrodders' Lounge 1 08-25-2004 10:45 AM
Would like cam advice, I am down to three, thanks 357ford Engine 33 05-08-2004 08:09 PM
Cam Help black66 Engine 3 05-12-2003 06:15 PM
Residual Pressure Valve?? Dave E Shank Suspension - Brakes - Steering 1 12-27-2002 07:12 PM


All times are GMT -6. The time now is 10:45 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.