valvetrain problems - Hot Rod Forum : Hotrodders Bulletin Board -- 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
lost password?   |   register now

LinkBack Thread Tools
  #1 (permalink)  
Old 12-15-2002, 01:49 PM
New Member
Join Date: Oct 2002
Location: Mineola, Texas
Posts: 24
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Unhappy valvetrain problems

Ok I need everyones collective wisdom once more. Three months ago I put a Lunati 490 lift 292 duration cam in my 77 T.A. It is a 400 engine. In the last 2 months it has bent both pushrods on the #3 cylinder three times, only the #3 cyl. I set the valves 1/4 turn past zero lash. And if you are wondering,(like I did) no the valves are not sticking. I just removed the head today and there is nothing in the cylinder that would cause the valve not to open. And there are no marks on the piston and the valves to indicate a clearance problem. Any help here would be much appreciated. Thanks in advance. <img src="confused.gif" border="0">

[ December 15, 2002: Message edited by: pontiac man ]</p>

Reply With Quote Quick reply to this message
Sponsored Links
  #2 (permalink)  
Old 12-15-2002, 03:12 PM
johnsongrass1's Avatar
Race it, Don't rice it!
Last photo:
Join Date: Jul 2002
Location: Columbia, Mo
Age: 40
Posts: 5,891
Wiki Edits: 0

Thanks: 52
Thanked 398 Times in 324 Posts

Maybe you gotta mixed up rocker ratio problem that causes the retainer to hit the guide, or maybe a bad lifter thats gone solid on ya. Roll the motor over statring fronm the Tdc on three and check the clearances every few degrees of crank rotation. I'll bet you find it then. Not enough tolerances that is.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 12-16-2002, 02:49 AM
Join Date: Nov 2002
Location: denver, nc
Posts: 79
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts

I agree, check all your tolerances and have you're springs checked for allowable lift - DON"T trust what someone told you. I made that mistake once and the springs would coil bind .015". Comp Cams makes a good spring set 988-16, which I just installed in my 455, they allow up to .600" lift. You want to have .075" travel left in you're springs at full lift.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 12-16-2002, 03:39 PM
2x4's Avatar
2x4 2x4 is offline
New Member
Join Date: Dec 2002
Location: someplace better than where you are!
Posts: 20
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts

Ditto on what 455Poncho said.
I was sitting here thinking of what causes a bent pushrod, and physically stopping one end from moving is all I came up with. Spring bottoms out, rocker wont go down anymore, pushrod bends or lifter collapses.

I'll bet that all the others are close to bending on ya too. You already have a head off, might as well get them hopped up a bit & make them able to handle that cam. Good luck!
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply

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:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Please select your insurance company (Optional)


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 01:37 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999 - 2012. All Rights Reserved.