Did I wipe a lobe? - Third Generation F-Body Message Boards

Tech / General Engine Is your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!

Did I wipe a lobe?

Thread Tools Search this Thread
Old 06-14-2018, 05:29 AM   #1  
Thread Starter
turd_gen's Avatar
Join Date: Feb 2016
Location: Hog Town, Ontario
Posts: 146
Car: 1985 Trans Am
Engine: 350
Transmission: T5

Did I wipe a lobe?

My car was burning oil so I decided to adjust my valves. I used the method where you set it to #1 TDC and set 8 of the valves, then set the other 8 at #6 TDC. I used a 1/2 turn of pre-load.

I started her up and it was running rough as hell. Misfiring and backfiring like crazy. So I shut it down and go back to readjust the valves only to realize I have a solid lifter motor. I assumed it was a hydraulic motor because it's a mid 90's crate engine (truck motor).

Not knowing the specs for my cam, I set my lash to 0.020" using the same method as before (at #1 and #6 TDC). I replaced my spark plugs just to be safe. My wires are only a few months old (and yes they are in the right order). Started it up and it was still running like hot garbage. Running on 6-7 cylinders and backfiring through the carb. It would idle okay, but backfire and miss hard under any load.

So I got through the whole process again using the EOIC method. I got them all set perfectly. I started it up and it sounded normal at idle. No major misfires. Under load it would still backfire through the carb. I set my timing and it still didn't help.

So did I wipe a lobe? This motor has unknown mileage, but based on the blow-by and oil consumption, I'm assuming it's rather high.

What should be my next step?
turd_gen is offline   Reply With Quote
Old 06-14-2018, 06:57 AM   #2  
Junior Member
PaulyC's Avatar
Join Date: Apr 2018
Location: Illinois
Posts: 58

Re: Did I wipe a lobe?

Adjusting valve lash to fix oil burning? Interesting. While you may or may not have damaged a lobe, to check you are going to have to get a dial indicator and measure lift on each lobe. You can do that at the rocker arm. While you are doing that you can verify base circle and adjust the lash using a slight correction due to the engine being cold (you can find this cold engine correction data online). This will get you to a decent point to start the engine and warm it up so you can set the correct lash at temp. That is, of course, unless you find a bad lobe.

Maybe I’m old school but I don’t subscribe to a lot of the “this is faster and accurate enough” methods of doing things.
PaulyC is offline   Reply With Quote
Old 06-14-2018, 09:03 AM   #3  
Supreme Member
iTrader: (1)
Join Date: Sep 2005
Posts: 20,434
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere

Re: Did I wipe a lobe?

Easiest way to locate the base circle with absolutely certain accuracy, is to locate peak lift of the same valve on the cyl that's 4 cyls away in the firing order. E.g. #1 int is on the base circle when #6 int is at peak lift. (heel of lobe vs tip)

Backfiring in the carb could be caused by a wiped exh lobe. Compression test will tell: 1 cyl w very high comp has this failure. It can also be caused by a head gasket: 2 adjacent cyls w low comp, especially 5 & 7.
sofakingdom is offline   Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
Why can't I wipe the smile off my face?...... coptzer LTX and LSX 20 02-25-2012 10:39 AM
Tell me how to wipe this SRT-4 off the road 90CamaroTBI Carburetors 2 12-11-2005 09:56 PM
wipers dont park, wipe right, and are loose 85berlinetta2.8 Body 0 05-01-2005 06:32 PM
iroc2nv wipe out on VIDEO!! 88redxtsy Third Gen Association of Ontario 12 09-25-2002 07:08 PM
Lobe separation! AFBCamaro Tech / General Engine 11 10-09-2000 06:19 PM

Go Back   Third Generation F-Body Message Boards >

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

Featured Sponsors
Vendor Directory

1982 Camaro '82 || 1983 Camaro '83 || 1984 Camaro '84 || 1985 Camaro '85 || 1986 Camaro '86 || 1987 Camaro '87 || 1988 Camaro '88 || 1989 Camaro '89 || 1990 Camaro '90 || 1991 Camaro '91 || 1992 Camaro '92

All times are GMT -5. The time now is 03:25 PM.

All content copyright © 1997 - 2018 ThirdGen.org. All rights reserved. No part of this website may be reproduced without the expressed, documented, and written consent of ThirdGen.org's Administrators.
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.
  • Ask a Question
    Get answers from community experts
Question Title:
Your question will be posted in: