Go Back   Tech Support Forum > Automotive Center > Automotive Support


1968 Pontiac FIrebird w/ Chevy 400 engine issues

This is a discussion on 1968 Pontiac FIrebird w/ Chevy 400 engine issues within the Automotive Support forums, part of the Tech Support Forum category.


Reply
 
Thread Tools Search this Thread
Old 02-16-2017, 07:16 AM   #1
Registered Member
 
Join Date: Feb 2017
Posts: 2
OS: Windows 10



I have a 1968 Pontiac Fire bird with a Chevy 400 in it. I am running an aggressive Comp Cam XTREME Energy™ Hydraulic Flat Tappet Camshaft. The cam is the 11-250-3 cam. I have a Pertonix Billet Flamethrower Distributor and Flamethrower Coil. I have the timing set at 18 degree before TDC for initial as I was told that because of the cam that I shoud start around there. Now I have a 750 cfm Quickfuel carb on it and the Edelbrok RPM high rise intake. I have recently purchased this car and it came already equipped with these parts. It had been sitting for a while and ran rough and very rich so I pulled the distributer and tried a new HEI Billet. It would not run so I swapped it back. Set timing and now it still will barely run and only if I am feathering the throttle and then wont run long. Smells like over fueling. I checked spark on all cylinders and have spark. However here is the wierd part. I am only getting it firing on cylinder 1 and cylinder 4. The rest of the header pipes are ice cold. I no longer think it is timing related as I have set TDC about a bazillion times and checked firing order about the same amount. However I am open to any ideas. Could I be over fueling and fouled that many plugs? I am getting new MSD plugs today but dont want to mess them up as they are $15 each. Any help would be greatly appreciated. Thanks in advance.
Tcrash is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 02-16-2017, 08:19 AM   #2
Administrator
TSF Manager
 
SABL's Avatar
 
Join Date: Jul 2008
Location: Galena, Ohio
Posts: 21,823
OS: WinXP Pro SP3, Vista Home Premium SP2



Have you confirmed the cam is in proper timing with crankshaft?? One tooth off will make a world of difference. On firing order, are you going by Chevy or Pontiac specs?? Last time I worked on a GM the dist rotations are different.....at least the old Olds engines were different rotation than a Chevy. My son found out the hard way..... Two days wasted trying to get his Olds running......was going by Chevy specs.

How are you determining the timing?? If the dist is one tooth off it will mess up your calculations.
__________________
It's a good thing I never had any sanity......I would have lost it by now.
SABL is offline   Reply With Quote
Old 02-16-2017, 08:33 AM   #3
Registered Member
 
Join Date: Feb 2017
Posts: 2
OS: Windows 10



I put the timing to 18 degrees before TDC on the compression stroke. I even ran a scope inside the head to make sure that the piston was at the top and both valves were closed. Then I checked where the distributer was aligned and the rotor was pointing at the number 1 cylinder so I started my number 1 plug where the rotor was pointing and went clockwise with the firing order 1-8-4-3-6-5-7-2. The only way it seems to even want to fire is if I advance the distributer alot and then pump the fuel to it. You can smell the fuel but the second I let off the gas the engine doesnt even seem to want to start. I did hook a timing light to it and the only time the light will flicker while turning over is when it is trying to start. Which puzzles me as shouldnt it flicker every time a spark is sent down the plug wire?? I did pull all the plug wires and test them with the same spark plug and they are getting spark. Atleast to that 1 spark plug. I havent tested all the spark plugs though. Im wondering if they have been fouled from running soo rich and new ones might make er fire up quickly..
Tcrash is offline   Reply With Quote
Old 02-16-2017, 09:04 AM   #4
Administrator
TSF Manager
 
SABL's Avatar
 
Join Date: Jul 2008
Location: Galena, Ohio
Posts: 21,823
OS: WinXP Pro SP3, Vista Home Premium SP2



Been a long time since I worked on anything with a coil. Are you getting power to the + side of the coil with the ignition on?? Sounds like the ign switch isn't supplying 12V in the run position. Have you tried to "hot wire" the coil and start it??

Sounds like everything is in order. Dist not out 180....piston all the way up and both valves closed. But.....where is the timing on the harmonic balancer pointing when that happens. Should be dead on 0.
__________________
It's a good thing I never had any sanity......I would have lost it by now.
SABL is offline   Reply With Quote
Old 02-17-2017, 07:42 AM   #5
Moderator Automotive Center
 
octaneman's Avatar
 
Join Date: May 2009
Posts: 2,755
OS: WINXP



Hi Tcrash

What you are describing is the fuel has gummed up the jetting it happens often on modified engines that have been sitting for a while. These engines run rich from the get-go so even though your timing is set correctly, the carburetor is either over-fueling or under-fueling the engine. To resolve the issue you need to re-set the carburetor float level, flush out the jetting for any deposits that may have accumulated. These carbs are as sensitive as a tooth ache, so any small adjustment to it will have impact on how the engine runs. Too high a float level will flood out the engine, too low and the engine is starved of fuel causing backfiring through the carburetor. the metering system has to be set perfectly to give it the right air/fuel ratio. Since you are running a 750 QF carb its best you get the specs and then proceed to make your adjustments accordingly.


NOTE: Adjusting fuel pressure with the engine running could cause a fire hazard.

post back your findings.
__________________



" What were dealing with is the battle between the future and the past, between the powers that were and the powers that have yet to be. " --- John Perry Barlow
octaneman is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Similar Threads
Thread Thread Starter Forum Replies Last Post
BSOD Help
I have been getting BSOD, Mainly when I am watching video from any source (Mpeg, AVI, youtube, Hulu). As far as I can tell my drivers are all up to date. I am not the best at this stuff but have tried everything I can think of and everthing I have found online before asking for help. Any help would...
jon33jon2003 BSOD, App Crashes And Hangs 5 09-27-2011 04:22 PM
Windows7 BSOD DRIVER_POWER_STATE_FAILURE
Hi, I have been trying to find out the reason for the BSOD, but to no avail. Please help. Attaching the Dump files. Thanks, Abhishek.
abhishek.ardey BSOD, App Crashes And Hangs 14 08-14-2011 03:01 AM
[SOLVED] Random BSODs Please Help!
So my brother and I made a computer for the first time about a year ago. 5 months in, it started crashing everytime on after starting up and logging in. However, when we rebooted the computer, it loads up normally. Since me and my brother are both in college, this is the first time we've been able...
AtomicSkittles BSOD, App Crashes And Hangs 9 07-16-2011 03:34 AM
[SOLVED] Blue Screen when playing games
Hi guys, my computer's about 2 years old, and every time I play a game installed on my hard drive, my computer has always been blue screening. I didn't bother to fix it because I had no time for games because of school. Now, I had just finished installing Champions Online, and started playing. Blue...
telekinoble BSOD, App Crashes And Hangs 21 05-09-2011 01:56 AM
Bsod windows 7 home premium
Hello All, I have the original Windows 7 64-bit home premium Intel (R) Pentium4 CPU 2.80 Ghz Motherboard ASRock 4CoreDual-SATA2 2GB Ram GRAPHICS CARD Geforce 7200GS/7300SE Power Supply-450watts The operating system since last year I have done for parts but every few days it gives me blue...
niram1111 BSOD, App Crashes And Hangs 4 04-18-2011 01:09 PM

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


Post a Question


» Site Navigation
 > FAQ
  > 10.0.0.2


All times are GMT -7. The time now is 11:28 AM.


vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 2001 - 2015, Tech Support Forum

Windows 7 - Windows XP - Windows Vista - Trojan Removal - Spyware Removal - Virus Removal - Networking - Security - Top Web Hosts

 

Partially Powered By Products Found At Lampwrights.com