79 400 backfiring? HELP

Reply Subscribe

Thread Tools

Search this Thread

Jan 27, 2011 | 03:43 PM

#16

78 PEB

Cargo Master

Joined: Oct 2010

Posts: 2,674

Likes: 16

From: Ideeho

Sounds like you are starting to get it nailed down.........The low compression on one cylinder would point to a burnt, stuck or improperly seating valve. Have you run a wet compression test yet? That would help narrow it down further.

Jan 30, 2011 | 11:39 AM

#17

alex severson

Freshman User

Joined: Jan 2010

Posts: 28

Likes: 1

I dont know if this will help but when was the last time you changed you fuel filter, my truck was doing the same thing till I changed the fuel filter and put some seafoam stuff in in the fuel filter ran then let it sit over night.I started it the next morning, backfired 1 or 2 times then ran great ever sense.

Jan 31, 2011 | 10:39 AM

#18

1979super4x4

New User

Joined: Dec 2010

Posts: 7

Likes: 0

just a suggestion but if you r runnin a holley carb have you tried changin out the power valve i no i went through a few of them before i got p off and riped the peace of s@#* off and slaped an edelbrock on

Jan 31, 2011 | 12:09 PM

#19

Roller150

Senior User

Joined: Jun 2007

Posts: 374

Likes: 0

Like Alex said make sure your fuel filter is cleaned too. I changed everything out and it cleared up the backfire issue. Now I just need to rebuild the carb so it runs even better. Holly 4180 4br.

Feb 1, 2011 | 11:40 AM

#20

radar457

Senior User

Joined: Mar 2010

Posts: 222

Likes: 1

From: western ks

you might check your vacum advance. I had a similar problem and was at wits end as to why it backfired and lacked power. Found that the vac advance had gone **** up and turned into a vac leak.. replaced it and problem solved..