Popping from exhaust while cruising
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 3,365
Likes: 0
From: Farmers Branch TX
Cruise-In VI Veteran
St. Jude Donor '09
Popping from exhaust while cruising
Hi everyone, I was driving my 78 on saturday evening and while at a steady cruise, I was getting a lot of loud popping from the exhaust, and also the car did not feel like it was accelerating smooth, not really a dead miss, but just like it was very lightly missing while accelerating. The car has a 350, mild cam with big valve heads, edelebrock performer intake and q-jet carb with HEI ignition, anything that would be a common cause of this?
Thanks for any help,
Chris
Thanks for any help,
Chris
Melting Slicks
Joined: Oct 2005
Posts: 2,056
Likes: 8
From: Redruth Cornwall
was readind Doug Roes book on the q jet a few days ago and remember a bit that mentioned popping from the exhaust....
Well, when I say remember, I can remember the poppping bit but not the cause...DOH! Will go check, possibly a lean condition.
Have you done any work on the Q jet recently?
Well, when I say remember, I can remember the poppping bit but not the cause...DOH! Will go check, possibly a lean condition.
Have you done any work on the Q jet recently?
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 3,365
Likes: 0
From: Farmers Branch TX
Cruise-In VI Veteran
St. Jude Donor '09
No I havent done any engine work to the car in months, and it just all of sudden started while I was crusing at about 50mph, and progressivly got worse until I finally reached home about 5 miles later.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by Today's problem is..
No I havent done any engine work to the car in months, and it just all of sudden started while I was crusing at about 50mph, and progressivly got worse until I finally reached home about 5 miles later.
Check all your plugs to make sure you're getting spark, and check all the gaps. Sounds like a clear cut sign of plug fouling. maybe not every cycle, but you may have a failing plug. As cheap as they are, it'd be a good time to upgrade anyway.
I recommend NGK plugs. They come gapped, (Check anyway), and install. Then, double check the fuel metering screws. Back them down a full turn each and see how it runs. Do both at the same time. If it drives well, leave it. If it seems like it's too lean, adjust each a 1/4 turn out, and try again. Do all this while it runs. You may have a rich mixture causing one or some of the plugs to foul.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Have you ever done work to the spark plugs? You'll be very surprised sometimes what ends up in the hole. I've seen plugs with NO gap, mismatched brands and broken plugs. A nice new set of NGKs will make things nice and smooth.
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 3,365
Likes: 0
From: Farmers Branch TX
Cruise-In VI Veteran
St. Jude Donor '09
No I havent done any type of work with removing the spark plugs in well over a year when I had to do a valve job, I put a new set of NGK plugs in back then, hopefully I will get a chance this week to pull them out and check them all to see if they are fouling, that is really what it feels like when I am accelerating, like they are intermitently not firing, or just not firing well but I wasnt sure if that would cause the loud pops in the exhaust pipes I was getting
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Team Owner
Joined: Aug 2006
Posts: 24,125
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From: Columbia Missouri
Checking the mixture is important when changing plugs because too rich of a mixture can cause these problems for you again in 6 months to a year and you'd have no way of seeing it coming until it happens. If you have never tuned a carb get a buddy to help.
Melting Slicks
Joined: Mar 2006
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From: Connecticut
Originally Posted by jotto
possibly a lean condition.
Go figure....
Team Owner
Joined: Aug 2006
Posts: 24,125
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From: Columbia Missouri
Originally Posted by Vettkeeper
Sounds like a valve might be sticking. Add a can of Marvel Mystery oil to the oil and run it for awhile (500 miles) and then change the oil.
This could be checked fairly easily by removing the valve cover while the engine runs. Watch the valves, and adjust any if needed. Loosen the rocker retainer nuts until they clatter, and tighten them up until they stop. If a rocker is clattering even at full adjustment then the valve under it is stuck. Now if that were the case you'd have some other problems to deal with.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by 73, Dark Blue 454
Classic vacuum leak symptom,..check for that first.
