The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 04-06-2012, 10:32 PM   #1
vectorit
What?
 
vectorit's Avatar
 
Join Date: Jun 2007
Location: Southern California
Posts: 7,617
My ears are still ringing

I just got my 1970 K10 back from getting a new exhaust system today, and went out for a spin to enjoy the latest upgrade to be done to the truck. The system is OE ram manifolds, dual exhaust with H pipe, and hemi turbo mufflers exiting behind the rear tires.

Truck sounded great! I could hear the engine, and everything else going on in and out of the truck. So I went for a little scenic route to get up to highway speeds, then pulled over to snap a couple pictures while the truck idled for a few minutes.
Hopped back in the truck, put her in gear and took off with a little bit of zip. As soon as I took my foot off the gas to shift... BANG! It sounded like a rifle shot fired from my cab out the window. Engine still running along, so I shifted into 4th and tooled along wondering what the hell could have caused that.
Then just as my ears are back to adjusting to some what normal noises, my exhaust sounded different...

I drove all the way home wondering what the hell let loose.

Well, as you can see both new mufflers with less than an hours worth of drive time on them are blown out and now have to be replaced.

Any ideas on what could be the cause of this?
I am suspecting my Pertronix II ignition may have caused this, so that is the first thing I am going to investigate tomorrow.

The truck runs great, and has never back fired like that since I have owned it.
Attached Images
  
__________________
Chris
1968 K20 Suburban
1972 K10 LWB PU
vectorit is offline   Reply With Quote
Old 04-06-2012, 10:53 PM   #2
GASoline71
"I ain't nobody, dork."
 
GASoline71's Avatar
 
Join Date: Sep 2007
Location: Whidbey Island, Washington
Posts: 8,971
Re: My ears are still ringing

If that was from a backfire... that was one helluva backfire! Holy cats!

Gary
__________________
'cuz chicks dig scars...

My 1972 GMC 1500 Super Custom (Creeping Death) "long term" build thread.

The Rebuild of Creeping Death after the wreck

Quote:
Originally Posted by LONGHAIR View Post
I would never rebuild a 305.
Quote:
Originally Posted by prostreetC-10 View Post
I love using vacuum gauges as part of the carb tuning process. I hook the gauge to the inside of my garbage can and leave it there.
Quote:
Originally Posted by Marv D View Post
Remember Murphys 2nd law of mechanical relationships... "OPPOSING COMPONENTS ATTEMPTING TO OCCUPY THE SAME SPACE, AT THE SAME TIME, GENERALLY END UP OCCUPYING ADJOINING SPACE AT THE BOTTOM OF THE OIL PAN"
Quote:
Originally Posted by cableguy0 View Post
Its cheaper to listen to advice given when you ask for help than it is to ignore everyone and wait for carnage.
GASoline71 is offline   Reply With Quote
Old 04-06-2012, 10:56 PM   #3
LockDoc
The Older Generation


 
LockDoc's Avatar
 
Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,774
Re: My ears are still ringing

-
Sounds like raw fuel build up in the exhaust system but I would think it would have died if it was getting that much fuel while idling. Really weird...

LockDoc
__________________
Leon

Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles

(My Dually Pickup Project Thread)

http://67-72chevytrucks.com/vboard/s...d.php?t=829820

-
LockDoc is offline   Reply With Quote
Old 04-06-2012, 11:30 PM   #4
Classic Bowties
Always on the hunt...
 
Join Date: Sep 2006
Location: Portland, OR.
Posts: 5,747
Re: My ears are still ringing

Wow, didn't even get a chance to get a little mud on them. Talk with your exhaust guy and let him know you never had a backfire issue before the new setup, maybe the time to try a flowmaster or one of the flow knockoff types out? You could also drop fellow member Jerry Moss a message to pick his brain on the subject. Mel
Classic Bowties is online now   Reply With Quote
Old 04-06-2012, 11:51 PM   #5
70cst
Senior Member
 
70cst's Avatar
 
Join Date: Feb 2001
Location: New Madison, Ohio
Posts: 21,373
Re: My ears are still ringing

__________________
A husband can be right...or...A husband can be happy.

67-72 Chevy and GMC Trucks...The Classic Truck for the Classic Folk.

1970 CST Two tone green, 402BB, 400 Automatic, Tach, Buckets, AC, AM-FM, Tilt, GM CB, GM 8 Tract, LWB, etc

JOHN 17:3...The better side of "LIFE"


Remember: Everyday is a good day...Some are just gooder!
70cst is offline   Reply With Quote
Old 04-06-2012, 11:59 PM   #6
VA72C10
VA72C10
 
VA72C10's Avatar
 
Join Date: Mar 2008
Location: Midlothian, VA
Posts: 25,267
Re: My ears are still ringing

Quote:
Originally Posted by LockDoc View Post
-
Sounds like raw fuel build up in the exhaust system but I would think it would have died if it was getting that much fuel while idling. Really weird...

LockDoc
that's what I was thinking...
__________________
Looking for a 67-72 swb or blazer project in or around VA.
VA72C10 is offline   Reply With Quote
Old 04-07-2012, 12:05 AM   #7
shawno72
C/10 junkie
 
shawno72's Avatar
 
Join Date: Nov 2010
Location: Stockton Ca
Posts: 9,093
Re: My ears are still ringing

Weld them back up and your good to go
Posted via Mobile Device
__________________
Shawn

70 LWB C10 current driver/project
http://67-72chevytrucks.com/vboard/s...d.php?t=663051
68 SWB C10 Work in progress.....SOLD
http://67-72chevytrucks.com/vboard/s...d.php?t=559520
72 LWB C10 Sold
71 LWB C10 Sold
68 LWB C10 CST Sold


http://youtu.be/kbB0QrBIs9k

My mom always had the best advice. It was just a tad late. After a fall that involved blood, she'd say....."Careful!"
shawno72 is offline   Reply With Quote
Old 04-07-2012, 12:18 AM   #8
Already Gone
70+ ( Old Skool Club )
 
Already Gone's Avatar
 
Join Date: Nov 2003
Location: Saskatoon, Saskatchewan ,Canada
Posts: 9,143
Re: My ears are still ringing

Subscribed, as I'm really curious.
__________________
1972 C10 Custom/Deluxe 613 Highlander 406/700R4
1999 White Tahoe LS 4x2 with Z56 Police Package
1992 K1500 GMC Suburban

Members I have personally met: MusicMan70 - HeavyD - ChewyChevy67 - StingRay -71SWB4x4 - 67 Burb - DeadheadNM - too much stuff - bc65 - das601

" Circumsatances Do Not Change Responsibility "

" The Sky is not the Limit, Your Mind is." Marilyn Monroe ..


RIP Charlie Watts 1941 - 2021
Already Gone is offline   Reply With Quote
Old 04-07-2012, 12:27 AM   #9
67c10rustbuket
Registered User
 
67c10rustbuket's Avatar
 
Join Date: Apr 2011
Location: Mustang, Oklahoma
Posts: 2,806
Re: My ears are still ringing

Cheap crimp mufflers? I saw a few blown and returned when I was a little man working at autozone.
__________________
Dan <---(my name)



67 SWB C10 project "GEORGIA"-59 Brookwood 2dr wag...Next project-03 Tahoe 4x4 5.3 family ride-07 Hondur Accord, commuter car
67c10rustbuket is offline   Reply With Quote
Old 04-07-2012, 12:32 AM   #10
shawno72
C/10 junkie
 
shawno72's Avatar
 
Join Date: Nov 2010
Location: Stockton Ca
Posts: 9,093
Re: My ears are still ringing

I wasn't going to mention the crimp mufflers, but since you did upgrade to a set of fully welded units ie flowmaster or magnaflow or the likes
Posted via Mobile Device
__________________
Shawn

70 LWB C10 current driver/project
http://67-72chevytrucks.com/vboard/s...d.php?t=663051
68 SWB C10 Work in progress.....SOLD
http://67-72chevytrucks.com/vboard/s...d.php?t=559520
72 LWB C10 Sold
71 LWB C10 Sold
68 LWB C10 CST Sold


http://youtu.be/kbB0QrBIs9k

My mom always had the best advice. It was just a tad late. After a fall that involved blood, she'd say....."Careful!"
shawno72 is offline   Reply With Quote
Old 04-07-2012, 12:44 AM   #11
vectorit
What?
 
vectorit's Avatar
 
Join Date: Jun 2007
Location: Southern California
Posts: 7,617
Re: My ears are still ringing

Quote:
Originally Posted by GASoline71 View Post
If that was from a backfire... that was one helluva backfire! Holy cats!

Gary
Believe me, it was loud... hours later my ears are still ringing.
__________________
Chris
1968 K20 Suburban
1972 K10 LWB PU
vectorit is offline   Reply With Quote
Old 04-07-2012, 10:42 AM   #12
cdowns
Senior Member
 
cdowns's Avatar
 
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
Re: My ears are still ringing

with the price of gas now i'd think you might b money ahead by having your engine gone thru and tuned by a shop in stead of dumping it out the exhaust pip[e
__________________
71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane

MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF

DONT BELIEVE EVERYTHING YOU THINK

TAKE MY ADVISE;I DON'T USE IT ANYWAY
cdowns is offline   Reply With Quote
Old 04-07-2012, 10:43 AM   #13
special-K
Special Order

 
special-K's Avatar
 
Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,851
Re: My ears are still ringing

Are there potatoes in you pipes? It may just be cheap mufflers. I wouldn't blame it on being crimped mufflers. Millions of those (literally) have been under cars and trucks forever without blowing out. I've never seen one fail like that. But,poor quality is my suspicion since the truck runs fine otherwise.
__________________
"BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed"

GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project)
GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling)
Tim

"Don't call me a redneck. I'm a rough cut country gentleman"

R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~
special-K is offline   Reply With Quote
Old 04-07-2012, 11:02 AM   #14
Classic Heartbeat
Project Junkie! Fishing Poor!!
 
Classic Heartbeat's Avatar
 
Join Date: Dec 1999
Location: Olympia,Wa. 98512
Posts: 10,766
Re: My ears are still ringing

My guess is exess fuel made it into the exhaust. I blew a muffler like that once with a big block. Funny thing was the motor seemed to run better after that.. WES
__________________
On-line catolog
Classic Heartbeat Pickup Parts
WEHEPP@comcast.net
Call us Toll Free (888) 338-2502
Like Us on Facebook
No appointment necessary.
72 BB Chevy Custom Deluxe / Custom Camper
67 I-6 (Soon to be 5.7 LS1) Panel
68 BB Chevy Short Bed
72 6.0 LQ9 Short Bed Chevy 4X4
Olympia's fastest growing truck parts supplier.
Olympia's home for Wayward Chevys
Classic Heartbeat is offline   Reply With Quote
Old 04-07-2012, 02:46 PM   #15
beautimus
Registered User
 
beautimus's Avatar
 
Join Date: Mar 2002
Location: woodstock, alabama, usa
Posts: 938
Re: My ears are still ringing

i did this myself, a long time ago on a ford ranger. i had replaced the timing belt and in the process of reassbling everything i had forgot to put the coil wire back on. i cranked and cranked and cranked on it. then i remembered that coil wire, i put it back on and was starting to crank on it some more, but just as i turned the switch something in the back of my mind said no!!, bu i let the key turn in my hand, the ignition fired and boom! sounded like a cannon went off. a dust cloud came up around the truck . the muffer had split lengthwise down the seam. the neighbors all came running to see what i blew up. it was that loud. The reason i am telling you is that the guys above have it right you were difinitly pooling unburned gas in the exhaust system, and thats what took the mufflers out. if you go down the road and turn the ignition to off for a few seconds and then back to run it will do the same thing, but not as violently. (don't try it with switch on the column because of steering wheel might lock) but i can't say what caused it.
best of luck. Tony
__________________
i survived cancer and kidney stones, but my kids are killing me.

Last edited by beautimus; 04-07-2012 at 02:46 PM. Reason: to correct spelling
beautimus is offline   Reply With Quote
Old 04-07-2012, 03:40 PM   #16
rkn463
Registered User
 
rkn463's Avatar
 
Join Date: Jan 2012
Location: Iredell, Texas
Posts: 582
Re: My ears are still ringing

I suspect a carb problem caused this. Some carbs (like quadrajets) have vacuum controled fuel mixture. If you've ever been inside one the primary metering rods ride up and down depending on how much vacuum you have, more vacuum - more lean. So if your carb works like that and the metering system gets gunked up you can get a situation where you run hard then let off the metering rods should slam shut but stick in the rich position which dumps a bunch of gas down the exhaust. Then you give it some throttle and blow a little fire in there and ignite the whole thing and BANG! It really sound like a rifle shot. I used to have an 80 model Ford p/u with a 300 six in it and it did this very predictably. So predictably that it was loads of fun. Now I'm not saying that I ever made it "shoot" at a motorcycle cop under a bridge but I'm not denying it either. In that truck after I blew out the old rusted stock muffler I had Midas put on one with a lifetime guarantee and it never blew out.
__________________
I may have too many Chevys... Is that possible?
68 c50 pickup build: http://67-72chevytrucks.com/vboard/s...d.php?t=704713
rkn463 is offline   Reply With Quote
Old 04-07-2012, 04:21 PM   #17
vectorit
What?
 
vectorit's Avatar
 
Join Date: Jun 2007
Location: Southern California
Posts: 7,617
Re: My ears are still ringing

Well, this morning I go out to take a look at things.
Nothing out of sort that I can see, other than a destroyed pair of mufflers.

So I hop in the truck to take it to my friends shop, and notice the clutch peddle seems light.

So I proceed to go down the street, and get a couple blocks and the truck jerked hard after shifting into second. Then I notice the clutch peddle even more light.

Get to a stop sign, and it lets me put it into 2nd but at this point I am thinking I am not going to make it through the intersection. Just then as I let the clutch peddle up to move forward, it jerked hard and stalled the engine.
At this point there is no pressure feed back on the clutch, and luckily I am on a hill so I let it roll back to the side of the road.
Open the hood, and the clutch linkage is fine with nothing looking out of the ordinary.

Call the tow truck and have it towed to the shop, and now I am waiting for the damage report.

At this point I am so mad I can barely see straight.


As for the votes for raw fuel collecting in the mufflers - I have to agree with that assessment.

Though I am perplexed as to how that can be, since the exhaust doesn't give off the smell of raw fuel and there is no black smoke. The plugs were just out to be inspected, and all of them were a light chocolate color showing a good burn.
The carburetor is a new reman Q-jet from Jegs.
The plug wires, cap, and rotor are all new.

The only thing that was not right about the truck was that it was gutless at WOT, to where the secondaries never really seemed to open up and give you a the feeling of the engine pulling hard. Low end power is great though.

The plan was to get the exhaust system done, then head over to my buddies shop to diagnose the weak performance at WOT. Since the old exhaust system was headers, and worn out turbo mufflers along with much needed new ignition components.
__________________
Chris
1968 K20 Suburban
1972 K10 LWB PU
vectorit is offline   Reply With Quote
Old 04-07-2012, 09:14 PM   #18
special-K
Special Order

 
special-K's Avatar
 
Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,851
Re: My ears are still ringing

If you had intermittent power to your ignition then it could cause a backfire. But,you never heard a backfire,right?
__________________
"BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed"

GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project)
GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling)
Tim

"Don't call me a redneck. I'm a rough cut country gentleman"

R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~
special-K is offline   Reply With Quote
Old 04-07-2012, 10:07 PM   #19
67ChevyRedneck
Hittin E-Z Street on Mud Tires
 
67ChevyRedneck's Avatar
 
Join Date: Nov 2004
Location: Greenville, SC
Posts: 23,090
Re: My ears are still ringing

Holy crap. NEVER have I seen mufflers do that!

About your clutch... weirdest thing that ever happed to me with the 67 was that a flywheel bolt actually backed itself out and got hung up in the clutch not allowing it to release. After playing with it for a while I heard a REALLY LOUD BANG and it worked again... The bolt actually almost blew a hole in the bottom bellhousing cover (the thin metal piece that bolts on). It left a hexagon impresson and a half tear mark where it almost went though. Wish I had kept it...
__________________
Jesse James
1967 C10 SWB Stepside: 350/700R4/3.73
1965 Ford Mustang: 289/T5-5spd/3.25 Trac-Loc
1968 Pontiac Firebird: Project Fire Chicken!
2015 Silverado Double Cab 5.3L Z71
2001 Jeep Wrangler Sport 4.0L 5spd
2020 Chevrolet Equinox Premium 2.0L Turbo
2011 Mustang V6 ~ Wife's ride
American Born, Country by the Grace of God
1967 CST Shop Truck Rebuild!
My 1967 C-10 Build Thread
My Vintage Air A/C Install
Project "On a Dime"
Trying my hand at Home Renovation!
1965 Mustang Modifications!
67ChevyRedneck is offline   Reply With Quote
Old 04-07-2012, 11:38 PM   #20
vectorit
What?
 
vectorit's Avatar
 
Join Date: Jun 2007
Location: Southern California
Posts: 7,617
Re: My ears are still ringing

Just got back from the shop, and the transmission/transfer case is coming out.
The clutch is gone, but I didn't see anything broken while it was up on the rack.

Luckily my buddy knows the exhaust shop guy, and so next week he is going to show him the carnage. My friend who owns and operates a shop, is shocked to see this happen in such a short period of time (less than and hour on new mufflers, and the truck never backfired like this before).

I will know more next week.
__________________
Chris
1968 K20 Suburban
1972 K10 LWB PU
vectorit is offline   Reply With Quote
Old 04-07-2012, 11:52 PM   #21
treveiger
Senior Member
 
treveiger's Avatar
 
Join Date: Jul 2010
Location: South Dakota
Posts: 4,093
Re: My ears are still ringing

Wow, that's insane!
Posted via Mobile Device
__________________
1969 Chevy c20(Miss Hackjob)
treveiger is offline   Reply With Quote
Old 04-08-2012, 12:14 AM   #22
67c10rustbuket
Registered User
 
67c10rustbuket's Avatar
 
Join Date: Apr 2011
Location: Mustang, Oklahoma
Posts: 2,806
Re: My ears are still ringing

I didn't mean that all crimp mufflers are cheap crap, just maybe you got a bad pair. Working in a factory I know the first few parts made at setup may be "good enough". The gas pooling issue seems to be the most logical. I'm curious to see the result. Later
__________________
Dan <---(my name)



67 SWB C10 project "GEORGIA"-59 Brookwood 2dr wag...Next project-03 Tahoe 4x4 5.3 family ride-07 Hondur Accord, commuter car
67c10rustbuket is offline   Reply With Quote
Old 04-08-2012, 12:35 AM   #23
vectorit
What?
 
vectorit's Avatar
 
Join Date: Jun 2007
Location: Southern California
Posts: 7,617
Re: My ears are still ringing

Quote:
Originally Posted by 67c10rustbuket View Post
I didn't mean that all crimp mufflers are cheap crap, just maybe you got a bad pair. Working in a factory I know the first few parts made at setup may be "good enough". The gas pooling issue seems to be the most logical. I'm curious to see the result. Later
That's what my buddy at the shop was saying, in regards to raw fuel collecting in the mufflers.
He is concerned that they may have been defective as well, and is going to call the guy that I had install the system over to his shop to show him.
__________________
Chris
1968 K20 Suburban
1972 K10 LWB PU
vectorit is offline   Reply With Quote
Old 04-09-2012, 05:36 PM   #24
vectorit
What?
 
vectorit's Avatar
 
Join Date: Jun 2007
Location: Southern California
Posts: 7,617
Re: My ears are still ringing

Update:

Transmission/T-case are out, and the pressure plate appears to be broken inside. It's a Borg Warner brand, and only has about 4 thousand miles on it.

Clutch disc and fly wheel still look new.

Didn't have my camera, but I will take a picture of it and post. But, unfortunately you can not see or hear any damage to it. It is like the diaphragm connection inside has broken, and they don't allow the pressure plate to lift when the pedal is depressed.

Strange how this goes out at the same time of the backfire incident.


Muffler shop is not going to do anything about the cost involved to replace the mufflers either, since something apparently with my ignition caused a premature ignition to cause the back fire.
I have had multiple mechanics look at the truck, and assess how it is running and all of them pointed out that it is not running rich.

Once the clutch issue is resolved, we are going to dig into the ignition system.
__________________
Chris
1968 K20 Suburban
1972 K10 LWB PU
vectorit is offline   Reply With Quote
Old 04-09-2012, 06:56 PM   #25
67ChevyRedneck
Hittin E-Z Street on Mud Tires
 
67ChevyRedneck's Avatar
 
Join Date: Nov 2004
Location: Greenville, SC
Posts: 23,090
Re: My ears are still ringing

I skimmed through old threads you started to see if you posted pics but I didn't find any... I've seen the pics and vids of your burb which is awesome... so what does this one look like?
__________________
Jesse James
1967 C10 SWB Stepside: 350/700R4/3.73
1965 Ford Mustang: 289/T5-5spd/3.25 Trac-Loc
1968 Pontiac Firebird: Project Fire Chicken!
2015 Silverado Double Cab 5.3L Z71
2001 Jeep Wrangler Sport 4.0L 5spd
2020 Chevrolet Equinox Premium 2.0L Turbo
2011 Mustang V6 ~ Wife's ride
American Born, Country by the Grace of God
1967 CST Shop Truck Rebuild!
My 1967 C-10 Build Thread
My Vintage Air A/C Install
Project "On a Dime"
Trying my hand at Home Renovation!
1965 Mustang Modifications!
67ChevyRedneck is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

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

Forum Jump


All times are GMT -4. The time now is 01:46 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com