Backfire? The motor is not even a year old - The 1947 - Present Chevrolet & GMC Truck Message Board Network

70' GMC · 03-31-2008, 06:53 AM

The motor made a pop like sound and there was a grayish black smoke that came into the cab. I have not rawhided it none. I gave it HE77 going toward wilmington, I was passing everything on the road except near lake waccamaw, when I got towards a Citgo, an ABC store(Alcohol) I saw Blue lights and slowed Ol' Blue down. I was running 70 to 90 MPH, but mostly 75 to 80. So did this might have caused it to backfire I guess. What is Backfire, really never had any vehicle to backfire and my autotech class never covered it or mentioned. Is it over for my motor or do I need another motor?
Is my motor O.K.?

Please don't bash me cause I never had this to happen to me til now.

HavinSomeFun · 03-31-2008, 07:07 AM

did it just pop and smoke a little or is it still blowing smoke out of the exhaust?

straitnate14 · 03-31-2008, 07:15 AM

how many RPM's where you running? I have been in a few cars that back fire/gurgle coming off high RPMs for an extended amount time running rich would be my guess?

Camper Power · 03-31-2008, 08:10 AM

don't worry, the engine just needs to be tuned a bit. backfire happens wen the fuel doesnt burn quickly enough, and is still burning wen the exhaust valve opens.

Pont406 · 03-31-2008, 08:58 AM

Do you run a point dist? Check your timing.

ChevLoRay · 03-31-2008, 05:37 PM

IF you are still running points, AND the condensor is going bad, it CAN cause a popping in the exhaust while you are sitting still and giving it a little gas at a time and holding the pedal (linkage) steady. But, the points popping is different than a backfire, which was explained already, as unburned fuel in the combustion chamber when the exhaust valve opens.

But, for it to backfire as you are coming off of a higher speed, ain't unusual. There is increased engine vacuum at that time, which will pull gas/air into the combustion chamber and increase the possibility of a backfire, depending on how your timing is set....and it may be right.

So, what is "rawhiding"? Do you stick a whip out the side of the window and give the bedsides a good whack to make it go faster? I may need to get me a "Fleetside Whip".....reckon LMC has 'em?

70' GMC · 04-01-2008, 04:32 AM

Quote:

Originally Posted by ChevLoRay

IF you are still running points, AND the condensor is going bad, it CAN cause a popping in the exhaust while you are sitting still and giving it a little gas at a time and holding the pedal (linkage) steady. But, the points popping is different than a backfire, which was explained already, as unburned fuel in the combustion chamber when the exhaust valve opens.

But, for it to backfire as you are coming off of a higher speed, ain't unusual. There is increased engine vacuum at that time, which will pull gas/air into the combustion chamber and increase the possibility of a backfire, depending on how your timing is set....and it may be right.

So, what is "rawhiding"? Do you stick a whip out the side of the window and give the bedsides a good whack to make it go faster? I may need to get me a "Fleetside Whip".....reckon LMC has 'em?

Rawhiding is getting down hard on the gas pedal while on the road and watchin for the donut eaters(cops).

I was just sitting there and then turned it off and heard it make a pop sound. It is a distributor and it is black and it has Accel on it.

03-31-2008, 06:53 AM	#1
70' GMC HERE.......Somewhere Join Date: Oct 2006 Location: Birmingham AL Posts: 2,488	Backfire? The motor is not even a year old The motor made a pop like sound and there was a grayish black smoke that came into the cab. I have not rawhided it none. I gave it HE77 going toward wilmington, I was passing everything on the road except near lake waccamaw, when I got towards a Citgo, an ABC store(Alcohol) I saw Blue lights and slowed Ol' Blue down. I was running 70 to 90 MPH, but mostly 75 to 80. So did this might have caused it to backfire I guess. What is Backfire, really never had any vehicle to backfire and my autotech class never covered it or mentioned. Is it over for my motor or do I need another motor? Is my motor O.K.? Please don't bash me cause I never had this to happen to me til now. __________________ Current rides: 2013 Hyundai elantra gt DD 1995 camaro my first crush lmao Was: 1970 with a 350 4barrel and 288 horses Classics make it possible! Last edited by 70' GMC; 03-31-2008 at 07:02 AM.

03-31-2008, 07:07 AM	#2
HavinSomeFun Still Just Havin Some Fun! Join Date: Jun 2007 Location: Piedmont, Oklahoma Posts: 1,145	Re: Backfire? The motor is not even a year old did it just pop and smoke a little or is it still blowing smoke out of the exhaust? __________________ a green one with some stuff done to it....

03-31-2008, 07:15 AM	#3
straitnate14 Registered User Join Date: Feb 2008 Location: Bartonville IL Posts: 415	Re: Backfire? The motor is not even a year old how many RPM's where you running? I have been in a few cars that back fire/gurgle coming off high RPMs for an extended amount time running rich would be my guess? __________________ ΜΟΛΩΝ ΛΑΒΕ

03-31-2008, 08:10 AM	#4
Camper Power Registered User Join Date: Feb 2008 Location: Grande Prairie Alberta Posts: 261	Re: Backfire? The motor is not even a year old don't worry, the engine just needs to be tuned a bit. backfire happens wen the fuel doesnt burn quickly enough, and is still burning wen the exhaust valve opens. __________________ eh 1970 Chevy C20 daily driver 1975 GMC Jimmy 4x4 project 1966 GMC C10 Dad's project

03-31-2008, 08:58 AM	#5
Pont406 Registered User Join Date: Aug 2007 Location: West Hills, California Posts: 679	Re: Backfire? The motor is not even a year old Do you run a point dist? Check your timing.

03-31-2008, 05:37 PM	#6
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: Backfire? The motor is not even a year old IF you are still running points, AND the condensor is going bad, it CAN cause a popping in the exhaust while you are sitting still and giving it a little gas at a time and holding the pedal (linkage) steady. But, the points popping is different than a backfire, which was explained already, as unburned fuel in the combustion chamber when the exhaust valve opens. But, for it to backfire as you are coming off of a higher speed, ain't unusual. There is increased engine vacuum at that time, which will pull gas/air into the combustion chamber and increase the possibility of a backfire, depending on how your timing is set....and it may be right. So, what is "rawhiding"? Do you stick a whip out the side of the window and give the bedsides a good whack to make it go faster? I may need to get me a "Fleetside Whip".....reckon LMC has 'em? __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.



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