Engine runs great, but backfires bad.
Thread Starter
Supreme Member
Joined: Mar 2001
Posts: 1,346
Likes: 2
From: Monticello, IN USA
Car: 1991 Z-28
Engine: 350
Transmission: T-5 (gonna buy the farm)
Engine runs great, but backfires bad.
The 350 I have sunk my sons college fund into runs real good. I do have 1 question: When I set the timing so that the engine runs smooth, or as smmoth as can be expected, the throttle response is instantanious. The "issue is when I let off it backfires through the exhaust real bad. Now, I do only have headers on it. Is this normal, and if not, what may be causing it?
Thanks,
JOsh
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Joshua Johnston
1991 Z-28
350, T-5, K&N, Ported Vortec heads, Edelbrock RPM, Holley 750 D.P., HEI, 11.07:1 CR, Comp Cams Roller-.510"/.520"-282*/288* dur., Shorty Headers, Dual 2.5 Exhaust,Dynomax Bullet Mufflers, T&R Motorsports custom air intake
Thanks,
JOsh
------------------
Joshua Johnston
1991 Z-28
350, T-5, K&N, Ported Vortec heads, Edelbrock RPM, Holley 750 D.P., HEI, 11.07:1 CR, Comp Cams Roller-.510"/.520"-282*/288* dur., Shorty Headers, Dual 2.5 Exhaust,Dynomax Bullet Mufflers, T&R Motorsports custom air intake
Junior Member
Joined: Mar 2001
Posts: 39
Likes: 0
From: my garage, mi
This is normal especially considering you have headers. If you remove the CAT it gets worse and if you put on flowmaster exhaust it gets even worse but from what I have found is the car still runs fine and it never detonates. Now considering you have dual exhaust (I am guessing this is true dual?) then you will get alot more backfire than I got with mine when I had my TES on. Good luck with the car 
.
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1987 Firebird Formula
305 LG-4
GM Vortec heads 2.02x1.6 valves
Crane CompuCam 2030
700-R4 Trans
4 barrel quadrajet
edelbrock performer intake
Hypertech Thermomaster Chip installed in a nonworking computer
Open Element Air Filter
No Cat with flowmaster exhaust
NO MORE COMPUTER CRAP
NON computer HEI Distributer
700R4 Lockup kit
- Soon to be installed
Edelbrock TES
Stall convertor
[This message has been edited by 87formula (edited September 08, 2001).]
.------------------
1987 Firebird Formula
305 LG-4
GM Vortec heads 2.02x1.6 valves
Crane CompuCam 2030
700-R4 Trans
4 barrel quadrajet
edelbrock performer intake
Hypertech Thermomaster Chip installed in a nonworking computer
Open Element Air Filter
No Cat with flowmaster exhaust
NO MORE COMPUTER CRAP
NON computer HEI Distributer
700R4 Lockup kit
- Soon to be installed
Edelbrock TES
Stall convertor
[This message has been edited by 87formula (edited September 08, 2001).]
Supreme Member
Joined: Jul 1999
Posts: 2,010
Likes: 0
From: Homestead, Fla
<font face="Verdana, Arial" size="2">Originally posted by johnsjj2:
The 350 I have sunk my sons college fund into runs real good.
</font>
The 350 I have sunk my sons college fund into runs real good.
</font>
Now thats the kind of dedication I like to hear
Thread Starter
Supreme Member
Joined: Mar 2001
Posts: 1,346
Likes: 2
From: Monticello, IN USA
Car: 1991 Z-28
Engine: 350
Transmission: T-5 (gonna buy the farm)
Well, he's only 2 so I have a little while to build back the funds. He already wants to see where the money went, but until I get exhaust on it, I don't like him riding in it. I don't want to find out what the sound, and fumes from open headers will do to a young child.
Thanks for the help.
------------------
Joshua Johnston
1991 Z-28
350, T-5, K&N, Ported Vortec heads, Edelbrock RPM, Holley 750 D.P., HEI, 11.07:1 CR, Comp Cams Roller-.510"/.520"-282*/288* dur., Shorty Headers, Dual 2.5 Exhaust,Dynomax Bullet Mufflers, T&R Motorsports custom air intake
Thanks for the help.
------------------
Joshua Johnston
1991 Z-28
350, T-5, K&N, Ported Vortec heads, Edelbrock RPM, Holley 750 D.P., HEI, 11.07:1 CR, Comp Cams Roller-.510"/.520"-282*/288* dur., Shorty Headers, Dual 2.5 Exhaust,Dynomax Bullet Mufflers, T&R Motorsports custom air intake
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