Backfiring through carb under hard acceleration! ???

yoshi351w · 10-15-2003, 03:46 PM

What cause this. I am kinda learning on a trial and error basis here. I just rebuilt my carb and got it running halfway decent again. This car does not deserve to run decent. It should run like a bat out of hell! What causes this? Lean? Rich? I dont know.

It is a 750 dp mech secondary with a proform main body and quik fuel throttle plate

__________________
86 gt, 359w, PA reverse manual c4 with 3800 JW convertor, stock fully ported studded heads with pioneer springs, manley 1.94 1.60 valves, trick flow stage 1 cam, pushrods, and HS 1.7 rockers. Bottom end was balanced and assembaled with clevite H series bearings and ARP studs, KB pistons. Victor jr. intake, proform 750 dp, and a lot more.

billheis · 10-16-2003, 02:01 AM

Backfire throught the carb is a lean condition. Make sure all your holes line up for accel pumps. Maybe a gasket not lining up or something like that. Without engine running open up the throttle and watch the action of accel pumps (did you change the cams on the throttle linkage?) Then look down the venturis and watch the spray coming out of the nozelles. Make sure pump arms are adjusted right.

yoshi351w · 10-19-2003, 01:23 PM

How do I adjust the pump arms?

billheis · 10-19-2003, 09:46 PM

Everyone has their way of doing it but I like to adjust the spring loaded bolt as tight as it can get and just touch the pump arm. This way you get good action and still have some play left at full throttle.

10-15-2003, 03:46 PM	#1
yoshi351w Registered Member Join Date: Aug 2003 Location: s. fl Posts: 23	Backfiring through carb under hard acceleration! ??? What cause this. I am kinda learning on a trial and error basis here. I just rebuilt my carb and got it running halfway decent again. This car does not deserve to run decent. It should run like a bat out of hell! What causes this? Lean? Rich? I dont know. It is a 750 dp mech secondary with a proform main body and quik fuel throttle plate __________________ 86 gt, 359w, PA reverse manual c4 with 3800 JW convertor, stock fully ported studded heads with pioneer springs, manley 1.94 1.60 valves, trick flow stage 1 cam, pushrods, and HS 1.7 rockers. Bottom end was balanced and assembaled with clevite H series bearings and ARP studs, KB pistons. Victor jr. intake, proform 750 dp, and a lot more. __________________ 351w powered 86 gt with a reverse manual c4. Lots more but whos counting.

10-16-2003, 02:01 AM	#2
billheis Registered Member Join Date: May 2001 Location: Fernandina Beach, FL 32034 Posts: 178	Backfire throught the carb is a lean condition. Make sure all your holes line up for accel pumps. Maybe a gasket not lining up or something like that. Without engine running open up the throttle and watch the action of accel pumps (did you change the cams on the throttle linkage?) Then look down the venturis and watch the spray coming out of the nozelles. Make sure pump arms are adjusted right. __________________ Bill Heiser 90 Convertable 5.0 LX, ported E7s w/ THumper valve job, TFS street, FR 65mm TB, B cam w/1.7 cobra rockers, kirban AFPR, Mac CAI, Mac Headers, off road h, 3 chamber flows, Crane ign. box, 3:73s, Art Carr AOD & 2600 converter

10-19-2003, 09:46 PM	#4
billheis Registered Member Join Date: May 2001 Location: Fernandina Beach, FL 32034 Posts: 178	Everyone has their way of doing it but I like to adjust the spring loaded bolt as tight as it can get and just touch the pump arm. This way you get good action and still have some play left at full throttle. __________________ Bill Heiser 90 Convertable 5.0 LX, ported E7s w/ THumper valve job, TFS street, FR 65mm TB, B cam w/1.7 cobra rockers, kirban AFPR, Mac CAI, Mac Headers, off road h, 3 chamber flows, Crane ign. box, 3:73s, Art Carr AOD & 2600 converter

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10-19-2003, 01:23 PM	#3
yoshi351w Registered Member Join Date: Aug 2003 Location: s. fl Posts: 23	How do I adjust the pump arms?