popping through the carb

gofastmercury · 05-18-2001, 11:59 PM

My 351w in a 66 comet has developed a really bad popping noise when I rev it up. It has a really big solid cam,70 351w heads,vic jr, and a 700 holley. it is a new cam, but it replaced a even bigger roller.I have run the valves.

Dark Knight · 05-19-2001, 03:13 AM

well, if one of the exhaust rockers isnt loose, check the timing... maybe 180* off... or even 1 tooth...

------------------
84 convt,'95 302,AFR's, performer
3.55's, underdrives stock shorties
stock cam, 1.7's
14.06@100.21, 255RWHP on a hot day
265 on the mph/weight chart

Dark Knight · 05-19-2001, 03:15 AM

oh yeah... which firing order are you running?

------------------
84 convt,'95 302,AFR's, performer
3.55's, underdrives stock shorties
stock cam, 1.7's
14.06@100.21, 255RWHP on a hot day
265 on the mph/weight chart

les1 · 05-19-2001, 11:38 AM

could be fuel mixture,bad plug or wire or im sure youve checked timing, i do know that if its 180 out on the distributor it wont run at all and if your running wrong firing order same thing, but it could be because you never said if it runs if it pops through the carb when trying to start and pops but wont start then it is 180 out or wrong order.

j's69stang · 05-19-2001, 11:43 AM

i had a popping noise coming through my carb and i snapped a rocker arm in half so take the valve covers off and see what you got

gofastmercury · 05-19-2001, 11:54 AM

I've pulled the valve covers checked the lash, it starts and idles fine. i've tried a difffent carb and it does the same thing.

gofastmercury · 05-19-2001, 04:04 PM

when ajusted the same rocker for the second time, I stared to look at it. the new cam went flat on 2 lobes. I guess the roller going back in.

Dark Knight · 05-20-2001, 12:59 AM

what kind of heads? if they're the press in stud type, you could be pulling a stud out of the head.... if one of the exhaust valves is getting loose, it will backfire thru the carb all the time.. if it only does it when you give it gas, it sounds like it's a tooth off in the Dist.... try re-checking the timing...

------------------
84 convt,'95 302,AFR's, performer
3.55's, underdrives stock shorties
stock cam, 1.7's
14.06@100.21, 255RWHP on a hot day
265 on the mph/weight chart

Dark Knight · 05-20-2001, 01:01 AM

another thing to check might be the acc. pump on the carb... might not be getting enough fuel when you open the throttle..

------------------
84 convt,'95 302,AFR's, performer
3.55's, underdrives stock shorties
stock cam, 1.7's
14.06@100.21, 255RWHP on a hot day
265 on the mph/weight chart

gofastmercury · 05-21-2001, 11:07 PM

thanks for all your help. I put the roller in and it runs as good as new. took it to the track and in the 12's right off the trailer.lost in the 2nd round with a .479 and a dead-on dail.

05-18-2001, 11:59 PM	#1
gofastmercury Registered Member Join Date: May 2001 Location: calgary alberta canada Posts: 366	popping through the carb My 351w in a 66 comet has developed a really bad popping noise when I rev it up. It has a really big solid cam,70 351w heads,vic jr, and a 700 holley. it is a new cam, but it replaced a even bigger roller.I have run the valves.

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05-19-2001, 03:13 AM	#2
Dark Knight Registered Member Join Date: Oct 1998 Location: Az Posts: 854	well, if one of the exhaust rockers isnt loose, check the timing... maybe 180* off... or even 1 tooth... ------------------ 84 convt,'95 302,AFR's, performer 3.55's, underdrives stock shorties stock cam, 1.7's 14.06@100.21, 255RWHP on a hot day 265 on the mph/weight chart

05-19-2001, 03:15 AM	#3
Dark Knight Registered Member Join Date: Oct 1998 Location: Az Posts: 854	oh yeah... which firing order are you running? ------------------ 84 convt,'95 302,AFR's, performer 3.55's, underdrives stock shorties stock cam, 1.7's 14.06@100.21, 255RWHP on a hot day 265 on the mph/weight chart

05-19-2001, 11:38 AM	#4
les1 Registered Member Join Date: Mar 1999 Location: seattle Posts: 76	could be fuel mixture,bad plug or wire or im sure youve checked timing, i do know that if its 180 out on the distributor it wont run at all and if your running wrong firing order same thing, but it could be because you never said if it runs if it pops through the carb when trying to start and pops but wont start then it is 180 out or wrong order.

05-19-2001, 11:43 AM	#5
j's69stang Registered Member Join Date: Apr 2000 Posts: 102	i had a popping noise coming through my carb and i snapped a rocker arm in half so take the valve covers off and see what you got

05-19-2001, 11:54 AM	#6
gofastmercury Registered Member Join Date: May 2001 Location: calgary alberta canada Posts: 366	I've pulled the valve covers checked the lash, it starts and idles fine. i've tried a difffent carb and it does the same thing.

05-19-2001, 04:04 PM	#7
gofastmercury Registered Member Join Date: May 2001 Location: calgary alberta canada Posts: 366	when ajusted the same rocker for the second time, I stared to look at it. the new cam went flat on 2 lobes. I guess the roller going back in.

05-20-2001, 12:59 AM	#8
Dark Knight Registered Member Join Date: Oct 1998 Location: Az Posts: 854	what kind of heads? if they're the press in stud type, you could be pulling a stud out of the head.... if one of the exhaust valves is getting loose, it will backfire thru the carb all the time.. if it only does it when you give it gas, it sounds like it's a tooth off in the Dist.... try re-checking the timing... ------------------ 84 convt,'95 302,AFR's, performer 3.55's, underdrives stock shorties stock cam, 1.7's 14.06@100.21, 255RWHP on a hot day 265 on the mph/weight chart

05-20-2001, 01:01 AM	#9
Dark Knight Registered Member Join Date: Oct 1998 Location: Az Posts: 854	another thing to check might be the acc. pump on the carb... might not be getting enough fuel when you open the throttle.. ------------------ 84 convt,'95 302,AFR's, performer 3.55's, underdrives stock shorties stock cam, 1.7's 14.06@100.21, 255RWHP on a hot day 265 on the mph/weight chart

05-21-2001, 11:07 PM	#10
gofastmercury Registered Member Join Date: May 2001 Location: calgary alberta canada Posts: 366	thanks for all your help. I put the roller in and it runs as good as new. took it to the track and in the 12's right off the trailer.lost in the 2nd round with a .479 and a dead-on dail.