Go Back   The Ford Barn > General Discussion > Early V8 (1932-53)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 08-09-2018, 07:46 PM   #1
adileo
Senior Member
 
adileo's Avatar
 
Join Date: Jun 2014
Location: New Jersey
Posts: 1,772
Default Rapping exhaust

Hi guys

When I 1st bought the 52 F1 (all stock v8), it use to rap / backfire through the exhaust, when backing off on gas. I did a tune up about 3 months ago, adjusted timing and it stopped. At the same time I installed a new carb. Tonight it started again, only when coming off the gas. When at idle it seems like the idle is too slow.

Now I have (I am guessing) two options:
1) check timing
2) turn carb idle screw up.

Which would you go for first?
__________________
Thanks

Andy
1952 F1
adileo is offline   Reply With Quote
Old 08-09-2018, 07:58 PM   #2
WABOOM
Senior Member
 
WABOOM's Avatar
 
Join Date: Jun 2018
Location: Minnesota
Posts: 347
Default Re: Rapping exhaust

It doesn't matter. I'd start with idle. Then time it.
WABOOM is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 08-09-2018, 08:02 PM   #3
40cpe
Senior Member
 
40cpe's Avatar
 
Join Date: May 2010
Location: Star, MS
Posts: 4,022
Default Re: Rapping exhaust

Timing affects the idle speed, but idle speed should be correct to time correctly. You might have to re-adjust idle after timing. IMHO
40cpe is offline   Reply With Quote
Old 08-09-2018, 08:13 PM   #4
40 Deluxe
Senior Member
 
Join Date: May 2010
Location: now Kuna, Idaho
Posts: 3,774
Default Re: Rapping exhaust

If you were a teenager in the fifties, you lived for that backfire sound. Don't be an old fogie!
40 Deluxe is offline   Reply With Quote
Old 08-09-2018, 08:15 PM   #5
JSeery
Member Emeritus
 
JSeery's Avatar
 
Join Date: Nov 2012
Location: Wichita KS
Posts: 16,132
Default Re: Rapping exhaust

Quote:
Originally Posted by 40 Deluxe View Post
If you were a teenager in the fifties, you lived for that backfire sound. Don't be an old fogie!
That's what I was thinking! I had a big engine mustang with very short pipes that would back down and shoot fire out of both sides under the doors. Boy did I think that was cool.
JSeery is offline   Reply With Quote
Old 08-10-2018, 07:48 AM   #6
Mike51Merc
Senior Member
 
Mike51Merc's Avatar
 
Join Date: May 2010
Location: Northeast Pennsylvania
Posts: 1,582
Default Re: Rapping exhaust

Sponsored Links (Register now to hide all advertisements)
Rapping (or popping) on deceleration indicates a lean condition. Adjust idle mixture richer.
Mike51Merc is offline   Reply With Quote
Old 08-10-2018, 08:13 AM   #7
RKS.PA
Senior Member
 
RKS.PA's Avatar
 
Join Date: Jun 2010
Location: Marana, AZ
Posts: 1,192
Default Re: Rapping exhaust

Quote:
Originally Posted by Mike51Merc View Post
Rapping (or popping) on deceleration indicates a lean condition. Adjust idle mixture richer.
2X Mike51. After I installed my Bubba distributor, I had the same experience because finally it was timed properly. Adjusted the idle screws, and that was the end of the "popping" on deceleration.

Dick.
RKS.PA is offline   Reply With Quote
Old 08-11-2018, 12:17 PM   #8
Vic Piano
Senior Member
 
Vic Piano's Avatar
 
Join Date: May 2010
Location: Odessa, FL
Posts: 7,611
Default Re: Rapping exhaust

Flathead rapping is a beautiful thing. Why would you want to stop it???
__________________
Imagination is more important than knowledge.
Vic Piano is offline   Reply With Quote
Old 08-11-2018, 01:09 PM   #9
adileo
Senior Member
 
adileo's Avatar
 
Join Date: Jun 2014
Location: New Jersey
Posts: 1,772
Default Re: Rapping exhaust

Simple. My wife doesn’t like it and I’m afraid of her.
__________________
Thanks

Andy
1952 F1
adileo is offline   Reply With Quote
Old 08-11-2018, 08:11 PM   #10
JSeery
Member Emeritus
 
JSeery's Avatar
 
Join Date: Nov 2012
Location: Wichita KS
Posts: 16,132
Default Re: Rapping exhaust

Quote:
Originally Posted by adileo View Post
Simple. My wife doesn’t like it and I’m afraid of her.
Good answer!!
JSeery is offline   Reply With Quote
Old 08-11-2018, 08:34 PM   #11
Tinker
Senior Member
 
Tinker's Avatar
 
Join Date: May 2010
Location: MN
Posts: 7,053
Default Re: Rapping exhaust

If you don't like it. Change it.
Tinker is offline   Reply With Quote
Old 08-12-2018, 12:07 AM   #12
Brendan
Senior Member
 
Brendan's Avatar
 
Join Date: May 2010
Location: At my kitchen table in Santa Rosa, Ca
Posts: 2,902
Default Re: Rapping exhaust

Quote:
Originally Posted by JSeery View Post
That's what I was thinking! I had a big engine mustang with very short pipes that would back down and shoot fire out of both sides under the doors. Boy did I think that was cool.
i had a 350 chebby that would do the same thing i'm 51 and i still think its kool!
__________________
If it would have been a snake it would have bit ya!

i can't spell my way out of a paper bag!
Brendan is offline   Reply With Quote
Old 08-12-2018, 04:36 AM   #13
aussie merc
Senior Member
 
aussie merc's Avatar
 
Join Date: Sep 2016
Location: sydney australia
Posts: 1,025
Default Re: Rapping exhaust

its just part of real motoring the 3 'Cs' [cams carbs compression] or as we say here NBC [no blo''' computers ] so embrace and enjoy
aussie merc is offline   Reply With Quote
Old 08-12-2018, 10:31 AM   #14
adileo
Senior Member
 
adileo's Avatar
 
Join Date: Jun 2014
Location: New Jersey
Posts: 1,772
Default Re: Rapping exhaust

Checked points, rotor and distro cap all looked good. Pulled plugs and they all looked a lil sooty. Cleaned, re-gapped and installed. Adjusted fuel mixture and idle is now nice smooth and truck starts and a quick hit of button.

Took for ride was still backfiring out exhaust when de-acceleration. Shut truck off did couple errands and now it’s not backfiring on de-acceleration.

Could it be condenser going bad? Could it be Electical?
__________________
Thanks

Andy
1952 F1

Last edited by adileo; 08-12-2018 at 12:02 PM.
adileo is offline   Reply With Quote
Old 08-12-2018, 01:34 PM   #15
Steves46
Senior Member
 
Steves46's Avatar
 
Join Date: May 2010
Location: Lithia, FL
Posts: 1,050
Default Re: Rapping exhaust

Andy, this is a long shot-are the carburetor mounting nuts snug? Sometimes a small vacuum leak will cause a backfire. May want to hook up a vacuum gauge and see what the readings are.
__________________
If it aint broke, don't fix it!
Steves46 is offline   Reply With Quote
Old 08-12-2018, 02:29 PM   #16
adileo
Senior Member
 
adileo's Avatar
 
Join Date: Jun 2014
Location: New Jersey
Posts: 1,772
Default Re: Rapping exhaust

Steve

Thanks. I just checked and the back carb nut took a qtr turn. I’ll drive it this week and see if this inconsistent back fire returns.
__________________
Thanks

Andy
1952 F1
adileo is offline   Reply With Quote
Old 08-12-2018, 02:42 PM   #17
Bob C
Senior Member
 
Join Date: May 2010
Location: So Cal
Posts: 8,713
Default Re: Rapping exhaust

Even though I never had one I love the sound of the old Chevy 6's with
twice pipes. https://www.youtube.com/watch?v=kVvtPCyo1-M


Bob
Bob C is offline   Reply With Quote
Old 08-12-2018, 08:21 PM   #18
Rand
Senior Member
 
Rand's Avatar
 
Join Date: Feb 2011
Location: Buford, GA
Posts: 380
Default Re: Rapping exhaust

I think that I've been on Face Book to much lately...I kept looking for the "like" button on a lot of those comments. Ha Ha....I love the sound of my Flatty rapping too. going to be even better when I'm able to switch over to straight pipes!
Randy
Rand is offline   Reply With Quote
Old 08-17-2018, 09:55 AM   #19
adileo
Senior Member
 
adileo's Avatar
 
Join Date: Jun 2014
Location: New Jersey
Posts: 1,772
Default Re: Rapping exhaust

That back carb nut being a lil loose may have been it. Took truck out few times no popping on deacceleration. Thanks Steve and rest!
__________________
Thanks

Andy
1952 F1
adileo is offline   Reply With Quote
Old 08-17-2018, 10:08 AM   #20
Jack E/NJ
Senior Member
 
Jack E/NJ's Avatar
 
Join Date: May 2010
Posts: 2,171
Default Re: Rapping exhaust

Are you gonna try to lean it out again to see if you can make the rapping come back at will? Jack E/NJ
Jack E/NJ is offline   Reply With Quote
Reply

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

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 01:57 AM.