H Backfires Deceleration

Farmall H, HV & Super H, 300 & 350, 1939-1958

Moderator: Team Cub

Forum rules
Notice: For sale and wanted posts are not allowed in this forum. Please use our free classifieds or one of our site sponsors for your tractor and parts needs.
User avatar
AgTires4295
5+ Years
5+ Years
Posts: 181
Joined: Fri Dec 30, 2011 7:36 pm
Zip Code: 20646
Tractors Owned: 1940 Farmall A
1947 Farmall H
1951 Farmall Cub
1970 Cub Cadet 127
1970 Simplicity Broadmoor 728 (x2)
1984 Cub Cadet 782
1964 Simplicity Landlord
2014 Simplicity Broadmoor 23/50
Location: La Plata, MD

H Backfires Deceleration

Postby AgTires4295 » Tue May 16, 2017 8:53 pm

Hey all, Ive been enjoying the H for awhile and have added a few mods. One recent was a chrome straight pipe to spruce it up from the old canned muffler.

I drove the H for the first time at night since the switch to a straight pipe and noticed a very uniform response. Upon deceleration from full throttle and/or going downhill, it backfires, throwing light flames and pops like a shotgun blast. It's quite entertaining as I never noticed this trait before with the canned muffler but is this normal? I have it timed pretty well so I'm not sure what's what.

I'm hoping to not cause any damage but it seems as though this may be normal. Any input?
Image
1954 Farmall Cub
1970 Cub Cadet 127

Jim Becker
Team Cub
Team Cub
Posts: 12729
Joined: Sun Feb 02, 2003 2:59 pm
Zip Code: 55319
Circle of Safety: Y
Location: MN

Re: H Backfires Deceleration

Postby Jim Becker » Tue May 16, 2017 11:25 pm

Sounds normal to me.

User avatar
Rick Spivey
Cub Pro
Cub Pro
Posts: 2005
Joined: Sun Jul 01, 2007 10:07 pm
Zip Code: 29681
Circle of Safety: Y
Location: SC, Simpsonville 29681

Re: H Backfires Deceleration

Postby Rick Spivey » Wed May 17, 2017 5:03 am

They tend to run rich, so the excess fuel is detonating in the straight pipe. The original muffler would have, well, muffled this, and had baffles to stop the fireworks show.
Rick Spivey
'52 Cub ("Great Personality") 148xxx
'48 Cub with FH ("Gunny Cub") 38xxx
'57 Lambretta (a slow work in progress)
'74 Triumph TR6 (Mama's toy)

User avatar
AgTires4295
5+ Years
5+ Years
Posts: 181
Joined: Fri Dec 30, 2011 7:36 pm
Zip Code: 20646
Tractors Owned: 1940 Farmall A
1947 Farmall H
1951 Farmall Cub
1970 Cub Cadet 127
1970 Simplicity Broadmoor 728 (x2)
1984 Cub Cadet 782
1964 Simplicity Landlord
2014 Simplicity Broadmoor 23/50
Location: La Plata, MD

Re: H Backfires Deceleration

Postby AgTires4295 » Wed May 17, 2017 5:50 am

Thanks for the responses. I figured as much but wanted to be sure. The fireworks show was fun on the long downhill deceleration.
Image
1954 Farmall Cub
1970 Cub Cadet 127

v w
5+ Years
5+ Years
Posts: 944
Joined: Thu Jun 10, 2010 6:56 am
Zip Code: 49053
Circle of Safety: Y
Location: Galesburg, MI

Re: H Backfires Deceleration

Postby v w » Wed May 17, 2017 5:55 am

The H was ok but I liked the M. It had a louder pop. I would leave the throttle full and close quickly just to hear it. Close the throttle slowly if the pop bothers you. This does nothing for the downhill however. :D Vern

User avatar
Urbish
501 Club
501 Club
Posts: 886
Joined: Sat Sep 07, 2013 3:45 pm
Zip Code: 48158
Tractors Owned: ~
1948 Farmall Cub
1947 Farmall H
1946 Farmall B
1953 Willys CJ3B
Circle of Safety: Y
Location: Manchester, MI

Re: H Backfires Deceleration

Postby Urbish » Wed May 17, 2017 6:22 am

Jim Becker wrote:Sounds normal to me.


:Dito:

Pretty much any carbureted engine running with nothing but a short straight pipe from the exhaust will backfire and pop. This is a consequence of not having any back-pressure and the fact that a carburetor briefly allows an over-rich fuel ratio into the engine during deceleration. Don't run that thing under any low-hanging dead trees :)

User avatar
AgTires4295
5+ Years
5+ Years
Posts: 181
Joined: Fri Dec 30, 2011 7:36 pm
Zip Code: 20646
Tractors Owned: 1940 Farmall A
1947 Farmall H
1951 Farmall Cub
1970 Cub Cadet 127
1970 Simplicity Broadmoor 728 (x2)
1984 Cub Cadet 782
1964 Simplicity Landlord
2014 Simplicity Broadmoor 23/50
Location: La Plata, MD

Re: H Backfires Deceleration

Postby AgTires4295 » Wed May 17, 2017 10:05 am

I love the responses. Many thanks, gents! I definitely enjoy the show. It gives the H a neat characteristic that my A and Cub (straight pipe) don't have.
Image
1954 Farmall Cub
1970 Cub Cadet 127


Return to “Farmall H, HV, Super H, 300 & 350”

Who is online

Users browsing this forum: No registered users and 1 guest