replacement mufflers?

Hafi mods and resto work reports

Moderator: TechMOGogy

Post Reply
User avatar
audiocontr
United States of America
Posts: 1868
Joined: Fri May 01, 2009 1:30 pm
Location: Buffalo NY

replacement mufflers?

Post by audiocontr »

Has anyone had success with a non OEM muffler? Mine pops and backfires. I'd like to build something a bit quieter for as little $ as humanly possible =)
1973 712m
1968 Haflinger
1965 Pathfinder
1978 GMC Palm Beach (Hey, its got 6 wheels!!)
Heinkeljb
Great Britain
Posts: 391
Joined: Wed Feb 27, 2013 1:09 pm
Location: Lewes,Southern England

Re: replacement mufflers?

Post by Heinkeljb »

I built a "cherry bomb" silencer for Lurch - it's a bit loud as it is basically a straight through pipe, but if you are looking for something quite your biggest issue will be to find a silencer which has less than a 2 inch diameter pipes in and out. Haflingers have 1.25" pipes from the manifolds and the exit pipe on the standard silencer box is less than that.

Most usual reason for popping and backfiring is due to air leaks and have too rich a mixture. i.e. there is still some unburnt fuel in the exhaust gas as it leaves the cylinder, then it sucks in some more fresh air when you take your foot off the throttle. The gas mixture then becomes correct of it to ignite and it goes "bang"!

John
New exhaust system 1.jpg
New exhaust system 1.jpg (169 KiB) Viewed 1531 times
New exhaust system 2.jpg
New exhaust system 2.jpg (166.08 KiB) Viewed 1531 times
New exhaust system 3.jpg
New exhaust system 3.jpg (179.15 KiB) Viewed 1531 times
Lurch has the Heat exchanger heating system.
Last edited by Heinkeljb on Wed Aug 29, 2018 3:33 pm, edited 1 time in total.
User avatar
pcolette
United States of America
Posts: 1614
Joined: Sun Dec 10, 2006 7:38 pm
Location: Southwest Wisconsin

Re: replacement mufflers?

Post by pcolette »

If you have an RV supply place or RV dealer near by, you might take a look at the various resonators for Cummins and Onan generators. They are usually fairly short and have small diameter in/out pipes. Just might work.
Paul C.
_________
'73 Swiss 710M
'89 Puch 230GE
User avatar
TechMOGogy
Canada
Posts: 2831
Joined: Wed Feb 01, 2012 11:39 am
Location: Ontario, Canada

Re: replacement mufflers?

Post by TechMOGogy »

Skidoo, quad and side x side mufflers are another option.
Soni in NM used a skidoo one but not sure of model

Image
72 Pathfinder | 75 710M 2.7i | 96 350GDT Worker
pinzi
Belgium
Posts: 154
Joined: Sun Nov 09, 2008 4:23 am
Location: belgium

Re: replacement mufflers?

Post by pinzi »

Or your contactpoints are bad...or the ignition timing isnt on point or a bit late it backfires in the exhaust :roll:
off-road until i die
User avatar
audiocontr
United States of America
Posts: 1868
Joined: Fri May 01, 2009 1:30 pm
Location: Buffalo NY

Re: replacement mufflers?

Post by audiocontr »

Jim l rebuilt this engine. I'm hoping he set the timing properly... I have confidence in the man. I'll check to be sure.

It has an aftermarket hack job exhasut as is. I believe it's time to remove and replace over the winter.
1973 712m
1968 Haflinger
1965 Pathfinder
1978 GMC Palm Beach (Hey, its got 6 wheels!!)
User avatar
Garrycol
Australia
Posts: 423
Joined: Sat Oct 06, 2012 6:49 am
Location: Canberra Australia

Re: replacement mufflers?

Post by Garrycol »

OEM mufflers do not pop and backfire (through the exhaust rather than inlet)- that is a function of your tuning settings - ignition and fuelling - worse case are valves not sealing on compression and letting fuel mix into the exhaust. Without fixing this any muffler will pop and backfire.

Pop and backfiring is unburnt fuel being burnt (exploded in the exhaust). The reasons for this can be varied - retarded timing, too rich a mixture, intermittent ignition, leaking valves etc. I have a Landrover V8 that was timed and tuned perfectly but it started backfiring and then blew the muffler apart with a huge bang. The LT lead to the coil came away from its connector making intermittent contact so every now and then no spark to individual cylinders but of course fuel was still going in and then out of the non firing cylinder into the exhaust but then ignited by the next firing cylinder.

So get you fuelling and ignition sorted before worrying about the muffler.

My Haf is 762cc and is tuned to standard specs - so 7mm before TDC as per the handbook - ensure mixtures are correct and you should not have an issue.

PS when I had my Haf last tuned it had hi hydrocarbons in the exhaust - tappets were too tight stopping the valves from completely closing allowing unburnt fuel into the exhaust - not enough to pop or backfire but enough to lower performance and hi hydrocarbons in the exhaust.

So get your tuning sorted first.

Garry
1973 Haflinger AP700
1977 Landrover FC 101
2007 Range Rover Sport TDV6
1971 Jaguar Series 3 E-Type Conv
1957 Landrover 88" Station Wagon
1957 Landrover 88"
Post Reply