Hi Guys ,  my 86 gl  ea82 stock Hitachi carb   is backfiring between  shifts ,  I just put a carb kit in , it runs and idles flawlessly ,  adjusted the timing and   the sputtering   between shifts stopped .  but when I accelerate sharply and then put the clutch in  it takes about 2 seconds and  backfires  like a shot gun , it exploded the muffler.  it backfired before and after the carb kit.. no change..  I  don't want to put a new muffler on till I get it to stop.  so I cant drive it on the road....anny one else ever have this happen ?

 

wasn't there some sort of anti backfire set up on a lot of our Subarus ? Like a reed valve air feed on backing off throttle position ? Extra complexity of hoses and a valve that looks a bit the shap of a sand timer .....

Check out the first two photos I have posted in a thread I made when I was having a little trouble converting my car to a weber carburettor.

 

http://www.ultimatesubaru.org/forum/topic/146444-its-inevitablemy-weber-questions/

 

Those two black things, on your car, are they connected to the air box? I was having massive backfiring issues when letting my foot off the gas in my car both before and after I put the weber on.

There's this thing around these message boards called the quarter trick. You take a quarter, or a nickle, whatever you can get to fit there right, and shove it in to the hose to block it. (For instance, that second picture I have, of the one on the pass. side, you can see the hose open towards the bottom of the pic. I took that end of the hose off the ASV, put the quarter in there, and then put the hose back on. No more backfiring.

Anti back fire valve fixed mine. available at ultimate subaru parts store

Yea, what Jono said.

 

I can't remember all of what Skip said from many years ago, when one of the BRAT's were doing that.

 

But it has to do with air intering the exhaust system.

 

Either the Anti-Afterburn-Valve, (AAV), or the Air-Suction-Valve, (ASV), system(s) are the most likely culprit(s).

 

I blocked it all off, then promptly removed all that MABS when I swapped to a Weber carb.

 

MABS = Miscelanious Assorted Bull S**T

ILL TRY THIS TODAY , LOOKS EASY ENOUGH ,  THANKS GUYS.

I deleted all the   air valves , blocked off the exhaust ports , plugged the air cleaner ports.  works perfectly . no backfire issues at all .. thanks   tom .duncanee, i75eya,jono.  you guys rock .