I have a 72 Cuda with a 318. I get loud pops in the exhaust. The only thing I can think of to cause it is that one of the header bolts is broken in the head. Of course, it is the bolt closest to the firewall, so there is little if any room to work on it. Could this be causing the backfire and does anyone have a suggestion to get the bolt out of the head?
exhaust leaks can allow air into the exhaust can cause the unburned fuel in the exhaust to explode in backfires from the exhaust.. removing the broken stud/bolt is a LOT more complicated...the first and last exhaust bolts on small block mopars are WET... they are exposed to coolant as i recall...have you ever drilled out a broken bolt before.. its not for the beginner in the location you have..you might want to talk to a local engine builder.. or a local machine shop.. see if they have anybody who does field service calls and specializes in broken bolt extraction. i worked in a cylinder head rebuilder so i know how to get them out..it takes quite a few tools to remove them from the rear most position...a right angle close quarters drill is usually a requirement.. variable speed and reversible.. a variable speed dremel and a bunch of carbidebits will help..the bolt that is broken is 5/16-18... you will need some double ended 1/8" drill bits from the auto body/paint supply store.. used for drilling holes for dent pulling.. you will find that several sizes of LEFT hand drillbits may help..a several small straight fluted easy outs...some talented welders have welded NUTS to the top of the broken stud... and remove them before it cools... its an easy job to screw up with.. the last one next to the fire wall took me 3 partial days..my disaster story..when i started drilling with the 1/8 drill it spun in slightly... so i tried a left hand drillbit but it would NOT come out.. so i drilled all the way through.. this is on a full size gm pickup.. i was up over the grill reaching out as far as i could.. i tried the left bit again.. nothing... i went to the next size up.. it turned in again.. i went to the left again.. nothing.. i shoved an easy out in.. .it would NOT budge.. i managed to slip and break the easy out off .. and it was stuck in tight.. that blew the first day..the next day..i got out my smallest carbide drill bits.. yep.. solid carbide.. drilled all the way through beside the broken easy out.. then it jammed as i was taking it out.. snapped it off deep in the hole..end of second day.. these were partial days.. as i had several other things to do elsewhere.. spent the third day with my dremel carving out the metal around the broken drill .. i had jacked up the truck.. pulled the front wheel.. the inner fender.. the steering intermediate shaft.. managed to get it all out.. what a pain.. because you are working with an open back hole.. you need to be very careful... if you get off center.. you will have issues of coolant leaking.. if you have to.. you will want to install a solid thread insert instead of heli coils.. as heli coils would need sealant on the bolt threads to stop the coolant...more than the conventional sealant.. needed ... want to see pictures??
Thanks for that detailed response. I'll take a stab at it, but I think this gives me the final motivation to pull the heads. I've never had them off and I think I have a valve train issue too.