"dad's 67" running really rough after huge backfire

let me start off of by saying that i know nothing about 60's American cars. with that out of the way ill start at the beginning. Dads van was running pretty good with a very rhythmic idle surge that wasn't causing any problems. the P.O. didn't extend the exhaust all the way to the back and we were getting some bad fumes so we went to the junkyard and picked up another exhaust. we attached it with two mufflers inline thinking that it would be ok. (i thought that because a lot of newer cars have that setup) a muffler shop also told us it would be ok to have the two mufflers inline.

A few weeks go by with no no fumes, no problems, then we are driving along and smelling this horrible rotting smell. after a while we stop and figure out its the battery boiling over causing the smell. at that point we needed a jump to continue our trip. we get a jump, get back on the road and a few miles later theres a huge backfire and the engine shuts off. since or battery is dead we can't start it and require a tow truck. we get it home and see that one of the mufflers is puffed up out of shape. Dad removes the second muffler and tubing and we are left with the short exhaust we started with.

As of now the van starts but idles really rough, spits, and sputters, and backfires. it will stay running without holding the throttle down. we noticed that the exhaust is loose where the header meets the exhaust piping also.

my question is where do we start?

thanks in advance.

I'd guess at this point the entire fuel/carb/air intake/valve/cylinder/exhaust/electrical systems need a thorough going-over.

Check the engine oil. See if it's contaminated with raw gas.

Check the breather hose from the crankcase to the airbox.

Check the PCV valve.

Check/rebuild the carb to make sure it's not forcing the motor to run too rich.

Check the air filter... is it clogged?

Check the distributor/timing. Is it retarded?

Check the valve lash adjustment. You didn't say if it was a six or eight.

Check the alternator/voltage regulator/charging system.

Check the engine compression.

Check the engine cylinders' ability to hold pressure (leakdown test)

Check that the original exhaust system isn't clogged.

Check the exhaust header heat riser valve, if present (my '67 V8 has one). These can freeze up and cause rough running on a regular basis.

Ill go with donnivans suggestions-happy vannin

Ill go with donnivans suggestions-happy vannin

thanks for all the suggestions, it's a 230 six, i'm not new to old cars, just old American cars. the battery has been replaced. the plugs, distrubutor cap, and wires were changes a few hundred miles ago by dad but he didn't check the gap.

is there a good shop manual for the 67 van that i could buy anywhere?

what should the timing be at? where is the PCV valve? what should the compression be?

unrelated but, the rear pumpkin seal is leaking and needs to be replaced, when i asked about a new seal at the auto parts store, they asked what size it is in inches, how do i find that out? the body tag in the back right corner says "H024 3.36" but is ripped after that.

thanks again

i also wanted to mention that someone told dad that it could be the voltage regulator or coil that caused the battery to overheat, any thoughts on that?

wow thanks donovan, big help. that old battery is gone. it smelled like rotten eggs and sounded like it was boiling inside with steam shooting out of the sides. i googled and read that when the battery overheats, smells like rotten eggs, and steams it's because the voltage regulator has failed.

i also think i found the right size gasket based on the "H024" part of the tag. rockauto.com shows only one gasket for the "H024" rear end as the 10 bolt and it looks different from the other one.

the engine is the 230

looking at the 9th line from the bottom of that scanned page, for the 230 engine, is "CP" crank pully? is "4B" 4 degrees before TDC? where is the fuseable link?

thanks for all your patience and for answering my questions

just ordered the two factory manuals from the ebay seller, thanks for the link.

Instaled a new voltage regulator today. pulled one of the plugs and it was black but no carbon build up, and also a little oily.

That plug would tell me its running very rich. I bet that major back fire rupchured a gasket in the carberetor and its possible now sucking gas through a back carb gasket which of course will mean the mixtur is notonly very rich but uncontrolled which would explain the rough running.

M1D

Today i took the carb off (a Carter YF), and separated the top from the middle section. I didn't disassemble it any further, I just was checking for anything obvious. I sprayed it out with carb cleaner and it's a little cleaner but not spotless. The gasket looked to be in good shape still and I reassembled everything and reinstalled it.

I also was curious about the timing and loosened the distributor so I could adjust it to see if I could make it idle better. It starts and it does idle better sometimes but when I push the throttle it spits, sputters and dies. There is also a pretty bad fuel leak coming from the bottom of the carb now, I didn't touch anything down there, just sprayed it.

The two things that did change is that a small brass needle came out when I turned over the middle part of the carb body. I found where it goes and put it back in. and I removed the idle vent assembly thinking it had to come off to separate the two parts, I counted the turns to remove it and screwed it in the same number of turns.

We don't have a timing gun or multimeter here so i can't really do those checks. Dad says hes gonna take it to a mechanic. This is annoying.

best weak on the I can suggest is what dad says - Im susposing (not By anyway condeming) the experience is a little lacking in the mechanical knowledge area?? Dont consider this a pun - as wever all been there a time or 10 & all have had to build out experiences. Maybe you have a friend @ work that is mechanical with this stuff?? The very 1st thing id suggest is to check dwell(points) opening, spark plugs & firing order. Then also id look at flooding (gas issues) and carb?? Backfire ususlly is from a bad spark plug, points bad, or lean(lack of fuel) in carb to run. Even spark plug wires?? Heck if I were near you id come over & help -It does get flustrating for all of us at times.

i agree, i know nothing about this van. it is so simple that it seems that it should be easier to diagnose. I've owned many old vw's and a bunch of newer cars and have always tried to do my own work. I do have some mechanical knowledge. I'd rather take it to a mechanic too, but I like to try to fix things myself first. its not my money paying the mechanic anyway.

didn't think about the accelerator pump diaphragm, and that is where is leaking from. thanks.

if we wanted to replace the entire carb with a new or rebuilt one, what would be a good choice?

is one better than another?
thanks

delux68 wrote:is one better than another?
thanks

They all work pretty good if their rebuilt & adjusted correctly. I've been using the Rochester "B" for years on the L6's with great success.

Dan