Backfire issues

[greenkeeper]

I was driving on the highway when my 87 350 custom deluxe backfired 
And of course it happened in a tunnel which made it sound worse.  It ended up splitting the driver side  muffler wide open  Now it sounds like a sherman tank comming down the road.  What should I be checking as the possible cause?  I just replaced the carburetor, filters, plugs and wires as well as the rotor. And just did work on the clutch.

[Captkaos]

An 87 with a Carb, did you change it over?  It should be TBI?
What was changed last on the engine.

[greenkeeper]

Its technically an 88 according to the vin .  However, many of its parts are from the 87 line.  It has the old body style and a Rochester Quadrajet carb on it. Thats what was replaced last.

[choptop]

since it backfired and blew the muffler out, I think it may have showed you the problem.Possibly the muffler or cat was stopping up.

[85MudMonster]

since it backfired and blew the muffler out, I think it may have showed you the problem.Possibly the muffler or cat was stopping up.

I think we've got a winner here....

[Captkaos]

I am curious, What is the VIN?  You stated you bought it new in 1990. 
It is definitely an 87.   I have never seen a 1/2T truck from the factory with a Carb on it from 1987.
The VIN should be 1GCDR14KXH?XXXXXX
What is the RPO's in the glovebox?

[greenkeeper]

I bought it from a dealer in 1990 . He ordered it for a mason contractor who then backed out on the deal.  It sat on his lot for a year before I negotiated for it.  the vin #1GBJR34M6JJ100659 is for a 1988 series, but everything about it says its a 1987. Go figure.  It makes working on it a challenge, but after 18 years I've gotten used to it.

[VileZambonie]

What does the VECI label under the hood say for model year. According to the vin it is an 88. We had an 89 or 90 R series that came with a Q-jet at my old shop.

If it's running fine now I would just replace the exhaust.

[greenkeeper]

The veci say 88.  This truck was originally destined for California.  It has dual air pumps no o2 sensor or cats.  It was designed for California emmissions there is a set of tubes off the manifold that go to a carbon filter canister.  Vacuum tubes from carb go to a main tube that also goes to the charcol canister ???Most of the techs up here never saw anything like it.  And getting parts for the emmission system is getting harder to find

[VileZambonie]

Getting parts shouldn't be a big deal just make sure you look up parts for an 88 R 2wd or V 4wd. Is your truck 2 or 4wd? Is it 1/2, 3/4 or one ton?

[DnStClr]

Didn't the early 87's have a carburetor until April or so, and then the tbi models were produced?
Anyway- I hope the backfire on your 88(?) goes away with a new muffler, greenkeeper.

[85MudMonster]

According to the VIn # he gave it's a 1 ton 2wd, am I right?

[Captkaos]

The VIN indicates that it is a 1988 R30 1 Ton.
Got a pic of it.  They could have a carb...

[greenkeeper]

Yup, its  a 1 ton 2wd dump truck  4 on the floor.  the truck is still back firing on the left side.  I think it might still be a timing issue.

[Lt.Del]

check your air/fuel mixture on that side.   If its a little too rich, mixed with O2 from an exhaust leak or something, add heat,  boom, boom.

If it isnt running rich, perhaps your plugs need some looking into.  You are getting fuel in the exhaust somehow.