Re: Re Delorean went BOOM

["content22207" <brobertson@xxxx>]

Actually, this was technically a muffler explosion, not a backfire.
Backfires go backwards towards intake (flames out of carburetor),
muffler explosions go forward.

Am willing to bet timing is way off. Spark escaping through open
valves causes all kinds of problems. Can ignite fuel mixture towards
metering device or unburned in exhaust system

Unplug fuel pump and put a timing light on cylinder #1 while someone
cranks car (or run a wire from jump start post to starter solenoid).
Will be well retarded from 13 degrees, but should still be on scale.

If timing mark OK, pop passenger valve cover off. Is really quite easy
on that side. Watch intake valve and you will see TDC. Paint or
otherwise mark timing mark to distinguish and try timing light again.
That will tell you if 180 degrees off.

Doubt if you hurt engine itself. Like David T suggests, check exhaust
gaskets, O2 sensor, and perhaps honeycomb inside catalytic converter.
Check belts and radiator hoses for collateral damage.

Bill Robertson
#5939

>--- In dmcnews@xxxxxxxxxxxxxxx, "David Teitelbaum" <jtrealty@xxxx> wrote:
> For the muffler to explode you had to have filled it with unburned
> fuel and then it ignited. I would check to see if the camshaft is
> really all right after ruining the rocker arms. Get a micrometer on
> it. A missfiring cylinder or the cold start valve staying on would be
> my first thoughts. You are correct in that a way off timing problem
> could cause this (like having the camshaft way off). To check the
> engine for damage I would try a compression test. This will also give
> you a hint if the camshaft is way off if you can't get compression on
> some cylinders. You may have blown out the exhaust manifold gaskets
> and destroyed the O2 sensor and possibly damaged the catalytic
> converter. You are lucky no one was hurt. I had a similar experience
> but in that case the engine had a burnt exhaust valve and it only blew
> the exhaust pipes apart when it backfired.
> David Teitelbaum
> vin 10757 
> 
> 
> --- In dmcnews@xxxxxxxxxxxxxxx, "bepositive2000" <BePositive2000@xxxx>
> wrote:
> > Hi Everyone,
> > 
> > It's been a couple long weeks.
> > 
> > You guys will probably get a BLAST out of this. I did?LITERALLY. 
> > 
> > I just finished replacing a couple of bad rocker arms on the #4
> > cylinder. The oiling holes were plugged and the cam eventually made a
> > concave slot in the rocker arms. Cam looked fine.
> >