Exhaust Leak

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Ltine - 19 Aug 2004 05:10 GMT

Hi Everyone,

I have been reading your post for a long time but have never
submitted one until now. I hope that somebody out there can help me.
I have a 68 ford Bronco, Brand new 302cid, 351 windsor heads (bigger
valves), Holley Truck avenger carb, and a brand new bronco c4. The
reason I have posted this message is because I have a problem I just
cant beat. I have exhaust fumes coming into the cab. This may sound
easy to correct at first, but I have already done all of the obvious.
I have replaced both of the mufflers, the pipes only have about 3000
miles on them, and for good mesure I have checked them anyway. I did
the donughts off of the manifolds which (did seem to help a little),
and I have put exhaust tips on just to make sure it is clearing the
back of the truck.
The exhaust system is 2" and it is straight back without a cross over
of any kind. And finally the manifolds are stock but not cracked or
broken in anyway, and have brand new gaskets and I have checked the
torque several times.
However the only time that I have any problem is when the window
is down. I have heard tidbits about a vortex being created by having
the window down, that sucks into the cab. I'm not sure this is true
but any help will be greatly appreciated. Anyone who has ever ridden
in an old Bronco knows that in the summer there is no way to not open
the window or take off the top in the summer. I am truely desperate
here. I am a competative athlete and cannot take the fumes. I'm
afraid that if I cant solve this problem I will have to get rid of my
old bronc, and thats too bad because with this engine set up she
screeams!

Thank you in advance for any help, I throw myself on the wisdom
of the group.

Reply to this Message

Ltine - 22 Aug 2004 20:11 GMT

> Hi Everyone,
>
[quoted text clipped - 27 lines]
> Thank you in advance for any help, I throw myself on the wisdom
> of the group.

Hey Mike and Steve, thank you both for your ideas. I did
recently adjust that mix, I had been running rich throughout the
winter. That did help a little. What is the major difference between
the exaust porting out the side of the truck rather than the straight
out the rear? And I think your both right about the seams and rubber
on the truck letting in fumes. I have a few rust spots, and a couple
on the tail gate, close to where the exhaust pipes come off of the
bronc.

Thanks again

Reply to this Message

tom - 22 Aug 2004 20:45 GMT

if the exhaust exits out the side, it will scavenge away while driving down
the road. if it exits out the back or down underneath with turndown off the
mufflers, it will vortex up the tailgate and be sucked in by the vacuumed
that is created inside while driving.

> > Hi Everyone,
> >
[quoted text clipped - 38 lines]
>
> Thanks again

Reply to this Message

Ltine - 27 Aug 2004 19:11 GMT

> if the exhaust exits out the side, it will scavenge away while driving down
> the road. if it exits out the back or down underneath with turndown off the
[quoted text clipped - 44 lines]
> >
> > Thanks again

Thanks Tom for the input. I am actually going to replace my
entire tailgate assembly (gaskets and all). I realize now that the
whole back is full of all kinds of gaps and openings. I hope that
this will eventually solve this problem once and for all. Thanks
again everyone, your advice has been very helpfull.

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