Fordnatics List Archive

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Mail From: (email redacted)

Once upon a time there was a 85 Mustang with a carborated 302 which had a
weird surge problem. It accelerated fine and decelerated fine but, would
intermittently (no problem when cold - in spades when warm) behave like it
was shutting off (very briefly) while maintaining a constant speed. The "shut
off" period is long enough to really notice any and all lash in the rearend
(a new 8.8 unit). The problem is more pronounced when in a lower gear (like
4th) and at low RPM ranges (2000 and below). Since then the motor has been
rebuilt. The cam, heads, intake and ignition have been completely replaced
with aftermarket units. The carb was replaced with a factory unit. The
surge is still there!!!!!

Since then I have measured the vacume and have found it to be around 14" when
cold and 11" when warm (why does this vary?).
I'm running an E303 cam and I expected the vacume to be lower but, not this
low. Anyone have an idea what the typical vacume to expect for this cam is?

Could a plugged converter be causing my problem?

I tried disconnecting and plugging all the manifold vacume but, this seems to
make the reading lower (I don't understand this at all).

Any ideas would be GREATLY APPRECIATED!!!

Thanks,

Bill Bostic

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Mail From: (email redacted) (Alan Kennedy)

> Once upon a time there was a 85 Mustang with a carborated 302 which had a
> weird surge problem. It accelerated fine and decelerated fine but, would
> intermittently (no problem when cold - in spades when warm) behave like it
> was shutting off (very briefly) while maintaining a constant speed. The "shut
> off" period is long enough to really notice any and all lash in the rearend
> (a new 8.8 unit). The problem is more pronounced when in a lower gear (like
> 4th) and at low RPM ranges (2000 and below). Since then the motor has been
> rebuilt. The cam, heads, intake and ignition have been completely replaced
> with aftermarket units. The carb was replaced with a factory unit. The
> surge is still there!!!!!
>
> Since then I have measured the vacume and have found it to be around 14" when
> cold and 11" when warm (why does this vary?).
> I'm running an E303 cam and I expected the vacume to be lower but, not this
> low. Anyone have an idea what the typical vacume to expect for this cam is?

Bill,

This sound like a problem I am having. My car has a constant
surge. If I let it sit for a while it will eventually smooth
out but, the second you touch the gas it starts all over again.
Sometimes when I use the A/C the car will die. As far as acceleration,
the car run great, every now and then at lower rpms (below 2000)
the car will buck.

Which rocker are you running?

My car has GT40 heads, Cobra intake, 1.7 roller rockers, 24lbs
injectors, long tube headers, and other basic mods.

My car pull between 11-12" of vaccum at idle with the car warm.

I have a friend who is running the same combo that I am except he
is running a Vortech and 38lbs injectors. He is having the same
problem that I am.

I am starting to wonder if it might have somthing to do with the cam.
If you or anyone else has any idea please let me know. Is anyone else
running the E303 cam?
- --

ALAN S. KENNEDY
205-730-2485
MAIL PATH: (email redacted)

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Mail From: Eugene Y C Chu <(email redacted)>

Alan Kennedy (and someone else) wrote of surging problems in their cars.

You folks might try to find a vaccuum leak somewhere on your engine.
One not so obvious place that has bitten me twice is the little gasket
around the big tube feeding the brake booster. It can crack or get cut
by the sheet metal of the booster shell, and is very difficult to see
without removing.

good luck

eyc

This read-only message was archived from a public mail list.
Mail From: (email redacted)

>You folks might try to find a vaccuum leak somewhere on your engine.
>One not so obvious place that has bitten me twice is the little gasket
>around the big tube feeding the brake booster. It can crack or get cut
>by the sheet metal of the booster shell, and is very difficult to see
>without removing.

I'll check it. Thanks for the suggestion.....

Bill Bostic

This read-only message was archived from a public mail list.
Mail From: (email redacted)


>This sound like a problem I am having. My car has a constant
>surge. If I let it sit for a while it will eventually smooth
>out but, the second you touch the gas it starts all over again.
>Sometimes when I use the A/C the car will die. As far as acceleration,
>the car run great, every now and then at lower rpms (below 2000)the car will
>buck.

So, maybe it's not isolated to the carb.......

>Which rocker are you running?

I'm running 1.6 crane high intensity roller rockers.

>My car has GT40 heads, Cobra intake, 1.7 roller rockers, 24lbs
>injectors, long tube headers, and other basic mods.

Edlebrock heads, stock headers..

>My car pull between 11-12" of vaccum at idle with the car warm.

>I have a friend who is running the same combo that I am except he
>is running a Vortech and 38lbs injectors. He is having the same
>problem that I am.

What a drag........

>I am starting to wonder if it might have somthing to do with the cam.
>If you or anyone else has any idea please let me know. Is anyone else
>running the E303 cam?

I had the same problem with the stock cam so I don't think it is isolated to
the E303.

Bill Bostic ((email redacted))

This read-only message was archived from a public mail list.
Mail From: (email redacted) (Doug Bailey)


>
> >You folks might try to find a vaccuum leak somewhere on your engine.
> >One not so obvious place that has bitten me twice is the little gasket
> >around the big tube feeding the brake booster. It can crack or get cut
> >by the sheet metal of the booster shell, and is very difficult to see
> >without removing.
>
> I'll check it. Thanks for the suggestion.....
>
> Bill Bostic
>

Release butane lighter fuel near the leak. You'll hear the
engine revs change if a hole is sucking air into the motor.