I have a 74 F100 with a 390 bored 60 over with a mild cam, headers, new distributor, starter, alternator, timing chain, K&N filtercharger, splitfire plugs, accel wires, Mr Gasket 1 inch carb spacer, 600 cfm edelbrock,with dual exhaust going through a C6 trans and 9 inch rear that was just rebuilt with 373 gears. My timing is advanced as far as I can get it with it being able to start, dwell set at 30. Problem is, this thing is slow, runs only 11.1 in the 8th mile. My friends 89 silverado is running all over me with no mods. Whats the problem? Ive run out of ideas and think it should be doing way better than this. If you need more info just let me know what you need and Ill post back. Oh yeah, vacuum at 20 in idle. Thanks.

 

Ive never had mine down the strip,yet...
But i thought you were discribing my setup.
The only thing I would check is... see that the vacuum advance is NOT over advancing! As in what is your TOTAL advance at say 2,500 RPM. I keep mine at 40 deg.MAX i installed a `Crane` adjustable after the rebuilt dist was letting things go up to 54 deg at 3,000 RPM ...Can you say JUNK!!Iam getting 10 deg adv from the vacuum advance OVER my initial setting of 10 geg and then Mechanical curve to total 40.



__JOHN__Õ¿ö
72 F-250

 

I dont really know what its advancing to Ill have to check. The way its set know is way beyond even the marks on the balancer. If I start at 6 like the factory states then it runs real bad and backfires, probaly the cam, but where its at now there is no marks. Guess Ill make some on the balancer and see. So I dont want my total advance to be over 40 at 2500 rpms? Also when accelarating at about half to full throttle Im getting a metal slapping sound, Could this be the torque convertor and if so would that thing be slipping even as the rpms go up? The motor sounds and "seems" good but something cant be right. Oh yeah, I also have one of those vacuum advance canisters thats adjustible and its hooked to the carb. Should it be on the carb or the manifold? Thanks

 

You Write>>
> I dont really know what its
>advancing to Ill have to check.
>The way its set know is
>way beyond even the marks on
>the balancer.

[has the balancer slipped and are you checking the timing on #1 cylinder??]

If I start at
>6 like the factory states then
>it runs real bad and backfires,
>probaly the cam, but where its
>at now there is no marks.
[NOT GOOD... ]

>Guess Ill make some on the
>balancer and see. So I dont
>want my total advance to be
>over 40 at 2500 rpms?
[probally close! BUT your Initial setting like 8-10 is where I would start from... I `see` my Max setting at 2800...]
Also
>when accelarating at about half
>to full throttle Im getting a
>metal slapping sound, Could this be
>the torque convertor and if so
>would that thing be slipping even
>as the rpms go up?

[I don`t know about the noise!!]

The
>motor sounds and "seems" good but
>something cant be right. Oh yeah,
>I also have one of those
>vacuum advance canisters thats adjustible

[adjustable dist. vacuum advance right..]

and
>its hooked to the carb. Should
>it be on the carb or
>the manifold? Thanks

[On the Carb `Vac` port for distributor vac....Not Manifold!!!!]


__JOHN__Õ¿ö
72 F-250

 

Have you considered weight differences? '79 was the "last all steel truck", and you're a few years earlier.

 

Yea, Ive thought about the weight. But you can just "tell" somethings not right. I guess Ill have someone look at the trans for me since that seems to be the only thing it can be.