Peak HP 171.31 @ 4000RPM to the wheels Is it just me or does that sound way low even for a stock SBC. And mine isnt stock. It has a cam, Intake, Gear Drive, Demon 750, Mallory Unilite Dist. &Jacobs Ig. box and Ig.controller and headers at least..

 

Sounds low. 20% drive train loss from NET HP. It still seems low. And 750cfm carb. is to big for a stock small block.

250 hp - 20%=200HP ????

 

and your transmission is and rear gears are? alot of things including above mention 2 can affect hp at the wheel's. I took a 454 with intake cam& carb header's into a dyno once it gave up 195 hp to the wheels after some fine tuning of the carb and a tune up it pulled 210hp to the wheels this with a th 400 shift kit and a 355 12 posi

 

The gears are 373's and the tranny is a t-350. There seemed to be alot of black smoke coming from the exhaust. Also the jacobs ignition timer. It has to dials one for the rev limit and one for the timing. Should that be set to 0? or might it have to be set at something else?

 

Black smoke from the exhaust would be indicative of running too rich, you will soon notice that your exhaust pipes will have a black coating inside. On my '69 Z/28 302 cid with a 780cfm Holley, tune was optimized so the inside of the exhaust pipes would be grey/white on highway trips.
Clyde

 

My old V6 could have beat that!

haha jk man, have someone good tune the car up...

is it a 68 350?

or a 70's or 80's 350?

 

What kind of dyno was it? Mustang Dynos tend to show a lower number than a Dynojet. 750 is too much carb and that gear is just added drag. What cam is in there? Lower gears (higher number ie 4.10) will show a lower dyno number. This is why I say dynos are nothing more than tools to judge improvments form mods or tuning.

 

people think just because they bolt on all kinds of parts that say '20 extra horsepower', they think if you just add them all up, you get gobs of added power

in reality, if everything isn't component match and tuned correctly, you can end up with less HP that stock

one other thing, like everyone else said, ditch the carb. also, if the black smoke is coming out all the time then you are running way too rich, which can be fixed. if the black smoke only comes out at higher RPMS then your highspeed airbleeds are too big and this is where you would be getting a big drop off in power. I don't know if Demon has adjustable or changeable airbleeds.

I would like to see the graph from your pull to see where your weaknesses were. sometimes you can tell a lot from that

 

Here ya go:

[IMG]local://upfiles/8747/B48A95559497484D997C932B6C784D7F.jpg[/IMG]

 

couldn't really tell from your postings but it looks like it was still pulling at 3900, couldn't tell if it was dropping off or not? if it wasn't, they should have pulled for at least another 1500RPMs to get a good reading