I rebuilt my 350, I bored it .030, got flat top federal mougle aluminum pistons , ported my 882 heads, reseated the valves,a speed pro cam(pretty close to the gm 151 cam) got an edelbrock torker intake, 750 performer carb the metering rods are no. 7147, primary jets are 120 407, secondary jets are 120 413, I have headman headers, 1 5/8 primarys, then it goes into a 2" dual exaust, it has crappy mufflers that I know hurt performance. The timing is set at 10 BTDC and about 34 total. This car really seems to be lacking power,It has a 4 speed borg warner, and 3.23 gears. I think the fuel pump could be weak, so I am going to check it asap. But I write this because my friend with a stock 305 in his 85 Z kicked my but in a race. He looked like he was even pulling away from me. there is no way that should happen. So what could kill my performance that bad? I looked at all the obvious and all I could come up with is my exaust, or fuel pump that is choking my engine.

 

I'd maybe start with a Performer RPM intake and a 600CFM carb.

Does it run good on the topend only?

 

IT probably runs better from about 2500-4000 rpm then the power sucks when it gets higher. I figured it would run crappy below 2500 rpm because of the single plain manifold.

 

Read the plugs, see if they're rich or lean...best place to start.

Do a WOT run, and shut it down at the topend. Pull over a pull a few plugs to get an idea of how it's being fed.

 

I would recheck the timing situation, I beleave 10 is a little high for advancment your probably maxing out. change your pipes to a 21/4 in to 21/2-3" after the cats.is your fuel regulated? and make sure getting enough air in to your aplication. just my opinion.

 

It may be too late to change some of this, but...

You have 2 things in your buildup that either one of which is IMHO a sure-fire guarantee of a disappointing buildup. Those 2 things are the choice of head castings, and that cam. Those heads have huge valve guide bosses, low compression, poor intake port design, and just generally are poor performers. By your screen name I would assume you're old enough to remember how bad new cars sucked back in the mid-late 70s, when those heads were on every 350 and 400; they were one of the reasons that those motors were only rated at 165-180 HP, where the L69 just a couple of years later put out 190.

That cam has way too much "advertised" duration and too little lift in comparison to its .050" duration. IIRC it's something like 219°/219° @.050", 292° @ .006", .447"/.447". Go look at how lame a profile like that is compared to a modern cam like a Comp XE, say a 268, which is 268° @.006" (less compression "leak" from valves that are held barely cracked for much of the cycle), 224°/230° @.050" which is more duration for more power all the way around, plus it's a split grind to give more effective exhaust duration to help make up for the poorer flow on that side of the head, and about .030" or .040" more lift.

If you had a weak fuel pump chances are it would simply cut out after running at high RPM for a while; it would do something like pull fine through 1st and 2nd, then stumble and fall on its face all of a sudden halfway through 3rd. If it just runs lazy all the time (exactly what I would expect that combo to do), the cause isn't the fuel pump.

Get a real cam in it ASAP. I think there's a good solid 50 HP lurking right there. You should be able to get about 310-320 at the crank with a better one, I doubt it's doing much over 250 if it even makes it that far. I don't think any amount of tuning is ever going to wake it up as it sits.

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"So many Mustangs, so little time..."
ICON Motorsports

 

I agree that cam sucks, but the heads are ported lots, there is just about no valve guide boss left, and the runners have been opened up to gasket size, and so has the manifold. I think it is making lower than 250 a bone stock 305 beat me in an 85 camaro.I have not much of an exaust system it has two really small baffled glass packs then it exits in front of the rear tires. My age is 17 so that explains my poor cam selection as well as my exaust setup. I am primarily using this car for the 1/4 mile so I am not to concered about being street legal.