Last week I had my newly built 440 dyno’d, the results weren’t bad, but still disappointing.
I had installed edelbrock top end kit #2087 which advertised performance as 482 hp and 528 ft/lbs on a 9.27 compression short block.
My dyno results were 472 hp and 548 ft/lbs with the hp peaking at 4800 rpm and plateauing to 5700 rpm before dropping off.
I had my block bored .30 over, every possible bearing replaced, crank polished and had KB pistons installed which raised the compression to 10.2.
Rockers are adjustable rollers, ignition is Summit’s version of Mopar’s electronic box and distributor. The carb is a Barry Grant 850 Holley with edelbrock fuel pump.
Here what I think i did wrong. I had a clearance issue with my carb feed line and vac advance, so I installed a spacer. It’s an open 1” mr. gasket aluminum spacer and the manifold is a dual plane edelbrock. I feel like a split 1/2” or 3/8” would have been a better choice. Thoughts?

I don't really see what your problem is The numbers are almost a carbon copy of the claimed numbers, and different dynos never show the same numbers. Get it in your car and tune it there.

advertised numbers vs real world numbers. you've got 10 less horsepower but 20lbft gain in torque. i'd rather have yours than edelbrocks.

Thanks for the input fellas, I suppose I was splitting hairs. My only real concern was the way the hp seemed to peak early and flatten out rather than continuing upwards. I was pleased the torque gain though.

Small cam, not a lot of lift... not surprised by the results

Seems ok. Did you play around with the timing any? What was the A/F ratio on the pull?

needs bigger cam...

I would leave the 1" spacer alone. Good move IMO. I would check A/F ratio and play with the ignition curve. What exhaust are you running?

The timing was adjusted a few times during the session and the AFR was not represented on the printout though the dyno shop said it was “a little rich” but to leave it that way. The BSFC was .453 average.

I was a running a borrowed set of 1 7/8” Hooker Competition, which is what I intend to purchase later on.

I don't see anything wrong with those numbers but I will say you don't need that 850 carb with a 500 hp engine. You only need around 700 cfm to feed 500 hp so a slightly smaller carb might improve the street manners.

I'd be curious to see if a single plane intake would wake it up a little more.

There’s 25+ hp to be gained with a bigger cam........ but you’ll likely lose a bit of driveability to get it.

I dynoed a 505 last fall, rpm heads, about the same sized cam as yours....... made about 515hp.

I bet you'll be happy with that when its in the car.

Carb too rich, leave it that way? How rich? Did they touch the carb at all? Sounds like they just didn't want to tune your carb, and there is probably power in it still. But even without it, sounds like that engine is making good power for the parts in it.

i Think you’re right I’ll probably be fine once I’m driving it.

Yeah being told the carb was a little rich and that it’s ok was off putting but this man has a stellar reputation in the area. A local GM performance dealer uses his shop to dyno their crate motors before delivery. No they didn’t tune my carb that I saw, but he did swap mine for his test carb which was 830 cfm and it picked up power. It was my first time getting an engine dyno’d so I probably didn’t ask enough questions. I got a price for the test that was very good and didn’t feel right about splitting hairs probably to my detriment. Well when it goes in the car I’ll install an O2 sensor and afr guage that’ll help me tune it up right.

Nothing's wrong. It's in the tuning.
A/F ratio alone is worth more than 10hp.
Besides, 10 hp on a 470hp engine is about 2%. That's within testing error.

R.

Looking a little more closely at the numbers....... for the bottom several hundred rpm, the numbers look way low.
They start to look normal around 31-3200rpm.

Was the throttle not all the way open at the beginning of the pull?

The numbers on my print out before 3000 were separated from the others because it wasn’t at wot. I made that table and graph, probably should have left those off of there.

Its highly unlikely that there is not power in tuning the carb. A "little rich" really means nothing, other than your AFR is slightly lower than what that tuner considers right. But some engines like 13.0 for best power, and some like 11.7, and some like to be richer or leaner. Whatever a little rich is its probably not best for your engine. And whatever is best for your 440 is probably not exactly the same as whats best for my 440.

Its probably not way off, but the engine isn't tuned if the carb hasn't been touched.

Well it looks like the thing for me to do is tune it when it’s in the car. Of what I’ve read and heard about reading spark plugs it seems like this one is telling me “a little rich” was accurate. Thanks for the input.

-edit- for some reason the image won’t load on my tablet, but if you save it and then open it, it’ll work.