Cheap 383 dyno numbers

[Babyblue66]

This is the original 383 4 barrel non magnum engine from my 70 Coronet. Stock it had 8.5 to 1, 906 heads, Springs with dampers, an AVS, magnum exhaust manifolds and I assume the same cam as the 2 barrel engines although I did not degree it before I threw it away.
It was relatively good shape inside so I ball honed it, new rings, bearings, and timing chain. I had an old, lightly used Elgin cam. 224, 234 @.050, 465 488 lift on a 112 lobe separation. Degreed it in with new lifters. I had a decent set of 516 closed chamber heads I installed some good used valves, cut them for 1.74 exhaust and did some pocket porting. Ended up with 9.4 to one with .050 thou of quench. Serdi valve job and cut the guides for viton seals. Installed some used MP valve springs.
Stock cast intake and a 750 holley it made 380hp at 5600 and 408 tq at the beginning of the pull which was 3500. May have made more under 3500, but we didn't start the pull lower. Im pretty surprised actually. Just a bunch of old crap I had laying around.
Also with the factory avs it lost around 12 hp.

 

[Babyblue66]

Graph, and the sheet with the stock AVS numbers.

 

[IQ52]

Yeah...I like that.

 

[Babyblue66]

Yeah...I like that.

Would have liked to put on the old Edelbrock I have. Dp4B is it? I can't remember the numbers. But I wanted to use the stock parts with a working choke.

 

[Bee1971]

Thanx - Very nice

Did you dyno it with the HP Exhaust Manifolds ?

 

[Sweet5ltr]

That's a nice build, and you're at least down twenty using the OEM cast-iron intake manifold. Great truck or street engine.

Some of the differences in power, comparing the AVS to the Holley, could be in the tune. Looking at the dynograph, the operator ran the Holley fairly lean, up to 13.4:1 at peak, compared to the 12.3:1 at peak with the AVS. Compare the fuel flow as well between the two carburetors. Lots of great data here to go through, other than just the peak output.

Overall, you're using less fuel, and making more power with the Holley, and that's a great spot to be in. Although on the street, I would richen it up to 12.5 - 12.8 AFR, just simple jetting changes, you're real close with that fuel curve.

 

[Babyblue66]

That's a nice build, and you're at least down twenty using the OEM cast-iron intake manifold. Great truck or street engine.

Some of the differences in power, comparing the AVS to the Holley, could be in the tune. Looking at the dynograph, the operator ran the Holley fairly lean, up to 13.4:1 at peak, compared to the 12.3:1 at peak with the AVS. Compare the fuel flow as well between the two carburetors. Lots of great data here to go through, other than just the peak output.

Overall, you're using less fuel, and making more power with the Holley, and that's a great spot to be in. Although on the street, I would richen it up to 12.5 - 12.8 AFR, just simple jetting changes, you're real close with that fuel curve.

Yeah, we saw that but I didn't feel like playing with it. I also ran a 750 4779. The af was similar and made similar power to the 750 hp. The AVS was rich for some reason. It's an all stock carb too.

 

[Babyblue66]

Thanx - Very nice

Did you dyno it with the HP Exhaust Manifolds ?

I did not try it with manifolds. I wish I had, pretty sure I've got some shorty pipes around here somewhere too.

 

[Bee1971]

With so many people swapping out carbs over the years

Was it the Factory Carter AVS 630 CFM or an Carter AVS 750 CFM

Thanx

 

[Babyblue66]

With so many people swapping out carbs over the years

Was it the Factory Carter AVS 630 CFM or an Carter AVS 750 CFM

Thanx

It's the factory carb to this engine.

 

[Babyblue66]

Here's the 750 4779. We did most pulls with this carb.

 

[rumblefish360]

I like the OE AVS carbs. Simple, easy to tune, rock solid.
The two sizes are (as said) 630 & 750. Was that original to the engine a 630 or 750. I don’t remember (or know much about) the original sizes to what they did for what series engine and what year it was done in, but IIRC, a non Magnum 4bbl. would be the smaller 630. Correct me if I’m wrong here!

That would also be a good indication of why it ran rich.

Cool build! Glad you posted it up.

 

[Babyblue66]

I like the OE AVS carbs. Simple, easy to tune, rock solid.
The two sizes are (as said) 630 & 750. Was that original to the engine a 630 or 750. I don’t remember (or know much about) the original sizes to what they did for what series engine and what year it was done in, but IIRC, a non Magnum 4bbl. would be the smaller 630. Correct me if I’m wrong here!

That would also be a good indication of why it ran rich.

Cool build! Glad you posted it up.

All the b motors had the smaller AVS. The 750 was 440 only.

 

[PRHeads]

Nice.

Basically 1hp/ci out of a fairly stock build with some head tweaks and headers.

I actually like the stock heads and 2.08/1.74 valves for the milder 383/400 combos.

 

[Paul Secoy]

Almost identical to one I did years ago, except I had a Performer RPM intake. The cam was a Summit cheapie, with coincidentally .465/.488' lift. It ran a 12.38 on it's 3rd pass in an all steel '67 Barracuda, shifting at a whopping 5,000 Rpms. Thanks for the write up.

 

[INTMD8]

Very nice!!

 

[Babyblue66]

Almost identical to one I did years ago, except I had a Performer RPM intake. The cam was a Summit cheapie, with coincidentally .465/.488' lift. It ran a 12.38 on it's 3rd pass in an all steel '67 Barracuda, shifting at a whopping 5,000 Rpms. Thanks for the write up.

Dang that's moving. What gears did you have?

 

[qkcuda]

That is a well balanced combo. I ran a similar Crane cam in my 400 which made just over 1 HP per cubic inch. Ran high 12's in my old cuda.

 

[Babyblue66]

Another thing I just remembered, the 750 hp was leaner on one side for some reason. I just went through the carb. Everything looked good.

 

[rumblefish360]

That’s the intake for you.