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Old 04-09-2019, 06:10 AM
blykins blykins is offline
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Quote:
Originally Posted by 1795 View Post
I talk to the guy who built the Webers last night and he said that while they have built a lot of Weber systems for big blocks and stroked small blocks, this was the first small block with a standard stroke and iron heads.
I think that's a key component of what's going on: they're used to working on larger engines.

There are two major components of camshaft duration selection: displacement and head flow. Very generally speaking, a smaller engine requires less camshaft duration because there's less cylinder volume to fill. A higher flowing head also requires less camshaft duration because the head is efficient; it will allow the camshaft to "pack it in" more efficiently.

A mid 250's @ .050" camshaft for a 289 with Dart heads is absolutely HUGE. To only peak at 6500 shows that something is very much amiss somewhere.

For a couple of examples, that amount of duration in a factory headed 351C will peak the horsepower at 8000 rpm. That amount of duration in a 482ci Ford FE will peak the horsepower at 6500 with a set of CNC ported Edelbrock/Pond heads.

As another comparison, the camshaft that I use on my factory headed (ported C5 heads that flow 200 cfm at peak) road race 289's is only 242° at .050" duration and that engine, even with a "poor performing" factory head peaks at 7000.

I think you're going to run into a situation where, relatively speaking, you have a short powerband because the camshaft is too large to give you any bottom end and mid range and it's also out of the capability of the cylinder heads, so you won't get any top end either.

In addition, the way the horsepower goes "up and down" towards the end of the pull, from 6400 to 6900 leads me to believe that the valves were starting to float and you were losing control of the valvetrain; not a good situation for a road race engine. This could explain why the engine didn't make more horsepower than it should have.

I think your crank pulley is also bent.
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Last edited by blykins; 04-09-2019 at 06:14 AM..
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