289 FIA vintage race engine with Webers

[Gaz64]

Originally Posted by blykins

That camshaft, even with changing the LSA to 112, still has 73° of overlap.

Just randomly changing a cam to a wider LSA doesn't make it "friendly".

Yes, that's correct.

Reducing the overlap by widening the LSA delays the inlet closing point, all else being equal.

So the late closing inlet will still have reversion out the stacks on an IR intake.

One camshaft grind that sticks in my head is for the Cosworth DFV 3.0 V8. 68/86 for the inlet, 86/68 for the exhaust. 136 degrees of overlap. LSA 99. IR intake, Lucas mechanical injection.

Extreme example, I know.

Gary

[1795]

Originally Posted by CSX 4133

It was a hard choice between SAAC 44 and the Pitt Vintage Race, but time constraints dictated my attending only SAAC 44 this year. But at least I'll get to do the track days.

Steve,

I will be doing the test day and possibly some SAAC sessions as well, as I have never been on the Pitt Race track before. So I should see you there. Look for the red #10 car. What does your's look like?

Jim

[CSX 4133]

Originally Posted by 1795

Steve,

I will be doing the test day and possibly some SAAC sessions as well, as I have never been on the Pitt Race track before. So I should see you there. Look for the red #10 car. What does your's look like?

Jim

Jim,

Your basic '66 Shelby B/P GT350 (#74) in Sapphire Blue w/wht.stripes. I anticipate there being a large contingent of vintage Shelby & Cobra track cars using the track days as a test & tune opportunity for the following weekends race. Like you I've never driven this circuit, should be a fun time.

[moar_carbz]

Originally Posted by Gaz64

Yes, that's correct.

Reducing the overlap by widening the LSA delays the inlet closing point, all else being equal.

So the late closing inlet will still have reversion out the stacks on an IR intake.

One camshaft grind that sticks in my head is for the Cosworth DFV 3.0 V8. 68/86 for the inlet, 86/68 for the exhaust. 136 degrees of overlap. LSA 99. IR intake, Lucas mechanical injection.

Extreme example, I know.

Gary

Wow. The intake closed at 86? What was the reversion like?

[moar_carbz]

Originally Posted by 1795

Karl,

Here is a link to the engine idling when it was on the engine stand prior to the dyno tuning.

https://youtu.be/LmPoRwlaL1M

Jim

The idle seems surprisingly smooth for a 250@50 cam... but the idle speed does seem high. What's that idle set at?

[1795]

Originally Posted by moar_carbz

The idle seems surprisingly smooth for a 250@50 cam... but the idle speed does seem high. What's that idle set at?

I cannot recall what the idle speed was set at right now. After I ge the engine backing the car and start her up I will let you know. Race engines usually have a high idle speed, as they do not like low idle situations. Most of the time when you are on the grid you are feathering the engine to warm it up before hitting the track.

Jim

[Gaz64]

Originally Posted by moar_carbz

Wow. The intake closed at 86? What was the reversion like?

I'll assume it was evident, but that is a racing F1 engine peaking at around 11000 rpm.

Originally Posted by moar_carbz

The idle seems surprisingly smooth for a 250@50 cam... but the idle speed does seem high. What's that idle set at?

The engine is solid in a framework, so no rocking as such, and no tachometer.

Also exhaust system fitted while on the stand would affect idle quality.

Gary

[moar_carbz]

Originally Posted by Gaz64

The engine is solid in a framework, so no rocking as such, and no tachometer.

Also exhaust system fitted while on the stand would affect idle quality.

Gary

Yeah... not really a noticeable lope though either. If it's idling at 1600 or something I'll attribute some of the smoothness to that.