BRA289 customized recreation

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Dave Woodward
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Re: BRA289 customized recreation

Post by Dave Woodward »

The PCV valve creates negative crankcase pressure which killed any leaks on mine.

Apologies, I know I'm teaching granny to suck eggs here !
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Roger King
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Re: BRA289 customized recreation

Post by Roger King »

peterc wrote:I did have it recommended to have a vacuum advance control valve between carb and distributor on my Rover which dampens the affect of the ignition timing but not having this shouldn't affect the general running as it's more of an economy/smoother running for road use. Competition engines clearly don't bother.
Peter C
Distributor vacuum advance does nothing under acceleration, mechanical advance is all that's happening. Vacuum advance merely advances ignition timing on the over-run and at idle, helping economy, but not so's you'd notice with these engines. Original hipo engines did not have them, mechanical advance only.
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Migge
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Re: BRA289 customized recreation

Post by Migge »

Okay,

After Silverstone the OGP Nürburgring was the other no go. I had the brilliant idea to try again to adjust the 4 carbs. The result after a few hours of trying was a very bad running engine. Another try on sunday with the same result. I have to begin at start again :(

Another frustration is the leaky distributor. Changed on the new distributor the new o-ring with no result. Even a flat additional gasket placed directly unter dizzy stump where it fits the engine bore did not stop the leak. Too much pressure?
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Dave Woodward
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Re: BRA289 customized recreation

Post by Dave Woodward »

Omninone accersita!

Good luck resolving :)
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Karl
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Re: BRA289 customized recreation

Post by Karl »

How is the fit in the bore? you need some force to stick the dizzy in or does it slide in easy? Is perhaps a scratch inside or has the hole gone oval? There is normally no oil pressure at that point.
OGP: Johannes and me the only 289 there. Managed one hour on the Nordschleife, as the alternator on the MGB V8 gave up and the Cob was allowed as a replacement!
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Migge
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Re: BRA289 customized recreation

Post by Migge »

How is the fit in the bore? you need some force to stick the dizzy in or does it slide in easy?
The normal push I think but when it's in it's not very tight
Is perhaps a scratch inside have to inspect thator has the hole gone oval? oval???
There is normally no oil pressure at that point. I know Karl. I have that extra oil feed pipe that drops onto the drive gear. But that should not be the reason, that's below the bore tube inside the block but will check again
OGP: Johannes and me the only 289 there Have you been at the Cobra meeting area too? . Managed one hour on the Nordschleife, as the alternator on the MGB V8 gave up and the Cob was allowed as a replacement! Great

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Migge
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Re: BRA289 customized recreation

Post by Migge »

Was last month on the dyno to tune the Dellortos etc.

We got 326Nm @ 3500 RPM and 222 HP @ 5200 RPM. On the second run after changing venturis and jets etc. the clutch failed at 2700 RPM.

As you can see, it was just to weak and burnt. New one from AP will be in this week. And then again on the dyno to finish the "tuning" next month. Ignition is still on 10° and I think that we can go to 12°-14° to find some horses?

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Roger King
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Re: BRA289 customized recreation

Post by Roger King »

Bad luck on the clutch Migge. Odd that it should have failed at those figures. Do you have a T5 box? The adjustment for the Mustang-style release bearing is not what you'd expect, requiring a little preload - I wonder if it was an adjustment issue?
Sounds like your ignition timing is very conservative - presumably your 10° figure is at idle. If you're on a rolling road I'd disregard the idle figure completely, and advance for maximum power at around 5k rpm, with no pinking under hard acceleration in third. However with an SBF (especially if you've used Hypereutectic pistons) I would set an arbitrary limit of around 36° total advance as there can be piston crown problems at more than that. Then the idle timing will be wherever the distributor leaves it, could be anything from 12-14° right up to 20-24°, doesn't matter. I know where the max power advance figure is for my 289, but without checking it I've no idea where the idle timing is.
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Migge
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Re: BRA289 customized recreation

Post by Migge »

Thanks Roger but it's only the 3.5 RV8 with the LT77 gearbox :)
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Migge
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Re: BRA289 customized recreation

Post by Migge »

Yes 10° at idle
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