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8 & 10 cyl Bristol cars Type 407 onwards - restoration, repair, maintenance etc

Starting a 412

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Old 23-09-21, 07:20 PM
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Default Starting a 412

Hello,
I've finally got my Beaufighter running and MOT'd. My main problem now is knowing if it will reliably fire up. It needs about 10 squirts of petrol on the throttle before it will fire up.
The timing is supposed to be set at about 2 BTDC. However I've found to start cold it's best set about 15-20 BTDC. This doesn't make sense, I thought when starting ignition would be retarded. When warm I can adjust down to about 4-5 Btdc with a smooth tickover, but then it is hard to start.
I've rebuilt the Carter carb. The choke operates and when running seems to be performing ok.
The plugs and ignition are all new.
Have I missed something making it so unknown if it will fire-up?
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Old 24-09-21, 06:32 AM
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Smile Beaufighter slow to fire up

I suggest you get hold of the relevant Chrysler educational college handbook for your engine. All the troubleshooting tips a v8 owner will ever need explained in plain (US) English - even has cartoon characters to show you how! You regularly see them on eBay and Chrysler sent them round freq it entry to inform its many thousand mechanics about the mysteries of these devices.
Sadly I failed to buy the factory set last year at Windlesham, when BCL went bust .
Yours in Bristol
Stefan

Ps Didnít quite understand something. BTDC means Before Top Dead Centre, right? So , yes, you are retarding the ignition by increasing BTDC?
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Old 24-09-21, 11:12 AM
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This may be of no help but if you can I suggest that you use a timing light on the engine, you may find that the timing wanders about a fair bit on tickover, if so then the timing chain is worn and you will never be able to set the timing. Changing the chain is not difficult just tedious.
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Old 25-09-21, 06:03 PM
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Ps Didnít quite understand something. BTDC means Before Top Dead Centre, right? So , yes, you are retarding the ignition by increasing BTDC?[/quote]

Increasing BTDC means you are making the spark plug fire earlier, so that would be advancing the ignition according to convention.

https://help.summitracing.com/app/an...tion-timing%3F
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Old 26-09-21, 06:24 PM
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PS Syd Lovesy told me that he liked to tune engines by warming up then running them at indicated 3000 rpm. Then he slackened off the distributor clamp, and simply turned the distributor slightly by hand until the revs were maximised. I suppose this takes out some of the effects of play in slack bearings though not a worn out timing chain.
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Old 02-10-21, 04:10 PM
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Thanks for replies,
Turning distributer by hand and listening to tick-over is how I adjust timing and using timing light.
However, I reckon now that camshaft + chain are worn out. When cold ignition moves about all over, so hard to get a good reading. When warmed up, engine revs scream, so must be getting fuel and good spark
I've concentrated on fuel pump & carb & ignition and hadn't thought of other essentials like valve timing.
It doesn't look like an easy job to replace camshaft with engine in the car.
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Old 14-01-22, 10:05 PM
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Tuning the 360 engine is more complicated than you might imagine and I strongly suggest you get hold of the chrysler manual suggested by Stefan.

Ignition is of course only part of the problem. Fuel ration, air leaks from the multiple vacuum lines, ballast resistor issues etc. If all the above are correct one simple issue is to follow the owners manual on starting proceedure. You must press the throtle to the floor to set the choke. Once started allow the engine to run for at least 35 sec at fast idle then tap the throttle to release the fast idle control.

Although not entirely related I have found that installing a geared started has much improved starting not least by filling the float bowls faster after an extended period of not starting.

You don't mention if you car still has the turbo attached however I'm not sure this makes much difference to the problems you mentioned as it is only effective once the bypass is closed
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Old 17-01-22, 12:37 AM
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Hello,
I think I've finally found a reason for problems starting after scratching my head thinking of every possible fault.
The choke on starting opens completely - instead of slowly as temp. rises.
The carbs a Carter Thermoquad with a "divorced" choke.
Before starting the choke plate is closed and you can feel spring pressure opening it and it closes shut as it should.
Once I manage to fire engine up it falls wide open and have to rev very fast to keep engine going, if at all.
Once engine is stopped after about 5-10 minutes it somehow closes and all looks as normal.
I'm assuming it's a fault with "divorced" choke on inlet manifold.
Having a turbo it's pretty hard to get access and might be difficult to get a replacement as the connecting rod is longer than on a standard choke.
Anyway next step is to take it apart and see what needs doing.
If anyone's had this problem and knows what to do, advice would be welcome.
Thanks
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Old 17-01-22, 10:58 AM
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I can't help with advice but congratulations on successful sleuthing.

David
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