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Battery replacement

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Vince Caldicott:
Thanks Graham and Rob, I've tested the battery after a short run out and it reads 12.66 volts. I still need to test the alternator. I believe The compression ratio is quite high at 10.8 to 1. The car turns over quite well when cold on a fully charged battery and starts can take 30 seconds. When I switch it off it tends to over run for a couple of seconds which may have something to do with the difficult restarting. I'm tempted to purchase a higher Ah battery and hope that solves the problem when hot starting.
Vince

Rob.Hendriks:
Vince
You may have just given us the cause for the starting problems. Over-running or dieseling is not good for your engine and needs to be addressed asap. It occurs when there is no ignition source i.e. the key is turned off and the remaining fuel/air mix is ignited by a hot spot within the cylinder. This hot spot can be carbon build up (which would be unlikely in a newly built engine), the timing being too far advanced or the mixture being too lean making the engine run hot and thus causing the plugs to overheat. Sluggish starting when hot is also a symptom of the timing being too far advanced. Would carry out a few checks:

Spark plugs
First take out all the spark plugs and examine them carefully. Look at the electrodes and the nose of the insulator for any signs of overheating. The plugs should have a light brown coating all over - if they appear white or glazed they have been overheating

Check engine timing
If the spark plugs aren't at fault, you should next check the timing. Usually, you will have had other warning of over advanced timing, such as pinking under hard acceleration or hard/sluggish turn over when starting hot

Air leaks
If dieseling persists, your next avenue of investigation is the fuel system. The problem may be caused by a weak fuel/air mixture because of a badly adjusted carburettor or air leaking into the inlet manifold. A weak fuel/air mixture can make the engine run much hotter than it should.

Vince Caldicott:
Hi Rob, thank you for your reply and sorry for the delay in responding, I've been away on a family holiday and banned from the internet. I will forward your response to my mechanic who looks after my car for him to check out the possible causes you highlight. I will respond with results of his checks. Thanks again.
Vince

AC Ventura:
Vince, you mentioned difficult restarting, presumably from hot? With an FE side oiler this is almost certainly vapour lock (fuel vaporising in the carb feed line) caused by engine bay heat. You can rectify this with a fuel return line to the tank.
Also a high compression FE needs a high torque mini starter.

westcott:
Vince, beside the battery You shoud check the charging situation at idle.

After swapping engines from different engine families sometimes I made the experience that the new pulley ratios are a little bit off and the cooling and or charging circuit is affected.

In tjhe past I had situations in different engine swap projects were the alternator needed some kick on rpm to start charging at idle.

If the situation is like this the battery will discharge slowly at idle because the carry over alternator pulley is too big by diameter in the new constellation and rpm is not sufficient for charging.

A fix for that will a bigger pulley on the crank and or a smaller pulley for the alternator.

If your altenator sees enough rpm at idle it will charge the battery directly after the start and everything is perfect, voltage at idle measured at the battery poles should be 13,8-14,0 V.

   

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