Which Battery?

[parrish]

I have a new 60AH battery fitted, however car will only turn over at 200RPM when starting, this seems a little low to me, any ideas, any sugestions? any one else have any figures on starting (RPM)?
Ive changed the starter motor and that has made little difference.
Ive fitted an Omex ECU/EFI and need at least 200RPM for the injectors to start, and just as soon as i get to 200 injectors come in engine coughs and drops below 200 and injectors cut out! Im trying to get a fix from Omex supplier but for now and whilst im waiting im trying to sort out the low starting turn over.
Steve

[djape1977]

get a bigger battery. as big as you can fit into battery tray. i use 68ah in my 131 1600ohc and 75ah in my 2,0 dohc lada. i never experienced any problems with running a bigger battery than factory fitted. in my experience a factory fitted battery is as small as possible (cheapest) to turn over the engine. biger battery means more amps meaning more revs while cranking and more attempts available until engine starts.

basic electicity teaches us that bigger battery just takes longer time to charge to full capacity than smaller battery on same charge current. 55ah battery and 75ah battery take the same time to charge up to 55ah capacity and then 75ah continues charging to it's full capacity.

slow cranking may be also result of not so good starter motor. worn parts inside will cause drop in rpm. are you sure that the motor you installed is 100% good? swapping one used starter for other used is often futile.

solutions:
1: attach another battery to one already installed via jumper cables and try cranking. if it turns over faster, get a bigger battery.
2: if it doesn't turn over faster then starter motor is to blame. the one you already have out of the car proffesionally rebuilt. that solves the problem usually.
3. at what compression ratio is your engine running? high compression engines usually crank very slowly with ordinary starter motors. when i bolted a head from 1,8 onto a 2,0 block with dome pistons in it could barely turn over with rebuilt starter and 75ah battery. after about 20.000kms as the piston rings got worn and compression went down it began to turn over faster and faster...

[miro-1980]

I would do exactly the same !

This is how I selected my battery for 131.

Miro

[mirafioriman]

I would also try using jump leads to supplement the standard wiring to see if this is at fault. A bad earth lead can for example cause similar problems.

[djape1977]

good point mirafioriman!
i solved that problem by attaching another finger thick piece of cable between negative on battery and a bolt on a cylinder head holding the exaust manifold

[TOAD]

If you have a very high compression ratio and all else fails, why not try a split charge twin battery and go 24v start, 12 charge set up

  worked for me.

[miro-1980]

Toad , I would use the high RPM starter !
Worked for me !

Miro

[Thotos]

There's no need to mention the Ah rating of the battery here as it's immaterial. What you should be looking at is the CCA rating of the battery which denotes the amount of current or "strength" the battery can supply. If your battery has a CCA of less than 400 then it's probably too weak; you need over 400 and preferably close to 600. Once you've got a strong battery you need to make sure you can get that power to the starter motor. Ensure you have good cable connections especially the earth cable. Your car seems to have had some wires changed so make sure the main wire from the battery to the Starter solenoid hasn't been changed for a thinner wire; if in doubt fit new thick wires between the battery and the starter motor and endure you have a good earth lead on the battery and the engine/starter. Use a voltmeter on the starter's main feed wire and ensure you haven't got a voltage drop when the engine is being cranked. Finally, the most likely culprit is probably the starter motor or its solenoid so are you sure the replacement you tried is a good one?
 

[parrish]

Car started OK after some adjustment to the ECU.
Earth wire from the battery gets warm on long cranking.
All connections have been cleaned, and it still gets warm.
In  my original post i was wondering if anyone could check to see what their 131 cranks over at  startup?
Theo, although the car is running ill not be able to make 3MA10, as i will be in Singapore! the car is also still not road legal in Spain.
The brown cable to the solenoid is still their the extra 2 x brown cables you can see are for the OMEX relays.
The starter motor is suspect and ill be trying to get ano some time.
Car now has ECU/EFI just needs some fine tunning.
If your interested have a look here for the full story.
http://www.sfconline.org.uk/forum/topic.asp?TOPIC_ID=4151
Steve