11 replies to this topic

[babsbrown]

Hi guys,

This orignal topic related to bench testing an engine and
The jump cables been insufficient. I rigged up a fairly
Safer (imho) way to test the engine out the car. Pictures at the bottom.

Thanks for all your help guys

Edited by babsbrown, 21 March 2025 - 03:53 PM.

[68+86auto]

Which lead is getting hot? If it's the jumper leads then that's to be expected. Most jumper leads are useless as they use thin wire with very thick insulation. I've seen regular jumper leads get hot trying to start a mower. They can't do much at all despite the crazy amp ratings the sellers claim. I use nice thick jumper leads made from proper wire or welding leads.

 

In regards to the coil getting hot, check that the points are actually opening and that the negative side isn't shorted to ground. One time I was trying to test an engine and didn't realise that the locking pliers holding the coil on had moved to contact the coil negative.

Edited by 68+86auto, 18 March 2025 - 11:52 AM.

[babsbrown]

Excellent thanks,

That's answered a lot of my questions. Yes the jump leads were getting really hot. I'll double check the dizzy mate sure the points are opening. Cheers

[viz139]

If your cranking for oil pressure disconnect coil and remove sparkplugs. With new bearings ,new cold oil I would expect a higher (75 psi) reading. 

Only connect the coil + when attempting to start the engine otherwise if the points are closed it can heat up quickly. 

This is why when radios started being fitted to cars they had to add an accessory position to the ignition, to stop people burning out coils when parked with the radio on. 

As above check that the points are opening and closing.

[babsbrown]

If your cranking for oil pressure disconnect coil and remove sparkplugs. With new bearings ,new cold oil I would expect a higher (75 psi) reading. 
Only connect the coil + when attempting to start the engine otherwise if the points are closed it can heat up quickly. 
This is why when radios started being fitted to cars they had to add an accessory position to the ignition, to stop people burning out coils when parked with the radio on. 
As above check that the points are opening and closing.

Thanks mate, I've tried that with the coil and it's much better. I do have a gasket leak on the oil filter housing that pours out when I crank it over. I'm sure once this is sorted I should see more than 60psi. Although I'm still happy with that.

Not getting fuel to the bores either, but dash pot is full, but I think a lot of that is because the battery is on half charge. A good power up should see it go I think.

[Steam]

Not only are jumper leads usually very thin wire with thick insulation but the connector clamps only touch on a small area compounding the issue.

[babsbrown]

Not only are jumper leads usually very thin wire with thick insulation but the connector clamps only touch on a small area compounding the issue.

Thanks steam. I'm really just tempted to check it all in the car tbf. Rather than Jerry rig a potential fire hazard in my garage haha

[Ethel]

If you've got the coil powered via the jump leads there'll likely be a fair old voltage drop if they're that hot. You might fair better with a wire direct to coil from the battery post - or even a different source if you have a 12v charger, or cordless drill battery knocking about.

[babsbrown]

Thanks guys I've managed to connect up a nice little starting rig. I'll get some pics later in case anyone else has the same issue

[stuart bowes]

in a bit late to the party but bear in mind jump leads are only really designed for very short periods of use, you're talking about cranking for 10 seconds or longer, cheaper thinner ones would struggle with that 

 

as already said you'd really want a proper sized cable like welding lead, or the actual mini battery lead 

 

interested to see pics of the rig more out of curiosity than anything else

[babsbrown]

Thanks Stewart

So I say testing rig but this is the easiest and safest way I could do it with the items I had to hand so I have:

Thick earth cable from flywheel housing to battery Negative terminal
Positive battery lead from battery to main positive terminal on solonoid
A "flasher switch" from the positive solonoid terminal to the spade connector (where ignition switch would go) (not the other small terminal where the Ballast coil feed would be)
A toggle switch between the coil positive terminal to the battery (so the coil can be isolated when not been used)
Coil negative to condenser wire on dizzy.

 

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Edited by babsbrown, 21 March 2025 - 03:55 PM.

[floormanager]

I've done some thing similar

https://youtu.be/jQ2TWmucZIE