1925 dodge 4 cylinder, what rpm for starting?

[astroguy]

What is the starting RPM for the 25 Dodge and the generator/starter?

My engine turns about 6 to 10 rpm when trying to start. 10 rpm would certainly be the upper end.

Strong battery.

Thank you.

[Pete K.]

Starting RPM??---Anything over zero RPM to make a spark and pull in mixture to the cylinders. Ever try hand cranking an engine? "It works".

[astroguy]

Thanks Pete, however i am curious, what is the normal cranking speed with the starter generator?

[trimacar]

6 rpm? One turn of crankshaft every 10 seconds? That's a lot slower than hand cranking.

Hate to ask the obvious, you have a 12 volt battery in the car? (Early DB cars were 12volt) All connections to starter switch (button on floor) clean and tight? Ground is good? (with corrosion over the years best to run a ground wire directly to starter, a bolt as close as possible).

I'd think starting speed should be at least a revolution a second, thus 60 RPM or more......

Edited June 18, 2013 by trimacar (see edit history)

[MikeC5]

It's a good question.. I would estimate mine at roughly 1 rps (revs per second).

[R.White]

You get a feel for this sort of thing. It depends on the weather. On a cold morning there may not be enough in the battery and you crank it by hand. As far as I know there is no hard and fast rule with cars this old but you should probably turn at 1 rev. per second if everything is O.K. and it should fire up within the first turn.

Ray.

[JACK M]

I have been contemplating this a bit.

When cranking each compression you hear would equal 1/2 a turn on a 4 cyl 4 cycle engine.

So two compressions is one revolution. therefore if you hear two compressions per second you are cranking at 60 RPM.

I guess if one only hears two compressions in a second on an 8 cylinder engine then it would be cranking at 30 RPM.

All of this if I haven't confused myself which is entirely possible.

Here is a story that I read recently that pertains to very fast dragsters.

If one does the math these 2000 hp engines only turn about 500 times in the quarter mile. (then it gets rebuilt)