Hey guys,
long time lurker, first post...

Firstly a big thank you to everyone who makes the forum such a great source of easy to understand info (not like Haynes: Reassembly is a straight reversal of the dismantling process grr).

I'm currently in the process of starting my 1098 motor, which i have rebuilt. (re bored, new pistons, head work ect).

Anyhow the starter motor can crank the engine quite easily when the spark plugs are out, but with the spark plugs in, it cant. - the battery is fully charged.
Too add to this, when i turn the motor over by hand i can hear "hissing" (air leaking between head gasket?).

Excuse my ignorance/ lack of knowledge in advance, i am the first to admit that i don't know much about engines ect and am tackling it one step in a time.

Hey there, a few things that i can think of that may help

Concerning cranking the engine, does the engine not turn over at all with the plugs in? Or does the starter just struggle and do it very slowly?
When you say your battery is fully charged is it up to the job? If a battery is on its last legs, it might charge up to full voltage but be low on cold cranking amps.
Do you know the compression ratio of your engine? If you've just built a really high compression motor the starter/battery might not be up to the job.
Could also be something like tappets not adjusted correctly, if the valves dont open it won't turn over.

The "hissing" sound you hear could possibly just be the sound of the valves and the air moving past them due to compression.

My advice to you would be perform a compression test first, maybe try an alternative battery or wait for someone else to post

hiya



try another battery first - when I put dad's motor together I told him to bring a good battery to start it with, he said "I always use good batteries", and brought one out of one of his cars - the f'king thing could barely turn one stroke - once I put my battery in (560CCA) it went started easily

it's hard to turn over a new motor when everything is tight - as long as there is plenty of assembly lube in there, it'll be fine



doubt it, that's normal when turning it over by hand because it's turning over slowly and the gas has time to find the easiest way out, different story when it's running

doesn't quite add up though when you say turn it over by hand, do you mean by pushing the fan blades then maybe you should check the compression, I can't turn my motor over by hand



well you're having a good go and doing it yourself, which is excellent, more people should just jump in and have a bash at it

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did I tell you that I won a trophy?

Hissing sound is normal when turning it over by hand. It's the compressed air in the cylinders escaping I think (what else can it be?). You get this when turning the engine over when checking tappet clearances/valve lash. I wouldn't worry about that.

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Lillee - 1969 Morris Mini K

OR PERHAPS YOU NEEED ONE OF MY SPECIAL PLANETARY GEARED BOSCH MODIFIED STARTERS for Mini. I still have them available. They will start any Mini engine regardless the compression :lol:

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DID I MENTION THAT I AM THE BEST SUPPLIER FOR MINI ELECTRICAL PARTS AND REPAIRS?
"Let us remove your "SHORTS"

Not if the battery can;t cope.

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Thanks for the replies

Mini_Mad_matt:
The starter only makes about 1/8 of a revolution, and as for the compression ratio, im not sure. The head was decked when i sent it off to be machined, but that's about it (standard combustion chambers).

Simon K:
I tried a second battery out of my car, which didn't cut it.. looks like its battery shopping time!



That's good to know

Oh, and when i said turning over by hand, i really meant with a t-bar and socket on the crank pulley bolt.

Thanks again!

well,
i got my self a new battery (470cca) and tried that out, but it didnt make a difference, so i went down to the wreckers this arvo and got myself a Gemini starter, filed out the holes and stuck it on.

Anyway with the gemini starter and a new battery i get about half a revolution. progress! lol

Maybe my compression ratio's to high? How can i find this out?
And to lower it what are my options?

thanks again,
Steve

Ok well if it aint the starter motor or the battery check if the wireing to the batt is right then if that don't work try reseting the tappets if that don't work I have no idea lol good luck

It sound like it is not a battery or starter problem. I doubt that it is compression as the stock Lucas starter was used on F1 V8s in the 60s.

Does it spin Ok with the spark plugs out?

what about the the timing over advanced or plug leads in wrong order

Just disconect the plug leads and c if it spins umm timing sounds it though I remeber when I helped time my dads car advanced it to far or retarded it to far aand it would spin the go really hard then spin easy then go hard again like it was pulsating sorta thing

I do hope you fitted the conrod bearing caps on the right way round.
The 2 bearing locating lugs must always be on the same side of the journal. If not, the bore of the conrod isn't round.

My mate didn't do this, and it took 2x 12V batteries in series for the Lucas starter to spin it.
But, it wouldn't fire and run.
When we stripped it apart, all the bigend bearing shells were worn down to the copper.
Luckily, the freshly reground crank just needed a polish.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Hmm, i do hope they are fitted right, i actually got the shop that did the machining and reground the crank to fit the pistons crank...
Anyway i can check without stripping the motor down?

It still sounds like a starter motor problem to me,,, maybe the 2nd hand starter from the wreckers is buggered too???

Or maybe a bad earth connection,,, have you got the engine earth strap boted up to clean (unpainted) surface???

Or is the poor starter trying to earth through the throttle cable???

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.