G'day...

Recently I've had a few issues with the running of my engine. Any help would be appreciated.

I repleced the water pump about 6 mths ago. In the last month or so I've had to fill the radiator up every few days as the level drops below the fins causing the temp to rise. I can't see any obvious leaks. The radiator cap was replaced with a 13lb longneck cap from KC. A reliable source suggested I should try a similar one from Repco. There are no bubbles when running the engine with the cap off and no mayo under rocker or in the radiator.

Any suggestions on this?

Also, on hot days the engine will ping on light throttle (2-3000 rpm). The engine is not particularly advanced (It will stop if I retard it more). I am running BP5ES plugs. If I use BP6ES plugs they foul up quite quickly( not sure if it's oil or fuel). Do you think the BP5ES plugs getting hot could be the source of the pinging? If I put the BP6ES in and lean out the mixture would this assist?

Engine details:
1100S 1275
twin 1.5' SUs with no.6 needles
points dizzy with vac advance blocked off
original bore (I think the PO's rebuild was a re-ring type job)
standard? cam (lots of noise, little action)
occasional smoke under full throttle
some oil use - top up 2 times approx between oil changes
oil leaks between engine and gearbox

Any help would be great. Prepared for flames.

Thanks!!

Is it difficult to start?

Is your exhaust pipe shooting water out?

What poundadge is your radiator cap?

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What fuel are you running? I'd use 98 if not already.
Also how much advance?
But note it is more likely to ping down low with a stock cam than a modded one.

BP5Es plugs should be fine, I'm running them in the wife's 1412 stroker (BP 98 fuel) with a C/R of 10.5:1. No pinging...

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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.

Thanks for your replies!

Is it difficult to start? No, starts fine with choke out.

Is your exhaust pipe shooting water out? No, not that I can tell - No white smoke)

What poundadge is your radiator cap? 13lb long neck from Karcraft.



[i][i]What fuel are you running? I'd use 98 if not already.
Also how much advance?
But note it is more likely to ping down low with a stock cam than a modded one.

BP5Es plugs should be fine, I'm running them in the wife's 1412 stroker (BP 98 fuel) with a C/R of 10.5:1. No pinging...[/i][/i]

I'm using 98 octane.

Not sure exactly how much advance. Greig at Mini classic said a while back that it was pretty retarded already when I mentioned it was pinging. I have since messed around with it, timing it by backing it off until it doesn't ping. It only tends to ping when the water temp goes above about 85 degrees C (74? deg
thermostat.
I'm not sure of the C/R. The head looks standard (had it off previously to change weeping headgasket - had a fair bit of carbon buildup). Not sure if it's been skimmed or not.

So do you reckon the cam gives too much compression? Could it have been timed in poorly? dizzy advances too quick?

My gut tells me that the engine is due for a bit of a freshen up..??



[/quote]

If you are going to freshen it up, do it properly. Re-ring jobs don't work for long in either a 1098 or 1275 A series, as by the time the old rings were worn out the bore is oval and tapered too.
A nice new set of oversize Hypatec 9.75:1 pistons is under $200 (with rings) from Minis plus or Minisport SA. Add $150 for a rebore and hone job and it'll go like a new one (only better).

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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.

Been putting off a rebuild, but would do it properly if taking that option. Just working up the balls to do it - would be my first rebuild.

I guess I'm just trying to confirm that a rebuild is what is required and that it isn't something simple.

Could the water loss be from the cap? Or more likely hoses or gaskets?

It is pretty normal for a 1275 to push 1/2 the water out of the top tank (if you fill it to the top) as it warms up. The water expands and has to go somewhere.
Many Mini rads have a `fill level' mark ~1/2 way up the tank (visible below the filler neck). I only fill mine to that point and it goes months without a top-up.
You have replaced the cap, but check the ridge that it seats on inside the neck. If damaged or got crud on it, the cap won't seal. Clean with steel wool or a bit of 180 or so abrasive paper so it's shiny.
Karcraft's caps work fine.

If it's leaking elsewhere you should see it...

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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.

Cool.

I'll scrub up to radiator neck and see how it goes.

Thanks for your help! Much appreciated.