So I'm building an engine for my 850 Sport Coupé and I need a new oil pump.
But as I don't like to pay for overpriced original items, I was considering using a Seicento/Cinquecento/127 oil pump.
These have an integral pressure relief valve, but that shouldn't be a problem.
What about the oil pickup?

ppalma said:

So I'm building an engine for my 850 Sport Coupé and I need a new oil pump.
But as I don't like to pay for overpriced original items, I was considering using a Seicento/Cinquecento/127 oil pump.
These have an integral pressure relief valve, but that shouldn't be a problem.
What about the oil pickup?

Click to expand...

I think your main problem is that the 850 engine spins the opposite way to the others - anti-clockwise from the timing chain end - so I'm pretty sure I'm right in thinking the pump from a clockwise motor wouldn't work - would suck where it should blow and vice versa. Also, the Seicento/Cinquecento engine is either a FIRE or the rather odd (and gutless) 899cc unit depending on the model.

Hi Ppalma

Ok,

so the 850 pump pushes the oil out of the large tube bolted to it and this sends the oil to the main bearing cap, the oil going the other way through the pump body mostly goes to the oil pressure release valve in the main block.

On the 127 pump the oil mainly goes through its body and into the main engine block and some of the oil goes the other way through the oil pressure release valve, if you use this in an 850 then the ally sump will not fit

Hence why they look slightly different, so if you fit a 127 type pump into a new 850 engine then the oil will only be pumped through the block pressure release valve and your crank will get none(tiny amount going through cam bearing).

You may be able to remove the release valve off the 127 pump and fit the 850 pick up pipe and oil feed tube but some of the pump gear casings are different heights so the oil feed pipe may not fit and you will invalidate the new pumps warranty.

You are better off fitting the correct pump type as it gets a bit complicated, there is specific clearances that the pump needs so you could check the clearances of your existing pump, in the past i have adjusted the clearances by machining the casing and flattening the surface of the pick up pipe surface as the main wear in the pumps is either end of the gears in the casing.

be careful and understand the whole oil system before changing one component.

Tim

Forgot to say

All the pumps turn the same direction as the rotation direction differences are dealt with by different drive gears on the camshafts and the small shaft that drives the oil pump and dissy

Tim

forgot to ask, the 850 sport coupe engine you are building is it all standard

I forgot to say

there is a specific 850 section you might prefer to look at further up the forum page.

Tim

Thank you for your answers!
I'm building a 965cc engine with A112B pistons and a 100GBC block.
Regarding the oil pump, I'm guessing the only way to use newer pumps would be to reverse the oil flow and install an external oil filter...
Thanks again for pointing me the 850 section!

Hi Ppalma

So 67.2 pistons with 20mm pins, onto the standard conrods.

I did find a fiat 850 pump recently for £49.50, which is about the same as new 100gl pumps,

I did on one of my engines reset the clearance on my existing pump, it might be worth checking this before spending any money.

Or as you say reverse the oil flow and fit external filter, this works too. you do need to understand very well where the oil will go instead.

Tim

Oh and i forgot,

if you use the pump with the release valve built in then the 850 coupe alloy sump will not fit.

Tim

Really? I thought the valve just takes up the space of the feed tube. Or is the pickup pipe lower/to the side?

Hi Ppalma

Yep the release valve casing is taller on that side so it will foul on the sump by about 5mm. this is why the seat 133 had a different release valve system....

Tim

Hi Ppalma

I've been looking at some pumps that i have, it is possible that you could use the bain body of a new pump that comes with the release valve and fit your pick up pipe to it, it would be sensible to resurface the pick up pipe where the gears run against it, What i've never tried is using the steel plate from the newer pump in there too, but you will have to check the pick up pipe clearance against the inside of the sump pan.

Tim

Thanks, I was also looking at that. The bodies seem to be identical. Will let you know when I get a new pump.