Hi all,

I decided to drive the mini to work today as some fault finding before Rylstone & it started running really weird just before I got to work:

OK at idle & low rpm
Once I rev it up it was making a popping sound
I got to work and pulled off the ramflo and it's popping fuel back through the RH side barrel. Ramflo was damp from fuel on that side
Plug 1&2 look fine, a nice tan colour
Plug 4 is black and sooty
Plug 3 is black and wet

I tried:
New plugs - no improvement
New distributor cap - no improvement
If I pull off the spark plug lead to #3 while running it stops the spitting back

Any ideas?

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When mine did similar once it was the filter foam broken and got sucked in against the aux venturi.
Also check your valve clearances, if an inlet is riding that can do it too.
Could also be an air leak at the manifold, 'sneezing' is a symptom of a lean mixture.

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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 Kev. Checked the valves and they are all moving and have clearance when on the base side of the cam

I'll have to start the autopsy now I've got it towed home...

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Check that one of the aux venturies isn't spinning or offset?

This sure explains a lot! When I put on this gasket in mid 2020 there was absolutely no stock of small bore gaskets, so I had to use the budget copper one I had in the garage. It's probably not designed for big overbores and it overhung the cylinder bore. I have a Victor Reinz one to go on now

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Where did you get the new gasket? I may be looking to replace my copper gasket with a composite one... ideally in time prior to Rylstone.

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1964 MORRIS 850 - POST ZOMBIE APOCALYPSE CAFE RACER INSPIRED.

https://spotify.link/D0P4KtIP2yb

1098 +0.40
266 Kent Cam
GR Flat top pistons
HS6
1.3:1 Roller tip rockers
Stupid high CR

Karcraft had the Victor Reinz ones, but I think most mini shops should have them by now

I saw your photo of your rad cap, I’d give it a clean and see if the scum comes back. It might just be some residue in the block as it’s a fresh build

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