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rear 3 cylinders running rich

Posted: Thu Jul 12, 2018 5:11 pm
by GSouthee
Hi just back from Le Mans classic and found the engine when very hot ran on a bit after switch off. I have now checked the timing, and it was a bit advanced so adjusted it, checked the plugs and these were at 27 thou so reset to 25 thou, however I noticed that the rear 3 plugs were black and smelt a bit of fuel. I did tune the carbs when engine rebuilt 1200 miles ago. Could I have that wrong or is there a simple check on the carbs mainly the rear carb ( I guess) I can do.

Cheers for any assistance.

Gary

Re: rear 3 cylinders running rich

Posted: Thu Jul 12, 2018 5:23 pm
by Clifford Pope
Float needle valve sticking open?
Choke sticking on?
Dashpot diaphram perished? (Not sure which carb)

It can't have spontaneously gone out of adjustment - must be something sticking or not working properly?

Re: rear 3 cylinders running rich

Posted: Thu Jul 12, 2018 7:19 pm
by GSouthee
Cheers Clifford,

They are SU hs6's, they were rebuilt by a specialist at time of engine rebuild. Guess could be sticking float or needle will check them. I have checked the air flow with a hose and the ear both seem to sound the same. Choke looks ok but will check again.

Cheers G