Mystery Power Loss Solved

have had a mystery power loss on one of my cars that uses an SU carb and conventional points.

Engine ran fine at idle and in neutral but died as soon as the clutch was let out and it came under load.

All the symptoms pointed to a weak spark and I replaced the LT engine loom and the entire HT side (coils, points, leads - the lot). To be doubly sure I ran the coils direct from the battery.

This didn't solve the problem and it was then clear it could only be fuel. Fuel pressure was fine and fuel flow from the tank was good - still I replaced the all the fuel line and pressure tested the fuel pump which was new in any case.

This left the HIF44 carb as the only suspect. A strip down checking float height and needle valve showed nothing but it was very very difficult to blow through the petrol inlet into the float chamber.

On closer examination I found a small nylon mesh filter underneath the needle valve seat. NB This filter is not shown in the Haynes manual on SU Carbs, the Burlens exploded diagram or my manual on Powertuning SUs.

This filter was packed hard with very fine dust and bits of what looked like silicon, I cleaned it out and removed an incredible amount of debris (see pics with cotton buds for scale).

This is worth looking out for on cars with SU's that are loosing power.

 

Dang! that was nasty, wonder where the silicone came from???

 

Don't cha hate it when you go through all the trouble you did, replacing all those pieces & parts, & find out it was something that simple...AAAHHHH!!!

 

So Blackjack, how does it run now, what kind of car/engine is this SU on ?

 

Well, if it's got Lucas electrics to go with the SU carb, he's probably still working on it

 

Runs fine now - really strong and pulls hard like it used to.

It's not on a hot rod but I thought it was of general interest to anyone running a old car on carbs and points.

 

Ok are we talking siliCONE,or siliCON?? .Some people know the diffrence,but use the same word. SiliCONE is a a self-vulcanizing rubber product. SiliCON (if I am right in this case) is a sandy-slag like compound,like sand/dirt?? Or am I just being anal this morning??Sparky

 

I had an English car at one time. complete with su's and lucas electrical.

I had to sell it. I found that I worked on it so much that I was addicted I could not get enough.
To this day when I see an old english car my heart rate races, my fingers get tingly, I have the urge to throw tools, and curse words of the most fowl nature come to mind.
damn I miss that car.

 

Yes you are - it's a typo. If you want to be picky about spelling - did you know that there's a U in word like colour, favour, flavour etc ;-)

 

Sparky, anan ? NO . He was just trying to help !!!

 

So a SILICONE VALLEY,is just the cleavage,of a woman with breast augmentation?

 

It's "SILICOUNE"... did you read the post about spelling? And yes, your correct about cleavage. Hmmmmmm... cleavage. I gotta go....

 

Only pulling his leg mate ;-)

 

Hmmm. Seems to me there's a "c" in "schedule," too, but no "a" in "clerk"