engine losing power

[street]

Car recently legally allowed on roads so went for a spin, as part of process engine was rebuild and carbs tuned etc.

On highway going up hill car lost power, requiring change down to get revs up to carry on, did this a couple of time on flat when reaching around 50mph.

My thoughts are,

1. lack of fuel, not enough pressure or supply
2. Blocked silencer restricting exhaust fumes ( the reason is that I could clearly hear something lose in silencer when rebuilding car).

Any thoughts on what to check, how do you test/clean exhaust silencer?

[h20hamelan]

most silencers are rebuildable, new material and some welding
checking fuel pressure is easier, and better to start with the basics. distributor advance, or heating up component?

[street]

Thanks

I've got a SS exhausts so dont really want to cut it open, but then its been on the car since 1990.

Electronic ignition so should not be an advance issue.

Anyone know how to check fuel pressure?

thanks

[2cams70]

Does it lose power at the same RPM in every gear or is it just a top gear issue?

[street]

I would say top gear issue

[jono]

I once had something similar, turned out to be a partially blocked fuel filter

[2cams70]

Fuel starvation from your description is certainly a possibility. Don’t neglect the simple things though eg. ensuring that you have full throttle travel of the cable happening at the carbs. Always difficult to do these types of diagnoses by remote control.

[The Veg]

Quite recently I had a similar -but not identical- issue that was caused by one carb-float getting heavy.

[street]

As in the float was leaking, how did you diagnose that?

[The Veg]

The first clue was that once I was safely off the road and took a look at the engine, I saw fuel leaking from the front bowl's vent. That told me that too much fuel was being admitted to the bowl, meaning the valve was probably either staying open or opening too much. I opened both bowls, removed the floats and with just weighing the floats in the palm of my hand, could tell that the one in question was much heavier than the other. I allowed it to drain and gave it a good shake just to be sure, then as I was only about two miles from home was able to drive back before it loaded-up again. A new set of floats got installed and it runs fantastically now.

[2cams70]

The other trick to identify a leaking float is to put it in boiling water. Where you see bubbles is where the leak is.

[alanr]

Re-Leaking float.
I wonder if ethanol was to blame?
Was this a plastic float or brass float? Other classic car marques have recently been noticing the the effects of ethanol on plastic floats that were specifically not made of ethanol proof plastic material.
Ethanol will also I understand over a period of time attack the solder used in the manufacture of the traditional brass carburettor floats.

Alan.

[The Veg]

Re-Leaking float.
I wonder if ethanol was to blame?
Was this a plastic float or brass float? Other classic car marques have recently been noticing the the effects of ethanol on plastic floats that were specifically not made of ethanol proof plastic material.
Ethanol will also I understand over a period of time attack the solder used in the manufacture of the traditional brass carburettor floats.

Plastic, purchased seven or eight years ago, I forget from which usual suspect but one of the ones in the USA. The new replacements were described as ethanol-resistant and I did notice that they looked a little different. Got fingers crossed for the resistance to be durable.

[Hawksfield]

Street

Most retro fit electronic ignition kits use the distributor springs and weights on Lucas distributors.
So you need to check what type is fitted
Although I suspect you have a fuel problem.

Good luck and please report your final fix

John