Finding an exhaust leak on a sports exhaust.

[cjhillman]

I'm starting to think the Exhaust on my Capri might have a hole or be blowing. Lately I've started to think the lack of power and boomyness on the motorway might point to this. Only thing is, its a loud Sportex Exhaust anyway so I guess it would be loud so not sure if this makes it harder to find any problems??

Is there an easy way to find hole or gaps in it? I was going to drop into an Exhaust place but I'm aware a few garages have seen this car in my ownership and nobody has ever mentioned it (so maybe its fine). I don't want to throw money down the drain but I'm using it more now and wouldnt mind to know if its just slow/thursty or an exhaust problem.

Any advice?

[Rich]

A slight exhaust leak isn’t going to cause a running issue or lack of power. Best way to find out is hold a rag over the tailpipe with it running and see if it generates any pressure.

[kevins]

As above and you can also look for soooty marks where it's leaking. Boominess is pretty common with aftermarket sports exhaust, I ended up fitting a noise reducer in the tailpipe of our MX5. for the power loss I would suspect the usual culprits (ignition or fuel).

[cjhillman]

I’ll have a look for sooty marks when I get five. That’s interesting re boomyness . It just feels a bit like when your drive a car with a hole in the box or something but like you say could be something else.
I’ll have to go for a decent drive and check the plugs to see what they’re up to. Think I timed it to 8 degrees last time which should be good for a pinto (previously a garage set it to - 10 but didn’t realise the accelerator pump 🤔)

[gtviva]

Big exhausts arent always the best on a standard engine, you need back pressure in the system other wise you may loose power

[mk2cossie]

Is the crankshaft pulley on the Pinto solid, or rubber insulated?

As if it is rubber, the timing marks may have moved around on the pulley and no longer tally with TDC.
Then the timing would be out and cause running issues and lack of power

[cjhillman]

Mines definitely a solid pulley. Seen them timing marks a lot last year.

I might run it to a local garage if I can. It’s a new area but I found somewhere that’s old school and apparently good. Just sold my old suspension so willing to spend that money to sort it out if there’s even anything up. One thing with this car is it’s got a type 9 5 speed and a 1.6 diff so I wonder if maybe that’s not the best combo for low down speed. I’ve had it explained a few times but I just expected a bit more pull from the old pinto.

[mk2cossie]

Do you have any pics of said crankshaft pulley?

As my friends 2.8i Granada last weekend was checked for true TDC, and the original pulley was about 10 to 15° off with its factory mark

[kevins]

The smaller engine would usually have shorter gearing which improves the performance feel through the gears at the detriment of relaxed cruising and fuel economy.
After a basic service as it seems to have parts from various sources I would check you have the correct static and dynamic advance (change in advance with increase in engine speed) and the carb is the correct one with the correct chokes and jets.

Checking the timing marks is easy enough, remove no1 plug and place a piece of dowel on the piston with the engine at TDC and mark it against something, moving the crank in either direction should see the dowel drop.

[vitesseefi]

“Sports” exhausts, tubular “extractor” manifolds and high flow air filters should, if properly designed (not certain!) increase airflow through the engine and change its volumetric efficiency over the Rev-range. This will change its fuelling needs and potentially , to a lesser extent, it’s ignition timing needs. While a modern-ish car with engine management might be able to self compensate to a degree, carbs and clock dizzy cannot.

Re-jetting or re-needling the carb(s) is part of the process and you won’t get the best from the engine without it.

Nick