I have been working on a genuine 427 street cobra roadster over the last few months.
Many things have taken place and I am about 98% confident in the car now....Keep in mind I don't think these were ever 100% "ready"....even when brand new.
Anyway, I recently had a full undercar exhaust system fabricated
St Cloud Exhaust did an excellent job (thanks to Tim and James)
I was running a temporary straight pipe exhaust I fabbed to get through until the real system was installed.
I figured the carb tune would change a bit once the full exhaust was installed...and I was right.
I tuned some things, checked the gauges and meters, and while things measured good, the car just did not drive right....and the problems were getting a little worse each time I did something.
Hard to start, vapor locking a bit too easy, empty bowls after a fully hot engine sat for a while, stumbles and surges...but none of the issues were big, hard issues, just very subtle irritances and quirks.
Then things got worse so I made some things to be 100% certain I was setting things right.
This engine has LeMans bowls so I made a set of go-no go gauges to set the primary and secondary float levels....I know, without a doubt, they are set right and working properly...take that off the list.
I did the same with a bunch of other things too just to be certain I did not mess up, forget, or do it wrong somehow.
Then a thought hit me...what about the fuel supply line from tank to fuel pump?
I get the Cobra high up in the air, crawl under...and see a nicely made hard line the entire way, except for a 10" section between the feed and fuel pump.
This is an old piece of flexible line that was fabricated using fabric braided covered fuel hose and brass fittings. JIC/AN on one end and inverted flare on the other.
I pull it off to look at it and sure enough, the rubber is cracked, dried, but looking very nice because it has not been disturbed.
This old line was sucking air as the fuel pump tried to pull fuel from the tank.
No leaks, or even wetness, because it is sucking.
I fabricated a new flexible hose to fit the need and what do you know...The engine runs really nice now that it has a full supply of fuel and proper pressure.
What a tricky fault to diagnose due to no external signs of anything wrong.
What a doofus I was to keep second guessing myself and trying to "tune" around an unknown issue.
The Cobra now starts easy and quick, idles nice, runs well and boots and scoots nicely too.
The only issue I now have is a tiny bit of dieseling when shutting off, just a chug or two, but it is there.
All in all I can't complain too much though. I mean I have been driving around in a real Cobra while sorting the issues.
