My carbs are popping on decel. It could be timing, but I bet that my Eurorace headers are leaking from the collector. I know I can see exhaust coming from it at idle.

I think I remember seeing some sort of aluminum tape that you could put on exhaust pipes to seal a leak. I thought that might be an easy way to seal up those joins after I have the pipes ceramic coated.

Anyone know anything about it? What have others done to stop the collector leaks on their EuroRace headers?

Zach

"Could be timing"? 'Splain that, please. I see it pop up all the time in these discussions, but have never, in nearly 40 years of schooling and wrenching, seen any documentation to support this statement. The Cap'n

Red RTV Silicone. Sensor safe in my case...

http://www.youtube.com/watch?v=PbnVnjfgM8A

T4, backfire due to being 180 out of time (surrounded by World members).

I dunno about when time is close enough to be running. But another member recently had a thread about a running engine that was backfiring stop when he got the timing right.

But, as I said, I think my issue is exhaust leaks from the header collector, and not timing.

Zach

a fine gentleman like myself always learns something when hanging out with these gear heads.

lesson learned that day - fire out the carbs is bad : )

But none of those were backfiring on decel as you stated in your first post.


A otherwise good running engine that backfires on decel will most likely have an exhaust leak ...
Andy

Let's talk about this. Your car runs, right? I thought so. The evidence you give for reaching the conclusion that timing will cause backfiring consists of a video of an engine backfiring with the timing 180 degrees out. Note that it it never starts, and that the backfiring is through the intake, not the exhaust. An engine 180 out won't run. Nor will one 90 degrees off. Maybe even 45 degrees. Even at 5 or 10 degrees, timing won't cause backfiring in our exhaust systems. Exhaust backfires in T4s tuned for the street is usually either a serious lack of exhaust back pressure or a leak, allowing fresh air to be drawn into the system. Backfires through the carbs on a running engine are generally either intake leaks, badly worn carbs, or failure to properly adjust the carbs and the linkage.

The Cap'n

If your motor is backfiring from the carbs...you are running too lean.
Look for leaks at the manifolds, loose bolts at the carb base...that sort of stuff. re-tighten every single bolt/nut on the intake. Also clean your idle jets...one clogged jet will make it backfire up the carb.

If its backfiring from the exhaust at decel...well fix the damn leak.
Red RTV can be used...yup. I would take a closer look at the joints and come up with a better mechanical solution...not a fan of sealants in the exhaust setup....just a long term repair and maintenance issue that will never go away.

Rich

I have fiberglass exhaust wrap around mine. I doubt it plugs any leaks, but the header was a little less than tight at the collector and the wrap really tightens it all up as well as saving my cables from the heat. The header is ceramic coated, so I am hoping all the bad issues with rust found doing this (exhaust wrap) will not be a problem. After a year part of the wrap is worn, so I may unwrap it soon to check/maybe replace/clean out the crap it is likely collecting. My cables are doing great!
Use that red RTV on the stub pipes

Exhaust wrap is cool ... for a race car. The retained heat causes the metal to crystalize and crack or turn to dust in your hand. Just be prepared to spend more money.

A good gasket and High temp RTV. The copper stuff works well, but not sensor safe. The red works almost as good, but is sensor safe. The aluminum tape works like crap. Used to use that when I was a kid. Burns right through.

Okay, so if I understand Capt and Rich, since I am popping up through the carbs, it is not an exhaust leak, but an induction leak.

The carbs I have are fresh rebuilt, but I will clean the idle jets again.

The phenolic gasket between the head and the manifold has a thin smear of RVT on it, and the nuts are tight, so it is unlikely that it leaks there.

I can try putting a little rvt on the gasket between the carb and the manifold, and tighten the nuts again.

The linkage being off a bit is a possibility. it is close right now, but I do not think that it is exact.

I'll likely hit people up for tuning help at the MidEngine Invasion to get it running right.

Zach