stinkin' hot exhaust pipes

[Caprimaniac]

Hello everyone.

I have this question about the exhaust pipes, from front to back, gets really hot. You can hear the metal crimp back to regular size when engine is turned off.... (Exhaust is bolted to the floor- no rubber here!)

This is a small coupe (Euro Capri Mk1, 1970) and the exhaust run all the way to the back of the car.

Engine is 347 with 5/8" headers (medium length) wrapped.

Exhaust is 2 x 21/2" with H at rear of gearbox.

Heads are Vic Jrs. and cam is Comp 308 deg Magnum solid roller topped with Webers.

I have alwyays had this "problem". Engine temperature is quite OK- but could be a little hot sometimes- standing still idling, which doesn't happen very often.

The other day I timed my cam using the no. 1 intake centreline method. It showed 110 degrees. Comp suggest the cam should be installed at 106 degrees. Which mean I have installed it at 4 deg retarded. Could this be the cause for the hot exhaust? (Exhaust closing 4 deg later than adviced...?)

I checked my ignition the other day; had been playing with it at the track without a timing light.... It was som 30 deg at full! So, I put it where it belongs- at 18deg idling and 40!at full.

Had hoped this might had made the problem go away. But after stopping the car tonight- engine temp was low, the metal crimping sound might have been even louder than it used to be.... So; might ignition timing also be a matter concerning this problem?

Other issues? To restrictive headers? Exhaust wrapping?

I'd be happy for any input.....

Thanks
Rune

[CowtownCobra]

I'd be suspicious of the grade of metal used in your exhaust system. Where did you get it?

[JST4FUN]

Mine do get hot, but they cool rather quickly! I haven't heard any noise with the cooling process! Mine is a BB, but don't see why it would be any different...man that's strange symptom!! I would suspect metal as well!! It's got to be related I think!

[Caprimaniac]

The noice doesn't worry me at all. The question is: is this normal? I mean, the rear mufflers (lets say after 3 m tubing + 1 middle muffler) is quite hot.
I'm thinking restrective headers may show the warm gases/ flames rearwards.
2" primaries would dillute more. Maybe?
A retarded cam will let more hot gases out through the exhaust valve? Maybe?

I'll do both this fall/ winter, so I will soon know if this have any effect.
RS

[Jerry Clayton]

You wrote that the pipes were fastened directly to the floorboard without any rubber----

Your exhaust will grow a lot in length from the temp and needs to be hung with flexable mounts and/or have some flex sections in the length of pipe

most modern exhaust designs will have rubber slider biscuits mounted longitudally so the pipe length can grow and contract without pulling sideways into something